Oxytocin in the medial preoptic area facilitates male sexual behavior in the rat

Abstract

Oxytocin (OT) is a versatile neuropeptide that is involved in a variety of mammalian behaviors, and its role in reproductive function and behavior has been well established. The majority of pharmacological studies of the effects of OT on male sexual behavior have focused on the paraventricular nucleus (PVN), ventral tegmental area (VTA), hippocampus, and amygdala. Less attention has been given to the medial preoptic area (MPOA), a major integrative site for male sexual behavior. The present study investigated the effects of intra-MPOA administration of OT and (d(CH2)51, Tyr(Me)2, Thr4, Orn8, Tyr-NH29)-vasotocin, an OT antagonist (OTA), on copulation in the male rat. The relationship between OT receptor (OTR) binding levels in the MPOA and sexual efficiency was also explored. Microinjection of OT into the MPOA facilitated copulation in sexually experienced male rats, whereas similar injections of an OTA inhibited certain aspects of copulation but had no significant effect on locomotor activity in an open field. Contrary to expectation, sexually efficient males had lower levels of OTR binding in the rostral MPOA compared to inefficient animals. The present data suggest that OT activity in the MPOA is not necessary for the expression of male sexual behavior but is sufficient to facilitate copulatory behaviors and improve sexual efficiency in sexually experienced male rats. These data also suggest that OTR activity in the MPOA stimulates anogenital investigation, facilitates the initiation of copulation, and plays a role in the sensitization effect of the first ejaculation on subsequent ejaculations.

Oxytocin receptors modulate a social salience neural network in male prairie voles

“…We previously demonstrated that ICV administration of OTA reduces mating frequency in male prairie voles (Johnson et al, 2016). Taken together, these data suggest that OTRs in other nuclei modulate sexual behavior in male prairie voles, consistent with findings in rats (Argiolas and Melis, 2013; Gil et al, 2011). Importantly, these results suggest that any significant differences in Fos-ir between treatment groups are not due to differences in any of the analyzed sociosexual behaviors.…”

Oxytocin enhances the expression of morphine-induced conditioned place preference in rats

“…Each barrel was attached by polyethylene tubing (PE-10) to separate Hamilton syringes (2 l) and injections were made over 1 min using a microinjection pump (Nexus 3000, Chemyx Inc., Houston, TX, USA). The dose of oxytocin injected into the NAcSh was within the range effective doses of oxytocin used in previous studies (Gu and Yu, 2007;Baracz et al, 2011;Gil et al, 2011;Sanna et al, 2012).…”

Aging and estradiol effects on gene expression in the medial preoptic area, bed nucleus of the stria terminalis, and posterodorsal medial amygdala of male rats

“…Work from our lab on an ovariectomized female rat model found fewer effects of age and E2 on nonapeptide gene expression in the POA (Yin et al, 2015), suggesting a greater sensitivity of the male than the female brain. Oxytocin in the POA facilitates sexual behavior in males, and this undergoes age-related impairments (Gil et al, 2011). Furthermore, oxytocin colocalizes with the p450 aromatase enzyme in the male POA (El-Emam Dief et al, 2013), suggesting the capacity of these cells to convert testosterone to estradiol.…”