Fasting increases glucose and leucine uptake during regeneration of the hypoglossal nerve in the rat

Abstract

Glucose uptake is increased during motoneuron regeneration. Since this glucose is probably used as an energy source for axonal regeneration we postulated that hypoglycemia might interfere with motoneuron regeneration. In order to partially test this hypothesis we attempted to induce moderate hypoglycemia by fasting rats for 3 days between the time of hypoglossal nerve transection and the time of [14C]2-deoxyglucose (2-DG) and [14C]leucine measurement. We transected one hypoglossal nerve, leaving the other intact, and measured the glucose uptake quantitatively or leucine uptake semiquantitatively in the hypoglossal nucleus. We found that both glucose and leucine uptake were increased in the hypoglossal nuclei during regeneration of the nerve in the fasted animals above that in the normally fed animals. This suggests that fasting creates a deficit of glucose and perhaps leucine which induces increased uptake.