Male rat sexual behavior: Insights from inter-copulatory intervals

• Published in: Behavioural processes Vol. 190; p. 104458
• Main Authors: Huijgens, Patty T., Guarraci, Fay A., Olivier, Jocelien D.A., Snoeren, Eelke M.S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2021; Elsevier
• Subjects: Copulation; Mount bout; Post-ejaculatory interval; Psychology: 260; Psykologi: 260; Samfunnsvitenskap: 200; Sexual behavior; Social science: 200; Time out; VDP; Copulation; Post-ejaculatory interval; Time out; Mount bout; Sexual behavior
• ISSN: 0376-6357; 1872-8308; 1872-8308
• DOI: 10.1016/j.beproc.2021.104458

•Post-ejaculatory interval strongly correlates with mean time out duration in rats.•This effect is persistent across ejaculation series and copulation sessions.•Stimulation magnitude in a mount bout predicts duration of the following time out.•These results are consistent in three different cohorts of two different strains.•Mount bout-based analysis of copulation should be standard in male rats. The assessment of sexual behavior in male rats with the aim of unraveling underlying neurobiological mechanisms has in the recent decades been reduced to the annotation of mounts, intromissions and ejaculations. To provide a better understanding of the structure and patterns of copulation, it is necessary to extend and tailor the analysis to the natural organization of male rat copulation. This will lead to better formulation of hypotheses about neurobiological underpinnings of behavior. Mounts and intromissions are naturally organized in mount bouts consisting of one or more copulatory behaviors and are interspersed with time outs. We hypothesized that time outs and the post-ejaculatory interval (inter-copulatory intervals) are related and possibly under the control of a common copulatory inhibition mechanism that is the result of penile sensory stimulation. To test this hypothesis, we analyzed sexual behavior in male rats of three different cohorts from three different laboratories. Results showed that the post-ejaculatory interval and mean time out duration are strongly correlated in all cohorts analyzed. In addition, we showed that individual time out duration is at least partially predicted by the sum of sensory stimulation of copulatory components in the preceding mount bout, with more penile stimulation associated with longer time outs. These findings suggest that both time out and post-ejaculatory interval duration may be determined by the magnitude of sensory stimulation, which inhibits copulation. Whether the same neural pathways are involved in the central orchestration of both time outs and the post-ejaculatory interval should be subject to future studies.