Effect of aging on testicular metabolism in the rabbit

Abstract

Results of an investigation designed to establish and catagorize biochemical and metabolic changes in the rabbit testis with aging are presented. Testis size was significantly (P < .05) altered during the aging process. Several testicular constituents (e.g., protein, RNA, and RNA/DNA) declined with aging whereas others (e.g., cholesterol) remained unchanged. In vitro, metabolism (oxygen uptake, glucose uptake, and lactic acid production) was not significantly altered with age. Activities of the enzymes measured indicate that there is probably either an increase or decrease in enzyme protein depending on the specific reaction involved. It was shown for example that isocitric dehydrogenase decreased significantly (P < .01) with aging whereas lactic dehydrogenase increased (P < . 01). Blood flow to the rabbit testis perfused in vitro decreased (P < . 01) with advancing age but glucose uptake decreased through 18 mos. and increased at 36 mos. Evidence is presented which tends to support several possible mechanisms which might be acting to cause testicular involution in the aging rabbit.