Meeting Abstract

91.7  Wednesday, Jan. 7  Voluntary motor activity contributes to the increase in body temperature caused by menthol application to the skin of gerbils BOILY, P.; Western Connecitcut State University boilyp@wcsu.edu

In mammals, the perception of innocuous cold temperatures is partly mediated by the activation of TRPM8 ion channels found on the membrane of some sensory neurons. Menthol can activate these channels, thus causing the well-known cooling sensation produced when applied to the skin or oral mucosa. Further, the topical application of menthol to the skin of mice causes vasoconstriction and increased thermogenesis, and therefore appears to mimic cold exposure. These physiological responses, without being associated with a real cold exposure, result in an increased body temperature (Tajino et al. 2007). Because the body temperature of small rodents is highly dependent on motor activity, I hypothesized that the increase in body temperature induced by topical menthol applications is also, in part, the result of increased motor activity. Body temperature and voluntary motor activity of six Mongolian gerbils (Meriones unguiculatus) were monitored by telemetry after topical applications of menthol solutions (0, 5, 10% w/v). Menthol applications caused a dose-dependent increase in body temperature, by 2C and lasting more than 2 hours for the 10% concentration. Menthol application also induced a dose-dependent increase in motor activity. Regression analyses indicated that 25 to 38% of the menthol-induced increase in body temperature was related to voluntary motor activity (log transformed), depending on whether the data was analyzed separately for each menthol concentration or pooled. These results suggest that voluntary motor activity contributes to the increase in body temperature caused by menthol application to the skin of gerbils.