Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA239

Poster Communications

Beneficial effects of carotid sinus nerve resection on white adipose tissue metabolism

B. S. F.Melo1, C. S. Prego1, J. F. Sacramento1, S. V. Conde1

1. CEDOC, NOVA Medical School, Lisboa, Portugal.

Background and aims: The therapeutics to treat obesity are scarce(1). We have proposed a new role for the carotid body (CB) in the pathogenesis of metabolic disturbances, demonstrating that the abolishment of its activity, through resection of carotid sinus nerve (CSN), its sensitive nerve, prevents and reverses insulin resistance and glucose intolerance in animals with metabolic diseases(2,3). Furthermore, CSN resection decreased weight gain and improved metabolic function in an obese animal model, with metabolic dysfunction(4). Herein, we investigated if the effects on weight gain and glucose metabolism are related to a reduction on white adipose tissue (WAT) amount and an improvement on its metabolism. Materials and Methods: Experiments were performed in 9 weeks male Wistar rats. Animals were submitted to 10 weeks of high-fat diet (HF) (5.1Kcal/g) or to a standard diet (2.56Kcal/g). After 10 weeks of diet, rats were submitted to either bilateral CSN resection or to a sham procedure and kept under the respective diets for 9 weeks. Insulin sensitivity, glucose tolerance, caloric intake and body weight were monitored throughout the experimental protocol. At terminal experiment rats were anaesthetised with pentobarbital (60mg/kg i.p.) and WAT depots were collected, weighted and stored for analysis of proteins involved in WAT metabolism and quantification of UCP-1 protein, mitochondrial density and adipocytes perimeter. In a parallel study in vivo glucose uptake was evaluated by an intravenous glucose tolerance test. Results: HF diet increased total WAT amount by 120% as well as adipocyte perimeter in the perienteric depot by 151%. Also, HF diet induced whole-body insulin resistance (KITT HF before surgery = 4.4±0.9 %glucose/min; KITT HF after 10 weeks of diet = 1.8±1.0 %glucose/min), glucose intolerance (AUC controls = 20016.8±450.4 mg/dlxmin; AUC HF after 10 weeks of diet = 25415.3±689.3 mg/dlxmin) and decreased the uptake of glucose in perienteric WAT depot by 48%. CSN resection in HF animals decreased perinephric (18%), epididymal (22%), perienteric (38%) and subcutaneous (24%) as well as total WAT amount (24%). Also, CSN resection restored insulin sensitivity and glucose tolerance 1 week after surgery, an effect that was maintained until the last week of evaluation. Furthermore, it was observed a decrease in adipocyte perimeter by 56% and an increase in the uptake of glucose in the perinephric, epididymal and perienteric WAT depots by 51%, 77% and 97%, respectively.Conclusion: We conclude that the beneficial effects of CSN resection in weight gain involve a reduction in the total amount of WAT, contributing to a decrease in the size of the adipocytes and an improvement of glucose metabolism in this tissue.

Where applicable, experiments conform with Society ethical requirements