Konishi Shun-ichiro, Kasagi Yoko, Katsumata Harumi, Minami Shiro, Imaki Toshihiro
Department of Bioregulation, Institute of Gerontology, Nippon Medical School, Kawasaki 211-8533, Japan.
Endocr J. 2003 Feb;50(1):21-36. doi: 10.1507/endocrj.50.21.
We reported previously that acute stress and intracerebroventricular (i.c.v.) injection of corticotropin-releasing factor (CRF) increased neuronal activation and CRF type-1 receptor (CRFR-1) mRNA expression in the CRF-producing neurons of the parvocellular paraventricular nucleus (PVN) of the hypothalamus. In this study, to determine whether CRF can act directly on hypothalamic CRF neurons, thereby increasing CRFR-1 expression, microinjection of CRF into PVN neurons in vivo and primary cultures of dispersed rat fetal hypothalami in vitro were performed. Microinjection of 0.1 microg of CRF into the PVN significantly increased c-fos and CRFR-1 mRNA expression in the CRF-producing parvocellular PVN, 30 min or 180 min after injection, respectively. This effect was blocked by a CRF antagonist, alpha-helical CRF. CRF, when injected into the lateral ventricle at the same dose, increased neither CRFR-1 nor c-fos mRNA levels in the PVN. Primary culture of hypothalamic neurons revealed that CRFR-1 like immunoreactivity was located in CRF-containing neurons, and that the CRFR-1 mRNA level was significantly increased 4 h after incubation with 10(-8) M CRF. These results demonstrate that CRF directly affects hypothalamic neurons to increase CRFR-1 mRNA expression, providing evidence of a direct role for CRF in the regulation of CRFR-1 expression of hypothalamic neurons.
我们之前报道过，急性应激以及向脑室内（i.c.v.）注射促肾上腺皮质激素释放因子（CRF）会增加下丘脑室旁核小细胞部（PVN）中产生CRF的神经元的神经元激活以及CRF 1型受体（CRFR-1）mRNA表达。在本研究中，为了确定CRF是否能直接作用于下丘脑CRF神经元，从而增加CRFR-1表达，我们进行了向PVN神经元体内微量注射CRF以及体外分散的大鼠胎儿下丘脑原代培养实验。向PVN微量注射0.1微克CRF后，分别在注射后30分钟或180分钟显著增加了产生CRF的小细胞PVN中c-fos和CRFR-1 mRNA表达。这种效应被CRF拮抗剂α-螺旋CRF阻断。以相同剂量向侧脑室注射CRF时，PVN中的CRFR-1和c-fos mRNA水平均未增加。下丘脑神经元原代培养显示，CRFR-1样免疫反应性位于含CRF的神经元中，并且在与10(-8) M CRF孵育4小时后，CRFR-1 mRNA水平显著增加。这些结果表明，CRF直接影响下丘脑神经元以增加CRFR-1 mRNA表达，为CRF在下丘脑神经元CRFR-1表达调节中的直接作用提供了证据。
