Vagal nerve and sympathetic nerve activity in response to glucagon-like peptide-1 (GLP-1) receptor stimulation in conscious rats

GLP-1 (Glucagon-Like Peptide-1) is a type of gastrointestinal hormone that plays an integral role in regulating glucose homeostasis and appetite control. GLP-1 receptors are expressed throughout the body, and it has been suggested that GLP-1 can be detected by vagal afferent nerve activity, leading to changes in sympathetic nerve activity. However, the details of the effects of GLP-1 receptor stimulation on autonomic nerve activity have not been reported. Therefore, this study investigated the effects of different sites of GLP-1 receptor stimulation on autonomic nerve activity by administering GLP-1 receptor agonists via three routes: intravenous (IV), intraportal vein (iport), and intraperitoneal (iperi). Male Wistar rats were chronically implanted with electrodes, catheters for measuring cervical vagal activity, renal and lumbar sympathetic nerve activity, electroencephalogram, electromyogram, electrocardiogram, arterial pressure, sensors for tissue fluid glucose concentration, and catheters for drug administration in the vein, portal vein, and abdominal cavity. Exendin-4, a GLP-1 receptor agonist, was administered to conscious rats via one of the following routes: intravenous, intra-portal vein, or intra-abdominal. Cervical vagal activity was increased in all routes of Exendin-4 administration. Renal sympathetic nerve activity was rapidly decreased by Exendin-4 administration and gradually recovered to pre-administration levels. There were no significant differences in renal sympathetic nerve activity among the different routes of Exendin-4 administration. On the other hand, lumbar sympathetic nerve activity increased slowly after Exendin-4 administration through the iperi and iport routes, while it decreased initially, then gradually increased following administration through the IV route. These results demonstrate that stimulation of GLP-1 receptors by Exendin-4 increases vagal nerve activity, decreases renal sympathetic nerve activity, and produces regionally different responses in lumbar sympathetic nerve activity depending on the site of stimulation. JST (JPMJMS2023). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.