Journal article

'Hamster-like' cycles in testicular size in the absence of gonadotrophin secretion in HPD rams exposed to long-term changes in photoperiod and treatment with melatonin

GA Lincoln, IJ Clarke, T Sweeney

JOURNAL OF NEUROENDOCRINOLOGY | BLACKWELL SCIENCE LTD | Published : 1996

Abstract

Long term changes in the secretion of FSH, LH and testosterone, and the size of the testis were measured in groups of hypothalamo-pituitary disconnected Soay rams (HPD rams, n = 8) and control Soay rams (HPD-sham operated and unoperated, total n = 8) while exposed to an artificial lighting regimen of alternating 16-weekly periods of long days (16L: 8D) and short days (8L: 16D), and when treated with a constant-release implant of melatonin given under long days (total study: 136 weeks). Short term provocation tests using NMDA (glutamate receptor agonist), GnRH and LH were used to assess functionality of the hypothalamus, pituitary gland and testis, respectively. Control rams expressed normal ..

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University of Melbourne Researchers