Evidence for centrally initiated genital vasocongestive engorgement in the female rat: findings from a new model of female sexual arousal response

Purpose: In spite of rapidly growing interest, few research tools have been developed to study female sexual dysfunction. Using the D-1/D-2 agonist, apomorphine (APO), our objective was to develop a new model of the sexual arousal response in female rats based on one previously established for the male condition. Methods: APO (80 mug/kg, s.c.) was given during proestrus (P), estrus (E), metestrus (M), early diestrus (DI) and late diestrus (DII), and in ovariectomized (OVX) female Wistar rats. APO-induced behavioral and genital responses were characterized (30 min) using video monitoring. Results: APO-induced reproducible, periodic morphological changes in the external genitalia. The onset, timing and duration of these female APO responses were consistent with genital vasocongestive arousal (GVA) responses in males (ie erections). APO-induced GVAs occurred throughout the estrous cycle, peaking in E (1.4 +/- 1.21 overall; 0.9 +/- 0.64 in DII; 1.8 +/- 1.66 in E) and were markedly diminished by ovariectomy (OVX, 0.4 +/- 0.51). Conclusion: APO induced a reproducible sexual arousal response in female rats involving obvious genital vasocongestive engorgement. Further, the findings demonstrate that the APO-induced genital arousal responses are hormonally regulated.