Specialia

1190

F~XPERIENTIA 31/i0

Discussion. Quelle q u e soft la m 4 t h o d e utilis6e p o u r la p r 6 p a r a t i o n des s y n a p t o s o m e s o n a v a i t c o n s t a t 4 u n c e r t a i n degr4 de c o n t a m i n a t i o n p a r les m i t o c h o n d r i e s de diff4rentes tailles. L a pr6sence de lysosomes n ' a v a i t p a s 4t6 m e n t i o n n 4 e j u s q u ' i c i . Nos r 4 s u l t a t s m o n t r e n t u n e c o n t a m i n a t i o n i m p o r t a n t e de la f r a c t i o n s y n a p t o s o m a l e p a r des lysosomes i n t a c t s .

n a t e d b y lysosomes, as e v i d e n c e d b y t h e h i g h c o n t e n t of acid p h o s p h a t a s e , t h e i r b i o c h e m i c a l m a r k e r .

Summary. S u b c e l l u l a r fraction, e n r i c h e d w i t h s y n a p t o somes, o b t a i n e d f r o m r a t b r a i n h a s b e e n f o u n d c o n t a m i -

Departement de Biochimie, C.H.U. Henri Mondor, F-94010 Creteil Cedex (France), 26 mai 7975.

Reduction L-Dopa

of Hypoxia-Induced

Disturbances

by Previous

Treatment

with

Benserazide

and

in Rats

I m p r o v e m e n t of t h e p e r f o r m a n c e s d u r i n g h y p o x i a a f t e r t r e a t m e n t b y a n i n h i b i t o r of d o p a - d e c a r b o x y l a s e (benserazide) a n d L-Dopa s t r o n g l y suggests a role of c a t e c h o l a m i n e s 1. C e n t r a l c a t e c h o l a m i n e s m a y a l t e r e i t h e r c e r e b r a l b l o o d flow a n d / o r v e g e t a t i v e r e s p o n s e s i n d u c e d b y h y p o x i a , since t h e s e c a t e c h o l a m i n e s are k n o w n t o i n h i b i t c e n t r a l pressor effects p r o v o k e d b y s t i m u l a t i o n of c a r o t i d sinus 2,3. I n t h i s s t u d y , we a t t e m p t e d t o d e t e r m i n e w h e t h e r h y p o x i a causes a n y m o d i f i c a t i o n of c e r e b r a l b l o o d flow e s t i m a t e d b y r h e o e n c e p h a l o g r a p h y , of s p o n t a n e o u s m o t i l i t y , a n d level of c e r e b r a l c a t e c h o l a mines. Methods. L o n g E v a n s female rats, 3 m o n t h s old, were used. E v e r y m e a s u r e m e n t was p e r f o r m e d in a n h y p o b a r i c c h a m b e r . E a c h p a r a m e t e r (pO2, pCO2, p H , r h e o e n c e phalogramm, motility, central dopamine and norepinep h r i n e ) was r e g i s t e r e d a t 760 m m Hg, t h e n a t a p r e s s u r e of 500 m m I-Ig (4200 m), l a t e r o n a t 300 m m H g (7300 m) oo

a) 10 mg

m

J. c. KOUYOUMDJIAN, L. E. A. I~.ODRIGUES, M. F. BELIN et P. G O N N A R D

~

h

eoencephalogramm

4 b) .....

140 mmHg 12e

treated animals IDC + L- Dopa (100 m9 / kg)

untreated animals

/

"x'X, 80 60

/

"~Xo

/"

//i/"

"

