Impaired testicular function in rats with diet-induced hypercholesterolemia and/or streptozotocin-induced diabetes mellitus

Hypercholesterolemia and diabetes mellitus are known to be accompanied by r eproductive dysfunction. In this study, we investigated the effects of hype rcholesterolemia, hyperglycemia, and these conditions combined, on testoste rone (T) and testicular luteinizing hormone/human chorionic gonadotropin (L H/hCG) binding. Sprague-Dawley rats (8 weeks old) were divided into four gr oups: Group 1 was the control, group 2 was fed standard chow containing 2% cholesterol (C-diet), group 3 was administered streptozotocin (STZ, 65 mg/k g, i.p.), group 4 was treated with both the C-diet and STZ. After 4 weeks, rats were sacrificed. Serum glucose was significantly higher in the STZ gro up (304% that of controls) and the C-diet plus STZ group (345%), but there was no difference between the C-diet group (89%) and the control group. Ser um cholesterol was significantly higher in the C-diet group (206% that of c ontrols), the STZ group (452%) and the C-diet plus STZ group (2042%). Serum T, testicular T, and LH/hCG binding were significantly lower in the C-diet group (49%, 52%, and 81% that of controls, respectively), the STZ group (1 5%, 32%, and 72%) and the C-diet plus STZ group (8%, 21%, and 57%). These r esults suggest that hypercholesterolemia is an independent risk factor for testicular dysfunction and that the reduction of serum and testicular T lev els is due at least in part to a reduction in testicular LH/hCG binding in rats with hypercholesterolemia, hyperglycemia, and these conditions combine d. It is further suggested that the reduction in LH/hCG binding is mainly r elated to a rise in serum cholesterol levels.