Basal tail skin temperature elevation and augmented response to calcitonin gene-related peptide in ovariectomized...

Hyper-release of calcitonin gene-related peptide (CGRP) plays a direct and pivotal role in the induction of menopausal hot flushes (HFs), in which a drastic increase in skin temperature occurs. However, it is not possible to investigate whether CGRP induces skin temperature increase and whether skin temperature response to CGRP changes and contributes to the occurrence of HFs in postmenopausal women who are in oestrogen deficiency. By using rats' tail skin temperature (TST), a good marker to evaluate skin temperature regulation, we examined the effects of CGRP and calcitonin (3, 10 and 30 micrograms/kg, i.v.) on TST in female rats and further investigated the TST change induced by CGRP (10 micrograms/kg, i.v.) in ovariectomized (OVX) rats compared with that in sham-operated (Sham) rats. We found that CGRP, but not calcitonin, induced a TST increase in a dose-dependent manner and that the TST change induced by CGRP (0.6 +/- 0.2 degrees C for OVX rats vs 0.3 +/- 0.1 degree C for Sham rats, P < 0.05) and also the basal TST (26.0 +/- 0.2 degrees C for OVX rats vs 25.5 +/- 0.1 degree C for Sham rats) were significantly greater in OVX rats (P < 0.05). Furthermore, treatment with oestradiol (30 micrograms/kg, s.c.) for 8 days partially inhibited the augmented TST response to CGRP in OVX rats and almost completely inhibited (P < 0.05) the basal TST elevation, with the concomitant recovery of the serum oestradiol level to that in Sham rats. These results suggest that the augmented skin temperature response to CGRP and the elevation of basal skin temperature that are found in OVX rats, animals which are oestradiol deficient, may also occur in menopausal women and contribute to their HFs.