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Brain catecholaminergic system is involved in a secondary oscillation system in the rat circadian organization
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BRAIN CATECHOLAMINERGIC SYSTEM IS INVOLVED IN A SECONDARY OSCILLATION SYSTEM IN THE RAT CIRCADIAN ORGANIZATION. KEN-ICHI HONMA, MASATO MITOME, TOSHIHIRO YOSHIHARA, SATO HONMA, AND TSUTOMU HIROSHIGE L Department
o_ff P h y s i o l o g y , Hokkaldo U n i v e r s i t y School of Medicine, Sapporo 060, P e r i o d i c food p r e s e n t a t i o n induces a s e l f - s u s t a i n e d o s c i l l a t i o n which i s e x p r e s s e d most c l e a r l y in p r e f e e d l n g a c t i v i t i e s of many v a r l a b I e s . The f e e d i n g - a s s o c i a t e d o s c l l i a t l o n has a c i r c a d i a n n a t u r e but i s independent of the c i r c a d i a n pacemaker l o c a t e d i n t he s u p r a c h i a s m a t i c n u c l e u s . Howe v e r , n e i t h e r the s i t e of t h l s o s c i l l a t i o n nor i t s c e n t r a l mechanism i s known. P r e v i o u s l y we demonstrated the s p e c i f i c Involvement of the b r a i n e a t e c h o l a ~ l n e r g l c system i n t he e x p r e s s i o n of p r e f e e d i n g c o r t l c o s t e r o n e peak in r a t s . The p r e s e n t s t u d y was c a r r i e d out to examine whether t he c a t e c h o l a m l n e r g l c system i s i n v o l v e d in the o s c i l l a t i o n i t s e l f . AI1 e x p e r i m e n t s were performed under a l i g h t - d a r k c y c l e . Male r a t s of the W l s t a r s t r a i n were s u b j e c t e d to p e r l o d l c f e e d i n g f o r 2 to 3 weeks with f r e e - a c c e s s to food from 10 to 14 hours d a i l y . Then r a t s were r e t u r n e d t o a d l i b i t u m f e e d i n g f o r 7 days. 6-hydroxydopamlne (0.25mg) or p h y s i o l o g i c a l s a l i n e was i n j e c t e d i n t o the l a t e r a l v e n t r i c l e under p e n t o b a r b i t a l a n e s t h e s i a . From 4 days l a t e r , r a t s were f a s t e d f o r 3 days. Wheel-running, f e e d i n g , and d r i n k i n g a c t i v i t i e s were measured c o n t i n u o u s l y . As a r e s u l t , p r e f e e d l n g peaks in t h e s e a c t i v i t i e s reappeared d u r i n g f a s t i n g i n s a l i n e - t r e a t e d r a t s , w h i l e t he y were not observed In 6-OHDA-treated r a t s . 6-OHDA d i d not a f f e c t c i r c a d i a n a c t i v i t y rhythms. I t i s concluded t h a t the b r a i n c a t e c h o l a m l n e r g l c system i s i n v o l v e d not onl y In the p r e f e e d l n g c o r t l c o s t e r o n e peak but a l s o in the e x p r e s s i o n of o s c i l l a t i o n or in t he o s c i l l a t i o n i t s e l f .
