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 steroidog enesis and reduces Leydig cell volume and number; however, human chori onic gonadotropin (hCG) stimulates testosterone production, increases the number and volume of Leydig cells and prevents TCDD's inhibition o f testosterone production. The objective of this study was to determin e if hCG protects Leydig cell function by maintaining sufficient Leydi g cell cytoplasmic volume in TCDD-treated rats. Adult, male Sprague Da wley rats were divided into six treatment groups. Half of the animals received TCDD in corn oil (50 mu g/kg body wt) and half received corn oil alone on Day 7 only. Additionally the rats received daily treatmen t 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 te stis was evaluated by stereology to determine the volume of Leydig cel ls. Body weight was reduced (P < 0.01) in each TCDD-treated group; whe reas, 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 sa line-treated rats, but hCG eliminated the TCDD-induced reduction in Le ydig cell cytoplasmic volume. hCG prevented the TCDD-induced reduction in Leydig cell function for both the 7- and 14-day treatments. Variat ion in the total volume of Leydig cell cytoplasm induced by the variou s treatment combinations was positively correlated with stimulated tes tosterone 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 suf ficient Leydig cell cytoplasm and organelle content.