1036

Specialia

were utilized. The e x p e r i m e n t s were i n i t i a t e d b e t w e e n 08.15-09.15 h. T h e a n t e r i o r pituitaries, f r o m w h i c h t h e p o s t e r i o r a n d i n t e r m e d i a r y lobes were r e m o v e d , were s e p a r a t e d into identical halves. 3 p i t u i t a r y h a l v e s were used in e a c h g r o u p a n d t h e r e were 4-6 groups in each determination. T h e tissues were i n c u b a t e d , w i t h shaking, for 60 m i n a t 37~ in a n a t m o s p h e r e of 5% CO2-95~ O 2 in 1.0 1111 of K r e b s R i n g e r b i c a r b o n a t e b u f f e r c o n t a i n i n g 11 m M I)glucoseS7. T h e i n c u b a t i o n m e d i u m was t h e n r e p l a c e d b y fresh b u f f e r a n d glucose a n d t h e s o m a t o s t a t i n analogue was a d d e d as i n d i c a t e d in t h e Table. I n t h e p r e s e n t studies, a f t e r a f u r t h e r 2 m i n i n c u b a t i o n , 20 p.1 vehicle or PGE2 (1 • 10 -6 M) was a d d e d for t h e i n c u b a t i o n p e r i o d of 4 min. T h e vehicle e m p l o y e d for t h e PGE~ was 0.1 ml e t h a n o l , 0.1 m l s o d i u m c a r b o n a t e (1.8 mg/mI) a n d 0.8 ml w a t e r . F o r t h e a s s a y of t h e cyclic AMP, t h e cyclic A M P was e x t r a c t e d f r o m t h e tissues w i t h 5% t r i c h l o r o a c e t i c acid a n d m e a s u r e d b y t h e r e c e p t o r - b i n d i n g a s s a y of GILMAN 19 utilizing 10 lag of p r o t e i n of t h e i n h i b i t o r a n d f p.g of r e c e p t o r p r e p a r a t i o n (P-5511, Sigma Chemical Co.). [8-aH]-eyclic A M P ( S c h w a r z - M a n n Co.; 28 Ci/mole) was e m p l o y e d a t a final c o n c e n t r a t i o n of 40 riM. U n l a b e l l e d cyclic A M P was o b t a i n e d f r o m Calbiochem Co. Assays were p e r f o r m e d in triplicate. A f t e r filtration, t h e filters were dried a n d 10 m l t o l u e n e - p h o s p h o r ~0.4% 2,5-dip h e n y l o x a z o l e a n d 0.005%, 1,4-bis (5-phenyloxazole-2yl)benzene] e m p l o y e d for scintillation counting. Results and discussion. S o m a t o s t a t i n , 1 • -7 ~I, i n h i b i t e d b y 50% t h e a d e n o h y p o p h y s e a l cyclic A M P a c c u m u l a t i o n i n d u c e d b y PGE2; a t t h e lower level of 0.2• -7 M t h e i n h i b i t i o n was d e c r e a s e d (Table). Similar i n h i b i t o r y activities a t t h e s e c o n c e n t r a t i o n s were o b s e r v e d w i t h t h e Edesaminol~-, [desamino*Jldescarboxyl4~ - a n d [D-Lys4~-somatostatin analogues; t h e [descarboxy~4~-somatostatin was effective a t 5 • 10 -7 M . The [D-Lysg?-somatostatin analogue did n o t cause an alterat i o n in t h e cyclic A M P a c c u m u l a t i o n even a t 5 • 10-7 M .

