Dihydrotestosterone stimulates mounting behavior but not lordosis in female rats

The ability of androgens to stimulate masculine sexual behavior is thought to depend on the aromatization of such androgens to estrogens. In this scheme, reduced androgens such as dihydrotestosterone (DHT) which cannot be aromatized, are thought to exert major peripheral but little or no central nervous system influences on the display of masculine sexual behavior. Further, an early report that DHT can induce lordosis, an estrogen (E) dependent behavior, led to a notion that DHT may effect behavior through metabolic intermediates such as 5 alpha-androstane-3 beta, 17 beta-diol (ADIOL) which then binds to estrogen receptors eliciting the E-dependent lordotic response. The present study reexamined and compared the relative effectiveness of a range of DHT dosages in stimulating a characteristic masculine (mounting) and feminine (lordosis) sexual behavior. Adult ovariectomized rats were randomly assigned to either 250 micrograms or 1 mg daily injections of DHT or DHTP. Other animals received OIL injections or crystalline DHT delivered by two different lengths (20 mm or 40 mm) of Silastic capsules. Animals were tested once weekly (for 5 weeks) for mounting behavior (20 minute test). Then animals were tested thrice (once weekly) for lordosis 4 hrs after the addition of 500 micrograms Progesterone (P). Finally, all females were tested for lordotic potential to respond to 10 micrograms EB plus P. 1 mg DHT or DHTP dosages and the 40 mm-Silastic condition significantly increased mounting behavior over that of lower dosages and OIL controls. A significant correlation existed between mounting frequency and circulating level of serum DHT. Treatment with DHTP was not different than DHT in eliciting mounting behavior.(ABSTRACT TRUNCATED AT 250 WORDS)