CORPUS LUTEUM FUNCTION FOLLOWING SUBTOTAL HYSTERECTOMY IN THE PREPUBERAL GILT
University o f Georgia, A t b e n s 30602 and U.S. D e p a r t m e n t o f Agriculture, A t b e n s 30604
SUMMARY
The effect of subtotal hysterectomy- on maintenance of induced corpora lutea (CL) in prepuberal gilts, 120 to 130 days of age, was studied. Ovulation was induced with 1,000 IU Pregnant Mare Serum Gonadotropin (PMSG) followed 72 hr later with 500 IU Human Chorionic Gonadotropin (HCG). Thirteen gilts (bred controls) were inseminated on Day 0 (Day following HCG=Day 0). Fifty gilts were laparotomized on Days 6 through 9, their CL marked with charcoal and the gilts subtotally hysterectomized so that the amount of cervix and uterus left intact was: group 1 (n=13), posterior half of cervix; group 2 (n=12), cervix and posterior half of the uterine body; group 3 (n=12), cervix and uterine body; group 4 (n=13), posterior half of cervix and anterior 15% of one uterine horn. At necropsy (Day 30), three bred control gilts were pregnant while the ovaries of the remaining controls had only corpora albicantia (CA) present. The percentage of CL maintained to Day 30 for groups 1 through 4 were, respectively; 85.7, 65.9, 37.1 and 31.2. Based on these results, we suggest that, unlike mature gilts in which at least 25% of one uterine horn must be present to cause luteal regression and in which the presence of only the uterine body fails to cause luteal regression, as little as 15% of one uterine horn or the uterine body left intact will cause regression in the prepuberal gilt. (Key Words: Prepuberal, Corpus Luteum, Uterus, Hysterectomy, Progesterone, Pig.)
INTRODUCTION
Prepuberal gilts can be induced to ovulate and their ova can be fertilized, but the number of gihs that maintain pregnancy to 25 days of gestation is low (Dziuk and Gehlback, 1966; Baker and Coggins, 1968; Segal and Baker, 1973 ; Rampacek et al., 1976a). Administration of exogenous progestins or gonadotropins following induced ovulation will tend to increase the number of gilts that maintain pregnancy to at least 25 days of gestation (Shaw et al., 1971; Ellicott et al., 1973; Segal and Baker, 197t; Rampacek et al., 1976a). This need for exogenous gonadotropins or progestins suggests that regression of corpora lutea (CL) during pregnancy in the prepuberal gilt is due to a lack of luteotropic support. Rampacek et al. (1976b) demonstrated, however, that total hysterect o m y following induced ovulation in prepuberal gilts resulted in maintenance of functional CL to at least Day 30. This indicates that luteotropic support is sufficient to maintain CL in the absence of the uterus. Salisbury et al. (1975) reported that hysterectomy did not consistently maintain induced CL in the prepuberal gilt. Salisbury et al. (1975), however, did not remove the uterine body and thereby left part of the luteolysin-producing tissue intact. Therefore, the inability of the prepuberal gih to maintain pregnancy may not be completely due to a lack of luteotropic support, but may be due to an imbalance between the luteolytic and luteotropic mechanism. The effect of various amounts of intact uterine tissue on CL function in mature gilts has been demonstrated by the use of subtotal LDepartment of Animal and Dairy Science, Univer- hysterectomy. When more than one-fourth of the anterior end of one uterine horn was left sity of Georgia, Athens. Richard B. Russell Research Center, Agricultural intact, estrous cycles continued (du Mesnil du Research Service, USDA. Buisson, 1960; Anderson et al., 1961). When 3To whom correspondence should be addressed. only the uterine body remained intact, estrus 4The authors gratefully acknowledge Ms. E. Paige Jordan and Mr. Bennett Johnson for valuable technical was inhibited, indicating that the uterine body assistance. is an insufficient amount of uterine tissue to 707 JOURNAL OF ANIMAL SCIENCE, Vol. 46, No. 3, 1978
