Activity of castrated male voles: rhythms of responses to testosterone replacement.

摘要: Abstract Male Microtus montanus are reported to decrease nocturnality in the absence of testosterone (T). Castrated male voles, housed activity wheels under LD 16:8, received 21 daily injections either 0, 30, 60, or 120 μg T at 2 hours after lights on, midlight, before off, middark. Significant increases both and total occurred only response administration midlight off. For increasing nocturnality, animals were more sensitive midlight; for activity, Although rhythms these responses differed, most time each when plasma levels elevated intact voles 16:8. Thus, appear be mediated by separate pathways, possessing diel rhythmicity.