Ultra-structural study of the indomethacin-induced apoptosis and autophagy in rat gastric parietal cells

Chemical Composition of Mexicali Propolis and Its Effect on Gastric Repair in an Indomethacin-Induced Gastric Injury Murine Model

Propolis is a resinous substance produced by bees that has several biomedical properties that could contribute to the repair process of the gastric mucosa, such as antioxidant, anti-inflammatory, healing, and gastroprotective properties. Thus, this study aimed to determine the chemical composition of Mexicali propolis, its antioxidant capacity, and its effect on gastric repair. Three polarity-directed extracts were obtained: the ethanolic extract, the ethyl acetate extract, and the hexane extract. The antioxidant activity, total phenolic content (TPC), and flavone/flavonol content were determined for each extract. The chemical composition was analysed using HPLC-TOF-MS (High-Performance Liquid Chromatography-Time-Of-Flight Mass Spectrometry) and GC-MS (Gas Chromatography-Mass Spectrometry), and a total of 52 compounds were identified. The results revealed that the ethanolic extract had the greatest effect on free radical scavenging and the content of bioactive compounds. On the basis of these results, the effect of the Mexicali ethanolic extract of propolis (MeEEP) on gastric repair was subsequently evaluated. Prior to the evaluation, MeEEP was found to exhibit low oral toxicity, as determined under the Organisation for Economic Co-operation and Development (OECD) 425 guidelines. Gastric injury was induced in male C57BL/6 mice by intragastric administration of indomethacin (10 mg/kg). MeEEP (300 mg/kg) was administered 6 h after the induction of injury using indomethacin and daily thereafter. The mice were sacrificed at 12, 24, and 48 h to assess the effect. As a result, MeEEP enhanced the repair of the gastric lesion by decreasing the percentage of the bleeding area and attenuating the severity of histological damage, as demonstrated by H&E staining. This effect was associated with a reduction in MPO enzyme activity and in the levels of the proinflammatory cytokines TNF-α, IL-1β, and IL-6, maintaining controlled inflammation in gastric tissue. Furthermore, the administration of the extract increased SOD enzymatic activity and GSH levels, reducing the degree of oxidative damage in the gastric tissue, as demonstrated by low MDA levels. Finally, after evaluating the effect on apoptosis via immunohistochemistry, MeEEP was shown to reduce the expression of the proapoptotic marker Bax and increase the expression of the antiapoptotic marker Bcl-2. In conclusion, these findings suggest that MeEEP may enhance gastric repair through a cytoprotective mechanism by controlling inflammation exacerbation, reducing oxidative stress, and regulating apoptosis. These mechanisms are primarily attributed to the presence of pinocembrin, tectochrysin, chrysin, apigenin, naringenin, acacetin, genistein, and kaempferol. It is important to highlight that this study provides a preliminary exploration of the reparative effect of Mexican propolis, describing the potential mechanisms of action of the compounds present in Mexicali propolis.

Parthenolide alleviates indomethacin-induced gastric ulcer in rats via antioxidant, anti-inflammatory, and antiapoptotic activities

Parthenolide (PTL) is a sesquiterpene lactone that occurs naturally. It demonstrates a variety of beneficial effects, such as antioxidant, anti-inflammatory, and antiapoptotic properties. The study investigated the potential protective impact of PTL on indomethacin (INDO) induced stomach ulcers in rats. The rats were classified into 5 distinct categories. Group 1 served as the "control" group. Rats in the second group received a single oral dosage of INDO (50 mg kg-1). Rats in Groups three and four received 20 and 40 mg kg-1 oral PTL 1 h before INDO. Omeprazole (30 mg kg-1) was given orally to Group 5 rats 1 h before INDO. Pretreatment with PTL increased stomach pH and decreased gastric volume as well as reduced the morphological and histological changes induced by INDO. Analysis of probable pathways showed that pre-treatment with PTL successfully reduced oxidative, inflammatory, and apoptotic consequences caused by INDO. The ingestion of PTL leads to a notable increase in the levels of glutathione reduced (GSH) and the activities of superoxide dismutase (SOD) and catalase (CAT). Furthermore, PTL decreased the concentration of malondialdehyde (MDA). In contrast, it was shown that PTL increased both cyclooxygenase-1 (COX-1) and prostaglandin E2 (PGE2). PTL shows a significant decrease in the expression of interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), inducible nitric oxide synthase (iNOS), and nuclear factor kappa B (NF-κB). PTL therapy resulted in a decrease in Bcl-2-associated X protein (Bax) levels and an increase in B-cell lymphoma 2 (Bcl2) levels. In conclusion, PTL offers gastroprotection by its antioxidant, anti-inflammatory, and anti-apoptotic qualities.

