New functions of classical hormone α-melanophore-stimulating hormone
| Autor: | Tonosaki, Yoshikazu, Sugiura, Yasuo, Roubos, Eric W. |
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| Jazyk: | angličtina |
| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | 弘前医学. 59:S202-S209 |
| ISSN: | 0439-1721 |
| Popis: | application/pdf It is well-known that α-melanophore-stimulating hormone （α-MSH） release from the amphibian pars intermedia（ PI） depends on the light condition of the animal’s background. In the present study, we present two new functions of α-MSH in amphibians and mammals. In Xenopus laevis, we show that temperatures below 8 ℃ stimulate α-MSH secretion of the PI and skin darkening, with a maximum at 5 ℃, under regulation of the hypothalamus rule, independently from the illumination state of the background. The cold-induced α-MSH release of the PI was inhibited by neuropeptide-Y-producing suprachiasmatic-melanotrope-inhibiting neurons in the ventrolateral area of the suprachiasmatic nucleus but increasely in thyrotropin-releasing-hormene-containing neurons of the magnocellular nucleus. It is known that intracerebroventricular（ ICV） administration of a low dose of interleukin-1β（ IL-1β） induces hyperalgesia in rat and that this eff ect can be inhibited by α-MSH. To identify the part of the brain that is aff ected by hyperalgesiainducing IL-1β and the site of α-MSH concerned, we have examined Fos expression in the brain in response to ICV microinjection of α-MSH and/or IL-1β. Following injection of 10 pg IL-1β, hyperalgesia was induced and Fos became expressed in the paraventricular nucleus（ PVN） of the hypothalamus and in the arcuate nucleus（ ARC）, which contains α-MSH-producing neurons. ICV co-injection of IL-1β ・ with 30 ng α-MSH fully inhibited both hyperalgesia and Fos expression in the PVN and the ARC. We conclude that PVN neurons are activated by hyperalgesic IL-1β and propose that this eff ect is abolished by α-MSH released from the ARC but not from the pituitary gland. 弘前医学. 59(Suppl.), 2007, p.S202-S209 |
| Databáze: | OpenAIRE |
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