ENTRAINMENT OF CIRCADIAN BEHAVIORAL RHYTHMS TO THE LIGHT INTENSITY CYCLE OF A DESCENDING SAWTOOTH WAVE (ST-d) IN RATS. SETSUO USUI* AND YASURO TAKAHASHI. Department Of Psycholozy, Tgk~o
H e t r o v o l i t a n I n s t i t u t e f o r Neurosciences, 2-6 Musashidai, Fuehu. Tokyo 18~, Japan. In ou~ p r i o r work, we could not a s c e r t a i n e n t r a i n m e n t of c i r c a d i a n rhythms d u r i n g 28 d a y s ' exposure to the ST-d c y c l e , in which i l l u m i n a n c e was r e c t i l i n e a r l y d e c r e a s e d 300 lux t o 0 lux in a 24 h period, and then immediately r e t u r n e d to 300 lux. In the p r e s e n t study, d u r i n g 65 days of the ST-d c y c l e , ambulation, d r i n k i n g , and subcutaneous t e m p e r a t u r e were c o n t i n u o u s l y monitored in 10 male Sprague-Oawley r a t s . T h e r e a f t e r , the r a t s were r e l e a s e d i n t o c o n s t a n t d a r k n e s s (DD), and exposed to a s i n g l e ST-d c y c l e once every 2-3 weeks, and phase s h i f t s of t he c i r c a d i a n rhythms e l i c i t e d by the ST-d s t i m u l u s were measured to c o n s t r u c t a phase re s pons e curve (PRC). In most of the cases, t h e c i r c a d i a n rhythms of b e h a v i o r s and body t e m p e r a t u r e were e n t r a i n e d t o the ST-d cy cle, and f r e e - r a n a f t e r r e l e a s e i n t o DD. The e n t r a i n m e n t to a 24 h p e r i o d was a l s o confirmed by the c h i - s q u a r e periodogram. However, the onset of t he a c t i v i t y p e r i o d became u n c l e a r , and t he phases of the e n t r a i n e d c i r c a d i a n rhythms were u n s t a b l e throughout t he 65 days of ST-d. The s u b j e c t i v e n i g h t s of r a t s d u r i n g the ST-d e s t i m a t e d by backward e x t r a p o l a t i o n from t he a c t i v i t y p e r i o d s of f r e e - r u n n i n g rhythms in DD were v a r i a b l e among t he r a t s . These r e s u l t s i n d i c a t e a weak e n t r a i n i n g f o r c e of t h e ST-d c y c l e . The PRC f o r a s i n g l e ST-d c y c l e was q u i t e d i f f e r e n t from t h a t o b t a i n e d by s i n g l e l i g h t p u l s e s in r a t s . The PRC r e v e a l e d t h a t t he s i n g l e ST-d c y c l e produced delay s h i f t s a t a l l phases of the c i r c a d i a n c y c l e . I t seems d i f f i c u l t t o e x p l a i n t he e n t r a i n m e n t of c i r c a d i a n rhythms to the ST-d c y c l e by means of nonparametric e f f e c t s of l i g h t .
D I U R N A L V A R I A T I O N OF CHIASMATIC NUCLEUS.
VASOACTIVE
INTESTINAL
PEPTIDE
(VIP)
MRNA
IN
THE
RAT
SUPRA-
S ~ O N O S9U K E O K A M O T O *I "*TM A ~ %A~ I Y A K F ~*2 _~ HI~SHI OKAMURA 3 m SHIN TAKAGI 3 r KENJI E/JK[IT~ f f ~ 3 ~ O ~ ~ I R O S H I OKA/40TO ~ AND YASUHIKO IBATA J , Department ~_f l~phthalmology, ~Neuropsychiatry,~Anatomy, Kyoto Prefectural University of ~i~ine. K a w a r a m a t i - H i r o k o i ,........... ~ K y o t o 602, Japan. Department of 4 B i o c h e m i s t r y , T~Qh~ku U n i v e r ~ S c h o o ! of M e d i c i n e . S e n d a l 980, M i y a g i , Japan. . . . . . . . . . . . . In s i t u h y b r i d i z a t i o n using a nick-translated 35S-labelled cDNA probe has been applied to e x a m i n e vasoactive intestinal peptide (VIP) m e s s e n g e r RNA (mRNA), particularly its d i u r n a l v a r i a t i o n in the rat s u p r a c h i a s m a t i c nucleus (SCN). We could detect higher values of V I P m R N A f r o m 2 0 : 0 0 to 0 2 : 0 0 as c o m p a r e d with other times. A u t o r a d i o g r a m s of t h o s e d a t a w e r e a n a l y z e d in d e t a i l using a computerized image analyzing system. This finding was wellcorresponding with diurnal variation of V I P i m m u n o r e a c t i v i t y in o u r p r e v i o u s r e p o r t of i m m u n o c y t o c h e m i s t r y . Therefore, it is s t r o n g l y s u g g e s t e d that the p r o d u c t i o n of VIP m R N A VIP in that SCN n e u r o n s s h o w s d i u r n a l v a r i a t i o n u n d e r the c o n t r o l of l i g h t s t i m u l u s , and that consequently t h e s y n t h e s i s of V I P s h o w s a diurnal variation.
