Involvement of the Nervous System in the Control of Glucose Uptake in Contracting Hindlimb Muscle in the Rat

 

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Abstract

To probe into the possibility of neural control of glucose uptake in contracting peripheral skeletal muscle, rats were divided into two groups: one group is the “normal” (N) group in which the nervous system is intact, and the other is the “denervation” (D) group in which all nerves innervating the hindlimb were cut. The immediate changes in blood glucose (BC) and plasma insulin (PI) levels were measured at the commencement and termination of hindlimb muscle contraction induced with electrical stimulation of the sciatic nerve (distal part in D group). BG in N group temporarily but significantly decreased (p < 0.01) immediately after starting the stimulation, while BG in D group remained unchanged. And the difference between the changes in BG observed in 2 groups was significant (p < 0.03). PI did not change in either group during the sample period. On the other hand, PI temporarily but significantly decreased (p < 0.03) immediately after terminating the stimulation in both groups. The results suggest that the nervous system has some role in controlling glucose uptake in contracting peripheral muscle, at least in the early stage of contraction, that some feedback loop, including the central nervous system, is considered essential for the control, and that some local mechanism promotes an increase in insulin binding to receptors on muscle cells immediately after terminating the contraction.