Influences of Vagotomy on Gut Ischemia-Reperfusion Injury in Mice

Dexmedetomidine attenuates inflammation and pancreatic injury in a rat model of experimental severe acute pancreatitis via cholinergic anti-inflammatory pathway

BACKGROUND

Excessive inflammatory responses play a critical role in the development of severe acute pancreatitis (SAP), and controlling such inflammation is vital for managing this often fatal disease. Dexmedetomidine has been reported to possess protective properties in inflammatory diseases. Therefore, this study aimed to investigate whether dexmedetomidine pre-treatment exerts an anti-inflammatory effect in rats with SAP induced by sodium taurocholate, and if so, to determine the potential mechanism.

METHODS

SAP was induced with sodium taurocholate. Rats received an intraperitoneal injection of dexmedetomidine 30 min before sodium taurocholate administration. α-bungarotoxin, a selective alpha-7 nicotinic acetylcholine receptor (α7nAchR) antagonist, was injected intra-peritoneally 30 min before dexmedetomidine administration. The role of the vagus nerve was evaluated by performing unilateral cervical vagotomy before the administration of dexmedetomidine. Efferent discharge of the vagal nerve was recorded by the BL-420F Data Acquisition & Analysis System. Six hours after onset, serum pro-inflammatory cytokine (tumor necrosis factor α [TNF-α] and interleukin 6 [IL-6]) levels and amylase levels were determined using an enzyme-linked immunosorbent assay and an automated biochemical analyzer, respectively. Histopathological changes in the pancreas were observed after hematoxylin and eosin staining and scored according to Schmidt criteria.

RESULTS

Pre-treatment with dexmedetomidine significantly decreased serum levels of TNF-α, IL-6, and amylase, strongly alleviating pathological pancreatic injury in the rat model of SAP (TNF-α: 174.2 ± 30.2 vs. 256.1±42.4 pg/ml; IL-6: 293.3 ± 46.8 vs. 421.7 ± 48.3 pg/ml; amylase: 2102.3 ± 165.3 vs. 3186.4 ± 245.2 U/L). However, the anti-inflammatory and pancreatic protective effects were abolished after vagotomy or pre-administration of α-bungarotoxin. Dexmedetomidine also significantly increased the discharge frequency and amplitude of the cervical vagus nerve in the SAP rat model (discharge frequency: 456.8 ± 50.3 vs. 332.4 ± 25.1 Hz; discharge amplitude: 33.4 ± 5.3 vs. 20.5 ± 2.9 μV).

CONCLUSIONS

Dexmedetomidine administration attenuated the systemic inflammatory response and local pancreatic injury caused by SAP in rats through the cholinergic anti-inflammatory pathway involving vagus- and α7nAChR-dependent mechanisms.

Role of nutrition in gastroenterological surgery

Nutrition plays important roles in recovery after gastroenterological surgery. Severe surgical stress increases muscle breakdown and lipolysis, thereby accelerating wound healing and enhancing host defense against microbes. Malnourished patients have insufficient amounts of muscle and body fat. Therefore, they may not appropriately respond to surgical stress. Perioperative nutritional therapy maintaining nutritional status reduces postoperative complications and accelerates recovery after surgery, particularly for malnourished patients. In addition, perioperative oral or enteral nutrition is now recommended for preserving host defense mechanisms against microbes. Lack of enteral nutrition impairs gut and hepatic immunity, systemic mucosal defense and peritoneal host defense, even when nutrient amounts supplied by parenteral nutrition are adequate. Thus, surgeons should avoid no oral or enteral nutrition periods. Supplemental administration of specific nutrients such as glutamine, arginine and ω-3 fatty acids is termed "immunonutrition", and is expected to reduce the morbidity of infectious complications and length of hospital stay. Nutritional therapy is important even after discharge to maintain body weight and compensate for abnormalities in the digestion and absorption of nutrients. Understanding the significance of nutrition in gastroenterological patients leads to better outcomes.