Journal of Neurocken~im-~. 1976. Val. 26, pp. 643445.Pergamon Press. Printed in Great Brrta,n

SHORT COMMUNICATION Further studies on the distribution of [4-14C]cholesterol in the brain tissue after its intraventricular injection into conscious cats (Received 1 June 1975. Accepted 25 September 1975)

RECENTLY it was shown that [4-'4C]cholesterol entered counts corrected to 100% efficiency. All results were calcuthe brain tissue surrounding the cerebral ventricles after lated per g of dry tissue. 30 min following its intraventricular injection into conThe distribution of [4-'4C]cholesterol in the cerebral scious cats, but the amount of labelled cholesterol vaned grey matter at various times after its intraventricular injecaccording to the brain regions (BELESLIN et al., 1975). How- tion is shown in Table 1. Labelled cholesterol entered the ever, detailed results on the distribution of [4-14C]choles- brain tissue surrounding the cerebral ventricle as well as terol in the grey matter lining the cerebral ventricles as the cerebral cortex. However, from the results presented well as in the grey matter of the cerebral cortex as a func- in Table 1 it can be seen that the grey matter lining the tion of time after its intraventricular administration are cerebral ventricles not only take up the labelled choIestero1 scarce. Therefore, the aim of the present experiments was more rapidly than the grey matter of the cerebral cortex, to investigate more fully the distribution of labelled choles- but also fail to retain it in the same way. The amount terol at various times after its intraventricular injection of [4-'4C]cholesterol in the grey matter lining the cerebral ventricles was time-dependent. The highest values of into conscious cats. The experiments were performed on cats of both sexes radioactive material were found 3 to 10 min after intravenweighing 2.2-3.0 kg. For cannulation of the left lateral ven- tricular injection of [4-14C]cholesterol. Thereafter within tricle a Collison cannula was screwed into the skull 7 mm a few hours, most of the labelled cholesterol disappeared, . posterior to the coronal suture and 4 mm lateral to the and by the end of 48 h the grey matter surrounding the & SHERWOOD, 1953). The cannula, with cerebral ventricles retained only small amounts of it. On midline (FELDBERG a side hole 1 mm from its closed tip, was directed with the other hand, in the left or right somatosensory cortex the opening towards Monro's foramen. Implantation of the barely perceptible differences in the amount of [4-'4C]cholesterol were found throughout period of 48 h followng cannula was carried out aseptically under pentobarbitone sodium anaesthesia (35-45 mg/kg). A 5-day interval its intraventricular administration. In a separatc series of experiments the measurements elapsed postoperatively before the first experiment. Intraventricular injections of [4-14C]cholesterol (New England of [4-'4C]cholesterol in the venous blood were carried out. Nuclear Corp., Boston, MA, U.S.A.) were made in a Labelled cholesterol was found in the venous blood, but volume of 0.1 ml and washed in with 0.1 ml of pyrogen-free in very small amounts. After 30 min the level of radioactisaline containing 025% Tween 20. The labelled cholesterol vity was 97.33 d.p.m./ml of plasma (mean of three experwas dissolved in saline containing 0.25% Tween 20 (Tween iments) and after 4 h following intraventricular injection 20 in concentration of 0.25% had no detectable effects on of [4-L4C]cholesterol 93.83 d.p.m./ml of plasma (mean of cat's behaviour). In the injected solution 0.1 ml contained 4 experiments). In the experiments carried out after 4 h following intraventricular injection of [4-'4C]cholesterol 6 x 10' d.p.m. of radioactive cholesterol. Cats were killed by decapitation 3, 10 and 30 min and the amount of radioactivity showed such a low level that 4: 24 and 48 h after intraventricular injections of labelled a clear conclusion could not be drawn. Several different findings support the belief that once cholesterol. Then the brains were rapidly removed and washed with saline. Thereafter, the following parts of the [4-'4CJcholesterol is incorporated into the developing cenbrain were dissected: right and left caudate nucleus, right tral nervous system it persists with little change for a long and left hippocampus, right and left thalamus, the h y p - time. For instance, when radioactive cholesterol is administhalamus, the floor of the fourth ventricle and right and left tered parenterally into 17-day-old rabbits or chickens by somatosensory cortex. Most brain regions (caudate nuc- injecting this substance into the residual yolk-sac on the leus, hippocampus, thalamus, hypothalamus and floor day of hatching it enters the brain and the incorporated of the fourth ventricle) could be identified macroscopically cholesterol remains in the developing central nervous syset and the samples appeared free from white matter. The tem with little change for more than a year (DAVISON & WAJDA,1959). Further, it was samples from the somatosensory cerebral cortex were al., 1958, 1959; DAVISON obtained by cutting off the grey matter from the underlying shown that the grey matter of the brain differed from the white matter of the brain in respect of turnover of cholesfibres with fine scissors. Samples of the brain tissue were homogenized and total terol. In the first few months there was evidence of choleslipids extracted with chloroform--methanol (2: 1, v/v; terol turnover in the cerebral grey matter, while in the FOLCH-PI et al., 1957) as already described in detail (BELES- cerebral white matter there was little indication of its loss (DAMSON et al., 1959). In the present experiments, when LIN et al., 1975). Radioactivity was measured in a Nuclear [4-14C]cholesterol was injected intraventricularly into the Chicago Co liquid-scintillation spectrometer. Quenching was monitored by the channels ratio technique and all left lateral ventricle of conscious cats, it entered the grey 643