BRAIN CATECHOLAMINERGIC SYSTEM IS INVOLVED IN A SECONDARY OSCILLATION SYSTEM IN THE RAT CIRCADIAN ORGANIZATION. KEN-ICHI HONMA, MASATO MITOME, TOSHIHIRO YOSHIHARA, SATO HONMA, AND TSUTOMU HIROSHIGE L Department
o_ff P h y s i o l o g y , Hokkaldo U n i v e r s i t y School of Medicine, Sapporo 060, P e r i o d i c food p r e s e n t a t i o n induces a s e l f - s u s t a i n e d o s c i l l a t i o n which i s e x p r e s s e d most c l e a r l y in p r e f e e d l n g a c t i v i t i e s of many v a r l a b I e s . The f e e d i n g - a s s o c i a t e d o s c l l i a t l o n has a c i r c a d i a n n a t u r e but i s independent of the c i r c a d i a n pacemaker l o c a t e d i n t he s u p r a c h i a s m a t i c n u c l e u s . Howe v e r , n e i t h e r the s i t e of t h l s o s c i l l a t i o n nor i t s c e n t r a l mechanism i s known. P r e v i o u s l y we demonstrated the s p e c i f i c Involvement of the b r a i n e a t e c h o l a ~ l n e r g l c system i n t he e x p r e s s i o n of p r e f e e d i n g c o r t l c o s t e r o n e peak in r a t s . The p r e s e n t s t u d y was c a r r i e d out to examine whether t he c a t e c h o l a m l n e r g l c system i s i n v o l v e d in the o s c i l l a t i o n i t s e l f . AI1 e x p e r i m e n t s were performed under a l i g h t - d a r k c y c l e . Male r a t s of the W l s t a r s t r a i n were s u b j e c t e d to p e r l o d l c f e e d i n g f o r 2 to 3 weeks with f r e e - a c c e s s to food from 10 to 14 hours d a i l y . Then r a t s were r e t u r n e d t o a d l i b i t u m f e e d i n g f o r 7 days. 6-hydroxydopamlne (0.25mg) or p h y s i o l o g i c a l s a l i n e was i n j e c t e d i n t o the l a t e r a l v e n t r i c l e under p e n t o b a r b i t a l a n e s t h e s i a . From 4 days l a t e r , r a t s were f a s t e d f o r 3 days. Wheel-running, f e e d i n g , and d r i n k i n g a c t i v i t i e s were measured c o n t i n u o u s l y . As a r e s u l t , p r e f e e d l n g peaks in t h e s e a c t i v i t i e s reappeared d u r i n g f a s t i n g i n s a l i n e - t r e a t e d r a t s , w h i l e t he y were not observed In 6-OHDA-treated r a t s . 6-OHDA d i d not a f f e c t c i r c a d i a n a c t i v i t y rhythms. I t i s concluded t h a t the b r a i n c a t e c h o l a m l n e r g l c system i s i n v o l v e d not onl y In the p r e f e e d l n g c o r t l c o s t e r o n e peak but a l s o in the e x p r e s s i o n of o s c i l l a t i o n or in t he o s c i l l a t i o n i t s e l f .
