In female mice, the number of surviving cells in the AOB is increased by exposure to male soiled bedding. Such sensory experience is also known to facilitate estrous in females and halts embryo implantation soon after mating (Bruce effect). Exteroceptive estrous induction is lost by studmale odours through enhancement of granuletomitral synaptic inhibition during mating. This male-specific pheromone recognition process involves a restricted pool of granule cells in the AOB, which inhibits mitral cell signal transmission to the forebrain areas involved in estrous induction. Here we show that the neuronal addition in the AOB of female mice is modulated in the same sensory background characterizing this memory formation process: it depends on the detection of vomeronasal sensory stimuli, included in the LMW urine fraction, that requires an intact Trpc2 cation channel, and central inputs from the medial amygdala. Sustained by this evidence, we have halted the production of new neurons in the brain by AraC brain infusion and tested the ability of adult female mice to recognize their mating partners in order to avoid pregnancy block. As a result, we found a high rate of pregnancy failure in recently mated females after exposure to the mating partner. This effect was specifically due to the studmale reexposure since no such pregnancy failure did follow when AraC was given alone. Importantly, the high pregnancy failure rate induced by stud male exposure after neurogenesis blockade did not occur in VNX mice. Together, our results indicate that the pheromonal imprinting process required to block estrous induction by mate???s pheromones is preferentially localized on AOB newborn granule cells.
Newborn interneurons in the accessory olfactory bulb promote mate recognition in female mice
OBOTI, Livio;SCHELLINO, ROBERTA;FASOLO, Aldo;PERETTO, Paolo Marcello
2011-01-01
Abstract
In female mice, the number of surviving cells in the AOB is increased by exposure to male soiled bedding. Such sensory experience is also known to facilitate estrous in females and halts embryo implantation soon after mating (Bruce effect). Exteroceptive estrous induction is lost by studmale odours through enhancement of granuletomitral synaptic inhibition during mating. This male-specific pheromone recognition process involves a restricted pool of granule cells in the AOB, which inhibits mitral cell signal transmission to the forebrain areas involved in estrous induction. Here we show that the neuronal addition in the AOB of female mice is modulated in the same sensory background characterizing this memory formation process: it depends on the detection of vomeronasal sensory stimuli, included in the LMW urine fraction, that requires an intact Trpc2 cation channel, and central inputs from the medial amygdala. Sustained by this evidence, we have halted the production of new neurons in the brain by AraC brain infusion and tested the ability of adult female mice to recognize their mating partners in order to avoid pregnancy block. As a result, we found a high rate of pregnancy failure in recently mated females after exposure to the mating partner. This effect was specifically due to the studmale reexposure since no such pregnancy failure did follow when AraC was given alone. Importantly, the high pregnancy failure rate induced by stud male exposure after neurogenesis blockade did not occur in VNX mice. Together, our results indicate that the pheromonal imprinting process required to block estrous induction by mate???s pheromones is preferentially localized on AOB newborn granule cells.
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