Photoperiodic changes in opiate binding and their functional implications in golden hamsters

Maureen L. Tubbiola, Bruce Nock, Eric L. Bittman

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Daylength modulates gonadotropin secretion, gonadal steroid hormone feedback, sexual behavior and body weight in male golden hamsters. Endogenous opiates regulate each of these phenomena, and the ability of opiate receptor blockade to elevate serum LH secretion is photoperiod-dependent. We used in vitro autoradiography to localize and quantity effects of daylength in golden hamsters. Hamsters were exposed to stimulatory (14 h light:10 h dark) or inhibitory (10 h light:14 h dark) photoperiods for 10 weeks before specific [3H]naloxone binding was assessed. Short days significantly decreased binding in medial amygdala and the intercalated amygdaloid nucleus. This effect was reversed by superior cervical ganglionectomy. No significant effects of daylength were observed in other amygdaloid, hypothalamic or preoptic areas. Lesions of the medial amygdala decreased copulatory behavior, short day-induced weight loss, and anogenital chemoinvestigation but did not affect gonadal regression or other forms of chemoinvestigation. These lesions facilitated testosterone's negative feedback on luteinizing hormone in long days but did not intefere with the potentiation of negative feedback by short days.

Original languageEnglish
Pages (from-to)91-99
Number of pages9
JournalBrain Research
Volume503
Issue number1
DOIs
StatePublished - Nov 27 1989

Keywords

  • Amygdala
  • Hamster
  • Luteinizing hormone
  • Naloxone
  • Opiate
  • Photoperiod
  • Sexual behavior

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