Downloaded from https://academic.oup.com/jas/article-abstract/46/3/707/4700893 by Iowa State University user on 18 January 2019
Tony A. Puglisi I , George B. Rampacek 1,3 and Robert R. Kraeling 2,4
708
PUGLISI, RAMPACEK AND KRAELING
EXPERIMENTAL PROCEDURE
Sixty-three prepuberal crossbred gilts, 120 to 130 days of age and averaging 50 kg b o d y weight, were induced to ovulate with an intramuscular (IM) injection of 1,000 IU Pregnant Mare Serum G o n a d o t r o p i n (PMSG) f o l l o w e d 72 hr later by an IM injection o f 500 IU H u m a n Chorionic G o n a d o t r o p i n (HCG). Thirteen gilts (bred controls) were r a n d o m l y selected and inseminated on Day 0 (Day following HCG= Day 0). The remaining gilts were l a p a r o t o m i z e d on Days 6 through 9, their CL marked with sterile charcoal and the gilts subtotally hystere c t o m i z e d (Anderson et al., 1961) so that the a m o u n t of cervix and uterus left intact was: group 1 (n=13), the posterior one half of the cervix; group 2 (n=12), the entire cervix and the posterior one half of the uterine b o d y ; group 3 (n=12), the entire cervix and the entire uterine b o d y ; group 4 (n=13), the posterior cervix and the anterior 15% o f the uterine horn
ull~Ni
moo*
UVElINE n o a N OVA|V
Ci,wx
G 3ROU ~ P G P R4OU ~ Figure 1. Reproductive tract of the gilt. Shaded areas indicate portions of the uterus remaining after surgery in different experimental groups.
adjacent to the ovary with the m o s t CL. Figure 1 illustrates the p o r t i o n s o f cervix and uterine tissue left intact in each t r e a t m e n t group. Blood was o b t a i n e d by anterior vena cava p u n c t u r e on Days 10, 14, 16, 20, 24 and 29 and plasma progestin c o n c e n t r a t i o n d e t e r m i n e d by radioimmunoassay ( R a m p a c e k et al., 1976b). All gilts were necropsied on Day 30, the ovaries were e x a m i n e d for marked CL and marked corpora albicantia (CA) and the uteri of the control gilts e x a m i n e d for e m b r y o s . The percentage o f CL maintained to Day 30, based on comparison b e t w e e n the n u m b e r o f CL present at Days 6 through 9 and the n u m b e r of marked CL present at Day 30, were converted to arcsin values and subjected to analysis of
TABLE 1. EFFECT OF SUBTOTAL HYSTERECTOMY ON CL MAINTENANCE IN THE PREPUBERAL GILT
Group a
No. of gilts
Corpora lutea on Day 6 to 9 avg no. • SE
1 2 3 4
13 12 12 13
14.5 15.4 18.4 20.6
+- 2.2 -+ 2.3 • 3.2 • 3.5
Corpora lutea on Day 30 avg no. • SE
Percent CL maintained to Day 30 avg • SE b
12.1 10.4 5.2 5.6
85.7 65.9 37.1 31.2
-+ 2.6 c • 2.5 cd • 1.3 d + 1.2 d
+ + • •
1.3 c 1.8 cd 1.9 d 1.1 d
aAmount of cervix and uterus left intact: group 1, posterior one half of the cervix;group 2, entire cervix and posterior one half of the uterine body; group 3, entire cervix and entire uterine body;group 4, posterior cervix and the anterior 15% of the uterine horn adjacent to the ovary with the most CL. bThe percent values for each animal were converted to arcsin values and subjected to analysis of variance and Duncan's new multiple range test. The average arcsin values were then converted back to percent. C'dMeans in the same column not sh~rir 9 li~'e s,,p~rsrrintx ~re ~' mifir~nrl v cliffer~'nt (P< 05)
Downloaded from https://academic.oup.com/jas/article-abstract/46/3/707/4700893 by Iowa State University user on 18 January 2019
cause luteal regression in m a t u r e gilts (Anderson et al., 1961). If either an excess of l u t e o l y t i c substance is p r o d u c e d by the prepuberal uterus, or the induced CL o f the prepuberal gilt are m o r e sensitive to the luteolyric factor, then removal o f m o r e uterine tissue in the prepuberal gilt, as c o m p a r e d to the m a t u r e gilt, w o u l d be required to obtain luteal maintenance. This e x p e r i m e n t was c o n d u c t e d to determine the a m o u n t o f uterine tissue necessary to cause luteal regression following induced ovulation in the prepuberal gilt.
