The protective effects of ghrelin and leptin against stress-induced gastric ulcer in rats

Correlation between the tissue ghrelin presence, disease activity and laboratory parameters in ulcerative colitis patients; immunohistochemical study

Background

The aim of the study was to determine the differences in terms of ghrelin presence in the colon between the patients with ulcerative colitis (UC) and control patients.

Methods

Sixty-one UC and 15 control patients were included in the study. Immunohistochemical staining for ghrelin was investigated in colonic biopsy samples of UC and control patients. UC patients were subdivided into Group A (absence of ghrelin staining) and Group B (presence of staining for ghrelin in biopsy samples). Disease activity scores, laboratory parameters and quantitative ghrelin staining were compared in both groups of UC patients, as well as with the observations in control patients.

Results

Cells in colonic mucosa stained for ghrelin were identified in twenty-three (37.7%) UC patients, while this proportion in control patients was 6/15(40%). A significant difference was found between Groups A and B for serum albumin concentration but not for erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), hemoglobin concentration or leucocyte count. Mayo score/disease activity index (DAI) for UC were significantly higher in Group A than in Group B (p = 0.03).

Conclusions

There were no differences in the amount of colonic ghrelin staining between healthy individuals and UC patients. Colonic ghrelin staining in UC patients seems to be associated with the increased activity of this disease.

Role of Leptin in the Digestive System

Leptin is a pluripotent peptide hormone produced mainly by adipocytes, as well as by other tissues such as the stomach. Leptin primarily acts on the central nervous system, particularly the hypothalamus, where this hormone regulates energy homeostasis and neuroendocrine function. Owing to this, disruption of leptin signaling has been linked with numerous pathological conditions. Recent studies have also highlighted the diverse roles of leptin in the digestive system including immune regulation, cell proliferation, tissue healing, and glucose metabolism. Of note, leptin acts differently under physiological and pathological conditions. Here, we review the current knowledge on the functions of leptin and its downstream signaling in the gastrointestinal tract and accessory digestive organs, with an emphasis on its physiological and pathological implications. We also discuss the current therapeutic uses of recombinant leptin, as well as its limitations.

Kaempferol protects ethanol-induced gastric ulcers in mice via pro-inflammatory cytokines and NO

Gastric ulcers (GUs) are common pathologies that affect many people around the world. Excessive alcohol consumption is one of the main causes of GUs; however, there are still lack of effective drugs for the prevention or therapy of GUs. In this study, we evaluated the protective effects and possible mechanisms of kaempferol (KAE) against acute ethanol-induced lesions to the gastric mucosa in mice. Fasted mice were orally given vehicle (0.9% saline), omeprazole (20 mg/kg), or KAE (40, 80, or 160 mg/kg) for 1 h in different experimental sets prior to the establishment of the GU model by challenge with absolute ethanol (10 ml/kg). Animals were euthanized 1 h after ethanol intake, and their plasma and stomach tissues were subject to further examination. Macroscopic and microscopic lesions, and immunological and biochemical parameters were observed. The effects of inflammation were investigated using the following indicators: tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, myeloperoxidase (MPO), and nitric oxide (NO). Results showed that KAE significantly decreased the ulcer index, increased the preventive index, completely protected the mucosa from lesions, and preserved gastric mucosal glycoprotein. KAE decreased MPO activity and pro-inflammatory cytokine (TNF-α, and IL-1β) levels, and improved NO levels. The gastroprotective activity of KAE might be attributed to the preservation of gastric mucous glycoproteins levels, thus by inhibiting neutrophil accumulation and MPO activity, adjusting the levels of pro-inflammatory cytokines, and improving NO production.

Xiaotan Tongfu granules contribute to the prevention of stress ulcers

AIM: To investigate the efficacy and potential mechanism of Xiaotan Tongfu granules (XTTF) in stress ulcers.

METHODS: One hundred sixty rats were randomly divided into 4 groups (n = 10) as follows: the model group (MP group), the control group (CP group), the ranitidine group (RP group) and the XTTF granule group (XP group). Rats in the MP group received no drugs, rats in the CP group received 0.2 mL of a 0.9% sodium chloride solution via oral gavage, and rats in the RP and XP groups received the same volume of ranitidine (50 mg/kg) or XTTF granule (4.9 g/kg). The cold-restraint stress model was applied to induce stress ulcers after 7 consecutive days of drug administration. Afterwards, rats were sacrificed at 0, 3, 6 and 24 h. Gastric pH was measured by a precise pH meter; gastric emptying rate (GER) was measured by using a methylcellulose test meal; myeloperoxidase activity (MPO), macrophage migration inhibitory factor (MIF), proliferating cell nuclear antigen (PCNA), and heat shock protein 70 (HSP70) were measured by immunohistochemical staining; and mucosal cell apoptosis was measured by transferase dUTP nick end labeling.

