Visualization of corticotropin-releasing factor neurons by fluorescent proteins in the mouse brain and characterization of labeled neurons in the paraventricular nucleus of the hypothalamus.

Abstract

Corticotropin-releasing factor (CRF) is the key regulator of the hypothalamic-pituitary-adrenal axis. CRF neurons cannot be distinguished morphologically from other neuroendocrine neurons in the paraventricular nucleus of the hypothalamus (PVH) without immunostaining. Thus, we generated a knock-in mouse that expresses modified yellow fluorescent protein (Venus) in CRF neurons (CRF-Venus), and yet its expression is driven by the CRF promoter and responds to changes in the interior milieu. In CRF-Venus, Venus-expressing neurons were distributed in brain regions harboring CRF neurons, including the PVH. The majority of Venus-expressing neurons overlapped with CRF-expressing neurons in the PVH, but many neurons expressed only Venus or CRF in a physiological glucocorticoid condition. After glucocorticoid deprivation, however, Venus expression intensified, and most Venus neurons coexpressed CRF. Conversely, Venus expression was suppressed by excess glucocorticoids. Expression of copeptin, a peptide encoded within the vasopressin gene, was induced in PVH-Venus neurons by glucocorticoid deprivation and suppressed by glucocorticoid administration. Thus, Venus neurons recapitulated glucocorticoid-dependent vasopressin expression in PVH-CRF neurons. Noradrenaline increased the frequency of glutamate-dependent excitatory postsynaptic currents recorded from Venus-expressing neurons in the voltage clamp mode. In addition, the CRF-iCre knock-in mouse was crossed with a CAG-CAT-EGFP reporter mouse to yield the Tg(CAG-CAT-EGFP/wt);CRF(iCre/wt) (EGFP/CRF-iCre) mouse, in which enhanced green fluorescent protein (EGFP) is driven by the CAG promoter. EGFP was expressed more constitutively in the PVH of EGFP/CRF-iCre mice. Thus, CRF-Venus may have an advantage for monitoring dynamic changes in CRF neurons and CRF networks in different glucocorticoid states.

DOI: 10.1210/en.2014-1182

Cite this paper

@article{Itoi2014VisualizationOC, title={Visualization of corticotropin-releasing factor neurons by fluorescent proteins in the mouse brain and characterization of labeled neurons in the paraventricular nucleus of the hypothalamus.}, author={Keiichi Itoi and Ashraf Hossain Talukder and Toshimitsu Fuse and Takuji Kaneko and Ryo Ozawa and Takayuki Sato and Takuma Sugaya and Katsuya Uchida and Maya Yamazaki and Manabu Abe and Rie Natsume and Kenji Sakimura}, journal={Endocrinology}, year={2014}, volume={155 10}, pages={4054-60} }