SUBTOTAL HYSTERECTOMY IN THE PREPUBERAL GILT
+I
+I
+I
+I
z o < iz z o
_z
0
RESULTS AND DISCUSSION
There were no differences ( P > . 0 5 ) in average n u m b e r o f C L among t r e a t m e n t groups on Days
6 through 9 (table 1). On Day 30, three bred control gilts were pregnant while the ovaries of the remaining bred controls had only CA present. The low maintenance of pregnancy in the bred controls and the absence of previous ovulations in the treated gilts indicate that the gilts used in this study were actually prepuberal. Two gilts in group 1 had complete CL regression, one gilt had marked CL and CA while the remaining 10 gilts had complete CL maintenance. In group 2, complete CL regression occurred in two gilts while four animals had both marked CL and CA and the remaining six gilts maintained their CL. In group 3, complete CL regression occurred in six gilts, three gilts had both marked CL and CA and the remaining three animals maintained their CL. In group 4, complete CL regression occurred in two gilts while complete CL maintenance occurred in one gilt. The remaining 10 gilts had both marked CL and CA; however, seven of these 10 gilts had complete unilateral regression of CL on the ovary adjacent to the remaining uterine fragment in addition to some CL regression on the contralateral ovary. The percentage of CL that were maintained to Day 30 are presented in table 1. The results in group 1 demonstrate that total hysterectomy maintains functional CL until at least Day 30. The percentage of luteal maintenance was higher (P.05) were found in percentage o f luteal m a i n t e n a n c e a m o n g groups 2, 3 and 4. F u n c t i o n of CL t h r o u g h o u t the treatm e n t period is reflected by the plasma progestin c o n c e n t r a t i o n s (table 2). Progestin concentrations in groups 1 and 2 indicate functional CL t h r o u g h o u t the sampling period while groups 3 and 4 had l o w progestin c o n c e n t r a t i o n s by Day 29, indicating luteal regression in these t w o groups. The results of groups 3 and 4 indicate that luteal regression will occur when only the uterine b o d y or as little as 15% (X = 13.9 cm) of the anterior end o f one uterine horn are left inact in the prepuberal gilt. These results f r o m groups 3 and 4 differ f r o m results r e p o r t e d for the mature gilt in that CL were maintained in the presence of the uterine b o d y (Anderson et al., 1961) and m o r e than 25% (26cm) of one uterine horn was necessary to cause luteal regression (du Mesnil de Buisson, 1960; Anderson et al., 1961). This e x p e r i m e n t d e m o n s t r a t e s that luteotropic support is a d e q u a t e to maintain functional CL in the prepuberal gilt, until at least Day 30, w h e n the l u t e o l y t i c m e c h a n i s m is r e m o v e d by c o m p l e t e h y s t e r e c t o m y . However, the smaller a m o u n t of uterine tissue necessary to cause luteal regression in the prepuberal gilt, as c o m p a r e d to the m a t u r e gilt, suggests that there is an imbalance b e t w e e n the l u t e o l y t i c and l u t e o t r o p i c mechanisms in the prepuberal gilt and this imbalance could be expressed as an excess of uterine luteolysin a n d / o r an increased sensitivity of the induced CL to the uterine luteolysin.
