title: Effects of prolonged physical exercise and fasting upon plasma testosterone level in rats.
abstract: Prolonged physical exercise and fasting in male rats were studied to determine the effect of these two treatments on plasma testosterone level. Blood and tissue samples were drawn after 1 h, 3 h, 5 h, and 7 h treadmill running, and after 24 h, 48 h, and 72 h of fasting. Both treatments resulted in a significant fall in plasma testosterone, plasma luteinizing hormone (LH), plasma Insulin (IRI) and in liver and muscle glycogen stores. In the course of these two treatments the injection of a supra maximal dose of Human Chorionic Gonadotropin (HCG) produced a rise in plasma testosterone similar to that in control rats. This indicates that the decrease of plasma LH may be responsible for the decrease in plasma testosterone, which is time-related with the decrease in glycogen stores. The possible metabolic role of the decrease in plasma testosterone is discussed.
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005215:Fasting; D006003:Glycogen / Q000032:analysis; D008112:Liver Glycogen / Q000032:analysis; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D009132:Muscles / Q000032:analysis; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000097:blood* / Q000378:metabolism
chemical_list: D006063:Chorionic Gonadotropin; D008112:Liver Glycogen; D013739:Testosterone; D007986:Luteinizing Hormone; D006003:Glycogen