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 ERα and ERβ. However
the characteristics of ERβ-expressing neurons in the rat brain still remain poorly understood compared to that of ERα-expressing neurons. The main aim of this study is to determine the neurochemical characteristics of ERβ-expressing neurons in the rat hypothalamus using RNAscope in situ hybridization (ISH) combined with immunofluorescence. Strong Esr2 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 Esr2
whereas few kisspeptin neurons were found to co-express Esr2 in the arcuate nucleus. In the PVN
we observed a high ratio of Esr2 co-expression in arginine-vasopressin neurons and a low ratio in oxytocin and corticotropin-releasing factor neurons. The detailed neurochemical characteristics of ERβ-expressing neurons identified in the current study can be very essential to understand the estrogen signaling via ERβ.
