Testosterone decreases CA1 plasticity in vivo in gonadectomized male rats

Estrogen has been reported to enhance CA1 functional plasticity in adult ra ts, as measured by the induction of long-term potentiation (LTP). In the pr esent study, the effects of androgens on CA1 LTP were assessed in adult mal e Sprague-Dawley rats in vivo following peripubertal castration. Castrated rats with cholesterol implants showed significantly greater plasticity, bot h in degree and duration of potentiation, than castrated rats given testost erone or dihydrotestosterone implants. An LTP paradigm reported to produce decremental LTP in vitro produced nondecremental LTP in androgen-deprived r ats, but decremental LTP in androgen-treated rats. These results suggest th at androgens, unlike estrogens, act to reduce CA1 plasticity in the adult r at. Hippocampus 2000;10: 693-697. (C) 2000 Wiley-Liss, Inc.