Pathophysiology of Stress Ulcer and Its Prevention II. Prostaglandin El and Microcirculatory
Responses in Stress Ulcer
Yoshifumi Kawarada, MD, Philadelphia, Pennsylvania Jeffrey Lambek, Philadelphia, Pennsylvania Teruo Matsumoto, MD, PhD, FACS, Philadelphia, Pennsylvania
El (PGEI) is a long chain, unsatuProstaglandin rated, oxygenated fatty acid that is known to cause hypotension, tachycardia, stimulation of smooth muscles, a decrease in gastric acid secretion, stabilization of the lysosomal membrane, coma, and inhibition of platelet aggregation. In 1967 Robert, Nexamis, and Phillips [I] demonstrated that the administration of PGEl inhibited gastric secretion in dogs and rats. Since then, its effect on the digestive tract has been studied. Stress ulcers are considered to be the result of a chain of events initiated by acut.e gastric vascular constriction, resulting in focal ischemia of the gastric mucosa. Skillman et al [2] found that this decreased gastric blood flow also disrupts the mucosal barrier, causing increased acid back-diffusion which destroys the ischemic cells in the gastric mucosa. They speculated that PGEl may inhibit ulcer formation by decreasing the effect of vasoconstriction, protecting the lysosomal membrane from damage, and decreasing the secretion of gastric acid. The purpose of this study was to evaluate the efficacy of PGEl in preventing the formation of stress ulcers and to investigate the microangiohistologic changes in the gastric vasculature after stress with or without the administration of PGEI. From the Division of Surgical Research, Hahnemann Medical College and Hospital, Philadelphia, Pennsylvania. Reprint requests should be addressed to Dr Teruo Matsumoto. Division of Surgical Research, Hahnemann Medical College and Hospital, 230 North Broad Street, Philadelphia, Pennsylvania 19102. Presented at the Fifteenth Annual Meeting of the Society for Surgery of the Alimentary Tract, San Francisco, California, May 21 and 22, 1974.
Volume 129, February 1975
Material and Methods Three hundred thirty white male Wistar rats, weighing between 125 and 150 gm, were used in this study. Each animal was deprived of food for twenty-four hours prior to the procedure and placed in a cold room (4°C) for two hours in a perforated conduit that was plugged with corks at each end. The animals were divided into nine groups on the basis of the amount of PGEl injected subdermally one hour before stress: group 1 (10 rats): group la (5 rats), normal rats, with no treatment and no restraint; group lb (5 rats), stomach inflated with air, with no PGEl and no restraint; group 2 (5 rats), 5 mg/kg group 3 (45 rats), no PGEj, rePGEI, no restraint; straint; group 4 (45 rats), 0.5 mg/kg PGEI, restraint; group 5 (45 rats), 1 mg/kg PGEI, restraint; group 6 (45 rats), 2 mg/kg PGE1, restraint; group 7 (45 rats), 3 mg/ kg PGEI, restraint; group 8 (45 rats), 4 mg/kg PGE,, restraint; group 9 (45 rats), 5 mg/kg PGEI, restraint. With the animals under ether anesthesia, laparotomy was performed. The stomachs of forty rats in groups 3 through 9 were excised, after which the incidence and severity of the stress ulcers were examined. Only stomach ulcers measuring over 1 mm in length were considered. The severity of the glandular portion of each stomach that exhibited ulcer was divided into four gr&ps according to the distribution of the ulcers [3]; grade 0, no ulcer; grade 1, 1 to 35 per cent; grade 2,35 to 70 per cent, and grade 3,70 to 100 per cent. For morphologic study, a double-color silicone rubber compound was perfused in five rats in each of the nine groups. First, a number 21 butterfly needle was inserted distally into the thoracic aorta and ligated around the aorta with 4-O silk. The rat was perfused with normal saline containing heparin (3,000 U in 1,000 CC). The blood and perfusion fluid were drained from an incision
217
Kawarada,
TABLE
Lambek,
I
Groups (number bf rats) 2 3 4 5 6 7 8 9
(5) (40) (40) (40) (40) (40) (40) (40)
and Matsumoto
Incidence and Severity Gastric Ulcer Dose of PGE,
Incidence of Ulcer ___
group 5,1.1
of Restraint
Grade of Severity
Mortality Rate
(w/kg)
No.
%
(O-3)
No.
