Identifying the physiological role of insulin receptors expressed by the cholinergic neurons

Abstract

The cholinergic neurons have been recognized that controlling autonomic function and contraction of the skeletal muscles. They express insulin receptors, but the role of the insulin receptors has not been reported yet. This study identified the physiological role of insulin receptors on cholinergic neurons. Firstly, using ex vivo electrophysiology, insulin inhibited parasympathetic preganglionic neurons. However, autonomic functions such as glucose homeostasis were normal when insulin receptors were knocked out specifically for cholinergic neurons. On the other hand, insulin activated cholinergic motor neurons and had an important role to form normal gastrocnemius muscle. The conditional knockout mice had less muscle mass, weakened muscle contraction force, and abnormal neuromuscular junctions. Together, this study suggested that the insulin receptors on cholinergic neurons are required for normal muscle growth, not autonomic functions.