The Prevention of Excessive Weight Gain Through the Induction of Mild-Hyperthermia in Rodents: A Pilot Study

Preliminary studies indicate that the use of dietary menthol may prevent excessive weight gain through the activation of the transient receptor potential melastatin family member 8 (TRPM8) ion channel. It has also been expressed that elevation of the core temperature (Tc) inducing mild hyperthermia via an increase in ambient temperature aids in a marked reduction of the drive to eat and weight gain. While caloric restriction (CR) aims to treat obesity and secondary sicknesses, weight regain is a common result during long term weight maintenance. The goal of these studies was to evaluate and identify if the menthol and mild hyperthermia mechanisms could couple synergistically to reduce or abrogate weight gain. Ambient temperature (Ta) was increased incrementally to identify the threshold in which rodents display mild hyperthermia. Our initial attempts at hyperthermia induction failed because of limitations in the environmental chamber. These trials fail to note a threshold at which elevated Tc is sustained for any period of time. The data suggests an ambient temperature of 36-38 °C would be appropriate to induce a mild hyperthermia. A mild hyperthermia is described as the elevation of Tc 2-3 ° above the hypothalamic set point. To facilitate future hyperthermia studies, an environmental chamber was designed. A wine cooler was converted to withstand the desired temperatures, through the use of heat tape, a proportional controller, and a translucent Plexiglas custom fit door. Beyond leveraging temperature to regulate weight gain, dietary changes including a comparison between standard chow food, high fat diet, and menthol supplemented chow food treatment illustrate a strong likelihood of weight gain variability. In this pilot study, weight gain expression when given a diet supplemented with menthol (1%) showed no statistical significance relative to a high fat diet nor chow food, however, it revealed a trend of reduced weight gain. It is assumed the combination of supplemental menthol and mild hyperthermia induction will exacerbate their effects.