Photoperiodic differences in in vitro pituitary gonadotropin basal secretion and gonadotropin-releasing hormone responsiveness in the golden hamster
| Autor: | Kristine D. Dahl, Fred W. Turek, Amy E. Jetton, Nancy B. Schwartz, P. C. Fallest |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
Male
endocrine system medicine.medical_specialty Pituitary gland Periodicity Light medicine.drug_class Hamster Gonadotropin-releasing hormone Biology In Vitro Techniques Gonadotropin-Releasing Hormone Basal (phylogenetics) Mice Endocrinology Internal medicine Cricetinae medicine Animals Secretion photoperiodism Granulosa Cells Mesocricetus Leydig Cells Luteinizing Hormone Rats medicine.anatomical_structure Pituitary Gland Biological Assay Female Gonadotropin Follicle Stimulating Hormone hormones hormone substitutes and hormone antagonists Golden hamster |
| Zdroj: | Endocrinology. 129(2) |
| ISSN: | 0013-7227 |
| Popis: | In order to examine pituitary gonadotropin secretion and responsiveness to GnRH after photic-induced changes in reproductive condition, an in vitro pituitary perifusion system was established for male golden hamster tissue. Anterior pituitaries from adult males which had been maintained on 14 h light:10 h dark (long days) or 6 h light:18 h dark (short days) for 10 weeks were perifused using an Acusyst perifusion system. Perfusates from unstimulated tissue (basal secretion) and from tissue stimulated with hourly pulses of GnRH (25, 50, or 100 ng/ml) were assayed for LH and FSH by RIA. Tissue from short-day animals had lower basal LH secretion than tissue from long day animals, but there were no significant photoperiodic differences for GnRH-stimulated LH secretion. In contrast, there were no photoperiodic differences in basal FSH secretion, but tissue from short-day animals secreted more FSH than tissue from long-day animals when stimulated with GnRH. Bioactivity of a small number of perfusate samples was assessed using in vitro rat granulosa cell and mouse Leydig cell assays for FSH and LH, respectively, and did not show any photoperiodic differences in LH or FSH bioactivity for GnRH-stimulated tissue. These studies indicate that the pituitaries of gonadally regressed hamsters are capable in vitro of responding to GnRH with similar or greater levels of gonadotropin release compared to pituitaries from animals with functional gonads. Therefore, it appears that the lowered serum gonadotropin levels seen in vivo in gonadally regressed animals are not due to a reduction in intrinsic pituitary sensitivity to GnRH. |
| Databáze: | OpenAIRE |
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