%
5 0 0.5 1 2 3 4 5
0 36 35 26 17 7 0 0
90 87 65 43 17 0 0
0 2.6 2.0 1.7 1.1 0.3 0 0
0 1 2 3 6 12 17 23
0 3 5 7.5 15 30 43 56
made in the right atrium of the heart. A second number 23 butterfly needle was inserted distally into the portal vein and ligated with 4-O silk. Yellow silicone rubber compound, MV-122, was injected into the aorta through the polyethylene tube of the first needle until, with gentle thumb pressure on the syringe, the yellow rubber compound filled the gastric and duodenal arteries and capillary vasculature. Red silicone rubber compound, MV-118, was injected into the mesenteric vein through the polyethylene tube of the second needle until it completely filled the venous vasculature of the stomach and duodenum using the same procedure. In five rats (group lb), before the injection of the compounds, a small hole was made on the anterior aspect of the duodenum approximately 2 cm from the pyloric ring. A polyethylene tube was inserted into the proximal duodenum and advanced into the stomach. The tube was ligated around the duodenum just proximal to the hole with 4-O silk. Approximately 12 or 13 cc of air was then injected into the stomach via the polyethylene tube with a 20 cc syringe. Sometimes, subsequent injections of air were necessary to maintain maximal distention of the stomach for two hours. Results The incidence,
severity,
and mortality
caused
by
ulcer formation in the restrained rats with or without treatment are given in Table I. The ulcers occurred only in the glandular portion of stomach. These ulcers never penetrated the muscularis mucosa and remained in the gastric mucosa. Incidence of Restraint Gastric Ulcers. Acute gastric ulcers developed in the following animals: 36 of 40 rats (90 per cent)
in group 8,
in group
3, 35 of 40 rats
group 8, and 56 per cent in group 9.
Microfile Perfusion Studies. Group 1: group la, normal stomach (Figure 1); group lb, stomach distended with air (Figure 2). Distributing arteries, connecting arterioles, capillaries, collecting venules, and collecting veins were observed in both groups la and lb. The mucosa, muscle layers, and serosa in group lb rats were thinner than those in group la rats. In comparing the vasculature of the two groups, we found moderate narrowing in the collecting veins and venules and extreme narrowing in the distributing arteries in group lb; however, in both groups, similar filling of the silicone rubber compound via the capillaries and into the mucosa was observed. Group 2 (5 mglkg PGEl without restraint): The mucosa, muscle layers, and serosa were stretched. As in group lb rats, collecting veins and venules were narrow and the distributing arteries were also narrow and difficult to see. Thus, because of distention, the vasodilatory effects of PGEi on the distributing arteries and arterioles could not be evaluated. (Figure 3.) Group 3 (restraint only, no PGE1): The silicone rubber compound failed to fill the mucosal capillaries well. Multiple avascular areas and necrosis with blood clots in the mucosal capillaries were observed. In addition, extra spillage of the silicone rubber compound on the surface of the mucosa was observed frequently. (Figure 4.) Groups 4 and 5 (0.5 to 1 mglkg PGEl and restraint): Vasculatures similar to those in group 3 rats were observed. Groups 6 and 7 (2 to 3 mglkg PGEl and restraint): The three layers of the stomach were moderately lecting
of 40 rats (17 per cent)
rats.
in group
7, none of 40 rats
(0 per cent) in group 8, and none of 40 rats (0 per in group 9.
Severity of the Ulcers. The severity of the ulcers averaged grade 2.6 in group 3,2.0 in group 4,1.7 in
218
in group 7,0
Morbidity and Mortality. PGEi caused diarrhea, loss of activity, labored breathing, and increased nasal secretion. These findings were observed to be dose-dependent, becoming extremely severe at doses of 2 mg/kg or more. Immediately after two hours of restraint, the mortality was Q per cent in group 2, 3 per cent in group 3, 5 per cent in group 4,7.5 per cent in group 5,15 per cent in group 6, 30 per cent in group 7, 43 per cent in
(87 per cent) in group 4, 26 of 40 rats (65 per cent) in group 5, 17 of 40 rats (43 per cent) in group 6, 7
cent)
in group 6,0.3
and 0 in group 9.
group
stretched,
lb or group
but not as distended
2 rats.
veins were narrower
The
arterioles
as in
and col-
than those in group
la
Groups 8 and 9 (4 to 5 mg/kg PGEl and restraint): The three layers of the stomach were extremely distended, and the arteries, arterioles, and collecting veins were similar to those in group lb
The American Journal of Surgery
Stress
Ulcers
and group 2 rats. Again, the distributing arteries and arterioles were very narrow and barely visible. (Figure 5.) Comments
There is no doubt that stress can cause gastric ulcers; however, the pathogenesis still remains unclear. Sympathetic stimulation or sympathetic amines can cause vasoconstriction. Ozdemir and Zimmerman [4] found that vasoconstriction and ulcer formation caused by stress were similar to those caused by the administration of serotonin. A precursor of serotonin, 5-hydroxytryptophan disrupts the mucosal barrier [5]. Ferguson et al [6] stated that serotonin releases a lysosomal enzyme, cathepsin D, from gastric cell walls and that this enzyme causes direct cell damage. Furthermore, since histamine increases gastric secretion and acidity, the acid is able to penetrate the barrier and develop ischemic cells. Consequently, the ischemic mucosal cells, whose cell membrane can be damaged by certain doses of steroids, vasoconstrictive agents, bile reflux, or increased serotonin levels, are exposed to more acid and increased back-diffusion. Drapanas et al [7] d escribed a unified concept that includes alterations in the gastric mucosal barrier, the release of vasoactive amines in the gastric mucosa, and vascular and pathogenic changes. It is impossible to explain the pathogenesis of stress ulcer formation with a single factor. Goodman and Osborne [8] mentioned that the defini-
Figure 2. A cross sectton of the gland&r portton of a stomach distended with air (group lb). Capillary (C), collecting venules (VI), collecting vein (V), nwco8a (C), mu&e layer (M), and saroaa (S). The mucosa, mu&e layer, and serosa were stretched, especially muscfe layer and $81088, compared wfth those seen In Figure 1. (Ortginalmagntffcation X 41v.)
