Gonadotropic dysfunction produced by Trypanosoma brucei brucei in the rat

Abstract Hormonal disorders have been frequently observed in humans and animals infected with tsetse-transmitted (African) trypanosomes. We studied the pituitary gonadal axis (plasma concentrations of testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH) and the pituitary gonadotropin (LH, FSH) concentrations) in rats as an experimental model infected with an acute stock of Trypanosoma brucei brucei (AnTat 1.1A). The same investigations in vivo were carried out with rats inoculated by trypanosomal preparations: surface coat components slowly released at pH 5.5 and the parasitic cellular pellet. The releasing procedure as firstly described by Baltz et al. (1976) was performed in the presence or the absence of protease inhibitors. We noted a testicular hypogonadism produced by the acute infection with the decrease of the testosterone level and an increase of the pituitary LH concentration, although the other circulating FSH and LH hormone levels were stable. The injection of the trypanosomal pellet, obtained in the presence of antiproteases, generated a similar clinical hormonal picture: decrease of testosterone level; increase in pituitary LH, FSH content; absence of significant variation of circulating FSH and LH rates. When the trypanosomal pellet was prepared in absence of antiproteases the circulating gonadostimuline levels were significantly decreased. In the same conditions (absence of antiproteases) the trypanosomal supernatant pH 5.5 induced the decrease of the testosterone and plasma LH levels. These results suggested that component(s) from trypanosomes generated hormonal perturbations.