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Sympathetic Regulation of Circadian Rhythm of Serotonin N ‐Acetyltransferase Activity in Pineal Gland of Infant Rat
Author(s) -
Deguchi Takeo
Publication year - 1982
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1982.tb08700.x
Subject(s) - reserpine , endocrinology , medicine , pineal gland , serotonin , circadian rhythm , biology , darkness , melatonin , receptor , botany
The circadian rhythms of serotonin N ‐acetyltransferase activity in the pineal glands of infant and adult rats were compared. The nighttime increase of N ‐acetyltransferase activity in the pineals of infant rats was blocked by removal of superior cervical ganglion or by pretreatment with reserpine, l ‐propranolol, and cycloheximide. Injection of isoproterenol to infant rats markedly elevated pineal N ‐acetyltransferase activity. When the pineal glands of infant rats were organ‐cultured, N ‐acetyltransferase activity spontaneously increased 7–12 h after the rats were killed. When infant rats were previously denervated or pretreated with reserpine and their pineals were cultured, this spontaneous elevation of N ‐acetyltransferase activity was abolished, indicating that the transient increase of the enzyme activity in organ culture was due to a liberation of catecholamine from degenerating nerve endings. Additional illumination until midnight prevented the nighttime increase of N ‐acetyltransferase activity in intact infant rats but not in blinded infant rats. These observations are taken to indicate that N ‐acetyltransferase rhythm in immature rat pineals is regulated by the sympathetic nerves in the same manner as in adult rat pineals, that the immature rat pineal does not contain a time‐keeping system, and that there is no extraretinal light perception in infant rats as far as N ‐acetyltransferase rhythm is concerned.