RESUMO
Background: Emerging evidence has demonstrated the impact of psychological stress on intestinal microbiota, however, the precise mechanisms are not fully understood. Enteric glia, a unique type of peripheral glia found within the enteric nervous system (ENS), play an active role in enteric neural circuits and have profound effects on gut functions. In the present study, we tested the hypothesis that enteric glia are involved in the alterations in the intestinal microflora and barrier induced by chronic water-avoidance stress (WAS) in the gut. Methods and results: Western blotting and immunohistochemical (IHC) staining were used to examine the expression of glial fibrillary acidic protein (GFAP), nitric oxide synthetase (NOS) and choline acety1transferase (ChAT) in colon tissues. 16S rDNA sequencing was performed to analyse the composition of the intestinal microbiota in rats. Changes in the tight junction proteins Occludin, Claudin1 and proliferating cell nuclear antigen (PCNA) in the colon tissues were detected after WAS. The abundance of Firmicutes, Proteobacteria, Lactobacillus and Lachnospiraceae_NK4A136 decreased significantly, whereas the abundance of Actinobacteria, Ruminococcaceae_UCG-005 and Christensenellaceae-R-7 increased significantly in stressed rats. Meanwhile, the expression of Occludin, Claudin1 and PCNA significantly decreased after WAS. Treatment with L-A-aminohexanedioic acid (L-AA), a gliotoxin that blunts astrocytic function, obviously decreased the abundance of Actinobacteria, Ruminococcaceae_UCG-005 and Christensenel-laceae_R-7 in stressed rats and significantly increased the abundance of Proteobacteria, Lactobacillus and Lachnospiraceae_NK4A136. In addition, the protein expression of colon Occludin, Claudin1, and PCNA increased after intraperitoneal injection of L-AA. Furthermore, the expression level of NOS in colon tissues was significantly decreased, whereas that of ChAT was significantly increased following L-AA treatment. Conclusions: Our results showed that enteric glial cells may contribute to WAS-induced changes in the intestinal microbiota and barrier function by modulating the activity of NOS and cholinergic neurones in the ENS.
RESUMO
Rat restraint water-immersion stress (RWIS) is a compound stress of high intensity and is widely used to study the pathological mechanisms of stress gastric ulcers. The spinal cord, as a part of the central nervous system, plays a dominant role in the gastrointestinal tract, but whether the spinal cord is involved in rat restraint water-immersion stress (RWIS)-induced gastric mucosal damage has not been reported. In this study, we examined the expression of spinal astrocytic glial fibrillary acidic protein (GFAP), neuronal c-Fos, connexin 43 (Cx43), and p-ERK1/2 during RWIS by immunohistochemistry and Western blotting. In addition, we intrathecally injected the astrocytic toxin L-a-aminoadipate (L-AA), gap junction blocker carbenoxolone (CBX), and ERK1/2 signaling pathway inhibitor PD98059 to explore the role of astrocytes in the spinal cord in RWIS-induced gastric mucosal damage and its possible mechanism in rats. The results showed that the expression of GFAP, c-Fos, Cx43, and p-ERK1/2 was significantly elevated in the spinal cord after RWIS. Intrathecal injection of both the astrocyte toxin L-AA and the gap junction blocker CBX significantly attenuated RWIS-induced gastric mucosal damage and decreased the activation of astrocytes and neurons induced in the spinal cord. Meanwhile, the ERK1/2 signaling pathway inhibitor PD98059 significantly inhibited gastric mucosal damage, gastric motility and RWIS-induced activation of spinal cord neurons and astrocytes. These results suggest that spinal astrocytes may regulate the RWIS-induced activation of neurons via CX43 gap junctions and play a critical role in RWIS-induced gastric mucosa damage through the ERK1/2 signaling pathway.