EXPERIENTIA 32/8

S o m a t o s t a t i n a t 1 x 10 -7 M did n o t cause a n y a p p r e ciable c h a n g e in t h e b a s a l cyclic A M P a c c u m u l a t i o n nor did a n y of t h e a b o v e analogues a t 5 • 10 -7 M (e.g., c o n t r o l : 5.7 -~ 0.7 ; s o m a t o s t a t i n : 5.0 ~ 0.8 ; D - L y s ~ - s o m a t o s t a t i n : 5.2 • 0.3 p m o l e s cyclic A M P / a n t e r i o r p i t u i t a r y ~ SE). These results i n d i c a t e t h a t , in r e g a r d t o t h e s t r u c t u r e a c t i v i t y r e l a t i o n s h i p of t h e analogues, t h e t e r m i n a l a m i n o g r o u p does n o t a p p e a r t o be of i m p o r t a n c e for t h e inh i b i t o r y a c t i v i t y on t h e P G E ~ - i n d u c e d cyclic A M P acc u m u l a t i o n ; e l i m i n a t i o n of t h e t e r m i n a l c a r b o x y l g r o u p results in an analogue e x h i b i t i n g r e d u c e d a c t i v i t y . B o t h groups m a y be e l i m i n a t e d w i t h o u t altering t h e i n h i b i t o r y activity. Further, the configuration at the asymmetric c e n t e r of t h e lysyl m o i e t y a t p o s i t i o n 4 is i r r e l e v a n t since t h e [D-Lys ~]-analogue e x h i b i t e d a similar activity. I n cont r a s t , t h e c o n f i g u r a t i o n a t t h e a s y m m e t r i c c e n t e r of t h e lysyl m o i e t y a t p o s i t i o n 9 is of i m p o r t a n c e since t h e EDL y s "I-analogue did n o t e x h i b i t t h e i n h i b i t o r y a c t i v i t y even a t a h i g h e r level. S o m a t o s t a t i n e x h i b i t s a wide s p e c t r u m of s u p p r e s s o r a c t i o n on h o r m o n a l release in v a r i o u s species. I n a d d i t i o n t o an effect on g r o w t h h o r m o n e a n d t h y r o t r o p i n , s o m a t o s t a t i n also shows e x t r a p i t u i t a r y a c t i o n s in i n h i b i t i n g t h e release of insulin, g l u c a g o n a n d g a s t r i n 20. I n v i e w of t h e p r e s e n t findings, t h e effects of t h e s o m a t o s t a t i n analogues o n tile release of g r o w t h h o r m o n e , a n d o t h e r h o r m o n e s , are of interest. I n t h i s r e g a r d g e n e r a l l y similar relative a c t i v i t i e s as f o u n d in t h e p r e s e n t s t u d y h a v e b e e n obs e r v e d w i t h t h e analogues w i t h r e s p e c t to t h e i r abiIities to i n h i b i t basal gastric acid secretion in t h e u n a n e s t h e t i z e d r a t 2~. 19 A. G. GILMAN,Proc. natn. Acad. Sei., USA 67, 305 (1970). ~0 A. GO~aEz-PAN,J. D. REED, M. AImlNUS, B. SHAW, R. HALL, G. M. BESSER, D. H. Co'G A. J. KASTIN and A. V. SCHALLY,Lancet 1, 888 (1975). 21 W. LIPPMANN and L. E. ]~ORELLA,Pharmac. Res. Commun., in press.

T h e S e d a t i v e Effects of N i c o t i n a m i d e on G e r b i l W h e e l - R u n n i n g A c t i v i t y ~ J. M. B E A T O N

Neurosciences Program and Department o/ Psychiatry, University o/ Alabama Medical Center, University Station, Birmingham (Alabama 3529d, USA), 2 February 1976. Summary. The a c t i v i t y of 5 groups of gerbils was m o n i t o r e d over 22 days. 3 of t h e g r o u p s r e c e i v e d d a i l y i n j e c t i o n s of n i c o t i n a m i d e (125, 250 or 500 mg/kg) a n d a 4 t h g r o u p received saline. The 5th g r o u p was u n t r e a t e d . The r e s u l t s ind i c a t e d t h a t b o t h t h e 250 a n d 500 m g / k g n i c o t i n a m i d e a d m i n i s t r a t i o n s g r e a t l y r e d u c e d t h e a c t i v i t y levels of t h e gerbils. B e a a : o x e t al. 2 h a v e p r e v i o u s l y r e p o r t e d t h a t t h e adm i n i s t r a t i o n of 250 m g / k g n i c o t i n a m i d e to mice r e s u l t e d in a s i g n i f i c a n t increase in t h e a m o u n t of p a r a d o x i c a l or r a p i d eye m o v e m e n t sleep. WOOLLEY a h a d o b s e r v e d t h a t n i c o t i n a m i d e a d m i n i s t r a t i o n a p p e a r e d to i n d u c e s e d a t i o n in mice. This was l a t e r c o n f i r m e d 4 in r a t s using t h e Anim a x m o t i l i t y m e t e r , h o w e v e r t h e dosage used in t h e s e s t u d i e s w a s 1 g/kg. The p r e s e n t s t u d y describes t h e effects of lower doses of n i c o t i n a m i d e on gerbil a c t i v i t y . Methods. 25 adult, male gerbils w e i g h i n g b e t w e e n 55 a n d 65 g w e r e used. T h e gerbils were h o u s e d singly in a s o u n d - a t t e n u a t e d r o o m w h i c h h a d a reverse 12 h l i g h t / d a r k cycle. T h e lights were off f r o m 06.00 18.00 h. E a c h a n i m a l was given access to a L a f a y e t t e I n s t r u m e n t Comp a n y R u n n i n g Wheel, w i t h a c i r c u m f e r e n c e of 1.1 m e t e r s , for 30 mill on 2 c o n s e c u t i v e h a b i t u a t i o n sessions on w h i c h no d a t a were recorded. T h e a n i m a l s were given a f u r t h e r

