Characterization of the adenosine A1 receptor in summer and winter Arctic ground squirrels

• Main Author: Carlson, Zachary A.
• Other Authors: Drew, Kelly, Rasley, Brian, Kuhn, Thomas
• Format: Thesis
• Language: English
• Published: 2014
• Subjects: Arctic; Arctic ground squirrel; Urocitellus parryii
• Online Access: http://hdl.handle.net/11122/4898

Hibernation is an adaptation that allows the Arctic ground squirrel (Urocitellus parryii) to survive the harsh arctic winter. Recently the activation of the Adenosine A1 receptor (A₁AR) has been shown to be necessary for entrance into hibernation during the winter but not summer season. In the current study we characterize the A₁AR in the forebrain, hippocampus and hypothalamus of summer and winter AGS. We also tested the hypothesis that increased A₁AR agonist efficacy is responsible for increased sensitization of the A₁AR during the winter season. The resulting ³⁵S-GTPγS binding data indicated an increase in agonist potency during the winter season in all three brain regions. A plausible explanation of our results is that increased potency in the forebrain during the winter season is due to an increase in efficacy as indicated by a greater number of receptors in the high affinity state. In addition ³⁵S-GTPγS binding, [³H] DPCPX saturation and competition assays establish for the first time pharmacological characteristics such as EC⁵⁰, Kd, Kilo and Kihi in AGS brain.