Human chorionic gonadotropin protects Leydig cell function against 2,3,7,8-tetrachlorodibenzo-p-dioxin in adult rats: role of leydig cell cytoplasmic volume

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) alters testicular steroidogenesis and reduces Leydig cell volume and number; however, human chorionic gonadotropin (hCG) stimulates testosterone production, increases the number and volume of Leydig cells and prevents TCDD's inhibition of testosterone production. The objective of this study was to determine if hCG protects Leydig cell function by maintaining sufficient Leydig cell cytoplasmic volume in TCDD-treated rats. Adult, male Sprague Dawley rats were divided into six treatment groups. Half of the animals received TCDD in corn oil (50 μg/kg body wt) and half received corn oil alone on Day 7 only. Additionally the rats received daily treatment of saline for 14 days, saline for 7 days and then hCG for 7 days, or hCG for 14 days. Rats were sacrificed on Day 14 and tissues collected. The decapsulated left testes were incubated in Eagles MEM for 2 h to determine basal production of testosterone and for 2 additional hours after the addition of hCG (100 IU) to the culture media. The right testis was evaluated by stereology to determine the volume of Leydig cells. Body weight was reduced (P < 0.01) in each TCDD-treated group; whereas, testicular weight was not affected by TCDD or hCG treatment. hCG prevented the TCDD-induced reduction in prostate and seminal vesicles weights. TCDD reduced the total volume of Leydig cell cytoplasm in saline-treated rats, but hCG eliminated the TCDD-induced reduction in Leydig cell cytoplasmic volume. hCG prevented the TCDD-induced reduction in Leydig cell function for both the 7- and 14-day treatments. Variation in the total volume of Leydig cell cytoplasm induced by the various treatment combinations was positively correlated with stimulated testosterone production in vitro (r = 0.486; P < 0.01) and the weight of the androgen sensitive organs (seminal vesicles, r = 0.562, P < 0.01; prostate, r = 0.380, P < 0.05). These data support the hypothesis that hCG prevents the TCDD-reduced Leydig cell function by maintaining sufficient Leydig cell cytoplasm and organelle content.