Differential regulation of type-1 and type-2alpha corticotropin-releasing hormone receptor mRNA in the hypothalamic paraventricular nucleus of the rat.
Novel corticotropin-releasing hormone receptor (CRHR), designated type-2alpha CRHR (CRHR-2alpha), was recently cloned and functionally characterized. In situ hybridization study revealed that CRHR-2alpha mRNA had a distinct distribution from type-1 CRHR (CRHR-1) mRNA in the rat brain. Interestingly, CRHR-2alpha mRNA showed a relatively high expression in the hypothalamic paraventricular nucleus (PVN) even under unstressful condition. This may reflect the important role of CRHR-2alpha in the autoregulation of CRH secretion in the PVN. To determine the regulation of CRHR-2alpha mRNA expression in the PVN, we examined the alteration of CRHR-2alpha mRNA levels in the PVN in rats with lipopolysaccharide (LPS) injection, corticosterone (CORT) administration or adrenalectomy and compared with that of CRHR-1 mRNA, using in situ hybridization histochemistry. I.p. LPS injection (50 microg) induced a significant increase in PVN CRHR-1 mRNA at 3 and 6 h whereas CORT administration (10 mg/day for 12 days) or adrenalectomy (sacrificed 7 days after surgery) decreased CRHR-1 mRNA levels in the PVN. These alterations in PVN CRHR-1 mRNA are consistent with previous reports. In contrast, CRHR-2alpha mRNA levels in the PVN were not altered by any of these treatments. These results indicate that CRHR-1 and CRHR-2alpha mRNA are differentially regulated in the PVN. Further study will be necessary to elucidate the CRHR-2alpha function in the PVN.
Makino
S
S
2nd Department of Internal Medicine, Kochi Medical School, Okoh-cho, Nankoku, Japan. makinos@dtn.am400gw.kochi-ms.ac.jp
Takemura
T
T
Asaba
K
K
Nishiyama
M
M
Takao
T
T
Hashimoto
K
K
D000818:Animals; D003345:Corticosterone / Q000494:pharmacology*; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D017403:In Situ Hybridization; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018019:Receptors, Corticotropin-Releasing Hormone / Q000187:drug effects* / Q000378:metabolism
D008070:Lipopolysaccharides; D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; D003345:Corticosterone