[Stimulating effect of human chorionic gonadotropin on the activity of guanidinoacetate-N-methyltransferase of rat testes: role of cyclic AMP].

A study was made of the influence of human chorionic gonadotropin (HCGT) on the activity of guanidineacetate-N-methyltranspherase in human testes. Guanidineacetate-methyltranspherase proved to be stimulated in the testes of the sexually immature rats in vivo under the action of HCGT on the 19th day after birth and from the 24th to the 27th day after birth. The activity of the enzyme was also increased in adult rats weighing 35--40 g. The activity of guanidineacetate-methyltranspherase in the testes of rats was particularly sharply stimulated after a single administration of N6-O2'-dibutiryladenosine-3',5'-cyclophosphate against the background of a preliminary treatment of rats with HCGT for a period of 5 days. The enzyme stimulation induced by combined treatment of rats with HCGT and N6-O2'-dibutiryladenosine-3',5'-cyclophosphate was prevented by the administration of cycloheximide and actinomycine D. The activity of the enzyme decreased after the incubation of the rat testes tissue homogenate with HCGT.