v&me
129, February 1975
Figure 1. A normal stomach (group la). Distributing artery (A), capillary (C), collecting venules (VI), collecting vein (V), mucosa (C), muscle layer (M), and serosa (S). (Original magnification X #O.)
Kawarada,
Lambek, and Matsumoto
* ..
tion of stress ulcer has led to marked confusion and widespread misunderstanding because at least four distinct entities, such as shock and sepsis, burn, neurologic disorders, and corticosteroid administration, can all cause stress ulcers. After the restraint that caused the stress, we believe that vasoconstriction was a definite factor in the production of ischemia and necrosis of the gastric mucosa which followed. Therefore, we believe that in the theory of the restraint ulcer, the acute gastric vasoconstriction syndrome (AGVCS) may be considered. (Figure 6.) Many investigators have recently studied the effects of PGEI. Some [I] have found that it coun-
Figure 3. A cross section of the glandular portion of a stomach (group 2). Capilrary (C), coiiecting venuies (Vi), collecting vein (V), mucosa (C), muscle layer (M), and serosa (S). The mucosa, muscle layer, and serosa were stretched as in Figure 2. The distributing artery was difficuit to see. (Original magnification X 410.)
teracts the gastric secretory stimulants involved in the formation of ulcers, namely, histamine and serotonin [9]. Robert, Nexamis, and Phillips [IO] found that PGEr administered in doses of 0.1 to 0.2 mg/kg did not affect gastric acid secretion whereas PGEl in doses of 0.2 to 0.6 mg/kg caused dose-dependent inhibition of gastric secretion and acidity. Main [II] stated that larger doses of PGEr (2.5 mg/kg) injected subcutaneously will inhibit gastric secretion almost totally. Despite these reports and our study [12], the administration of PGEr in doses over 0.5 mg/kg greatly decreased the acidity of gastric juice. The fact that in our study 0.5 to 2 mg/kg did not significantly inhibit
Figure 4. A cross section of the glandular portion of a stomach (group 3). Capillary (C), distributing artery (A), collecting venuies (Vi), and collecting vein (V); black arrow demonstrates blood clots and extravasation of dye. Note the avascuiar area in the central portion of the mucosa (clear black arrows) compared with that on the left sides of the gastric mucosa (C). (Original magnification X do.)
220
The American Journal of Surgery
Stress Ulcers
Figure 5, A cross section oi glandular portion of a stomach (groups 8 and 9). Capillary (C), collecting venuks (VI), collecting vein (V), mucosa (C), muscle layer (hl), and serosa (S). The muscle layer and serosa were extremely dktended and the vasculature was similar to that in group lb and group 2 rats. (See Figures 2 and 3.) The dktrlbuting arteries or arterioles were very narrow and barely visible, but the silicone rubber compound was well filled in the mucosal area. (Original magnification X 4’Q.)
ulcer formation may imply that gastric acidity is not the determining factor in the production of the restraint ulcer. Although PGEi decreases gastric acidity due to interference of cyclic adenosine monophosphate (AMP) formation, PGEi might effect the stabilization of the lysosomal membrane in restraint condition. The dosage of PGEr used in our study was extremely greater than that used by Robert, Nexamis, and Phillips [IO]. Moreover, in our study ulcers resulted from restraint and cold temperature whereas in theirs the ulcers were caused by ligation of the pylorus. Therefore, in our study the ulcers were located exclusively in the glandular portion whereas Shay ulcers due to pyloric ligation are located mainly in the membranous portion of the stomach. Therefore, there is a difference in the pathogenesis of the two experimental gastric ulcers. The restraint ulcer is similar to a stress ulcer whereas the Shay ulcer is a stasis ulcer. Another effect of PGEi is that it greatly decreases the permeability of the gastric mucosal barrier, thereby inhibiting acid back-diffusion. PGEi also inhibits the lipolytic effects of serotonin. It significantly prevents the release of lysosoma1 enzymes caused by lipolysis and has been found to decrease membrane permeability of the gastric mucosa as well as the intestinal mucosa [2]. PGEl is well known as a potent vasodilator. Siggins [19] demonstrat.ed that PGEi causes vasodilation of the arterioles in the retrolingual membrane of the frog and in the cheek pouch of the hamster. He stated that PGEi was capable of antagonizing the vasoconstrictive action of norepinephrine and epinephrine.