/

,oi 760

pa 0 2

a n d f i n a l l y w h e n b a c k to a t m o s p h e r i c pressure. E a c h e x p e r i m e n t s t a r t e d 1 h a f t e r a d m i n i s t r a t i o n of L-Dopa. 2 g r o u p s were s t u d i e d : a c o n t r o l one (NaCI 0.9%) a n d a t r e a t e d one (RO 4 4.602 : 50 m g / k g i.p., L-Dopa 100 m g / k g i.p. 1 h later). E a c h a n i m a l ' s m o t i l i t y was r e c o r d e d b y a p h o t o e l e c t r i c a c t i m e t e r . C e r e b r a l flow was r e g i s t e r e d in a n a e s t h e t i z e d r a t s ( p e n t o b a r b i t o n e 35 m g / k g i.p.) b y m e a n s of i m p e d a n c e p l e t h y s m o g r a p h y w i t h 2 electrodes fixed o n temples. S i m u l t a n e o u s l y , h e a r t r a t e was r e c o r d e d (ECG); pO2, pCO 2, p H were r e g i s t e r e d in a r t e r i a l aortic b l o o d of a n a e s t h e t i z e d rats. Results and discussion. I n c o n t r o l animals, m e a s u r e m e n t s of b l o o d p a r a m e t e r s s h o w e d t h a t t h e d i m i n u t i o n of p r e s s u r e c h o s e n (300 m m Hg) i n d u c e d a sufficient h y p o x e m i a (45 m m Hg) w i t h o u t a n y m o d i f i c a t i o n of pCO 2. Therefore, a n o r m o c a p n i c h y p o x e m i a h a s b e e n realised a n d a n i n f l u e n c e of possible c h a n g e s of CO 2 o n c e r e b r a l b l o o d flow seems to b e r u l e d out. B u t it is i m p o r t a n t t o n o t i c e t h a t t h e b l o o d gas v a l u e s are n o t c h a n g e d a f t e r t r e a t m e n t b y b e n s e r a z i d e a n d L-Dopa. T h u s , t h e h y p o t h e s i s of a n i n t e r a c t i o n of t h e t r e a t m e n t u p o n a n i m a l ' s v e n t i l a t i o n c a n b e rejected. I n t h e c o n t r o l group, h y p o x i a i n d u c e d a n e l e v a t i o n of t h e r h e o e n c e p h a l o g r a m m w i t h o u t a n y c h a n g e in h e a r t rate. T h e r e t u r n t o a t m o s p h e r i c p r e s s u r e p r o v o k e d a n increase of p O 2 a n d a decrease of r h e 0 e n c e p h a l o g r a m m w h i c h r e a c h e d a lower v a l u e t h a n t h e initial one. P r e t r e a t e d a n i m a l s ( b e n s e r a z i d e + L-Dopa 100 m g / k g i.p.) s h o w v e r y d i f f e r e n t h e m o d y n a m i c m o d i f i c a t i 6 n s (Figure 1): t h e s e a n i m a l s ' r h e o e n c e p h a l o g r a m m s were u n c h a n g e d . Therefore, a d m i n i s t r a t i o n of b e n s e r a z i d e a n d L-Dopa a p p e a r e d t o a b o l i s h i n t e r a c t i o n s of h y p o x i a on c e r e b r a l b l o o d flow. I t seems to w o r k as if L-Dopa i n h i b i t ed t h e c h e m o r e c e p t o r s 2, s. A d m i n i s t r a t i o n of b e n s e r a z i d e a n d L-Dopa i n d u c e d a d i m i n u t i o n of m o t i l i t y , w h i c h is n o t o b s e r v e d *, 5 a f t e r t r e a t m e n t b y b e n s e r a z i d e alone. A r e d u c t i o n of m o t i l i t y is also p r o v o k e d b y h y p o x i a alone. T h e decrease in t h e r e d u c t i o n of m o t i l i t y a f t e r h y p o x i a in p r e t r e a t e d r a t s (benserazide a n d L-Dopa) m i g h t b e a s c r i b e d to t h e c e n t r a l effects of L-Dopa 1 (Figure 2).

CO, 500

300

760 mmHg

Fig. 1. a) surface of rheoencephalogramms 4- SE (rag of paper) measured at variable pressures (760, 500, 300 m m Hg and back to 760 mm Hg) (10 animals per group), b) pO z and pCO2 at he same different values of pressure, o p < 0.05. oop < 0.01 (statistical significance calculated by appared couple method and t-test inside).

