Evidence from animal models showed that when rats underwent removal of the superior autonomic mesenteric ganglia that contains mostly SNS neurons and were challenged with an oral glucose gavage; plasma insulin and C-peptide secretion were increased compared with controls (non-ganglionectomised rats). Furthermore, glucose levels were much lower in the ganglionectomised rats suggesting that the SNS splanchnic innervation plays a critical role in the maintenance of glucose homeostasis. The increased secretion of insulin and C-peptide levels in this model could be explained by an increase in incretin hormonal release. Additional studies using isolated guineas pig ileum (in vitro model) showed that GLP-1 secretion is inhibited by SNS nerve stimulation which is mediated by α-adrenergic receptors.