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Age‐Associated Changes in Pineal Adrenergic Receptors and Melatonin Synthesizing Enzymes in the Wistar Rat
Author(s) -
Dax Elizabeth M.,
Sugden David
Publication year - 1988
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.1471-4159.1988.tb02934.x
Subject(s) - melatonin , pineal gland , medicine , endocrinology , stimulation , period (music) , nocturnal , biology , receptor , darkness , senescence , photoperiodism , physics , botany , acoustics
The nocturnal stimulation of pineal melatonin synthesis and elevation of serum melatonin is known to be reduced in old age in several species. In Wistar rats the capacity of the β‐adrenoceptor to develop supersensitivity (increase in B max ) during the light period of the diurnal light/dark cycle is lost during maturation (3–6 months) rather than old age. Further, the present study shows that neither the α 1 ‐ nor β‐adrenoceptor density of the pineal declines as rats age. Pineal hydroxyindole‐ O ‐methyltransferase activity does fall (17–55%) in rats after 18 months of age, but nocturnal pineal arylalkylamine N ‐acetyltransferase activity is not significantly altered. Thus, from examination of these parameters across the life span of the rat, it seems likely that the reported reduction in serum melatonin in old animals is related to a reduced capacity of the pineal to synthesize melatonin, rather than an altered responsiveness of the gland to neural stimulation.