Plasma testosterone in Trypanosoma congolense-infected Toggernburg goats.

Trypanosomiasis induces histological testicular degenerative changes leading to suppression of spermatogenesis in goats and laboratory animals. We present evidence associating these changes with trypanosome-induced endocrine dysfunction. Toggenburg goats were infected with approximately 100,000 trypanosomes. They were bled every 2 days, and the plasma testosterone was analyzed by radioimmunoassay. Testes were perfused with and fixed in Bouin's fixative for histological evaluation. The infected plasma samples showed depressed testosterone levels with episodic peaks reduced in both amplitude and frequency. Histological characteristics of the testicular and epididymal tissues revealed aspermic tubules and epididymides and desquamation of the tubular germinal epithelia. These testicular degenerative changes may be partly due to the depressed plasma testosterone levels.