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Excitation and inhibition of suprachiasmatic nucleus neurones mediated by the direct retino-hypothalamic projection in rats
S56 EXCITATION AND INHIBITION OF SUPRACHIAS1VIATIC NUCLEUS NEURONES MEDIATED BY THE DIRECT RETIk~O--HYPOTHALAMIC PROJECTION IN RATS. YUKIKO SAWAKI*. Dept. P h y s i o l . , Nippon Med. S c h . , 1-1-5 Sendagi, Btmkyo-ku~. Tokyo 113. Suprachiasm ~$ic nucleus (SCN) neurones w e r e etectrophysiologically studied in female rats under urethan e anaesthesia. In rats with b i l a t e r a l transection of the optic tract, three stimulating palses of 100 Hz applied to the contralateral optic n e r v e evoked an excitation and inhibitioa in s o m e SCN units. The percentage of the r e s p o n s i v e SCN units was not significantly different between r a t s with the transected optic t r a c t (22.1%) and control intact r a t s (2l. 2%) (X 2 - t e s t , P > 0.5). Oscillatory responses with a period of 100 - 200 msec w e r e o : c a s i o n a l l y observed after stimulation of the optic nerve. Some SCN units w e r e found to receive couvergmg inputs both from the c o n t r a l a t e r a l and i p s i lateral optic n e r v e s . Sinl~le flash stimuli provided by a xenon lamp with weak intensity either excited or inhibite:l some SCN neurones. Mean firing rates changed significantly during e l e c t r i c a l or flash stimuli repeated 500 t i m e s at 0.97 Hz in some of the SCN twits which showed no t r a n s i t o r y r e s p o n s e to the stimulation. Some of the SCN neurones r e receiving visual inputs w e r e identified antidromicaUy as tuberoinfundibular n e u r o s e c r e t o r y neurones. Some other SCN neurones w e r e shown to receive converging inputs both from the optic nerve and from the axon collaterals of tuberoinfundibular nuuros e c r e t o r y neurones.
E F F E C T S O F II-YPNOTV."S O N S L E E P SPINDLE A C T M T Y ---- SPINDLE ENH/EN[CING DRUGS. K A Z U O AZUMI~ SHUICHIRO SHIRAKAWA*, N A G A T O S H I O H A M A * and M I T S U G U OGURI*. De:)t.Psychol., Tokyo Metropolitan Inst. Neurosoi., 2-6 Masashidai, Fuchu City, Tokyo 183. Th~s study evaluates the effects of hypnotics on spipd!o activity. The spindle a ~ i v i t y of Cz EEG was studied hi 16 male adults, aged 20-23, with routine sleep polygraphs. On the first 2 nights the subjects took a placebo one hour before going ~o bed. After placebobaseline nights they w e r e given active drugs on the 3 r d night, followed by one placebowithdrawal night. A slcindle is defined as waves repeated over 6 times which r~mge from 11 to 16 Hz and reach over 10 ~V in amplitude. To analyze the effects of 8 hypnotics, appearance r a t e s on baseline, drug, and with.trawal nights w e r e calculated, and w e r e given as t o ~ l spindle number p e r mime,re of NR~;M time. Group of barbituric acid derivatives: amobarbital (300rag) administration resulted in indefinite changer, and barbital (300mg) affected a negligible decre~,se. Group of noD-barbituric acid d e r i v a t i v e s : glutetMmide (500rag) made the r a t e d e c r e a s e by 13.0 & 8.4%, as dis b r o m v a l e r y l u r e a (500rag) 15.1 & 15.0%. But methaqualone (200 mg) r e m a r k a b l y increased the r a t e by 61.8 & 13.8%. Antihistamic agents; dipheJ~hydramine (30mg) affected no change. Group of benzodiazepine derivatives, nitrazepam (15 mg) administration resulted in an i n c r e a s e of 38.6 & 28.7%: and flurazepam (30rag) 76. 4
36.4%. Benzodiazepine and methaqualone caused an i n c r e a s e of spindl,.* aotivity. This result suggests that the effects of methaqualone might p a r t i a l l y (;riginate in a mechanism s i m i l a r to that of benzodiazepme. We would like to propose a concept of spindle enhancing drugs for investigating hypnotics.
E F F E C T S O F II-YPNOTV."S O N S L E E P SPINDLE A C T M T Y ---- SPINDLE ENH/EN[CING DRUGS. K A Z U O AZUMI~ SHUICHIRO SHIRAKAWA*, N A G A T O S H I O H A M A * and M I T S U G U OGURI*. De:)t.Psychol., Tokyo Metropolitan Inst. Neurosoi., 2-6 Masashidai, Fuchu City, Tokyo 183. Th~s study evaluates the effects of hypnotics on spipd!o activity. The spindle a ~ i v i t y of Cz EEG was studied hi 16 male adults, aged 20-23, with routine sleep polygraphs. On the first 2 nights the subjects took a placebo one hour before going ~o bed. After placebobaseline nights they w e r e given active drugs on the 3 r d night, followed by one placebowithdrawal night. A slcindle is defined as waves repeated over 6 times which r~mge from 11 to 16 Hz and reach over 10 ~V in amplitude. To analyze the effects of 8 hypnotics, appearance r a t e s on baseline, drug, and with.trawal nights w e r e calculated, and w e r e given as t o ~ l spindle number p e r mime,re of NR~;M time. Group of barbituric acid derivatives: amobarbital (300rag) administration resulted in indefinite changer, and barbital (300mg) affected a negligible decre~,se. Group of noD-barbituric acid d e r i v a t i v e s : glutetMmide (500rag) made the r a t e d e c r e a s e by 13.0 & 8.4%, as dis b r o m v a l e r y l u r e a (500rag) 15.1 & 15.0%. But methaqualone (200 mg) r e m a r k a b l y increased the r a t e by 61.8 & 13.8%. Antihistamic agents; dipheJ~hydramine (30mg) affected no change. Group of benzodiazepine derivatives, nitrazepam (15 mg) administration resulted in an i n c r e a s e of 38.6 & 28.7%: and flurazepam (30rag) 76. 4
36.4%. Benzodiazepine and methaqualone caused an i n c r e a s e of spindl,.* aotivity. This result suggests that the effects of methaqualone might p a r t i a l l y (;riginate in a mechanism s i m i l a r to that of benzodiazepme. We would like to propose a concept of spindle enhancing drugs for investigating hypnotics.