right side

32.185 f9.049

152.152 i21.426 155.300 k 61-994 65.848 f8.327

167.473 f67.078 65.263 f25.998

222-708 f.39706 57.037 f 16.862

15.2

30.9

72.8

71.3

306

78.5

267

104.4

38.732 +6146

153-766 f.19020 121.315 i8.956 86916 f.6.381

168.379 f22.681 58.861 f9494

I 15.370 f 18-514 81.776 37.995

2.542 f 527

1.1

2.294 f 523

1-768

Each value represents the mean of at least 6 experiments

Floor of the IV ventricle

Hypothalamus

right side

Thalamus left side

right side

Hippocampus left side

right side

Caudate nucleus left side

I.o

ir 284

2133

Somatosensory cortex Left side

k

21-9

49-1

68-6

88.1

33.3

952

462

65.2

I .4

I .o

S.E.

relatiw radioactivity

33.439

+ 6.746

85-145 i 13.676

t 18.355

72.759 i2.049 90274

110273 f 11.481 49,701 i9-008

+l5.W

103.691 f 16.053 68-745

f 109

3.037 i472 2.792

2x-I

29.7

23.9

16.4

363

226

341

0.9

I -0

I0365

+ 1.110

+

30.580 7.768 30.187 f2415 48.316 3.961

73.099 k3.411 30072 f3.794

66643 +7.323 47-915 f 12.538

3039 f 1,131

2 606

= 370

3.9

18.5

11.6

11.7

11.5

28.1

184

256

1.2

10

Radioactivity in d.p.m.ig of dry tissuc at various time interbals relative relative 30 min radioactivity 4 h radioactivity

5.859 i937

25.484 f7.989 27.080 i5.464 13881 f2537

3 I ,296 f 1.278 21.984 i 1-324

30418 f4096

? 9.643

39441

2131 +963 2.040 f518

24 h

2.8

65

127

11.9

103

14.7

143

18.5

0-9

I -0

relative rddioactlvity

3-546 C417

1.2

33

*

3.8 11.163

2.9

65

8.4

42

64

I .o

1.0

relative radioactivily

f3-716 9.707 2.593

11.331 f 1.966

24812 i- 3251 19.232 f 1.678

18.881 f 1.498 12.592 f 1.666

f703

2.917

5518

2.967

48 h

IN THE CtREBRAL G K t Y MATTER AT VARIOUS TIME lYTERVALS FOLLOWING ITS INTRAVEhTRICULAR INJFCTIOW INTO THF LLrT LATFRAL VFNTRICLE OF CONSCIOUS CATS

10 min

*3l3

3 min

relative radioactivity

OF [4-'4C]CHOLtSTtROL

Brain regions

TABLE1. THFDISTRIBUTION

6'

2

s2.