ENTRAINMENT OF CIRCADIAN BEHAVIORAL RHYTHMS TO THE LIGHT INTENSITY CYCLE OF A DESCENDING SAWTOOTH WAVE (ST-d) IN RATS. SETSUO USUI* AND YASURO TAKAHASHI. Department Of Psycholozy, Tgk~o
H e t r o v o l i t a n I n s t i t u t e f o r Neurosciences, 2-6 Musashidai, Fuehu. Tokyo 18~, Japan. In ou~ p r i o r work, we could not a s c e r t a i n e n t r a i n m e n t of c i r c a d i a n rhythms d u r i n g 28 d a y s ' exposure to the ST-d c y c l e , in which i l l u m i n a n c e was r e c t i l i n e a r l y d e c r e a s e d 300 lux t o 0 lux in a 24 h period, and then immediately r e t u r n e d to 300 lux. In the p r e s e n t study, d u r i n g 65 days of the ST-d c y c l e , ambulation, d r i n k i n g , and subcutaneous t e m p e r a t u r e were c o n t i n u o u s l y monitored in 10 male Sprague-Oawley r a t s . T h e r e a f t e r , the r a t s were r e l e a s e d i n t o c o n s t a n t d a r k n e s s (DD), and exposed to a s i n g l e ST-d c y c l e once every 2-3 weeks, and phase s h i f t s of t he c i r c a d i a n rhythms e l i c i t e d by the ST-d s t i m u l u s were measured to c o n s t r u c t a phase re s pons e curve (PRC). In most of the cases, t h e c i r c a d i a n rhythms of b e h a v i o r s and body t e m p e r a t u r e were e n t r a i n e d t o the ST-d cy cle, and f r e e - r a n a f t e r r e l e a s e i n t o DD. The e n t r a i n m e n t to a 24 h p e r i o d was a l s o confirmed by the c h i - s q u a r e periodogram. However, the onset of t he a c t i v i t y p e r i o d became u n c l e a r , and t he phases of the e n t r a i n e d c i r c a d i a n rhythms were u n s t a b l e throughout t he 65 days of ST-d. The s u b j e c t i v e n i g h t s of r a t s d u r i n g the ST-d e s t i m a t e d by backward e x t r a p o l a t i o n from t he a c t i v i t y p e r i o d s of f r e e - r u n n i n g rhythms in DD were v a r i a b l e among t he r a t s . These r e s u l t s i n d i c a t e a weak e n t r a i n i n g f o r c e of t h e ST-d c y c l e . The PRC f o r a s i n g l e ST-d c y c l e was q u i t e d i f f e r e n t from t h a t o b t a i n e d by s i n g l e l i g h t p u l s e s in r a t s . The PRC r e v e a l e d t h a t t he s i n g l e ST-d c y c l e produced delay s h i f t s a t a l l phases of the c i r c a d i a n c y c l e . I t seems d i f f i c u l t t o e x p l a i n t he e n t r a i n m e n t of c i r c a d i a n rhythms to the ST-d c y c l e by means of nonparametric e f f e c t s of l i g h t .
D I U R N A L V A R I A T I O N OF CHIASMATIC NUCLEUS.
VASOACTIVE
INTESTINAL
PEPTIDE
(VIP)
MRNA
IN
THE
RAT
SUPRA-
S ~ O N O S9U K E O K A M O T O *I "*TM A ~ %A~ I Y A K F ~*2 _~ HI~SHI OKAMURA 3 m SHIN TAKAGI 3 r KENJI E/JK[IT~ f f ~ 3 ~ O ~ ~ I R O S H I OKA/40TO ~ AND YASUHIKO IBATA J , Department ~_f l~phthalmology, ~Neuropsychiatry,~Anatomy, Kyoto Prefectural University of ~i~ine. K a w a r a m a t i - H i r o k o i ,........... ~ K y o t o 602, Japan. Department of 4 B i o c h e m i s t r y , T~Qh~ku U n i v e r ~ S c h o o ! of M e d i c i n e . S e n d a l 980, M i y a g i , Japan. . . . . . . . . . . . . In s i t u h y b r i d i z a t i o n using a nick-translated 35S-labelled cDNA probe has been applied to e x a m i n e vasoactive intestinal peptide (VIP) m e s s e n g e r RNA (mRNA), particularly its d i u r n a l v a r i a t i o n in the rat s u p r a c h i a s m a t i c nucleus (SCN). We could detect higher values of V I P m R N A f r o m 2 0 : 0 0 to 0 2 : 0 0 as c o m p a r e d with other times. A u t o r a d i o g r a m s of t h o s e d a t a w e r e a n a l y z e d in d e t a i l using a computerized image analyzing system. This finding was wellcorresponding with diurnal variation of V I P i m m u n o r e a c t i v i t y in o u r p r e v i o u s r e p o r t of i m m u n o c y t o c h e m i s t r y . Therefore, it is s t r o n g l y s u g g e s t e d that the p r o d u c t i o n of VIP m R N A VIP in that SCN n e u r o n s s h o w s d i u r n a l v a r i a t i o n u n d e r the c o n t r o l of l i g h t s t i m u l u s , and that consequently t h e s y n t h e s i s of V I P s h o w s a diurnal variation.