A physiological increase in LH may influence vascular permeability in the rat testis

Summary. Adult male rats were injected with different doses of hCG, or with 2\m=.\5\g=m\g ovine LH subcutaneously, and other rats were mated with oestrous females. The animals were examined 4 h after treatments. Treatment with hCG resulted in a dose\x=req-\ dependent increase in leucocyte concentration in testicular blood vessels and in the number of blood vessels which could be labelled with intravenously injected carbon particles. Carbon leakage was not observed in control testes. Treatment with a low dose of ovine LH or inducing an endogenous LH peak by mating also resulted in leucocyte accumulation and vascular leakage of carbon in the testis. The magnitude of the response was considerably lower than after high doses of hCG. The physio-logical relevance of the discrete response observed after physiological LH stimu-lation is unknown but LH-induced changes in testicular microcirculation could be of interest for the understanding of the physiology and pathophysiology of the testis