免疫刺激による視床下部神経内分泌応答におけるオキシトシン受容体の機能解析

We sought to examine the physiological functions of the OTR in mediating the neuroendocrine responses following immune challenges. Hypothalamic neuroendocrine responses were characterized in the OTR deficient mice, that we recently generated by genetic engineering, and comparison was made with those in wild type animals. Three groups of mice deficient in OTR (–/–)(groups 1, 2, 3) and 3 groups of wild type counterparts (+/+)(groups 4, 5, 6) were used. Groups 1 and 4 were naive groups, and these mice were decapitated without any challenge. Lipopolysacchride (LPS) at a dose of 10 mg/kg b.w. was injected i.p. into the animals in groups 2 and 5, and after 2 hr, these mice were sacrificed. 0.9% saline was injected instead of LPS in groups 3 and 6. Ten μm serial brain sections were made by cryostat and CRH mRNA and OT mRNA were detected by in situ hybridazation. CRH mRNA increased significantly in the paraventricular nucleus of the hypothalamus (PVN) after LPS injection both in OTR (–/–) and (+/+) group, but no statistical difference was observed between the two genotypes. OT mRNA increased in the caudal lateral division of the PVN in OTR (+/+) animals after LPS injection. However, this increase was not observed in OTR (–/–) animals. Thus, OTR may mediate autonomic activation via OT neurons in the PVN following immune challenge, since OT neurons in this division project to the sympathetic premoter neurons. [Jpn J Physiol 55 Suppl:S208 (2005)]