Chemosensory and hormone information are relayed directly between the medial amygdala, posterior bed nucleus of the stria terminalis, and medial preoptic area in male Syrian hamsters

Abstract

In many rodent species, including Syrian hamsters, the expression of appropriate social behavior depends critically on the perception and identification of conspecific odors. The behavioral response to these odors is mediated by a network of steroid-sensitive ventral forebrain nuclei including the medial amygdala (Me), posterior bed nucleus of the stria terminalis (BNST) and medial preoptic area (MPOA). Although it is well-known that Me, BNST, and MPOA are densely interconnected and each uniquely modulates odor-guided social behaviors, the degree to which conspecific odor information and steroid hormone cues are directly relayed between these nuclei is unknown. To answer this question, we injected the retrograde tracer, cholera toxin B (CTB), into the BNST or MPOA of male subjects and identified whether retrogradely-labeled cells in Me and BNST 1) expressed immediate early genes (IEGs) following exposure to male and/or female odors or 2) expressed androgen receptor (AR). Although few retrogradely-labeled cells co-localized with IEGs, a higher percentage of BNST-and MPOA-projecting cells in the posterior Me (MeP) expressed IEGs in response to female odors than to male odors. The percentage of retrogradelylabeled cells that expressed IEGs did not, however, differ between and female-and male-odorexposed groups in the anterior Me (MeA), posterointermediate BNST (BNSTpi), or posteromedial BNST (BNSTpm). Many retrogradely-labeled cells co-localized with AR, and a higher percentage of retrogradely-labeled MeP and BNSTpm cells expressed AR than retrogradely-labeled MeA and BNSTpi cells, respectively. Together, these data demonstrate that Me, BNST, and MPOA interact as a functional circuit to process sex-specific odor cues and hormone information in male Syrian hamsters.

The neurobiology of mammalian parenting and the biosocial context of human caregiving

“…Primed by the hormones of pregnancy and triggered by the increase in oxytocin and prolactin during parturition, the MPOA projects to the mesolimbic dopamine circuits, including VTA and NAcc, which increases maternal motivation to care for infants and places incentive value on stimuli from the child (Dobolyi et al, 2014;Numan and Stolzenberg, 2009;Shahrokh et al, 2010). The MPOA also projects to the amygdala, which increases maternal vigilance for infant safety (Been and Petrulis, 2012;Sheehan et al, 2001). These three structures, the oxytocin-producing hypothalamus, amygdala, and the limbic dopamine limbic, including both the mesolimbic and nigrostriatal pathways, constitute the central network that underpins maternal care in rodents, a network in which OT functions as a modulator (Coria-Avila et al, 2014;Insel and Young, 2001).…”

Morphological and Functional Features of the Sex Steroid-Responsive Posterodorsal Medial Amygdala of Adult Rats

“…Projections to the entorhinal area and to the postpiriform transitional area allow pheromonal influences to act on hippocampal circuitry [7]". Recent findings have updated and expanded upon the knowledge of this scenario [see, for example, [113][114][115][116][117][118][119].…”

A Novel Model for Neuroendocrine Toxicology: Neurobehavioral Effects of BPA Exposure in a Prosocial Species, the Prairie Vole (Microtus ochrogaster)

“…We also quantified the density of dopaminergic neurons in the principal bed nucleus of the stria terminalis (pBNST); an interconnection site for brain areas integral for social behaviors related to reproduction and defense, including locomotor activity and motivation (38 -40) as well as social stress (41,42). Dopaminergic pathways in this area are thought to regulate corticotropic affective states (43).…”