University o f Georgia, A t b e n s 30602 and U.S. D e p a r t m e n t o f Agriculture, A t b e n s 30604
SUMMARY
The effect of subtotal hysterectomy- on maintenance of induced corpora lutea (CL) in prepuberal gilts, 120 to 130 days of age, was studied. Ovulation was induced with 1,000 IU Pregnant Mare Serum Gonadotropin (PMSG) followed 72 hr later with 500 IU Human Chorionic Gonadotropin (HCG). Thirteen gilts (bred controls) were inseminated on Day 0 (Day following HCG=Day 0). Fifty gilts were laparotomized on Days 6 through 9, their CL marked with charcoal and the gilts subtotally hysterectomized so that the amount of cervix and uterus left intact was: group 1 (n=13), posterior half of cervix; group 2 (n=12), cervix and posterior half of the uterine body; group 3 (n=12), cervix and uterine body; group 4 (n=13), posterior half of cervix and anterior 15% of one uterine horn. At necropsy (Day 30), three bred control gilts were pregnant while the ovaries of the remaining controls had only corpora albicantia (CA) present. The percentage of CL maintained to Day 30 for groups 1 through 4 were, respectively; 85.7, 65.9, 37.1 and 31.2. Based on these results, we suggest that, unlike mature gilts in which at least 25% of one uterine horn must be present to cause luteal regression and in which the presence of only the uterine body fails to cause luteal regression, as little as 15% of one uterine horn or the uterine body left intact will cause regression in the prepuberal gilt. (Key Words: Prepuberal, Corpus Luteum, Uterus, Hysterectomy, Progesterone, Pig.)
INTRODUCTION
Prepuberal gilts can be induced to ovulate and their ova can be fertilized, but the number of gihs that maintain pregnancy to 25 days of gestation is low (Dziuk and Gehlback, 1966; Baker and Coggins, 1968; Segal and Baker, 1973 ; Rampacek et al., 1976a). Administration of exogenous progestins or gonadotropins following induced ovulation will tend to increase the number of gilts that maintain pregnancy to at least 25 days of gestation (Shaw et al., 1971; Ellicott et al., 1973; Segal and Baker, 197t; Rampacek et al., 1976a). This need for exogenous gonadotropins or progestins suggests that regression of corpora lutea (CL) during pregnancy in the prepuberal gilt is due to a lack of luteotropic support. Rampacek et al. (1976b) demonstrated, however, that total hysterect o m y following induced ovulation in prepuberal gilts resulted in maintenance of functional CL to at least Day 30. This indicates that luteotropic support is sufficient to maintain CL in the absence of the uterus. Salisbury et al. (1975) reported that hysterectomy did not consistently maintain induced CL in the prepuberal gilt. Salisbury et al. (1975), however, did not remove the uterine body and thereby left part of the luteolysin-producing tissue intact. Therefore, the inability of the prepuberal gih to maintain pregnancy may not be completely due to a lack of luteotropic support, but may be due to an imbalance between the luteolytic and luteotropic mechanism. The effect of various amounts of intact uterine tissue on CL function in mature gilts has been demonstrated by the use of subtotal LDepartment of Animal and Dairy Science, Univer- hysterectomy. When more than one-fourth of the anterior end of one uterine horn was left sity of Georgia, Athens. Richard B. Russell Research Center, Agricultural intact, estrous cycles continued (du Mesnil du Research Service, USDA. Buisson, 1960; Anderson et al., 1961). When 3To whom correspondence should be addressed. only the uterine body remained intact, estrus 4The authors gratefully acknowledge Ms. E. Paige Jordan and Mr. Bennett Johnson for valuable technical was inhibited, indicating that the uterine body assistance. is an insufficient amount of uterine tissue to 707 JOURNAL OF ANIMAL SCIENCE, Vol. 46, No. 3, 1978
Downloaded from https://academic.oup.com/jas/article-abstract/46/3/707/4700893 by Iowa State University user on 18 January 2019
