The pituitary-gonadal axis in experimental nephrotic syndrome in male rats

Basal and luteinizing releasing hormone-stimulated gonadotropin secretion were studied in male rats made nephrotic with puromycin, and in pair-fed and normal control animals. In addition, plasma concentrations of testosterone, androstenedione, estradiol, and estrone were measured in the three groups of animals. Urinary testosterone concentrations were also measured in the three experimental groups. The data showed that basal luteinizing hormone concentration was significantly elevated in the nephrotic group compared with the pair-fed and normal control groups. Gonadotropin response to luteinizing releasing hormone stimulation was not significantly different in the three groups, suggesting an intact hypothalamic-pituitary axis in nephrotic syndrome. Urinary testosterone concentration in the nephrotic animals was significantly higher than in the pair-fed and normal control groups. Plasma testosterone, androstenedione, estradiol, and estrone concentrations were significantly lower in the nephrotic and pair-fed animals than in the normal control animals, indicating possibly impaired gonadal steroidogenesis in these two groups that may be related to the catabolic state of the animals. It thus appears that urinary loss of protein-bound (sex hormone binding globulin-bound) testosterone in the nephrotic syndrome leads to increased basal secretion of luteinizing hormone, presumably as a result of increased luteinizing releasing hormone secretion. This occurs to compensate for the abnormal urinary testosterone loss and is an attempt to restore plasma testosterone concentrations to normal. The higher basal plasma luteinizing hormone concentration in the nephrotic group supports this conclusion.(ABSTRACT TRUNCATED AT 250 WORDS)