Activity Dependent Modulation of Granule Cell Survival in the Accessory Olfactory Bulb at Puberty

Abstract

The vomeronasal system (VNS) is specialized in the detection of salient chemical cues triggering social and neuroendocrine responses. Such responses are not always stereotyped, instead, they vary depending on age, sex, and reproductive state, yet the mechanisms underlying this variability are unclear. Here, by analyzing neuronal survival in the first processing nucleus of the VNS, namely the accessory olfactory bulb (AOB), through multiple bromodeoxyuridine birthdating protocols, we show that exposure of female mice to male soiled bedding material affects the integration of newborn granule interneurons mainly after puberty. This effect is induced by urine compounds produced by mature males, as bedding soiled by younger males was ineffective. The granule cell increase induced by mature male odor exposure is not prevented by pre-pubertal ovariectomy, indicating a lesser role of circulating estrogens in this plasticity. Interestingly, the intake of adult male urine-derived cues by the female vomeronasal organ increases during puberty, suggesting a direct correlation between sensory activity and AOB neuronal plasticity. Thus, as odor exposure increases the responses of newly born cells to the experienced stimuli, the addition of new GABAergic inhibitory cells to the AOB might contribute to the shaping of vomeronasal processing of male cues after puberty. Consistently, only after puberty, female mice are capable to discriminate individual male odors through the VNS.

Interneuron Functional Diversity in the Mouse Accessory Olfactory Bulb

“…IGCs are the most numerous and are currently the best-studied interneuron subtype in the AOB (Dudley and Moss, 1999; Jia et al, 1999; Araneda and Firestein, 2006; Smith et al, 2009; Taniguchi et al, 2013; Hu et al, 2016). Their known and hypothesized connections to experience-dependent plasticity make them a particularly compelling cell type to study (Brennan et al, 1990; Okutani et al, 1999; Cansler et al, 2017; Gao et al, 2017; Oboti et al, 2017). Despite the relatively strong set of inquiries into IGC function, there are many outstanding questions about IGCs’ role in AOB information processing and experience-dependent chemosensory plasticity.…”

Sex Steroids and Adult Neurogenesis in the Ventricular-Subventricular Zone

“…Male pheromones stimulate the production of ovarian hormones ( 63 ) as well as the neurogenesis in adult females ( 35 , 64 , 65 ). However, E 2 does not increase neurogenesis ( 66 ), nor cell proliferation in V-SVZ or neuroblasts density in OB, but it decreases cell survival in AOB, but not in MOB ( 24 ).…”

Interneuron functional diversity in the mouse accessory olfactory bulb

“…IGCs are the most numerous and are currently the best-studied interneuron subtype in the AOB (Dudley and Moss, 1999;Jia et al, 1999;Araneda and Firestein, 2006;Smith et al, 2009;Taniguchi et al, 2012;Hu et al, 2016). Their known and hypothesized connections to experience-dependent plasticity make them a particularly compelling cell type to study (Brennan et al, 1990;Okutani et al, 1999;Cansler et al, 2017;Gao et al, 2017;Oboti et al, 2017). Despite the relatively strong set of inquiries into IGC function, there are many outstanding questions about IGCs' role in AOB information processing and experience-dependent chemosensory plasticity.…”