1 R. BROWN, J. N. DAVISand A. CARLSSON,J. pharmac. Pharmacol. 25, 412 (1973). 2 H. SCHMITT, H. SCHMITT and S. FENARD, Eur. J. Pharmac. 17, 293 (1972). s A. IV[. WATANABEand P. V. CARDON, Circulation 44, 93 (1971). 4 M. GOUGE% P. SIMON, R. CH~RMATand J. P. ]3OISSIER,J. Pharmac., Paris 5, 387 (1974). 5 F. BOISMARE, J. LORENZO, P. LECHAT and N. LETTERON, J.

Pharmac. Fr. 5, 5 (1974).

15. 10. 1975

1191

Speeialia

Dopamine and norepinephrine brain levels (ng/g of brain) at 760 mm Hg, 300 mm Hg and return to 760 mm Hg Treatment

760 mm Hg DA

Control group Treated animals (benserazide 50 mg/kg and L-Dopa 100 mg/kg}

300 mm Hg NE

242•

58

3488~648

DA

Return to 760 mm Hg NE

554-10

2274- 43

523_14

2994-60

1551oc566~

196~780

DA 263~: 65

21352k700

NE 36:~

9

296-~106

~p < 0.05 (difference between levels at 760 and 300 mm Hg).

a)

15

Activity 10 OO

5 .E

E

oo

0

o= 100- ~ , , ..E % L.~ 75

b)

.....

treated animals IDC + L-Dopa (100mg/kg) untreated animals

S u m m a r y . P r e t r e a t m e n t b y b e n s e r a z i d e (50 m g / k g i.p.) a n d L - D o p a (100 m g / k g i.p.) in r a t s i n d u c e s a r e d u c t i o n of t h e d i m i n u t i o n of m o t i l i t y a f t e r h y p o x i a a n d a s t a b i l i z a t i o n of c e r e b r a l blood flow d u r i n g a n d a f t e r h y p o x i a . A n o v e r l o a d of c e r e b r a l d o p a m i n e a n d n o r e p i n e p h r i n e s e e m s to be t h e o r i g i n a l p r o c e s s of t h i s p h e n o m e n o n .

50 25

In control animals, dopamine and norepinephrine c e n t r a l levels are u n c h a n g e d b y h y p o x i a or r e t u r n t o a t m o s p h e r i c p r e s s u r e (Table) a c c o r d i n g to p r e v i o u s r e s u l t s 6. I n t r e a t e d a n i m a l s , t h e d o p a m i n e level falls d o w n d u r i n g a n d h y p o x i a a n d t h e n o r e p i n e p h r i n e level c o m e s b a c k to its initial v a l u e s a f t e r r e t u r n to a t m o s p h e r i c p r e s s u r e . T h i s h i g h level of n o r e p i n e p h r i n e d u r i n g p o s t - h y p o x i c period is p r o b a b l y r e s p o n s i b l e for r e t u r n go initial v a l u e of t h e motilityT. T h e r e s u l t s of t r e a t m e n t b y b e n s e r a z i d e a n d L - D o p a i n d i c a t e a s t a b i l i z a t i o n of t h e r h e o e n c e p h a l o g r a m m a n d a d e c r e a s e in t h e r e d u c t i o n of s p o n t a n e o u s m o t i l i t y i n d u c e d b y h y p o x i a . O v e r d o s e s of c e r e b r a l d o p a m i n e a n d n o r e p i n e p h r i n e s e e m to be t h e origin of these phenomenons.

"-Q2---

F. BOISMARE. ),~. LE PONClN, J. p. BELLIARD a n d L. HACPILLE J

760

2

500

--//

300

#

760 mm Hg

Fig. 2. Spontaneous activity measured at different pressures (10 animals per group), a) The parameters are represented in couuts/min (-J- SE). op < 0.05. oop .4 0.01 (appared couples arid t-test), b) The parameter was represented in percent of its initial value.