3

0

u . P

Short communication matter lining the cerebral ventricles as well as the grey matter of the cerebral cortex. In the grey mattcr of the cerebral cortex the labelled cholesterol was barely perceptible throughout the whole of 48 h of the experiment, while its movement in the grey matter lining the cerebral ventricles had two phases. In the first phase the labelled cholesterol steadily diminished within the first few hours and 4 h after its intraventricular injection, the rate of its decrease was perceptibly lower (second phase). At the end of the second phase the amount of remaining labelled cholesterol was low in all parts of the grey matter surrounding the cerebral ventricles. On the other hand, there was little indication that the labelled cholesterol once taken up by the grey mattcr of the cerebral cortex was later lost. Regional differences in the uptake and distribution of substances injected intraventricularly between various parts of the grey matter lining the cerebral ventricles have been demonstrated by many authors (DRASKOCI et al., 1960; AGHAJANIAN & BLOOM,1967; ANDJELKOVIC et nl., 1971). In the present experiments regional differences in the grey matter surrounding the cerebral ventricles in the distribution of labelled cholesterol were also found after its intraventricular administration into the left lateral ventricle of conscious cats. However, the data shown in the present paper do not indicate whether the distribution of the label relates to incorporation in structures or just follows the blood distribution in various brain areas. The loss of [4-'4C]cholesterol from the grey tissue lining the cerebral ventricles could be ascribed. as already pointed out, in part to its entry into the blood from the cerebrospinal Ruid (BELESLINet al., 1975). In the present experiments labelled material was also found in blood, though in very small amounts Finally, these experiments did not explain why the loss of [4-'4C]cholesterol from the grey matter lining the cerebral ventricles is much faster

645

in first few hours than in the second phase of the experiment and why in the grey matter of the cerebral cortex barely perceptible alterations in the amount of labelled cholesterol were found throughout the whole 48 h of the experiment after its intraventricular administration into the left lateral ventricle of conscious cats. Acknowledgernent-This work was supported by a grant from the Scientific Fund of the SR of Serbia (Z.M.N.U.), Beograd, Yugoslavia. Department of Pharmacology, D. B. BELESLIN Medical Faculty, and N. M. STOJANOVIC Department of Chemistry, LJILJANA DIMITRIJEVIC F a u l t y of Veterinary Medicine, Beograd, P.U. Box 662, Yugoslavia

REFERENCES AGHAJANIAN G. K. & BLOOMF. E. (1967) J . Pharmac. exp. Ther. 156, 23-30. ANDJELKOVLCD., BELESLIN D. B. & V A S R. ~ V. (1971). J . pharm. Pharmac. 23, 984985. BELESLrN D, B., STOJANOVIC N. M. & DIMITRIJEVIC' LJ. (1975) J . Neurochem. 24, 837-838. DAVISOK A. N.. DOURJNG J., MORGAN R. S. & PAYLING WRIGHTG. (1968) J. Neurochem. 3, 89-93. DAVISON A. N., DOBBING J., MORGAN R . S. & PAYLING WRIGHTG. (1959) Lancet i, 658-660. A. N. & WAJDAM. (1959) Nature, Lond. 183, DAVISON 1606- 1607. DRASKOCI M., FELDBERG W., FLEISCHAUER K. & HARANATH P.S.R.K. (1960). J . Physiol.. Lond. 150, 5Ck66. FELDRERG W. & SHERWOOD S. L. (1953) J. Physio!., Lond. 120, 34P. FOLCH-PI.J., LEESM. & SLOANE-STANLEY G. H. (1957) J . hiol. Chem. 226, 497-509.

Further studies on the distribution of (4-14C)cholesterol in the brain tissue after its intraventricular injection into conscious cats.

Journal of Neurocken~im-~. 1976. Val. 26, pp. 643445.Pergamon Press. Printed in Great Brrta,n SHORT COMMUNICATION Further studies on the distribution...
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