Neurochemical Characterization of Neurons Expressing Estrogen Receptor β in the Hypothalamic Nuclei of Rats Using in Situ Hybridization and Immunofluorescence

• Main Authors: Moeko Kanaya, Shimpei Higo, Hitoshi Ozawa
• Format: Article
• Language: English
• Published: MDPI AG 2019-12-01
• Series: International Journal of Molecular Sciences
• Subjects: estrogen receptor β; <i>esr2</i>; rnascope; kisspeptin; anteroventral periventricular nucleus; arcuate nucleus; vasopressin; oxytocin; corticotropin-releasing factor; paraventricular nucleus
• Online Access: https://www.mdpi.com/1422-0067/21/1/115

Estrogens play an essential role in multiple physiological functions in the brain, including reproductive neuroendocrine, learning and memory, and anxiety-related behaviors. To determine these estrogen functions, many studies have tried to characterize neurons expressing estrogen receptors known as ER&#945; and ER&#946;. However, the characteristics of ER&#946;-expressing neurons in the rat brain still remain poorly understood compared to that of ER&#945;-expressing neurons. The main aim of this study is to determine the neurochemical characteristics of ER&#946;-expressing neurons in the rat hypothalamus using RNAscope <i>in situ</i> hybridization (ISH) combined with immunofluorescence. Strong <i>Esr2</i> signals were observed especially in the anteroventral periventricular nucleus (AVPV), bed nucleus of stria terminalis, hypothalamic paraventricular nucleus (PVN), supraoptic nucleus, and medial amygdala, as previously reported. RNAscope ISH with immunofluorescence revealed that more than half of kisspeptin neurons in female AVPV expressed <i>Esr2</i>, whereas few kisspeptin neurons were found to co-express <i>Esr2</i> in the arcuate nucleus. In the PVN, we observed a high ratio of <i>Esr2</i> co-expression in arginine-vasopressin neurons and a low ratio in oxytocin and corticotropin-releasing factor neurons. The detailed neurochemical characteristics of ER&#946;-expressing neurons identified in the current study can be very essential to understand the estrogen signaling via ER&#946;.