Melatonin's differential inhibition of FSH and LH release from hamster pituitary glands.
Melatonin initially inhibited FSH secretion from superfused adult male hamster anterior pituitary glands obtained at 8:30 a.m. However, there was a gradual rebound during melatonin superfusion followed by an overshoot above baseline when melatonin was discontinued (morning response). Melatonin continuously inhibited FSH secretion during superfusion of hamster anterior pituitary glands obtained at 3:30 p.m., with a rebound evident only when melatonin was withdrawn (afternoon response). Melatonin continuously inhibited LH secretion from these superfused pituitaries, with a return to baseline levels only upon melatonin withdrawal. Prior pinealectomy or constant light could reverse the FSH morning response to an afternoon response, and late-morning melatonin injections could reverse the FSH afternoon response to a morning response. Neither prior pinealectomy, constant light nor melatonin injections affected melatonin inhibition of LH secretion from superfused pituitary glands. These results suggest that melatonin differentially inhibits FSH and LH secretion from isolated superfused hamster anterior pituitary glands.
D000818:Animals; D006224:Cricetinae; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D008647:Mesocricetus; D010477:Perfusion; D010870:Pineal Gland / Q000502:physiology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011863:Radioimmunoassay
D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D008550:Melatonin