Partner preference and mount latency are masculinized in androgen insensitive rats

The sexual motivation of male rats may be inferred from a preference to stay in proximity to estrous female partners, and also from a short latency to show mounting behavior. Here, partner preference was assessed in rats carrying the testicular feminization mutation (TFM), and compared to wild type (WT) males in one version of this paradigm, and WT females and males in another version. Additionally, mount latency was quantified in the TFMs and compared to WT males in order to assess arousal levels, as this has not been previously reported. When presented with a choice between proximity to an estrous or non-estrous female, WT males and TFMs demonstrated similar preferences for the estrous female. Estrous females, conversely, preferred to spend time with the WT male. In agreement with previous reports we observed several sexual performance deficits in the TFMs, but mount latencies were in the male range. Given that the TFMs reliably choose to spend time with the estrous female in the partner preference tests, and that they display normal arousal levels (reflected in masculinized mount latencies), the data suggest the motivation to engage in sexual behavior is masculine in the TFM rat and that possession of functional androgen receptors is not crucial in these behaviors.