ERα, but not ERβ, mediates the expression of sexual behavior in the female rat

Estrogen has well known effects on sexual behavior, however the role of the estrogen receptors (ER) alpha and beta on sexual behavior remains to be fully determined. This study investigated the individual and co-operative involvement of ER alpha and beta on sexual behaviors in the adult female rat. Subtype selective ER agonists, propyl-pyrazole triol (PPT; ER alpha agonist) and diarylpropionitrile (DPN; ER beta agonist) were utilized to examine each receptor subtype's contribution, individual and co-operative, for both receptive (lordosis) and proceptive (hopping/darting, 'ear wiggling') female sexual behaviors. Ovariectomized female rats received subcutaneous injections of either: sesame oil (OIL), dimethylsulfoxide (DMSO), estradiol benzoate (EB; 10 mu g/0.1 ml OIL), one of three doses of the ERa agonist PPT (1.25 mg, 2.5 mg or 5.0 mg/0.1 ml DMSO), one of three doses of the ERP agonist DPN (1.25 mg, 2.5 mg or 5.0 mg/0.1 ml DMSO) or a combination dose of PPT and DPN (2.5 mg PPT + 2.5 mg DPN/0.1 ml DMSO) for two consecutive days, 48 and 24 h prior to testing followed by a progesterone injection (500 mu g/0.1 ml OIL) 4 h prior to testing in order to elicit sexual behavior. The ER(x agonist PPT but not the ERP agonist DPN, elicited both proceptive and receptive behavior. PPT at doses of 2.5 and 5.0 mg significantly elicited lordosis and proceptive behavior ('ear wiggling', hopping and darting). Intriguingly, the administration of both agonists together at the 2.5 mg dose resulted in reduced levels of proceptivity and receptivity, suggesting that ERP modulates ER alpha's ability to elicit receptive and proceptive sexual behavior. (C) 2008 Elsevier B.V. All rights reserved.