Attraction to sexual pheromones and associated odorants in female mice involves activation of the reward system and basolateral amygdala.
Adult female mice are innately attracted to non-volatile pheromones contained in male-soiled bedding. In contrast, male-derived volatiles become attractive if associated with non-volatile attractive pheromones, which act as unconditioned stimulus in a case of Pavlovian associative learning. In this work, we study the chemoinvestigatory behaviour of female mice towards volatile and non-volatile chemicals contained in male-soiled bedding, in combination with the analysis of c-fos expression induced by such a behaviour to clarify: (i) which chemosensory systems are involved in the detection of the primary attractive non-volatile pheromone and of the secondarily attractive volatiles; (ii) where in the brain male-derived non-volatile and volatile stimuli are associated to induce conditioned attraction for the latter; and (iii) whether investigation of these stimuli activates the cerebral reward system (mesocorticolimbic system including the prefrontal cortex and amygdala), which would support the view that sexual pheromones are reinforcing. The results indicate that non-volatile pheromones stimulate the vomeronasal system, whereas air-borne volatiles activate only the olfactory system. Thus, the acquired preference for male-derived volatiles reveals an olfactory-vomeronasal associative learning. Moreover, the reward system is differentially activated by the primary pheromones and secondarily attractive odorants. Exploring the primary attractive pheromone activates the basolateral amygdala and the shell of nucleus accumbens but neither the ventral tegmental area nor the orbitofrontal cortex. In contrast, exploring the secondarily attractive male-derived odorants involves activation of a circuit that includes the basolateral amygdala, prefrontal cortex and ventral tegmental area. Therefore, the basolateral amygdala stands out as the key centre for vomeronasal-olfactory associative learning.
Moncho-Bogani
Jose
J
Department of Biologia Funcional i Antropologia Física, Facultat de Ciències Biològiques, Universitat de València, C. Dr Moliner, 50, 46100 Burjassot, València, Spain.
Martinez-Garcia
Fernando
F
Novejarque
Amparo
A
Lanuza
Enrique
E
D000679:Amygdala / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal; D002452:Cell Count / Q000379:methods; D003216:Conditioning, Operant; D005106:Exploratory Behavior / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D051379:Mice; D009474:Neurons / Q000378:metabolism; D016761:Oncogene Proteins v-fos / Q000378:metabolism; D012201:Reward; D012724:Sex Attractants / Q000494:pharmacology*; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D019147:Vomeronasal Organ / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
D016761:Oncogene Proteins v-fos; D012724:Sex Attractants