Release of endogenous hydrogen sulfide in enteric nerve cells suppresses intestinal motility during severe acute pancreatitis

Effects of exogenous hydrogen sulfide and honokiol intervention on the proliferation, apoptosis, and calcium signaling pathway of rat enteric glial cells

Hydrogen sulfide (H2S) is a gaseous signaling molecule that influences digestive and nervous system functions. Enteric glial cells (EGCs) are integral to the enteric nervous system and play a role in regulating gastrointestinal motility. This study explored the dual effects of exogenous H2S on EGCs and the influence of apoptosis-related pathways and ion channels in EGCs. We also administered honokiol for further interventional studies. The results revealed that low-concentration H2S increased the mitochondrial membrane potential (MMP) of EGCs, decreased the whole-cell membrane potential, downregulated BAX and caspase-3, upregulated Bcl2 expression, reduced apoptosis, and promoted cell proliferation. The Ca2+ concentration, Cx43 mRNA, and protein expression were also increased. A high concentration of H2S had the opposite effect. In addition, GFAP mRNA expression was upregulated in the test-low group, downregulated in the test-high group, and upregulated in the test-high + Hon group. Honokiol treatment increased MMP, reduced whole-cell membrane potential, inhibited BAX and caspase-3 expression, increased Bcl2 expression, decreased cell apoptosis, and increased cell proliferation. The Ca2+ concentration, Cx43 mRNA, and protein expression were also upregulated. In conclusion, our study showed that exogenous H2S can bidirectionally regulate EGC proliferation and apoptosis by affecting MMP and cell membrane potential via the Bcl2/BAX/caspase-3 pathway and modulate Cx43-mediated Ca2+ responses in EGCs to regulate colonic motility bidirectionally. Honokiol can ameliorate the damage to EGCs induced by high H2S concentrations through the Bcl2/BAX/caspase-3 pathway and improve colon motility by increasing Cx43 expression and Ca2+ concentration.

Dysregulated cystathionine-β-synthase/hydrogen sulfide signaling promotes chronic stress-induced colonic hypermotility in rats

BACKGROUND

Hydrogen sulfide (H₂ S), an important endogenous gasotransmitter, is involved in the modulation of gastrointestinal motility, but whether it mediates the intestinal dysmotility in irritable bowel syndrome (IBS) is not known. This study explored the significance of cystathionine-β-synthase (CBS)/H₂ S signaling in stress-induced colonic dysmotility.

METHODS

A rat model of IBS was established using chronic water avoidance stress (WAS). Colonic pathological alterations were detected histologically. Intestinal motility was determined by intestinal transit time (ITT) and fecal water content (FWC). Visceral sensitivity was assessed using the visceromotor response (VMR) to colorectal distension (CRD). Real-time PCR, Western blotting, and immunostaining were performed to identify the expression of CBS in the colon. The contractions of distal colon were studied in an organ bath system and H₂ S content was measured by ELISA. The effects of SAM, a selective CBS activator, on colonic dysmotility were examined. MEK1 was tested as a potential upstream effector of CBS/H₂ S loss.

KEY RESULTS

After 10 days of WAS, the ITT was decreased and FWC was increased, and the VMR magnitude in response to CRD was enhanced. The colonic CBS expression and H₂ S levels were significantly declined in WAS-exposed rats, and the density of CBS-positive enteric neurons in the myenteric plexus in WAS-treated rats was lower than that in controls. SAM treatment relieved WAS-induced colonic hypermotility via increased H₂ S production. AZD6244, a selective inhibitor of MEK1, partially reversed CBS downregulation and colonic hypermotility in WAS-treated rats.

CONCLUSIONS & INFERENCES

Decreased CBS/H₂ S signaling through increased MEK1 signaling might be important in the pathogenesis of chronic stress-induced colonic hypermotility. SAM could be administered for disorders associated with intestinal hypermotility.

H2S-mediated aerobic exercise antagonizes the hippocampal inflammatory response in CUMS-depressed mice

PURPOSE

This thesis was to investigate the protective effect and mechanism of H₂S-mediated aerobic exercise on the antagonism of the hippocampus inflammatory response in CUMS-depressed mice.

METHOD

Seventy C57BL/6 mice were randomly divided into control group (CG), model control group (MG), model exercise group (ME), H₂S enhanced group (HG) and H₂S enhanced and exercise group (HE). All mice except CG underwent a 28-day CUMS depression model. ME and HE received moderate-intensity aerobic treadmill training for 8 weeks. They were randomly selected for Nissl staining, Immunofluorescence, methylene blue colorimetric assay, and ELISA. The levels of IL-10 and TNF-ɑ were detected by qRT-PCR, and the expression levels of CBS and inflammatory-related factors in the hippocampus were detected.

RESULT

Compared with CG, the number of erections, modifications, and crossing grids in MG mice were significantly reduced, the time of forced swimming and forced tail suspension was significantly prolonged, the positive rate of 5-HT decreased, and the symptoms of depression were obvious. The positive rate of CD45⁺ increased, the inflammatory response was obvious, and the content of H₂S and the expression of biosynthetic enzyme CBS decreased. Aerobic exercise and H₂S-enhanced mice improved depressive symptoms, decreased proinflammatory factors, increased anti-inflammatory factors, increased H₂S content, increased CBS expression, and increased H₂S.

CONCLUSION

H₂S may participate in aerobic exercise to antagonize the inflammatory process of the hippocampus in CUMS-depressed mice by reducing the release of inflammatory response factors and hippocampus nerve injury factors, and effectively alleviate inflammatory injury in the hippocampus of depressed mice.

Fibroblast Growth Factor (FGF) Signaling Protects Against Acute Pancreatitis-Induced Damage by Modulating Inflammatory Responses

BACKGROUND Acute pancreatitis (AP) is a symptom of sudden pancreas inflammation, which causes patients severe suffering. In general, fibroblast growth factor (FGF) levels are increased and amylase and lipase activities are elevated during AP pathogenesis, but protein concentration are low. However, the mechanism through which FGF signaling regulates AP pathogenesis remains elusive. MATERIAL AND METHODS The concentrations of PGE2, TNF-alpha, sCRP, FGF1, and FGF2 in the serum samples of the AP group and healthy control group were detected by enzyme-linked immunosorbent assay. In addition, IkappaBalpha and p-IkappaBalpha levels were analyzed in the serum samples. Subsequently, the AP rat model was established, and FGF1, FGF2, anti-FGF1, and anti-FGF2 antibodies and Bay11-7082 were injected into AP rats. TNF-alpha, PAI-1 JNK, p-JNK, IkappaBalpha, and p-IkappaBalpha levels were also examined. RESULTS Results showed that levels of PGE2, TNF-alpha, sCRP, p-IkappaBalpha, FGF1, and FGF2, as well as amylase and lipase activity were increased in patients with AP compared with those in healthy people. In addition, protein concentrations were lower in patients with AP than in the healthy group. Activation of FGF signaling by injecting FGF1 or FGF2 also inhibited AP-induced inflammation response in the pancreas and increased amylase and lipase activities, as well as protein concentration. However, the injection of FGF1 and FGF2 antibodies accelerated AP-mediated inflammation responses in the serum. In addition, Bay11-7082 injection inhibited AP activation of inflammation response and amylase and lipase activities. Protein concentration were also increased in AP rats. CONCLUSIONS FGF signaling protects against AP-mediated damage by inhibition of AP-activating inflammatory responses.