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Updated: Jul 13, 2026

Parallel Measurement of Circadian Clock Gene Expression and Hormone Secretion in Human Primary Cell Cultures
Published on: November 11, 2016
Circannual prolactin rhythms: calendar-like timer revealed in the pituitary gland
1Department of Anatomy and Neurobiology, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536-0298, USA. marilyn.duncan@uky.edu
Abstract:
Although photoperiodic regulation of annual rhythms in reproduction and other functions has been well characterized, the basis for the endogenous generation of circannual rhythms during exposure to constant conditions has not been elucidated. Lincoln and colleagues have recently reported that circannual prolactin rhythms in rams persist after hypothalamo-pituitary disconnection, but not after pinealectomy. Does the pars tuberalis, the site of pituitary gland melatonin receptors, generate circannual rhythms and integrate photoperiodic signals mediated by melatonin?
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