MECHANISM OF CIRCADIAN OSCILLATION IN PHOTORECEPTIVE PINEAL ORGAN.

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THE AIM OF THIS RESEARCH IS TO CLARIFY THE ROLE OF PINEAL ORGAN IN LOWER VERTEBRATE AND RELATE IT TO THE REGULATOYR FUNCTION OF THE ORGANISM IN THE PHYLOGENTIC POINT OF VIEW.FOR THIS PURPOSE,AUTHORS DID THE FOLLOWING EXPERIMENTS.IN 1995, WE TRIED TO FIND OUT THE ENDOGENOUS OASILLATOR IN THE PINEAL ORGAN OF LOWER VERTEBRATE SUCH AS LAMPREY.AS A RESULT,WE SUCCESSFULLY DETECTED THE ENDOGENOUS OASILLATOR IN THE ISOLATED AND CULTURED PINEAL ORGAN OF LAMPREY BY MEASURING MELATONIN SECRETION RHYTHM IN THE CULTURE MEDIUM UNDER CONTINUOUS DARK CONDITION AS WELL AS UNDER LIGHT-DARK CONDITION.IN 1996, TEMPERATURE DEPENDENCE WAS OBSERVED IN THE MELATONIN SECRETION RHYTHM FROM THE ISOLATED AND CULTURED PINEAL ORGAN.MELATONIN SECRETION WAS SUPPRESSED COMPLETELY AT 10ﾟC.THIS WAS INTERPRETED THAT OSCILLTOR ITSELF DOES NOT STOP AT 10ﾟC BUT THE SOME PROCESS IN MELATONIN BIOSYNTHESIS IS HIGHLY TEMPERATURE DEPENDENT AND IT IS SUPRESSED AT 10ﾟC.IN 1996 AND 1997, THE EFFECT OF LIGHT SCHEDULE ON MELATONIN SECRETION WAS INVESTIGATED.WHEN LIGHT-DARK (LD) CYCLES WERE SHIFTED FORWARD OR BACKWARD,MELATONIN RHYHTM WAS ALSO SHIFTED FORWARD OR BACKWORD AND RE-ENTRAINED TO THE NEW LD CYCLE IMMEDIATELY.WHEN THE PINEAL ORGAN WAS KEPT UNDER CONTINUOUS LIGHT CONDITION,MELATONIN SECRETION RHYTHM WAS DUMPED AND DISAPPEARED WITHIN 3 TO 4 DAYS.THESE RESULTS INDICATE THAT THE ISOLATED PINEAL ORGAN IS STILL PHOTOSENSITIVE UNDER CULTURE CONDITION.IT SEEMS TO BE QUITE IMPORTANT TO CONTINUE THE EXPERIMENTS TO KNOW THE CELLULAR MECHANISM OF PHOTORESPONSE OF THE PINEAL OSCILLATOR.