Disturbed pituitary-testicular axis inhibits testicular descent in the prenatal rat.

Abstract

To investigate whether prenatal stress affects the pituitary-testicular axis in relation to testicular descent in rat fetuses, as maternal stress can alter the plasma testosterone concentration and inhibit testicular descent in male rat fetuses. Pregnant rats were divided into two groups and kept in reverse light-dark cycles, with lights-off at 08.00 hours and on at 20.00 hours. In group 1, 15 pregnant females were placed three times daily for 60 min each session in plastic rat-holders (13 x 6 x 8 cm) illuminated by two 150-W flood lights during the dark phase, from day 14 to 18 of gestation. In group 2, 10 pregnant females were not handled and thus were used as controls. At 19 days of gestation, five pregnant rats had a Caesarean section in each group, and both testes and the pituitary gland were removed from male fetuses at 10.00-11.00 hours. The tissue homogenates were analysed for testicular testosterone and pituitary luteinizing hormone (LH) by a radioimmunoassay. Thereafter, at 21 and 30 days of age, testicular descent was assessed in the remaining male offspring. Student's t- and the chi-square test were used to assess the results. The mean (sd) concentration of fetal testicular testosterone was significantly lower in group 1, at 312.9 (26.2) pg/mg, than in group 2, at 532.5 (18.2) pg/mg (P < 0.05); that of pituitary LH was also significantly lower in group 1, at 130.6 (22.7) and 295.6 (35.2) pg/mg, respectively (P < 0.05). The completion rate of testicular descent was 14% in group 1 (36 male rats) and 64% in group 2 (28 male rats) at 21 days old, and thereafter they were 81% and 100%, respectively, at 30 days old (P < 0.05). Maternal stress might inhibit the pituitary-testicular axis, thereby resulting in abnormal testicular descent in male fetuses.