6 p r e - s t u d y sessions t o d e t e r m i n e a baseline level of r u n n ing w h e e l activity. T h e s e sessions were on t h e M o n d a y , W e d n e s d a y a n d F r i d a y of t h e 2 weeks p r e c e e d i n g t h e s t u d y . The n u m b e r of w h e e l r e v o l u t i o n s per a n i m a l per session was n o t e d e a c h day. The t o t a l n u m b e r of wheel r e v o l u t i o n s per a n i m a l was c a l c u l a t e d over all 6 pres t u d y sessions. On t h e basis of t h e s e d a t a t h e gerbils were d i v i d e d into 5 e q u a l groups w h i c h were m a t c h e d on t h e level of wheel r u n n i n g a c t i v i t y .

1 This work was supported in part by FacuIty Research Grant No. 82-6209 from the University of Alabama in Birmingham to J.M.B. J. M. BEATON,G. V. PEeRAge, J. R. SMYTHIESand R. J. BRADLZY, Experientia 30, 926 {1974). a D. W. WOOLLEY, Scieuee 128, 1277 (1958). B. SCHZRERand W. KRA~aER, Life Sci. 11, Part I, 189 (1972).

15. 8. 1976

Speeialia

1037

Table I. The mean and standard deviation for the number of wheel turns per group of gerbils per session Baseline

Pre-study Day1 Day3 Day8 Day 10 Day 15 Day 17 Day 22

Saline

361.9• 408.3~117 445.7J=138 446.1~109 431.4i133 522.64-130 428.2~=126 550.6n~i38

363.9~114 427.1xL 98 503.9-E 83 4 9 2 . 2 ~ 65 462.2n~ 78 5 2 5 . 4 ~ 51 4 5 2 . 0 ~ 84 506.2~= 93

Table II. The percentage change from the untreated baseline for the saline and nicotinamide groups Saline

Pre-study Day 1 Day 3 Day 8 Day 10 Day 15 Day 17 Day 22

Nicotinamide

100 105 113 110 107 101 106 92

125 mg/kg

250 mg/kg 500 mg/kg

100 66 68 98 116 105 116 97

99 69 80 81 90 90 86 67

100 69 87 68 65 55 80 59

Table III. The percentage difference between the nicotinamide treatments and the saline control

Day Day Day Day Day Day Day

I 3 8 10 15 17 22

125 ing/kg

250 mg/kg

500 mg/kg

---+ + + +

-------

-- 36 -- 26 -- 42 42 46 -- 26 -- 33

39 45 12 9 4 10 5

36 33 29 17 11 20 25

-

-

Because earlier studies with gerbils (unpublished data) h a v e s h o w n t h a t t h e b a s e l i n e l e v e l of a c t i v i t y s h i f t s e v e n a f t e r 20 s e s s i o n s , it w a s d e c i d e d t o i n c l u d e 1 g r o u p of gerbils to which no treatments were to be administered (baseline group). The 4 other groups consisted of a saline injected group and 3 nicotinamide groups (treated with 125, 250 a n d 500 m g / k g n i c o t i n a m i d e ) . T h e p H of all nicotinamide solutions was adjusted to approximately 7.4. A l l i n j e c t i o n s w e r e i n a v o l u m e of 0.1 m l / 2 0 g a n d w e r e g i v e n i.p. 30 m i n b e f o r e t h e a n i m a l s w e r e p l a c e d in the wheel. The baseline group was handled at this time. T h e a n i m a l s w e r e ruI1 in t h e w h e e l o n d a y s 1, 3, 8, 10, 15, 17 a n d 22, b u t w e r e i n j e c t e d d a i l y . T h e t o t a l n m n b e r of w h e e l r e v o l u t i o n s p e r 30 m i n s e s s i o n w a s n o t e d f o r each animal. Results. T h e m e a n a n d s t a n d a r d d e v i a t i o n w e r e calculated for each group for each data collection day and t h e s e d a t a a r e s h o w n i n T a b l e I. T h e s t a n d a r d d e v i a t i o n s are relatively large because of the small number of

