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Science 1 July 1966:
Vol. 153. no. 3731, pp. 73 - 74
DOI: 10.1126/science.153.3731.73
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Articles

Circadian Rhythm in Pineal Tyrosine Hydroxylase

Edith G. McGeer 1 and Patrick L. McGeer 1

1 Kinsmen Laboratory of Neurological Research, Departmnent of Psychiatry, University of British Columbia, Vancouver, Canada

Tyrosine hydroxylase is the rate-limiting enzyme in catecholamine synthesis. The rat pineal gland is richly innervated by sympathetic nerves from the superior cervical ganglia. The activity of tyrosine hydroxylase was measured in rat pineal gland at 4-hour intervals over a daily cycle of 12 hours of light (7 a.m. to 7 p.m.) and 12 hours of darkness. The results indicate a circadian rhythm with the maximum activity, at 11 p.m. to 3 a.m., about triple the low values observed at 3 p.m. The pattern is similar in phase to that previously reported for melatonin and hydroxyindole-O-methyl transferase activity.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Adenyl Cyclase Activity in Rat Pineal Gland: Effects of Chronic Denervation and Norepinephrine.
B. Weiss and E. Costa (1967)
Science 156, 1750-1752
   Abstract »    PDF »
Ambiguities in the Use of the Term Circadian.
R. J. Wurtman (1967)
Science 156, 104
   PDF »


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