Ameliorating Effects and Mechanisms of Intra-Operative Vagal Nerve Stimulation on Postoperative Recovery After Sleeve Gastrectomy in Rats

Vagus innervation in the gastrointestinal tumor: Current understanding and challenges

The vagus nerve (VN) is the main parasympathetic nerve of the autonomic nervous system. It is widely distributed in the gastrointestinal tract and maintains gastrointestinal homeostasis with the sympathetic nerve under physiological conditions. The VN communicates with various components of the tumor microenvironment to positively and dynamically affect the progression of gastrointestinal tumors (GITs). The intervention in vagus innervation delays GIT progression. Developments in adeno-associated virus vectors, nanotechnology, and in vivo neurobiological techniques have enabled the creation of precisely regulated "tumor neurotherapies". Furthermore, the combination of neurobiological techniques and single cell sequencing may reveal more insights into VN and GIT. The present review aimed to summarize the mechanisms of communication between the VN and the gastrointestinal TME and to explore the potential and challenges of VN-based tumor neurotherapy in GITs.

Study of Morphological Changes in Rat Liver Caused by Occlusion of Inferior Vena Cava

Background/objectives

Up to date, there are no reports on animal survival rate and morphological changes in the liver caused by the impairment of blood outflow from the liver and its time dependence. Moreover, the impact of duration and degree of occlusion of inferior vena cava on pathological changes was not investigated yet. This study aimed at the assessment of the survival rate and morphological changes in the liver with varying degrees of occlusion of inferior vena cava. The exact timing of the reversibility of pathological processes was determined.

Methods

Rats (n = 160) were randomly divided into five groups: I - control group (CG) (n = 20); II - sham group (SG) (n = 20); III - intervention group (IG-1) (narrowing of the lumen of the inferior vena cava by 25%) (n = 40); IV intervention group (IG-2) (narrowing by 50%) (n = 40); and intervention group V (IG-3) (narrowing by 75%) (n = 40). The level of postoperative pain, the body and liver weight of the animals, histological examination, morphometry, and macroscopic evaluation of abdominal organs were carried out on the 1, 3, 7, 14, and 30 days following the surgical intervention. The survival rate of animals was assessed using the Kaplan-Meier method.

Results

On the 30th day, the rat grimace scale indices in the IG-1 (P ≤ 0.05), IG-2, and IG-3 (P ≤ 0.001) groups were higher. By body weight, this indicator on the 30th day was lower in the IG-1 (P ≤ 0.05), IG-2, and IG-3 (P ≤ 0.001) groups compared to the CG and SG groups. In the IG1 and IG2 groups, the survival rates were 72.5% and 65.0%, respectively. The lowest survival rate was observed in the IG3 group (22.5%).

Conclusions

Compression of the inferior vena cava by 75% led to an increase in animal mortality and the development of persistent morphological changes in the liver. At the same time, the survival rate of animals and the extent of changes in the liver with narrowing of the inferior vena cava by 25% and 50% had similar results. The results acquired possess scientific and practical importance.

Auricular vagal nerve stimulation enhances gastrointestinal motility and improves interstitial cells of Cajal in rats treated with loperamide

BACKGROUND

Gastrointestinal (GI) motility disorders affect a large proportion of the population with limited treatment options. The aims of this study were to investigate the potential of a non-invasive method of auricular vagal nerve stimulation (aVNS) for treating GI dysmotility and to explore possible mechanisms involving slow waves and interstitial cells of Cajal (ICC).

METHODS

Normal rats were treated daily with loperamide for 1 week and then treated, while still on daily loperamide, with aVNS/Sham-aVNS for another 1 week. Gastric emptying (GE), small intestine transit (SIT), and GI slow waves were measured. The plasma level of pancreatic polypeptide (PP) and noradrenaline (NE) was assessed by ELISA. ICC in the gastric antrum were detected by immunohistochemistry.

KEY RESULTS

(a) aVNS significantly increased the percentage of normal GI slow waves (p < 0.05 for both fasting and postprandial states, vs. Sham-aVNS) and accelerated GE (p < 0.05, vs. Sham-aVNS) and SIT (p < 0.05, vs. Sham-aVNS) impaired by loperamide. (b) aVNS increased plasma PP (p < 0.01) and decreased plasma NE (p < 0.01), compared with Sham-aVNS. (c) Gastric ICC was decreased by loperamide (p < 0.01) but increased after aVNS (p < 0.01, vs. Sham aVNS).

CONCLUSIONS & INFERENCES

Loperamide induces upper GI dysmotility. aVNS accelerates upper GI transit and improving pace-making activity mediated via the ICC. Non-invasive aVNS may have a therapeutic potential for upper GI dysmotility.