A functional circuit underlying male sexual behaviour in the female mouse brain

Abstract

In mice, pheromone detection is mediated by the vomeronasal organ and the main olfactory epithelium. Male mice that are deficient for Trpc2, an ion channel specifically expressed in VNO neurons and essential for VNO sensory transduction, are impaired in sex discrimination and male-male aggression. We report here that Trpc2-/- female mice show a reduction in female-specific behaviour, including maternal aggression and lactating behaviour. Strikingly, mutant females display unique characteristics of male sexual and courtship behaviours such as mounting, pelvic thrust, solicitation, anogenital olfactory investigation, and emission of complex ultrasonic vocalizations towards male and female conspecific mice. The same behavioural phenotype is observed after VNO surgical removal in adult animals, and is not accompanied by disruption of the oestrous cycle and sex hormone levels. These findings suggest that VNO-mediated pheromone inputs act in wild-type females to repress male behaviour and activate female behaviours. Moreover, they imply that functional neuronal circuits underlying male-specific behaviours exist in the normal female mouse brain.

The main and the accessory olfactory systems interact in the control of mate recognition and sexual behavior

“…Interestingly, these results demonstrating the lack of a role for the VNO in mate recognition, have been broadly confirmed by performing lesions downstream in the accessory olfactory pathway at the level of the AOB [41,72]. The fact that mate recognition is not disrupted when the AOB is lesioned also confirms that previous results obtained by surgical removal of the VNO were not the consequence of an occlusion of the nasal cavity by blood clots, as was recently suggested by Kimchi et al [55].…”

From sexual attraction to maternal aggression: When pheromones change their behavioural significance

“…Since maternal aggression is severely reduced in mutant mice having olfactory (Cnag2 -/y , Mandiyan et al, 2005; AC3 -/-, Wang and Storm, 2011) or vomeronasal dysfunction (Leypold et al, 2002;Kimchi et al, 2007;Hasen and Gammie, 2009;Chamero et al, 2011;Leinders-Zufall et al, 2014), it seems likely that exposure to pup chemosignals detected by both the olfactory and vomeronasal epithelia is necessary for the induction of maternal aggression. However, our results indicate that virgin females that have been continuously exposed to pups for 3-4 days show negligible aggressive behaviour towards intruders approaching the nest (from which pups had been previously…”

“…When lactating females are used in maternal aggression tests, nest defence is also clearly impaired in trpc2 -/-mutants (Leypold et al, 2002;Kimchi et al, 2007) even when the mutation is shifted into a line of mice selected for their robust maternal aggression (Hasen and Gammie, 2009). This indicates that vomeronasal stimuli elicit both intermale and maternal aggression.…”

Task differences confound sex differences in receiver permissiveness in túngara frogs

“…In spadefoot toads (Pfenning et al 2000) and tú ngara frogs (this study), the outcome of any decision-making circuit involved in male and female phonotaxis is similar, although the details of the neural circuitry might differ. The differences between the sexes in their stimulus selectivity might be due to behaviour-specific responses associated with different effector circuits in the brain, as has been recently suggested of mice (Kimchi et al 2007). …”