GABAergic mechanisms of gastroprotection in the rat: role of sensory neurons, prostaglandins, and nitric oxide

Cenostigma macrophyllum Tul. var. acuminata Teles Freire Fraction Leaves Stimulate Gastric Healing in Rats and Human Cell Cultures

Cenostigma macrophyllum Tul. var. acuminata Teles Freire (Leguminosae-Caesalpinioideae) is a medicinal plant traditionally used for treatment of gastric ulcer. This study evaluated the ulcer-healing activity of the hydroalcoholic fraction of C. macrophyllum Tul. var. acuminata Teles Freire leaves (Cm-FHA) and the tea of the leaves of C. macrophyllum (Cm-tea), as well as the possible action of Cm-FHA, through in vitro models. Leaves of C. macrophyllum were dried and powdered to obtain the Cm-FHA. Subsequently, the Cm-FHA was characterized phytochemically and biologically. Besides, Cm-tea was prepared. The gastric healing effects of Cm-tea and Cm-FHA were analyzed using the model of acetic acid-induced gastric ulcer in rats. The human gastric adenocarcinoma (AGS) cell line was employed as an in vitro model. Cm-tea promoted a protective effect against gastric ulcers induced by absolute ethanol. Cm-FHA or Cm-tea (100 mg/kg/7 days) exhibited a significant healing effect on ulcers induced by acetic acid. In the histological analysis, gastric mucosa treated with Cm-FHA or Cm-tea advanced restoration of the mucosal epithelium. In vitro, lower concentrations of Cm-FHA stimulated cell proliferation in the BrdU assay and cell migration. Cm-tea and Cm-FHA present a significant gastric healing effect in in vivo and in vitro models.

(-)-Myrtenol accelerates healing of acetic acid-induced gastric ulcers in rats and in human gastric adenocarcinoma cells

The gastroprotective property of (-)-myrtenol, a monoterpenoid, has been demonstrated previously against acute gastric ulceration induced by ethanol. However, the healing property of (-)-myrtenol in a chronic gastric ulcer model remains to be verified. This study evaluated its healing efficacy and the mechanism involved using the rat model of chronic gastric ulcer induced by serosal injection of 80% acetic acid in vivo, and human gastric adenocarcinoma cells (AGS) in vitro. The results showed that compared to vehicle-treated ulcer controls, oral administration of (-)-myrtenol (50 and 100 mg/kg/day) for 7 days promoted ulcer healing, as indicated by significant decreases in ulcer area and volume. The macroscopic and microscopic findings confirmed the healing potential of (-)-myrtenol. The ulcer healing activity was also associated with significant increases in gastric mucin content, collagen deposition, number of cells with positive marking for proliferating cell nuclear antigen (PCNA), and by changes in the expression of the inflammatory parameters tumor necrosis factor (TNF)-α, interleukin (IL)-1β and cyclooxygenase (COX)-2, as well as a decrease of metalloproteinases (MMP-9 and MMP-2) activity. Furthermore, in vitro assays using the AGS cultures revealed that (-)-myrtenol favors wound healing activity via stimulation of cell proliferation and migration without altering the cell viability. Taken together, these findings indicate that (-)-myrtenol has gastro-cytoprotective and ulcer healing properties that can be further explored to develop a new therapeutic agent from a natural source for the treatment of gastric ulcer.

Gastroprotective effect of (-)-myrtenol against ethanol-induced acute gastric lesions: possible mechanisms

OBJECTIVES

(-)-Myrtenol is a natural fragrance monoterpenoid structurally related to α-pinene found in diverse plant essential oils. This study was aimed to assess the anti-ulcerogenic potential of (-)-myrtenol against ethanol-induced gastric lesions and to elucidate the underlying mechanism(s).

METHODS

Gastroprotective activity of (-)-myrtenol was evaluated using the mouse model of ethanol-induced gastric damage. To elucidate the gastroprotective mechanism(s), the roles of GABA, prostaglandins, nitric oxide and KATP channels were assessed. Besides, the oxidative stress-related parameters and the mucus content in gastric tissues were analysed.

KEY FINDINGS

(-)-Myrtenol at oral doses of 25, 50 and 100 mg/kg significantly decreased the severity of ethanol-induced gastric lesions affording gastroprotection that was accompanied by a decrease in the activity of myeloperoxidase and malondialdehyde, an increase in GPx, SOD, and catalase activity in gastric tissues, and with well-maintained normal levels of nitrite/nitrate, gastric mucus and NP-SHs. Pretreatment with GABA-A receptor antagonist flumazenil, the COX inhibitor indomethacin, and NO synthesis inhibitor L-NAME but not with KATP channel blocker glibenclamide significantly blocked the (-)-myrtenol gastroprotection.

CONCLUSION

These results provide first-time evidence for the gastroprotective effect of (-)-myrtenol that could be related to GABAA -receptor activation and antioxidant activity.

Effect of persistent positive acceleration on the quality of ulcer healing in rats with experimental gastric ulcer

AIM: To investigate the effect of positive acceleration (+Gz) on gastric ulcer healing in rats and to explore the possible mechanisms involved.