Tony A. Puglisi I , George B. Rampacek 1,3 and Robert R. Kraeling 2,4
708
PUGLISI, RAMPACEK AND KRAELING
EXPERIMENTAL PROCEDURE
Sixty-three prepuberal crossbred gilts, 120 to 130 days of age and averaging 50 kg b o d y weight, were induced to ovulate with an intramuscular (IM) injection of 1,000 IU Pregnant Mare Serum G o n a d o t r o p i n (PMSG) f o l l o w e d 72 hr later by an IM injection o f 500 IU H u m a n Chorionic G o n a d o t r o p i n (HCG). Thirteen gilts (bred controls) were r a n d o m l y selected and inseminated on Day 0 (Day following HCG= Day 0). The remaining gilts were l a p a r o t o m i z e d on Days 6 through 9, their CL marked with sterile charcoal and the gilts subtotally hystere c t o m i z e d (Anderson et al., 1961) so that the a m o u n t of cervix and uterus left intact was: group 1 (n=13), the posterior one half of the cervix; group 2 (n=12), the entire cervix and the posterior one half of the uterine b o d y ; group 3 (n=12), the entire cervix and the entire uterine b o d y ; group 4 (n=13), the posterior cervix and the anterior 15% o f the uterine horn
ull~Ni
moo*
UVElINE n o a N OVA|V
Ci,wx
G 3ROU ~ P G P R4OU ~ Figure 1. Reproductive tract of the gilt. Shaded areas indicate portions of the uterus remaining after surgery in different experimental groups.
adjacent to the ovary with the m o s t CL. Figure 1 illustrates the p o r t i o n s o f cervix and uterine tissue left intact in each t r e a t m e n t group. Blood was o b t a i n e d by anterior vena cava p u n c t u r e on Days 10, 14, 16, 20, 24 and 29 and plasma progestin c o n c e n t r a t i o n d e t e r m i n e d by radioimmunoassay ( R a m p a c e k et al., 1976b). All gilts were necropsied on Day 30, the ovaries were e x a m i n e d for marked CL and marked corpora albicantia (CA) and the uteri of the control gilts e x a m i n e d for e m b r y o s . The percentage o f CL maintained to Day 30, based on comparison b e t w e e n the n u m b e r o f CL present at Days 6 through 9 and the n u m b e r of marked CL present at Day 30, were converted to arcsin values and subjected to analysis of
TABLE 1. EFFECT OF SUBTOTAL HYSTERECTOMY ON CL MAINTENANCE IN THE PREPUBERAL GILT
Group a
No. of gilts
Corpora lutea on Day 6 to 9 avg no. • SE
1 2 3 4
13 12 12 13
14.5 15.4 18.4 20.6
+- 2.2 -+ 2.3 • 3.2 • 3.5
Corpora lutea on Day 30 avg no. • SE
Percent CL maintained to Day 30 avg • SE b
12.1 10.4 5.2 5.6
85.7 65.9 37.1 31.2
-+ 2.6 c • 2.5 cd • 1.3 d + 1.2 d
+ + • •
1.3 c 1.8 cd 1.9 d 1.1 d
aAmount of cervix and uterus left intact: group 1, posterior one half of the cervix;group 2, entire cervix and posterior one half of the uterine body; group 3, entire cervix and entire uterine body;group 4, posterior cervix and the anterior 15% of the uterine horn adjacent to the ovary with the most CL. bThe percent values for each animal were converted to arcsin values and subjected to analysis of variance and Duncan's new multiple range test. The average arcsin values were then converted back to percent. C'dMeans in the same column not sh~rir 9 li~'e s,,p~rsrrintx ~re ~' mifir~nrl v cliffer~'nt (P< 05)
Downloaded from https://academic.oup.com/jas/article-abstract/46/3/707/4700893 by Iowa State University user on 18 January 2019
cause luteal regression in m a t u r e gilts (Anderson et al., 1961). If either an excess of l u t e o l y t i c substance is p r o d u c e d by the prepuberal uterus, or the induced CL o f the prepuberal gilt are m o r e sensitive to the luteolyric factor, then removal o f m o r e uterine tissue in the prepuberal gilt, as c o m p a r e d to the m a t u r e gilt, w o u l d be required to obtain luteal maintenance. This e x p e r i m e n t was c o n d u c t e d to determine the a m o u n t o f uterine tissue necessary to cause luteal regression following induced ovulation in the prepuberal gilt.
