Prenatal stress is a potent disruptor of the normal course of sexual differentiation, affecting both males and females. In the present study, we wished to examine a sexually dimorphic endocrine response, estradiol (E2)-induced prolactin (Prl) release, in prenatally-stressed (P-S) males and females. Sprague-Dawley female rats were timed-mated (+ sperm = Day 1). From gestation days 15-22 one group of females was subjected to a thrice-daily regimen of heat and restraint stress (0830, 1230, and 1630 hr) consisting of placing the rats into a Plexiglas restraint tube over which were poised two 100 W floodlights. Control females remained undisturbed throughout pregnancy. At parturition all offspring were cross-fostered to untreated, recently-parturient dams and weaned at 25 days of age. Separate groups of P-S and Control males and females were gonadectomized and, for males, paired testes weights and body weights were recorded. Four days later the animals were implanted with Silastic capsules containing E2, and fitted with intra-atrial cannulae. The following day, blood samples were taken at 0900, 1300, 1500, and 1700 hr for a total of five days. Beginning with the 1700 hr sample on Day 2, and with the exception of the 1500 hr sample on Day 3, P-S males had significantly lower plasma Prl values than Control males through Day 4, and at the 1500 hr sample on Day 5. Moreover, at no point did P-S males exhibit a significant daily afternoon increase in Prl values, whereas Control males did so on Days 2 and 4.(ABSTRACT TRUNCATED AT 250 WORDS)