Volume 129, February 1975
Large doses of PGEi relax the circular muscles and contract smooth muscles [14]. PGEi also inhibits vagally driven gastric motility [25]. Bennet et al [16,17] found that PGEi increases spontaneous activity of smooth circular muscle. In our study, gastric distention was observed after the administration of PGEi in doses of over 2 mg/kg. Gastric distention was moderate with doses of 2 to 3 mg/kg of PGEr but extreme with doses of over 4 mg/kg. This extreme distention in the restrained rats caused the narrow appearance of the vasculature due to the muscular stretch that masked the vasodilatory effects of PGEi.
Emergency
and regular
porr-op.
Figure 8. Development of stress ulcer.
221
Kawarada,
Lambek, and Matsumoto
PGEl therefore had the distinct effect of preventing the formation of stress ulcers possibly by (1) inhibiting vasoconstriction caused by stress; (2) protecting the gastric mucosal barrier or lysosomal membrane; or (3) decreasing acid secretion which, we believe, may be a contributing, but not a determining, factor in the formation of stress ulcers. Our results demonstrated that 4 to 5 mg/kg of PGEl definitely prevented stress ulcer formation and 3 mg/kg decreased the incidence of ulcer formation to 17 per cent. However, the complications and mortality rates were dose-dependent and higher than 40 per cent with dosages exceeding 4
mglkg. It is therefore essential to determine the safe and effective clinical dose of PGEl that will prevent stress ulcer formation.
4.
5.
6.
7.
6.
9.
10.
Summary PGEl completely prevented the formation of stress ulcers when administered in doses of 4 to 5 mg/kg or more. However, at this dose, complications and mortality were significant.
11.
12.
13.
Acknowledgment: We wish to thank The Upjohn Company, Kalamazoo, Michigan, for supplying PGEl and Mr Nolan Jones and Miss Jeanette Kienle for their technical assistance.
14.
15.
Reference 1. Robert A, Nexamis JE, Phillips JP: Inhibition of gastric secretion of prostaglandins. Am J Dig Dis 12: 1073, 1967. 2. Skillman J, Gould S. Chung R, Silen W: The gastric mucosal barrier: clinical and experimental studies in critically ill and normal man, and in the rabbit. Ann Surg 172: 564, 1970. 3. Kawarada Y. Weiss R, Matsumoto T: Pathophysiology of
222
16. 17.
stress ulcer and its prewntion. I. Pharmacological doses of steroid. Am J Surg in press. Ozdemir I, Zimmerman B: Serotonin and restraint-induced gastrointestinal ulceration and circulatory ischemia. Surg forum22: 319, 1971. Wise L, Ashford L, Ballinger WF: The effect of serotonin on the gastric mucosal barrier. Surg Forum 22: 3 12, 197 1. Ferguson WW, Edmonds AW. Starling JR, Wangensteen SL: Protective effect of prostaglandin El (PGE,) on lysosomal enzyme release in serotonin-induced gastric ulceration. Ann Surg 177: 646, 1973. Drapanas T, Woolverton WC, Reeder JW, Reed RL, Weichert RF: Experiments with surgical management of acute gastric mucosal hemorrhage: a unified concept in the pathology. Ann Surg 173: 626, 1971. Goodman AA, Osborne MP: An experimental and clinical definition of stress ulceration. Surg Gynecol D&et 134: 563, 1972. Lichtenstein LM, Henney CS: Prostaglandin inhibition of immediate and delayed hypersensitivity in vitro, p 293. Prostaglandins in Cellular Biology (Ramwel PW, Pharriss BB, ed). New York, Plenum Press, 1972. Robert A. Nexamis JE, Phillips JP: Effect of PGE, on gastric secretion and ulcer formation in the rat. Gastroenterology 55: 481. 1968. Main IHM: Prostaglandins and the gastrointestinal tract. The Prostaglandins (Cuthbert MF, ed). London, William Heinemann, 1972. Kawarada Y, Lambek J, Matsumoto T: The effects of a large dose of Decadron and PGE, on pyloric ligation rats. Unpublished data. Siggins GR: Prostaglandins and the microvascular system: physiological and histochemical correlation. p 45 1. Prostaglandins in Cellular Biology (Ramwell PW, Pharriss BB, ed). Plenum Press, New York, 1972. Radmanovic BZ: Effect of prostaglandin El on the peristaltic activityof the guinea pig isolated ileum. Arch lnt Phermacodyn Ther 200: 396, 1972. Chawla RC, Eisenberg MM: Prostaglandin inhibition of innervated antral motility in dogs. froc Sot Exp Biol Med 132: 1081, 1969. Bennet A, Friedman CA, Vane TR: Release of prostaglandin El from the rat stomach. Nature 216: 673, 1967. Bennet A, Murray JG, Wyllie JH: Occurrence of prostaghndin El in the human stomach, and a study of its effects on human isolated gastric muscle. Br J Pharmacol32: 339, 1968.
