Investigating the role of ghrelin in male rat sexual behavior

Lindsay Thompson (2015)L.M. Hyland, S. Rosenbaum, B. Woodside, J. Pfaus, A. Abizaid

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The physiology of reproduction in animals depends on the organism’s metabolic state and energy availability. The orexigenic peptide hormone ghrelin plays an integral role in energy metabolism and is known to have an inhibitory effect on reproductive physiology. In contrast, ghrelin and its receptor, the GHSR-1a, is also key for generating motivated behaviors, including sex behaviors. The aim of the current study was to investigate the effects of a GHSR knock out genetic manipulation animal model on appetitive and consummatory male sexual behavior using bi-level chambers. Male wild type (n=10) and GHSR KO rats (n=7) were exposed to sexually receptive females for 30 minutes inside bi-level chambers and were allowed to copulate. This protocol was followed every four days for a total of five sessions. During these sessions we measured appetitive (locomotor activity in anticipation of a female) and consummatory behaviors (latency to mount, intromissions, latency to ejaculate, and number of ejaculations). Results show that GHSR KO rats have a shorter latency to approach a female during the initial exposure to the female, and this effect disappears by the fifth session. Interestingly, male GHSR KO rats displayed less anticipatory locomotor activity in the bi-level chambers than their WT littermates. These data suggest that ghrelin has a modulatory effect on male rat sexual behavior, and may differentially affect appetitive and consummatory behavior.