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Circadian Rhythm in Pineal N ‐Acetyltransferase Activity: Phase Shifting by Light Pulses (II)
Author(s) -
Binkley Sue
Publication year - 1983
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.1471-4159.1983.tb11839.x
Subject(s) - circadian rhythm , pineal gland , rhythm , nat , melatonin , endocrinology , medicine , light effects on circadian rhythm , biology , chemistry , neuroscience , suprachiasmatic nucleus , biophysics , physics , quantum mechanics
N ‐Acetyltransferase (NAT) is an enzyme whose rhythmic activity in the pineal gland and retina is thought responsible for melatonin circadian rhythms. The enzyme has properties of a circadian biological clock—its rhythm persists in constant conditions and it is precisely controlled by light and dark. Experiments are reported in which light pulses of 1 to 10 h duration were imposed on chicks during their dark‐time. The effect of these pulses upon the NAT was measured and the effect of the pulses on subsequent NAT was also determined. The experiments support the conclusion that the amount and/or duration of dark‐time NAT is limited. This finding is interpreted as supporting the idea that a fixed amount of some substance, an initiator, is synthesized during the subjective day.