The American Journal of Surgery
Responses in Stress Ulcer
Yoshifumi Kawarada, MD, Philadelphia, Pennsylvania Jeffrey Lambek, Philadelphia, Pennsylvania Teruo Matsumoto, MD, PhD, FACS, Philadelphia, Pennsylvania
El (PGEI) is a long chain, unsatuProstaglandin rated, oxygenated fatty acid that is known to cause hypotension, tachycardia, stimulation of smooth muscles, a decrease in gastric acid secretion, stabilization of the lysosomal membrane, coma, and inhibition of platelet aggregation. In 1967 Robert, Nexamis, and Phillips [I] demonstrated that the administration of PGEl inhibited gastric secretion in dogs and rats. Since then, its effect on the digestive tract has been studied. Stress ulcers are considered to be the result of a chain of events initiated by acut.e gastric vascular constriction, resulting in focal ischemia of the gastric mucosa. Skillman et al [2] found that this decreased gastric blood flow also disrupts the mucosal barrier, causing increased acid back-diffusion which destroys the ischemic cells in the gastric mucosa. They speculated that PGEl may inhibit ulcer formation by decreasing the effect of vasoconstriction, protecting the lysosomal membrane from damage, and decreasing the secretion of gastric acid. The purpose of this study was to evaluate the efficacy of PGEl in preventing the formation of stress ulcers and to investigate the microangiohistologic changes in the gastric vasculature after stress with or without the administration of PGEI. From the Division of Surgical Research, Hahnemann Medical College and Hospital, Philadelphia, Pennsylvania. Reprint requests should be addressed to Dr Teruo Matsumoto. Division of Surgical Research, Hahnemann Medical College and Hospital, 230 North Broad Street, Philadelphia, Pennsylvania 19102. Presented at the Fifteenth Annual Meeting of the Society for Surgery of the Alimentary Tract, San Francisco, California, May 21 and 22, 1974.
Volume 129, February 1975
Material and Methods Three hundred thirty white male Wistar rats, weighing between 125 and 150 gm, were used in this study. Each animal was deprived of food for twenty-four hours prior to the procedure and placed in a cold room (4°C) for two hours in a perforated conduit that was plugged with corks at each end. The animals were divided into nine groups on the basis of the amount of PGEl injected subdermally one hour before stress: group 1 (10 rats): group la (5 rats), normal rats, with no treatment and no restraint; group lb (5 rats), stomach inflated with air, with no PGEl and no restraint; group 2 (5 rats), 5 mg/kg group 3 (45 rats), no PGEj, rePGEI, no restraint; straint; group 4 (45 rats), 0.5 mg/kg PGEI, restraint; group 5 (45 rats), 1 mg/kg PGEI, restraint; group 6 (45 rats), 2 mg/kg PGE1, restraint; group 7 (45 rats), 3 mg/ kg PGEI, restraint; group 8 (45 rats), 4 mg/kg PGE,, restraint; group 9 (45 rats), 5 mg/kg PGEI, restraint. With the animals under ether anesthesia, laparotomy was performed. The stomachs of forty rats in groups 3 through 9 were excised, after which the incidence and severity of the stress ulcers were examined. Only stomach ulcers measuring over 1 mm in length were considered. The severity of the glandular portion of each stomach that exhibited ulcer was divided into four gr&ps according to the distribution of the ulcers [3]; grade 0, no ulcer; grade 1, 1 to 35 per cent; grade 2,35 to 70 per cent, and grade 3,70 to 100 per cent. For morphologic study, a double-color silicone rubber compound was perfused in five rats in each of the nine groups. First, a number 21 butterfly needle was inserted distally into the thoracic aorta and ligated around the aorta with 4-O silk. The rat was perfused with normal saline containing heparin (3,000 U in 1,000 CC). The blood and perfusion fluid were drained from an incision
217
Kawarada,
TABLE
Lambek,
I
Groups (number bf rats) 2 3 4 5 6 7 8 9
(5) (40) (40) (40) (40) (40) (40) (40)
and Matsumoto
Incidence and Severity Gastric Ulcer Dose of PGE,
Incidence of Ulcer ___
group 5,1.1
of Restraint
Grade of Severity
Mortality Rate
(w/kg)
No.
%
(O-3)
No.