RESULTS: In the cold-restraint stress model, the development of stress ulcers peaked at 3 h and basically regressed after 24 h. Gastric lesions were significantly different in the RP and XP groups at each time point. Interestingly, although this index was much lower in the RP group than in the XP group immediately following stress induction (7.00 ± 1.10 vs 10.00 ± 1.79, P < 0.05. Concerning gastric pH, between the RP and XP groups, we detected a statistically significant difference immediately after stress induction (0 h: 4.56 ± 0.47 vs 3.34 ± 0.28, P < 0.05) but not at any of the subsequent time points. For GER, compared to the RP group, GER was remarkably elevated in the XP group because a statistically significant difference was detected (3 h: 46.84 ± 2.70 vs 61.16 ± 5.12, P < 0.05; 6 h: 60.96 ± 6.71 vs 73.41 ± 6.16, P < 0.05; 24 h: 77.47 ± 3.17 vs 91.31 ± 4.34, P < 0.05). With respect to MPO and MIF, comparisons between the RP and XP groups revealed statistically significant differences at 3 h (MPO: 18.94 ± 1.20 vs 13.51 ± 0.89, P < 0.05; MIF: 150.67 ± 9.85 vs 122.17 ± 5.67, P < 0.05) and 6 h (MPO: 13.22 ± 1.54 vs 8.83 ± 0.65, P < 0.05; MIF: 135.50 ± 9.46 vs 109.83 ± 6.40, P < 0.05). With regard to HSP70, HSP70 expression was significantly increased in the RP and XP groups at 3 and 6 h compared to the MP and CP groups. In addition, comparing the RP and XP groups also showed statistically significant differences at 3 and 6 h. The expression of PCNA was higher in the RP and XP groups 3 h after stress induction. Between these two groups, small but statistically significant differences were observed at all of the time points (3 h: 69.50 ± 21.52 vs 79.33 ± 15.68, P < 0.05; 6 h: 107.83 ± 4.40 vs 121.33 ± 5.71, P < 0.05; 24 h: 125.33 ± 5.65 vs 128.50 ± 14.49, P < 0.05) except 0 h. With regard to apoptosis, the apoptotic activity in the RP and XP groups was significantly different from that in the MP and CP groups. The XP group exhibited a higher inhibition of cell apoptosis than the RP group at 3 h (232.58 ± 24.51 vs 174.46 ± 10.35, P < 0.05) and 6 h (164.74 ± 18.31 vs 117.71 ± 12.08, P < 0.05).

CONCLUSION: The Xiaotan Tongfu granule was demonstrated to be similar to ranitidine in preventing stress ulcers. It exhibited multiple underlying mechanisms and deserves further study.

Melatonin or L-tryptophan accelerates healing of gastroduodenal ulcers in patients treated with omeprazole

Melatonin and L-tryptophan (Trp) are highly gastroprotective in humans, but no study has assessed their impact on healing of chronic gastroduodenal ulcers in humans. Three groups (A, B and C) of 14 idiopathic patients in each treatment group with gastroduodenal chronic ulcers were treated with omeprazole (20 mg twice daily) combined either with placebo (group A), melatonin (group B) or with Trp (group C). The rate of ulcer healing was determined by gastroduodenoscopy at day 0, 7, 14 and 21 after initiation of therapy. Plasma melatonin, gastrin, ghrelin and leptin were measured by RIA. On day 7, omeprazole by itself (group A) had not healed any ulcers, but four ulcers were healed with omeprazole plus melatonin and two with omeprazole plus tryptophan. At day 21, all ulcers were healed in patients treated with melatonin or Trp, but only 10-12 ulcers were healed in placebo-treated patients. After treatment with omeprazole plus melatonin (group B) or Trp (group C), plasma melatonin levels rose several-fold above initial values. Plasma gastrin level also rose significantly during treatment with omeprazole plus melatonin or Trp, but it was also significantly increased in patients treated with omeprazole plus placebo. Plasma ghrelin levels did not change significantly after treatment with melatonin or Trp, while plasma leptin increased significantly in patients treated with melatonin or Trp but not with placebo. We conclude that melatonin or Trp, when added to omeprazole treatment, accelerates ulcer healing and this likely depends mainly upon the significant increments in plasma melatonin.