Interactions of pinealectomy and short-photoperiod exposure on the neuroendocrine axis of the male Syrian hamster

R. W. Steger, R. J. Reiter, T. M. Siler Khodr

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


The effect of pineal gland removal on neuroendocrine function of male Syrian hamsters housed under long (14 h light:10 h dark) or short (5 h light:19 h dark) photoperiod conditions was tested. In sham-operated, but not in pinealectomized, animals, exposure to the short photoperiod resulted in a significant reduction in testicular weight. Median eminence (ME), medial basal hypothalamus (MBH), and medial preoptic-suprachiasmatic (MPOA-SCN) norepinephrine (NE) turnover was significantly reduced in 5 L:19 D sham-operated animals as compared to 14 L:10 D sham-operated or 14 L:10 D pinealectomized controls. The effects of short photoperiod on ME and MPOA-SCN NE turnover were reversed by pinealectomy, but reductions in MBH NE turnover were not dependent on the presence of the pineal gland. Pineal-dependent decreases in MBH and increases in MPOA-SCN dopamine turnover were also observed after transfer of hamsters from long to short photoperiods. Both ME and MBH luteinizing hormone-releasing (LHRH) levels were increased after short-photoperiod exposure, but pineal removal prevented these increases of LHRH levels only in the MBH of the 5 L:19 D hamsters. Levels of serotonin or its metabolite, 5-hydroxyindole-acetic acid, were not affected by pinealectomy and/or short-photoperiod exposure. We conclude that short-photoperiod-induced gonadal atrophy in the Syrian hamster is associated with pineal-dependent and pineal-independent changes in hypothalamic neurotransmitter turnover and hypothalamic LHRH content.

Original languageEnglish (US)
Pages (from-to)158-163
Number of pages6
Issue number2
StatePublished - 1984

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology
  • Endocrine and Autonomic Systems
  • Cellular and Molecular Neuroscience


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