%
5 0 0.5 1 2 3 4 5
0 36 35 26 17 7 0 0
90 87 65 43 17 0 0
0 2.6 2.0 1.7 1.1 0.3 0 0
0 1 2 3 6 12 17 23
0 3 5 7.5 15 30 43 56
made in the right atrium of the heart. A second number 23 butterfly needle was inserted distally into the portal vein and ligated with 4-O silk. Yellow silicone rubber compound, MV-122, was injected into the aorta through the polyethylene tube of the first needle until, with gentle thumb pressure on the syringe, the yellow rubber compound filled the gastric and duodenal arteries and capillary vasculature. Red silicone rubber compound, MV-118, was injected into the mesenteric vein through the polyethylene tube of the second needle until it completely filled the venous vasculature of the stomach and duodenum using the same procedure. In five rats (group lb), before the injection of the compounds, a small hole was made on the anterior aspect of the duodenum approximately 2 cm from the pyloric ring. A polyethylene tube was inserted into the proximal duodenum and advanced into the stomach. The tube was ligated around the duodenum just proximal to the hole with 4-O silk. Approximately 12 or 13 cc of air was then injected into the stomach via the polyethylene tube with a 20 cc syringe. Sometimes, subsequent injections of air were necessary to maintain maximal distention of the stomach for two hours. Results The incidence,
severity,
and mortality
caused
by
ulcer formation in the restrained rats with or without treatment are given in Table I. The ulcers occurred only in the glandular portion of stomach. These ulcers never penetrated the muscularis mucosa and remained in the gastric mucosa. Incidence of Restraint Gastric Ulcers. Acute gastric ulcers developed in the following animals: 36 of 40 rats (90 per cent)
in group 8,
in group
3, 35 of 40 rats
group 8, and 56 per cent in group 9.
Microfile Perfusion Studies. Group 1: group la, normal stomach (Figure 1); group lb, stomach distended with air (Figure 2). Distributing arteries, connecting arterioles, capillaries, collecting venules, and collecting veins were observed in both groups la and lb. The mucosa, muscle layers, and serosa in group lb rats were thinner than those in group la rats. In comparing the vasculature of the two groups, we found moderate narrowing in the collecting veins and venules and extreme narrowing in the distributing arteries in group lb; however, in both groups, similar filling of the silicone rubber compound via the capillaries and into the mucosa was observed. Group 2 (5 mglkg PGEl without restraint): The mucosa, muscle layers, and serosa were stretched. As in group lb rats, collecting veins and venules were narrow and the distributing arteries were also narrow and difficult to see. Thus, because of distention, the vasodilatory effects of PGEi on the distributing arteries and arterioles could not be evaluated. (Figure 3.) Group 3 (restraint only, no PGE1): The silicone rubber compound failed to fill the mucosal capillaries well. Multiple avascular areas and necrosis with blood clots in the mucosal capillaries were observed. In addition, extra spillage of the silicone rubber compound on the surface of the mucosa was observed frequently. (Figure 4.) Groups 4 and 5 (0.5 to 1 mglkg PGEl and restraint): Vasculatures similar to those in group 3 rats were observed. Groups 6 and 7 (2 to 3 mglkg PGEl and restraint): The three layers of the stomach were moderately lecting
of 40 rats (17 per cent)
rats.
in group
7, none of 40 rats
(0 per cent) in group 8, and none of 40 rats (0 per in group 9.
Severity of the Ulcers. The severity of the ulcers averaged grade 2.6 in group 3,2.0 in group 4,1.7 in
218
in group 7,0
Morbidity and Mortality. PGEi caused diarrhea, loss of activity, labored breathing, and increased nasal secretion. These findings were observed to be dose-dependent, becoming extremely severe at doses of 2 mg/kg or more. Immediately after two hours of restraint, the mortality was Q per cent in group 2, 3 per cent in group 3, 5 per cent in group 4,7.5 per cent in group 5,15 per cent in group 6, 30 per cent in group 7, 43 per cent in
(87 per cent) in group 4, 26 of 40 rats (65 per cent) in group 5, 17 of 40 rats (43 per cent) in group 6, 7
cent)
in group 6,0.3
and 0 in group 9.
group
stretched,
lb or group
but not as distended
2 rats.
veins were narrower
The
arterioles
as in
and col-
than those in group
la
Groups 8 and 9 (4 to 5 mg/kg PGEl and restraint): The three layers of the stomach were extremely distended, and the arteries, arterioles, and collecting veins were similar to those in group lb
The American Journal of Surgery
Stress
Ulcers
and group 2 rats. Again, the distributing arteries and arterioles were very narrow and barely visible. (Figure 5.) Comments
There is no doubt that stress can cause gastric ulcers; however, the pathogenesis still remains unclear. Sympathetic stimulation or sympathetic amines can cause vasoconstriction. Ozdemir and Zimmerman [4] found that vasoconstriction and ulcer formation caused by stress were similar to those caused by the administration of serotonin. A precursor of serotonin, 5-hydroxytryptophan disrupts the mucosal barrier [5]. Ferguson et al [6] stated that serotonin releases a lysosomal enzyme, cathepsin D, from gastric cell walls and that this enzyme causes direct cell damage. Furthermore, since histamine increases gastric secretion and acidity, the acid is able to penetrate the barrier and develop ischemic cells. Consequently, the ischemic mucosal cells, whose cell membrane can be damaged by certain doses of steroids, vasoconstrictive agents, bile reflux, or increased serotonin levels, are exposed to more acid and increased back-diffusion. Drapanas et al [7] d escribed a unified concept that includes alterations in the gastric mucosal barrier, the release of vasoactive amines in the gastric mucosa, and vascular and pathogenic changes. It is impossible to explain the pathogenesis of stress ulcer formation with a single factor. Goodman and Osborne [8] mentioned that the defini-
Figure 2. A cross sectton of the gland&r portton of a stomach distended with air (group lb). Capillary (C), collecting venules (VI), collecting vein (V), nwco8a (C), mu&e layer (M), and saroaa (S). The mucosa, mu&e layer, and serosa were stretched, especially muscfe layer and $81088, compared wfth those seen In Figure 1. (Ortginalmagntffcation X 41v.)
