Neuroanatomical and functional characterization of Bombesin-like receptor 3 (Brs3) neurons using Brs3-T2A-CreER T2 mice

Authors

• SH Zahler
• C Xiao
• RA Pinol
• ML Reitman

Abstract

Introduction: Bombesin-like receptor 3 (Brs3) is an orphan G protein-coupled receptor. Brs3 is expressed largely in the central nervous system and is involved in the regulation of metabolic rate, food intake, and heart rate. We now report a mouse line that produces tamoxifen-regulated Cre in cells expressing Brs3 and use this line to identify Brs3 neurons that co-express leptin receptor. Methods: Brs3-T2A-CreERT2mice were produced by homologous recombination into the native Brs3 locus on the X-chromosome. Brs3-T2A-CreERT2 and Ai9 mice (carrying a Cre-inducible tdTomato reporter) were bred, and the progeny were treated with tamoxifen to express the fluorescent reporter. Brs3 neurons co-expressing leptin receptor were identified by treating these mice with leptin and performing immunohistochemistry for phosphorylated STAT3 (pSTAT3). Results: Dense tdTomato fluorescence in neurons was observed in the following hypothalamic regions: preoptic area (POA), paraventricular nucleus of the hypothalamus (PVH), dorsomedial hypothalamus (DMH), and bed nucleus of the stria terminalis (BNST). High expression was also present in the medial amygdala (MeA) and parabrachial nucleus (PBN). Dense fibers were observed in the dorsal raphe nucleus (DR), nucleus of the solitary tract (NTS), ventral tegmental area (VTA), and periaqueductal gray (PAG). The Cre expression pattern is consistent with that previously reported for Brs3 using mRNA in situ hybridization and ligand binding. TdTomato fluorescence colocalized with pSTAT3 staining in the POA, DMH, and lateral hypothalamus (LH) Conclusions: The Brs3-T2A-CreERT2 mice faithfully express Cre in Brs3 neurons, including multiple hypothalamic nuclei. Brs3 is coexpressed with leptin receptor in certain hypothalamic nuclei.

Scientific Focus Area: Neuroscience

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