Epinephrine Responsiveness is Reduced in Livers from Trained Mice

The purpose of this thesis was to determine if exercise training could alter the liver’s response to epinephrine. We hypothesized that training would reduce the response to an epinephrine challenge in vivo as demonstrated by a blunted rise in blood glucose, an attenuated reduction in glycogen, and an abrogated induction of PKA responsive genes. To examine this, male C57BL/6 mice were exercise-trained through VWR or remained sedentary for 12 days, then subjected to an intraperitoneal epinephrine or vehicle challenge. Trained mice had a blunted rise in glucose 15 minutes post-epinephrine injection and a decreased reduction in liver glycogen compared to sedentary mice. This was followed by similar changes in protein content/phosphorylation and gene expression for enzymes involved in the beta-adrenergic signaling pathway. Together our data suggest that prior exercise training reduces the liver’s response to epinephrine. This could be beneficial in the context of glycogen sparing during exercise. HAD gratefully acknowledges funding from the Ontario Graduate Scholarship program (2018-2019; 2019-2020)