Cholecystokinin activation of central satiety centers changes seasonally in a mammalian hibernator

► We measured NTS Fos expression induced by IP CCK in SPR, SUM, and HIB squirrels. ► Basal NTS Fos expression is lower in HIB than in SPR or SUM squirrels. ► CCK induces greater Fos expression in SPR vs. SUM or HIB squirrels. ► Fold increase in Fos expression is greatest in HIB. ► Changes in CCK-induced NTS activation may regulate appetite in hibernators.