Gonadectomy impairs T-maze acquisition in adult male rats

Recent studies have shown that chronic gonadectomy increases the density of dopaminergic axons in prefrontal but not sensorimotor cortices in adult ma le rats. Since supranormal prefrontal cortical dopamine stimulation is know n to impair rats' performance in T-maze delayed alternation paradigms, we t ested whether longterm gonadectomy might also impair T-maze performance. Fo r comparison, sensorimotor functions were also assessed. Adult male rats we re gonadectomized and placebo-, estradiol-, or testosterone propionate-trea ted or were sham operated and placebo-treated. Four weeks after surgery, th e subjects were tested using a rotorod apparatus acid in the acquisition of a T-maze delayed alternation paradigm. Gonadectomized placebo-treated and estradiol-treated rats took significantly longer to acquire the T-maze rule than controls, and gonadectomized, testosterone-treated rats acquired the task within the same time frame as controls. No group differences were dete cted in rotorod performance. Thus, chronic gonadectomy induced testosterone -sensitive, estradiol-insensitive acquisition deficits in a spatial learnin g task but had no demonstrable effects on the sensorimotor functions tested . (C) 2001 Academic Press.