Effects of Adenosine Outside the Brain in Hibernation for Arctic Ground Squirrels

Overview

Fairbanks Hibernation is an adaptation found in animals that, if it can be safely induced in humans, may help extend space missions and help the human brain recover from low oxygen situations. However, the physiological causes of hibernation are not well understood. One factor that plays a crucial role in hibernation is adenosine, a molecule that is found in the bloodstream and brain. In past studies, torpor was induced by exciting adenosine A1 receptors in the brain via a central administration of an adenosine agonist, while a central administration of an adenosine antagonist reverted torpor. It is unclear if these receptors play the same role outside of the brain. In this study we conduct experiments on 5 Arctic Ground Squirrels to assess whether adenosine outside of the brain has any effect on hibernation. We habituated them to get used to the handling and injection of the drugs. Two drugs were injected into them, one with a mol ecule to block the adenosine’s receptor (an adenosine antagonist) and another with sterile water. Three measurements, carbon dioxide (CO2) production, heart rate (HR), and body temperature (Tb) were acquired for two hours after each drug treatment. From the data, we concluded that adenosine in the bloodstream did not have an effect on the hibernation of Arctic Ground Squirrels as the drug with 8-sulfophenyl theophylline (8 -SPT), the adenosine a ntagonist, did not show any significant difference with sterile water. Our findings further highlight the role played by adenosine A1 receptors in the brain to regulate hibernation. Arizona