[The state of heat exchange and thermoregulation in animals castrated at different ages]

A change of the indices of thermal metabolism and of thermoregulation in male rats with reduction of the gonad function in the aging animals and following castration at different age was studied by means of calorimetric unit permitting to record total heat emission, "direct" heat production, and also the body temperature of the animals in experiments of any duration. Functional "cold" test was used to assess the adaptive possibilities of thermoregulation. Old unoperated males showed a reduction of background values of heat exchange, diminished increase of the indices of heat production and lesser rate of body temperature restoration following the "cold" test. Castration of old animals produced no effect on already changed indices of heat exchange. But in the young castrated males there was a reduction of the initial values of heat emission and of heat production, and a change of thermoregulation reaction in response to chilling. Administration of testosterone-propionate to young castrated animals led to a partial restoration of the indices under study.