v&me
129, February 1975
Figure 1. A normal stomach (group la). Distributing artery (A), capillary (C), collecting venules (VI), collecting vein (V), mucosa (C), muscle layer (M), and serosa (S). (Original magnification X #O.)
Kawarada,
Lambek, and Matsumoto
* ..
tion of stress ulcer has led to marked confusion and widespread misunderstanding because at least four distinct entities, such as shock and sepsis, burn, neurologic disorders, and corticosteroid administration, can all cause stress ulcers. After the restraint that caused the stress, we believe that vasoconstriction was a definite factor in the production of ischemia and necrosis of the gastric mucosa which followed. Therefore, we believe that in the theory of the restraint ulcer, the acute gastric vasoconstriction syndrome (AGVCS) may be considered. (Figure 6.) Many investigators have recently studied the effects of PGEI. Some [I] have found that it coun-
Figure 3. A cross section of the glandular portion of a stomach (group 2). Capilrary (C), coiiecting venuies (Vi), collecting vein (V), mucosa (C), muscle layer (M), and serosa (S). The mucosa, muscle layer, and serosa were stretched as in Figure 2. The distributing artery was difficuit to see. (Original magnification X 410.)
teracts the gastric secretory stimulants involved in the formation of ulcers, namely, histamine and serotonin [9]. Robert, Nexamis, and Phillips [IO] found that PGEr administered in doses of 0.1 to 0.2 mg/kg did not affect gastric acid secretion whereas PGEl in doses of 0.2 to 0.6 mg/kg caused dose-dependent inhibition of gastric secretion and acidity. Main [II] stated that larger doses of PGEr (2.5 mg/kg) injected subcutaneously will inhibit gastric secretion almost totally. Despite these reports and our study [12], the administration of PGEr in doses over 0.5 mg/kg greatly decreased the acidity of gastric juice. The fact that in our study 0.5 to 2 mg/kg did not significantly inhibit
Figure 4. A cross section of the glandular portion of a stomach (group 3). Capillary (C), distributing artery (A), collecting venuies (Vi), and collecting vein (V); black arrow demonstrates blood clots and extravasation of dye. Note the avascuiar area in the central portion of the mucosa (clear black arrows) compared with that on the left sides of the gastric mucosa (C). (Original magnification X do.)
220
The American Journal of Surgery
Stress Ulcers
Figure 5, A cross section oi glandular portion of a stomach (groups 8 and 9). Capillary (C), collecting venuks (VI), collecting vein (V), mucosa (C), muscle layer (hl), and serosa (S). The muscle layer and serosa were extremely dktended and the vasculature was similar to that in group lb and group 2 rats. (See Figures 2 and 3.) The dktrlbuting arteries or arterioles were very narrow and barely visible, but the silicone rubber compound was well filled in the mucosal area. (Original magnification X 4’Q.)
ulcer formation may imply that gastric acidity is not the determining factor in the production of the restraint ulcer. Although PGEi decreases gastric acidity due to interference of cyclic adenosine monophosphate (AMP) formation, PGEi might effect the stabilization of the lysosomal membrane in restraint condition. The dosage of PGEr used in our study was extremely greater than that used by Robert, Nexamis, and Phillips [IO]. Moreover, in our study ulcers resulted from restraint and cold temperature whereas in theirs the ulcers were caused by ligation of the pylorus. Therefore, in our study the ulcers were located exclusively in the glandular portion whereas Shay ulcers due to pyloric ligation are located mainly in the membranous portion of the stomach. Therefore, there is a difference in the pathogenesis of the two experimental gastric ulcers. The restraint ulcer is similar to a stress ulcer whereas the Shay ulcer is a stasis ulcer. Another effect of PGEi is that it greatly decreases the permeability of the gastric mucosal barrier, thereby inhibiting acid back-diffusion. PGEi also inhibits the lipolytic effects of serotonin. It significantly prevents the release of lysosoma1 enzymes caused by lipolysis and has been found to decrease membrane permeability of the gastric mucosa as well as the intestinal mucosa [2]. PGEl is well known as a potent vasodilator. Siggins [19] demonstrat.ed that PGEi causes vasodilation of the arterioles in the retrolingual membrane of the frog and in the cheek pouch of the hamster. He stated that PGEi was capable of antagonizing the vasoconstrictive action of norepinephrine and epinephrine.