AMPK/mTOR-driven autophagy & Nrf2/HO-1 cascade modulation by amentoflavone ameliorates indomethacin-induced gastric ulcer

Gastric ulcer (GU) is a worldwide gastrointestinal disorder associated with NSAID use. Recently, amentoflavone proved to be a potent autophagy modulator, antioxidant, anti-inflammatory, and anti-apoptotic agent. Eight-week-old male Wistar rats received amentoflavone orally for 14 days at 25, 50, or 100 mg/kg/day. On day 14 of treatment, GU was induced by a single oral instillation of 100 mg/kg indomethacin, one hour after the last treatment. Amentoflavone dose-dependently alleviated indomethacin-induced GU, as demonstrated by repression of gastric mucosa pathological manifestations (ulcer index, ulcer surface area, histopathological deviations, and score) and increased ulcer inhibition percentage. These protective effects were due to the enhancement of gastric mucosa autophagy, as demonstrated by increased levels of beclin-1, MAP1LC3B, and CTSD, and reduced expression of p62 (SQSTM1). In addition, amentoflavone modulated the AMPK/mTOR pathway by increasing p-AMPK and reducing mTORC1 levels. Moreover, it hindered the redox aberrations by reducing MDA level and enhancing SOD activity, GSH level, and Nrf2/HO-1 cascade. Furthermore, a decrease in caspase-3 levels, Bax/Bcl-2 ratio and an increase in Bcl-2 expression suggest inhibition of the apoptotic process. Additionally, amentoflavone suppressed gastric mucosal inflammation by decreasing IL-1β, TNF-α, IFN-γ levels, IL-4, IL-6 mRNA expressions and MPO activity, and increasing IL-10 mRNA expresion. Therefore, amentoflavone could consider a promising natural agent protecting against indomethacin-induced GU.

Mechanistic insights into the protective effects of chlorogenic acid against indomethacin-induced gastric ulcer in rats: Modulation of the cross talk between autophagy and apoptosis signaling

BACKGROUND

This study aimed to investigate the gastroprotective effect of chlorogenic acid (CGA) against Indomethacin (IND)-induced gastric ulcer (GU) in rats and its underlying mechanism, especially through autophagic and apoptotic pathways.

METHODS

Seventy-five rats were divided into five groups; control, IND (50 mg/kg, p.o.), CGA (100 mg/kg, p.o., 14 days), IND pretreated with CGA (50 mg/kg or 100 mg/kg, p.o., 14 days). The stomach tissues were examined to calculate the ulcer index and analyze markers of autophagy (beclin-1, LC3-II/LC3-I and p62), lysosomal function (cathepsin-D) and apoptosis (Bcl-2, Bax and caspase-3), along with expression of Akt/mTOR pathway using western blot or ELISA techniques. In addition, viability of gastric mucosal cells was detected by flowcytometry. Structural changes were assessed histologically, while autophagic and apoptotic changes of gastric mucosa were observed by transmission electron microscopy.

RESULTS

CGA exhibited a dose-dependent gastroprotective effect by reversing IND-induced accumulation of autophagic vacuoles, significant reduction in beclin-1, LC3-II/LC3-I, and p62 levels, and down-regulation of p-Akt/p-mTOR expression. CGA100 also restored normal autolysosomal function by modulation of cathepsin-D levels. Furthermore, pretreatment with CGA100 was significantly associated with an increase in antiapoptotic protein Bcl-2 along with a decrease in proapoptotic Bax and caspase-3 proteins in such a way that impairs IND-induced apoptosis. This was confirmed by CGA-induced significant decrease in annexin V⁺ cells.

CONCLUSIONS

The natural compound CGA offers a novel gastroprotective intervention against IND-induced GU through restoration of normal autophagic flux, impairment of apoptosis in a crosstalk mechanism mediated by Akt/mTOR pathway reactivation, and alleviation of IND-induced lysosomal dysfunction.