SUBTOTAL HYSTERECTOMY IN THE PREPUBERAL GILT
+I
+I
+I
+I
z o < iz z o
_z
0
RESULTS AND DISCUSSION
There were no differences ( P > . 0 5 ) in average n u m b e r o f C L among t r e a t m e n t groups on Days
6 through 9 (table 1). On Day 30, three bred control gilts were pregnant while the ovaries of the remaining bred controls had only CA present. The low maintenance of pregnancy in the bred controls and the absence of previous ovulations in the treated gilts indicate that the gilts used in this study were actually prepuberal. Two gilts in group 1 had complete CL regression, one gilt had marked CL and CA while the remaining 10 gilts had complete CL maintenance. In group 2, complete CL regression occurred in two gilts while four animals had both marked CL and CA and the remaining six gilts maintained their CL. In group 3, complete CL regression occurred in six gilts, three gilts had both marked CL and CA and the remaining three animals maintained their CL. In group 4, complete CL regression occurred in two gilts while complete CL maintenance occurred in one gilt. The remaining 10 gilts had both marked CL and CA; however, seven of these 10 gilts had complete unilateral regression of CL on the ovary adjacent to the remaining uterine fragment in addition to some CL regression on the contralateral ovary. The percentage of CL that were maintained to Day 30 are presented in table 1. The results in group 1 demonstrate that total hysterectomy maintains functional CL until at least Day 30. The percentage of luteal maintenance was higher (P.05) were found in percentage o f luteal m a i n t e n a n c e a m o n g groups 2, 3 and 4. F u n c t i o n of CL t h r o u g h o u t the treatm e n t period is reflected by the plasma progestin c o n c e n t r a t i o n s (table 2). Progestin concentrations in groups 1 and 2 indicate functional CL t h r o u g h o u t the sampling period while groups 3 and 4 had l o w progestin c o n c e n t r a t i o n s by Day 29, indicating luteal regression in these t w o groups. The results of groups 3 and 4 indicate that luteal regression will occur when only the uterine b o d y or as little as 15% (X = 13.9 cm) of the anterior end o f one uterine horn are left inact in the prepuberal gilt. These results f r o m groups 3 and 4 differ f r o m results r e p o r t e d for the mature gilt in that CL were maintained in the presence of the uterine b o d y (Anderson et al., 1961) and m o r e than 25% (26cm) of one uterine horn was necessary to cause luteal regression (du Mesnil de Buisson, 1960; Anderson et al., 1961). This e x p e r i m e n t d e m o n s t r a t e s that luteotropic support is a d e q u a t e to maintain functional CL in the prepuberal gilt, until at least Day 30, w h e n the l u t e o l y t i c m e c h a n i s m is r e m o v e d by c o m p l e t e h y s t e r e c t o m y . However, the smaller a m o u n t of uterine tissue necessary to cause luteal regression in the prepuberal gilt, as c o m p a r e d to the m a t u r e gilt, suggests that there is an imbalance b e t w e e n the l u t e o l y t i c and l u t e o t r o p i c mechanisms in the prepuberal gilt and this imbalance could be expressed as an excess of uterine luteolysin a n d / o r an increased sensitivity of the induced CL to the uterine luteolysin.
