Di Sebastiano AR, Yong-yow S, Coolen LM (2008) The role of orexin in sexual behavior and sexual reward of the male rat. Neuroscience 2008 Abstracts 97.4/UU18. Society for Neuroscience, Washington, DC.
Summary: The hypothalamic neuropeptide orexin has been demonstrated to play a role in reward related to drugs of abuse and is potentially involved in regulation of natural rewarding behaviors. Male sexual behavior has been shown to activate orexin neurons and this behavior is altered by administration of orexin receptor agonists or antagonists. However, the exact role of orexin in male sexual performance, sexual motivation and reward is currently unclear. Therefore, the goal of the current study was to test the hypothesis that orexin plays a critical role in sexual behavior, motivation and reward. First, using Fos as a marker for neural activation, we investigated activation of orexin neurons following different parameters of sexual behavior in sexually naïve and experienced male rats. It was demonstrated that orexin neurons in the lateral hypothalamic area (LHA) and in the dorsal medial hypothalamus/perifornical (PFA-DMH) region become activated with presentation of the female and there is no further increase in activation with other components of mating (15-30% in LHA; 65-80% in PFA-DMH). Next, we tested the functional role of orexin utilizing orexin-cell body specific lesions. Adult male rats underwent lesion or sham surgery using the targeted toxin orexin-saporin or blank-saporin respectively. Following two weeks recovery, sexual behavior was recorded over the course of four mating trials. During the first mating trial, males with complete lesions showed significantly shorter latencies to mount and intromit. This suggests that lesions facilitated sexual performance in naïve animals. This facilitation was attenuated by sexual experience as lesions did not affect any parameter of sexual behavior in experienced animals. Next, runway tests were conducted to determine motivation to run towards a potential partner over two conditioning trials. Lesions did not alter sexual motivation, as lesion and sham males all demonstrated increased speed to run towards an estrous female during the second trial. Finally, a conditioned place preference (CPP) paradigm was conducted as a measure of sexual reward. All groups formed a conditioned preference for the mating-paired chamber, indicating that lesions did not significantly disrupt sexual reward. Overall, these findings suggest that orexin does not play a critical role in male sexual performance, motivation, and reward, however may be involved in general arousal related to sexual behavior.
Related Products: Orexin-B-SAP (Cat. #IT-20), Blank-SAP (Cat. #IT-21)