In vivo pretreatment with human chorionic gonadotropin fails to reverse the dysfunction of isolated Leydig cells from chronically uremic rats

Testicular function in uremic rats: in vivo assessment of testosterone biogenesis

The mechanism of testosterone (T) production defect in uremic rats has not yet been clearly defined and hypothalamo-hypophyseal impairment as well as primary testicular dysfunction have been suggested. In 42 rats followed monthly after subtotal nephrectomy up to 7.1 +/- 0.3 months, we observed a progressive significant decline of T and androstenedione (A) compared to control rats. Two months before the terminal phase of chronic renal failure (CRF), T/A ratio abruptly declined. T and its precursors on the 4-ene pathway, A, progesterone (P) and 17-hydroxyprogesterone were evaluated in pampiniform plexus testicular vein (PPTV) and in peripheral blood (PV) in end stage uremic rats (blood urea greater than 30 mmol/l, creatinine clearance less than 0.5 ml/min). Under basal conditions, all steroids but peripheral P were significantly lower in uremic rats than in controls as well as T/P and A/P ratios. After human chorionic gonadotropin (hCG) stimulation, T concentration in PV and PPTV remained highly significantly lower than in controls whereas T precursor concentrations were partially corrected by hCG administration. T/P ratio remained lower than in controls whereas A/P ratio was not significantly lower than in controls. Those data show a decline in all the steps of T biogenesis in uremic rats in basal conditions. The defect in 17 beta-hydroxysteroid dehydrogenase evidenced by T/A decrease at the end stage of CRF seems of primary testicular origin as it is not corrected by hCG administration as shown by T/P and A/P ratios in PPTV and in PV.

Pituitary response to LHRH during chronic renal insufficiency in the male rat

Chronic renal insufficiency was induced in young adult male rats by a 2-step 5/6 nephrectomy. Four weeks after surgery the rats were anesthetized with ketamine and injected with saline or 1, 5, 10, 50, or 100 ng of LHRH/100 g BW and blood samples were collected at various times and assayed for LH. A second group of rats was injected with saline or 5, 10, 50, 100, or 200 ng of LHRH/100 g BW and serum samples assayed for FSH. A third experiment tested for the presence of a self-priming effect of LHRH on LH secretion. Rats were primed with three iv injections of 10 ng of LHRH/100 g BW or saline at 30-min intervals and challenged with 50 ng of LHRH/100 g BW 30 min after the last priming injection. Ten min after the challenge injection, the LH increment was determined. The data indicate that male rats suffering from chronic renal insufficiency have an impaired LH response to low doses of LHRH, essentially normal FSH responses to most doses of LHRH examined, and lack a self-priming effect of LHRH on LH secretion. These results suggest that part of the reproductive abnormalities found in chronic renal failure may be due to alterations in pituitary LH responses.