Prostaglandin-Induced

Department o/Pharmacology, Hdtel-Diezt, rue de Lecat, F - 7 6 0 3 6 Rouen (France), 5 December 797,I. J. N. DAVIS and A. CARLSSON, J. Neurochcm. 2?, 783 t1973). 7 T. H. SVENSSONand B. WALnECK,Fmr. J. Pharmae. 7, 278 (1969).

Choleresis in the Rat

A l t h o u g h p r o s t a g l a n d i n s (PG) affect m a n y biological processes, P G E 2 failed to a l t e r bile flow in t h e d o g ~ a n d in t h e i s o l a t e d p e r f u s e d r a t liver 2. I n v i e w of i t s ATlPase i n h i b i t o r y p r o p e r t i e s a a n d t h e h y p o t h e t i c a l role of N a + K + - A T P a s e in bile f o r m a t i o n *, P G A~ w o u l d a p p e a r to be a m o r e likely c a n d i d a t e to i n f l u e n c e bile secretion. T h e effect of P G A I on bile flow was, t h e r e f o r e , s t u d i e d in anesthetized rats. The results d e m o n s t r a t e t h a t intrap o r t a l i n f u s i o n of P G A~ s i g n i f i c a n t l y i n c r e a s e s bile s a l t i n d e p e n d e n t bile f o r m a t i o n . Materials and methods. S t u d i e s were p e r f o r m e d in 6 m a l e W i s t a r r a t s w e i g h i n g 232 t o 263 g w h i c h h a d free access t o food ( A l t r o m i n IR) a n d w a t e r . U n d e r p e n t o b a r b i t a l a n e s t h e s i a (5 m g / 1 0 0 g, i.p.) t h e f e m o r a l v e i n a n d a r t e r y were c a n n u l a t e d w i t h P E 50 p o l y e t h y l e n e t u b i n g for i n f u s i o n of t a u r o c h o l a t e or s a l i n e a n d r e c o r d i n g of t h e b l o o d p r e s s u r e , r e s p e c t i v e l y . F r o m a m i d l i n e incision t h e c o m m o n bile d u c t w a s c a n n u l a t e d w i t h P E 10 t u b i n g j u s t below t h e b i f u r c a t i o n in o r d e r to p r e v e n t

d r a i n a g e of p a n c r e a t i c secretion. Bile w a s collected in 10 m i n p e r i o d s a n d w e i g h e d . F o r t h e i n f u s i o n of P G A 1, P E 10 c a t h e t e r w a s i n s e r t e d i n t o t h e p o r t a l v e i n v i a t h e g a s t r o d u o d e n a l vein. A f t e r a c o n t r o l p e r i o d of 30 r a i n d u r i n g w h i c h 0 . 9 % NaC1 (3.3 m l / h ) w a s i n f u s e d i n t o t h e p o r t a l vein, a s o l u t i o n of P G A t w a s i n f u s e d for 30 r a i n a t a s i m i l a r r a t e in a c o n c e n t r a t i o n y i e l d i n g 1 [,g P G A1/ m i n / 1 0 0 g b o d y wt. T h e p o r t a l v e i n w a s c h o s e n as t h e

1 j. SOKOLO~Fand R. N. BERK, Invest. Radiol. 8, 9 (1973). R. A. LE'V~NE, ir~ Prostaglandins and Cyclic A M P (Eds. R. H. KAIIN and W. E. M. LANDS; Academic Press, New York, London 1973), p. 75. a J. j. LAFFERTY, H. KANNEGIESSER,J. B. LEE and L.W. PARKER, in Advances in the Bioscienees (Eds. G. •ASPE and S. BERNHARD; Pergamon Press, Vieweg, Germany 1972), vol. 9, p. 293. 4 S. ERLINGER, in Progress in Liver Diseases (Eds. H. POPPER and F. SCHAFFNER; Grune and Stratton, New York, London 1972), p. 63.