METHODS: Thirty-two male SD rats were randomly and equally divided into a control group, a +5Gz exposure group, a +10Gz exposure group, and a +10Gz exposure plus KangFuXin solution group. Gastric ulcer was induced in rats with acetic acid. After 3 d, rats in the latter three groups were exposed to +Gz each other day for 1 wk (four times in all, five minutes each time). The rats in the +10Gz exposure plus KangFuXin solution group were additionally gavaged with 2 mL of KangFuXin solution every day for 1 wk. Tissue and bloods samples were taken to detect the contents of prostaglandin E2 (PGE2) in the gastric mucosa and calcitonin gene-related peptide (CGRP) in blood by radioimmunoassay and the content of nitric oxide (NO) in blood by nitrate reductase assay.

RESULTS: The higher +Gz, the thinner restored mucosa thickness and the more the number of cystically dilated glands. The contents of PGE2 in the gastric mucosa were significantly lower in the +10Gz exposure group than in the +5Gz exposure group, control group, and +10Gz exposure plus KangFuXin solution group (3.438 pg/mL ± 0.908 pg/mL vs 5.147 pg/mL ± 0.652 pg/mL, 6.986 pg/mL ± 0.743 pg/mL, 6.133 pg/mL ± 0.545 pg/mL, all P < 0.01). The contents of CGRP in blood were significantly lower in the +10Gz exposure group than in the +5Gz exposure group, control group, and +10Gz exposure plus KangFuXin solution group (62.254 pg/mL ± 15.943 pg/mL vs 78.333 pg/mL ± 11.290 pg/mL, 82.583 pg/mL ± 11.788 pg/mL, 78.455 pg/mL±12.645 pg/mL, all P < 0.05). The contents of NO in blood were significantly lower in the +10Gz exposure group than in the +5Gz exposure group, control group, and +10Gz exposure plus KangFuXin solution group (44.773 μmol/L ± 6.858 μmol/L vs 47.783 μmol/L ± 2.847 μmol/L, 53.806 μmol/L ± 9.272 μmol/L, 53.853 μmol/L ± 7.372 μmol/L, all P < 0.05).

CONCLUSION: Positive acceleration delays gastric ulcer healing in rats, and treatment with KangFuXin Solution can improve the quality of ulcer healing.

Bidirectional crosstalk between stress-induced gastric ulcer and depression under chronic stress

Stress contributes to a variety of diseases and disorders such as depression and peptic ulcer. The present study aimed to investigate the correlation between stress ulcer and depression in pathogenesis and treatment by using chronic stress depression (CSD), chronic psychological stress ulcer (CPSU) and water immersion restrain stress models in rats. Our data showed that the ulcer index of the animals after CSD exposure was significantly higher than that of controls. Depression-like behaviors were observed in rat after CPSU exposure. Fluoxetine hydrochloride significantly reduced the ulcer index of rats exposed to CPSU stress, while ranitidine inhibited depression-like behavior of the animals in CSD group. The ulcer index of rats administered with mifepristone after CPSU stress was markedly reduced compared to CPSU group, although there was no significant difference in the depression-like behavior between mifepristone-treated CSD group and naive controls. We also found that the rats exposed to CPSU or CSD stress displayed a lower level of corticosterone than naive controls, however, the acute stress (AS) group showed an opposite result. Additionally, in order to study the relevance of H(2) receptors and depression, we treated the CSD group with cimetidine and famotidine respectively. The data showed that cimetidine inhibited depression-like behavior in CSD rats, and famotidine had no impact on depression. Overall our data suggested that the hypothalamic-pituitary-adrenal (HPA) axis dysfunction may be the key role in triggering depression and stress ulcer. Acid-suppressing drugs and antidepressants could be used for treatment of depression and stress ulcer respectively. The occurrence of depression might be inhibited by blocking the central H(2) receptors.

The gender difference of selective serotonin reuptake inhibitor, fluoxetine in adult rats with stress-induced gastric ulcer

We investigated the gender difference of selective serotonin reuptake inhibitor, fluoxetine in adult rats with stress-induced gastric ulcer. The rats were randomly divided into six groups: Group I, control males and group II, control females; group III, acute cold restraint stressed males and group IV, acute cold restraint stressed females; group V, fluoxetine-treated stressed males and group VI, fluoxetine-treated stressed females. Acute cold restraint stress was established by fixing the four limbs of the rat and placing it in a refrigerator at 4°C for 3h. Fluoxetine was given intraperitoneal in a single dose of 10mg/kg/day. After 2 weeks, stomach and brain tissues were collected for the assay of gastric malonaldehyde (MDA), catalase, nitric oxide (NO) and cortical gamma aminobutyric acid (GABA). Stressed animals exhibited increased total acidity in association with decreased gastric secretion volume. Gastric MDA was increased while gastric catalase, NO, and cortical GABA were decreased in stressed male rats when compared to stressed females. However, fluoxetine administration attenuated these stress-induced changes especially in stressed male animals. Stressed male rats were more responsive to the antiulcer effect of fluoxetine more than stressed females. However, fluoxetine might be considered to be the first-choice drug in depressive patients with gastric ulcers in the future.