The Interplay between Reproductive Social Stimuli and Adult Olfactory Bulb Neurogenesis

Abstract

Adult neurogenesis is a striking form of structural plasticity that adapts the brain to the changing world. Accordingly, new neuron production is involved in cognitive functions, such as memory, learning, and pattern separation. Recent data in rodents indicate a close link between adult neurogenesis and reproductive social behavior. This provides a key to unravel the functional meaning of adult neurogenesis in biological relevant contexts and, in parallel, opens new perspectives to explore the way the brain is processing social stimuli. In this paper we will summarize some of the major achievements on cues and mechanisms modulating adult neurogenesis during social behaviors related to reproduction and possible role/s played by olfactory newborn neurons in this context. We will point out that newborn interneurons in the accessory olfactory bulb (AOB) represent a privileged cellular target for social stimuli that elicit reproductive behaviors and that such cues modulate adult neurogenesis at two different levels increasing both proliferation of neuronal progenitors in the germinative regions and integration of newborn neurons into functional circuits. This dual mechanism provides fresh neurons that can be involved in critical activities for the individual fitness, that is, the processing of social stimuli driving the parental behavior and partner recognition.

Sexual Behavior Increases Cell Proliferation in the Rostral Migratory Stream and Promotes the Differentiation of the New Cells into Neurons in the Accessory Olfactory Bulb of Female Rats

“…After the new cells are born, they migrate tangentially for about 2 weeks until reaching the OB and incorporating into their final location in the MOB and AOB. Regulation of the neurogenesis process is highly sensitive to internal and external changes, and since the OB is involved in controlling reproductive behaviors in most mammals, the relevance of the neurogenesis process in OB mediated behaviors is well documented (see Oboti et al, 2009 ; Nunez-Parra et al, 2011 ; Peretto et al, 2014 ). For example, in male hamsters the majority of new cells that incorporate into the MOB and AOB are activated in response to mating and a low percentage of them respond to estrous female odors or to the female presence without physical contact (Huang and Bittman, 2002 ), suggesting a possible role of the new cells in the processing of sexual related odors and sexual behavior.…”

Opposite-sex attraction in male mice requires testosterone-dependent regulation of adult olfactory bulb neurogenesis

“…These neural circuits include several nuclei of the vomeronasal system (VNS) and hypothalamus, and the integration of pheromonal and endocrine signals in these circuits is required to regulate the activity of the hypothalamic-pituitary-gonadal (HPG) axis and thus reproduction6. Pheromones and sex hormones are also key regulators of adult neurogenesis, the process of the continuous generation of new neurons that occurs in restricted regions of the adult brain, namely the olfactory bulb (OB) and the dentate gyrus of the hippocampus78. In the accessory olfactory bulb (AOB; i.e., the first relay station in the VNS) of female mice, adult neurogenesis is positively regulated by male pheromonal stimuli and is essential for one of the best-known examples of neuroendocrine responses elicited by pheromones: the exteroceptive block of pregnancy or Bruce effect91011.…”

“…In addition, pheromonal perception in both sexes, as well as pregnancy and lactation in females, drives the secretion of adenohypophyseal hormones (e.g., prolactin and luteinizing hormone) and sex steroids (e.g., oestradiol and testosterone -TST), which in turn influence adult neurogenesis12131415. Thus, increasing evidence points to a role for adult neurogenesis in the control of reproduction through the integration of pheromonal and sex hormonal cues81617, yet the mechanisms underlying this integration remain largely elusive. To address this issue, here, we investigated adult AOB neurogenesis and activation of the VNS in the context of pre-copulatory sexual behaviour in Sema7A ko mice18.…”

Spatio-Temporal Recruitment of Adult Neural Stem Cells for Transient Neurogenesis During Pregnancy

“…The copyright holder for this preprint (which this version posted July 12, 2021. ; https://doi.org/10.1101/2021.07.11.451957 doi: bioRxiv preprint 6 neurons have been implicated in social and reproductive behaviour (17). Neurons born at Gd 4.5 and Gd 7.5 were selectively increased in the GCL of the AOB (Fig.…”