Volume 129, February 1975
Large doses of PGEi relax the circular muscles and contract smooth muscles [14]. PGEi also inhibits vagally driven gastric motility [25]. Bennet et al [16,17] found that PGEi increases spontaneous activity of smooth circular muscle. In our study, gastric distention was observed after the administration of PGEi in doses of over 2 mg/kg. Gastric distention was moderate with doses of 2 to 3 mg/kg of PGEr but extreme with doses of over 4 mg/kg. This extreme distention in the restrained rats caused the narrow appearance of the vasculature due to the muscular stretch that masked the vasodilatory effects of PGEi.
Emergency
and regular
porr-op.
Figure 8. Development of stress ulcer.
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Kawarada,
Lambek, and Matsumoto
PGEl therefore had the distinct effect of preventing the formation of stress ulcers possibly by (1) inhibiting vasoconstriction caused by stress; (2) protecting the gastric mucosal barrier or lysosomal membrane; or (3) decreasing acid secretion which, we believe, may be a contributing, but not a determining, factor in the formation of stress ulcers. Our results demonstrated that 4 to 5 mg/kg of PGEl definitely prevented stress ulcer formation and 3 mg/kg decreased the incidence of ulcer formation to 17 per cent. However, the complications and mortality rates were dose-dependent and higher than 40 per cent with dosages exceeding 4
mglkg. It is therefore essential to determine the safe and effective clinical dose of PGEl that will prevent stress ulcer formation.
4.
5.
6.
7.
6.
9.
10.
Summary PGEl completely prevented the formation of stress ulcers when administered in doses of 4 to 5 mg/kg or more. However, at this dose, complications and mortality were significant.
11.
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13.
Acknowledgment: We wish to thank The Upjohn Company, Kalamazoo, Michigan, for supplying PGEl and Mr Nolan Jones and Miss Jeanette Kienle for their technical assistance.
14.
15.
Reference 1. Robert A, Nexamis JE, Phillips JP: Inhibition of gastric secretion of prostaglandins. Am J Dig Dis 12: 1073, 1967. 2. Skillman J, Gould S. Chung R, Silen W: The gastric mucosal barrier: clinical and experimental studies in critically ill and normal man, and in the rabbit. Ann Surg 172: 564, 1970. 3. Kawarada Y. Weiss R, Matsumoto T: Pathophysiology of
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stress ulcer and its prewntion. I. Pharmacological doses of steroid. Am J Surg in press. Ozdemir I, Zimmerman B: Serotonin and restraint-induced gastrointestinal ulceration and circulatory ischemia. Surg forum22: 319, 1971. Wise L, Ashford L, Ballinger WF: The effect of serotonin on the gastric mucosal barrier. Surg Forum 22: 3 12, 197 1. Ferguson WW, Edmonds AW. Starling JR, Wangensteen SL: Protective effect of prostaglandin El (PGE,) on lysosomal enzyme release in serotonin-induced gastric ulceration. Ann Surg 177: 646, 1973. Drapanas T, Woolverton WC, Reeder JW, Reed RL, Weichert RF: Experiments with surgical management of acute gastric mucosal hemorrhage: a unified concept in the pathology. Ann Surg 173: 626, 1971. Goodman AA, Osborne MP: An experimental and clinical definition of stress ulceration. Surg Gynecol D&et 134: 563, 1972. Lichtenstein LM, Henney CS: Prostaglandin inhibition of immediate and delayed hypersensitivity in vitro, p 293. Prostaglandins in Cellular Biology (Ramwel PW, Pharriss BB, ed). New York, Plenum Press, 1972. Robert A. Nexamis JE, Phillips JP: Effect of PGE, on gastric secretion and ulcer formation in the rat. Gastroenterology 55: 481. 1968. Main IHM: Prostaglandins and the gastrointestinal tract. The Prostaglandins (Cuthbert MF, ed). London, William Heinemann, 1972. Kawarada Y, Lambek J, Matsumoto T: The effects of a large dose of Decadron and PGE, on pyloric ligation rats. Unpublished data. Siggins GR: Prostaglandins and the microvascular system: physiological and histochemical correlation. p 45 1. Prostaglandins in Cellular Biology (Ramwell PW, Pharriss BB, ed). Plenum Press, New York, 1972. Radmanovic BZ: Effect of prostaglandin El on the peristaltic activityof the guinea pig isolated ileum. Arch lnt Phermacodyn Ther 200: 396, 1972. Chawla RC, Eisenberg MM: Prostaglandin inhibition of innervated antral motility in dogs. froc Sot Exp Biol Med 132: 1081, 1969. Bennet A, Friedman CA, Vane TR: Release of prostaglandin El from the rat stomach. Nature 216: 673, 1967. Bennet A, Murray JG, Wyllie JH: Occurrence of prostaghndin El in the human stomach, and a study of its effects on human isolated gastric muscle. Br J Pharmacol32: 339, 1968.
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