Nicotinamide 125 mg/kg

250 ing/kg

500 mg/kg

360.5~-121 269.9=L 80 305.1=~170 438.9=c161 499.8=k112 550.3i118 497.0_-}z160 531.9:t=170

355.0~109 280.6-j=139 356.6i191 360.3i175 387.1-t=152 472.2~=116 369.5~144 366.6~b140

361.0~=104 280.0~-104 386.3~113 302.2~134 281.4• 285.4i113 343.6~134 322.41122

s u b j e c t s in e a c h g r o u p . A s w a s n o t e d i n t h e M e t h o d s section we have previously observed that the baseline shifts over time with this measurement. The data were t h e r e f o r e r e c a l c u l a t e d a n d e x p r e s s e d a s p e r c e n t a g e s of t h e untreated baseline group. These data are shown in Table II. Table III shows the percentage difference between the saline and nicotinamide treated groups. I t is q u i t e o b v i o u s f r o m T a b l e s I I a n d I I I t h a t t h e a d m i n i s t r a t i o n of 250 a n d 500 m g / k g n i c o t i n a m i d e resulted in decreased wheel-running rates. The lowest dosage of nicotinamide, although inducing an initial dec r e a s e in a c t i v i t y , w a s i n a c t i v e . Discussion. M u c h c o n t r o v e r s y s u r r o u n d s t h e u s e of n i a c i n in t h e t r e a t m e n t of s c h i z o p h r e n i a . H O r F E R 5 a n d his associates have repeatedly reported the effectiveness of n i c o t i n i c a c i d i n t h e t r e a t m e n t of s c h i z o p h r e n i a ; h o w e v e r , m a n y o t h e r i n v e s t i g a t o r s h a v e f a i l e d t o do so ( t h e s e s t u d i e s a r e r e v i e w e d b y W'ZATT e t al.6). N i c o t i n a m i d e w a s u s e d t h e r a p e u t i c a l l y b e c a u s e of i t s a l l e g e d role a s a m e t h y l g r o u p a c c e p t o r . H o w e v e r , it h a s n o t b e e n s h o w n that nicotinic acid can reverse the exacerbations observed in s c h i z o p h r e n i c s a f t e r t h e a d m i n i s t r a t i o n of m e t h i o n i n e ~, n o r is t h e r e a n y r e p o r t e d e v i d e n c e t h a t it i m p a i r s t h e m e t h y l a t i o n c a p a c i t y of t h e b o d y . F u r t h e r m o r e , B&LDESSARINI 8 r e p o r t e d t h a t n i c o t i n a m i d e is n o t a g o o d methyl group acceptor in the rat and does not lower levels of S - a d e n o s y l m e t h i o n i n e . We have previously observed that nicotinamide alters t h e s l e e p w a k e c y c l e s of m i c e s u c h t h a t t h e p e r c e n t a g e of rapid eye movement sleep increased significantly. Also WOO]LLEY a a n d o t h e r s ~ h a v e n o t e d a s e d a t i v e e f f e c t in m i c e a n d r a t s a f t e r t h e a d m i n i s t r a t i o n of n i c o t i n a m i d e . This present study shows quite clearly a marked decrease in w h e e l - r u n n i n g a c t i v i t y in g e r b i l s a f t e r 250 a n d 500 m g / k g of n i c o t i n a m i d e . T h e r e f o r e , n i c o t i n a m i d e m u s t h a v e c e n t r a l e f f e c t s u n r e l a t e d t o i t s role as a v i t a m i n . T h e d e g r e e t o w h i c h t h e t h e r a p e u t i c e f f e c t s of n i a c i n a r e r e l a t e d t o t h e o b s e r v e d s e d a t i v e e f f e c t s a r e w o r t h y of f u r t h e r investigation.

5 A. HOFF~R, Nic~cin Therapy ~;1r Schizophre~ia (C. C. Thomas, Springfield, Illinois 1962). 6 R. J. WYATT, B. A. TERMIni and J. DAVIS, Schizophrenia Bull. 4, 10 (1971). T. A. BAN, H. F~. LEHMANN and A. I~LINGER, Int. J. olin. Pharmac. Ther. Tox. 7, 44 (1973).s R. J. BALD~SSAmNI, Bioehem. Pharmae. 15, 741 (1965).