Photoperiod-driven changes in reproductive function in male rhesus monkeys
| Autor: | E. A. Libré, George R. Merriam, J. D. Booth, Constance L. Chik, D Renquist, Osborne F. X. Almeida |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Male
endocrine system medicine.medical_specialty Light Endocrinology Diabetes and Metabolism media_common.quotation_subject Clinical Biochemistry Biology Testicle Biochemistry Endocrinology Internal medicine Prepuberty Testis medicine Animals Testosterone Sexual Maturation media_common photoperiodism Reproductive function Reproduction Biochemistry (medical) Body Weight Testicular growth Macaca mulatta Prolactin medicine.anatomical_structure Darkness |
| Zdroj: | The Journal of clinical endocrinology and metabolism. 74(5) |
| ISSN: | 0021-972X |
| Popis: | Environmental lighting, which regulates seasonal breeding in many animal species, has not been examined as a regulator of reproduction or puberty in man or nonhuman primates. In this study we examined the effects of controlled alternating long and short daily photoperiods, independent of other environmental variables, on testicular size and function in rhesus monkeys. Sixteen animals, some pubertal, others prepubertal, were individually caged indoors in light-controlled rooms. They were subjected to a 32-week "year" with alternating 16-week cycles of long (16 h of light and 8 h of darkness) or short (8 h of light and 16 h of darkness) days. Animals were examined every 2 weeks over four 32-week "years". Body weight, testicular diameter, and testicular volume were measured, and blood was collected for testosterone and PRL determinations. We found that although short days did not trigger testicular development in prepubertal animals, testicular growth was markedly enhanced by short days in postpubertal animals, accompanied by increased plasma testosterone levels and reduced PRL levels. In long days, testes regressed, testosterone levels fell, and PRL levels rose. The periodicity of testicular size, as determined by spectral analysis, showed a strong signal at a cycle length of 31 +/- 13 weeks, but no signal at intervals close to the natural 52-week year, indicating that the observed periodicity is induced by the changes in lighting, rather than by circannual changes in other variables. These studies establish that changes in photo-period alone can modulate reproductive function in a higher primate and suggest that the onset of puberty is not directly driven by seasonal fluctuations in day length. |
| Databáze: | OpenAIRE |
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