Ground squirrels as an animal research model for eating and metabolic disorders

Abstract

Thirteen‐lined ground squirrels (Spermophilus tridecemlineatus) “binge” and stash food leading up to hibernation and “restrict” and ration food during hibernation. This requires a dramatic adaptation to changing environmental conditions. We have studied the transcription of appetite regulating hormone receptors in brains by quantitative PCR, and plasma hormone levels by ELISA, in hibernating and non‐hibernating squirrels. Transcription of ghrelin and leptin receptor genes were suppressed 10‐fold, and plasma leptin and ghrelin levels (n=5/condition) were significantly reduced by 20–25% during hibernation. In contrast, melanocortin and cholecystokinin receptor transcription was elevated during hibernation. Our preliminary studies suggest differential transcriptional regulation and hormone levels of key central (brain) and peripheral (gut and adipose tissue) appetite and metabolism regulatory systems. These differences warrant further investigation and correlation with nutrient intake during different seasonal phases. Moreover, comparison of these regulatory systems in different squirrel states and comparable human dietary conditions (such as binging and restricting) may provide insight for effective points of behavioral, nutritional or pharmaceutical intervention. Funded by University of Wisconsin‐System, WiSys, and NSF‐REU grants.