Evaluation of central and peripheral effects of doxepin on acetic acid-induced colitis in rat and the involved mechanisms

The anti-inflammatory effects of antidepressants on colitis

Aim

Clomipramine (tricyclic antidepressant), Risperidone (a non-typical antidepressant), and Escitalopram (selective serotonin reuptake inhibitor antidepressant) might be good candidates for investigating the anti-colitis activity.

Background

The incidence of depression with ulcerative colitis in patients has led to the use of antidepressants in their treatment. In addition to the antidepressant effect of these drugs, anti-inflammatory effects have also been reported.

Methods

In this study, 36 rats were used 2 ml of 3% acetic acid solution rectally to show the colitis. Then, Clomipramine (25 mg/kg), Escitalopram (10 mg/kg), Prednisolone (5 mg/kg), Risperidone (2 mg/kg), and normal saline as the control was administered orally for six days. The levels of Tumor Necrosis factor-alpha (TNF-α), Interleukin-6 (IL-6), and myeloperoxidase (MPO) were measured by Enzyme-linked immune sorbent assay (ELISA), and changes in the tissue pathology were investigated.

Results

IL-6 level was significantly reduced after the administration of clomipramine and Prednisolone (p=0.025). Risperidone has significantly reduced MPO activity in colonic tissue (P=0.006). We did find no statistical decrease in MPO activity and TNF-α and IL-6 levels after consumption of Escitalopram (p>0.05).

Conclusion

Clomipramine showed the best anti-inflammatory effect compared to Escitalopram and Risperidone. Therefore, clomipramine showed the best relieving effect on inflammation of ulcerative colitis in rats.

Protective Effect of Apium graveolens L. (Celery) Seeds Extracts and Luteolin on Acetic Acid-Induced Colitis in Rats

INTRODUCTION

Anti-oxidant, antispasmodic, anti-inflammatory, and analgesic effects have been reported for Apium graveolens Linn. ) Celery( seeds and its active component luteolin. So, this study was carried out to investigate the protective effects of hexane (AGHE) and methanol (AGME) extracts of A. graveolens seeds and luteolin on acetic acid-induced colitis in rats.

METHODS

Three doses of AGHE (100, 200, and 400 mg/kg), AGME (200, 400, and 800 mg/kg), and luteolin (5, 10, and 20 mg/kg) were administered orally (p.o.) to separate groups of male Wistar rats, 2 h before ulcer induction (acetic acid 4%) and continued once daily for 4 days. Prednisolone (4 mg/kg) and mesalazine (100 mg/kg) were used as reference and vehicle (2 mL/kg) as control groups. Colon biopsies were taken for weighting, macroscopic and histopathologic evaluation, and measuring myeloperoxidase (MPO) activity.

RESULTS

Our findings showed that AGHE (200 and 400 mg/kg), AGME (400 and 800 mg/kg), and luteolin (10 and 20 mg/kg) were effective to reduce colonic ulcer score, area, and index as well as total colitis index, and MPO activity significantly in comparison with controls. Since the lowest doses of extracts and luteolin were not significantly effective to diminish evaluated parameters of colitis, it is concluded that the ameliorative effect was dose related.

CONCLUSION

It is also concluded that both extracts and luteolin, as an important ingredient of celery extract, were effective in the amelioration of colitis in rats, but further clinical and detailed mechanistic experiments are required to introduce these natural agents for colitis treatment or prevention in human.

Potential Anti-Inflammatory Effect of Escitalopram in Iodoacetamide-Induced Colitis in Depressed Ovariectomized Rats: Role of α7-nAChR

Escitalopram, a drug of choice in the treatment of depression, was recently shown to possess an anti-inflammatory activity. The aim of the present study was to elucidate the effect of escitalopram on peripheral inflammatory cascades in iodoacetamide-induced colitis associated with depressive behavior in ovariectomized rats. Moreover, the role of α-7 nicotinic acetylcholine receptor in mediating the anti-colitic effect of escitalopram was examined using a nicotinic receptor antagonist methyllycaconitine citrate. Colitis was induced by intracolonic injection of 4% iodoacetamide in ovariectomized rats. Escitalopram (10 mg/kg/day, i.p.) was then injected for 1 week and several parameters including macroscopic (colon mass index and ulcerative area), microscopic (histopathology and scoring), and biochemical (myeloperoxidase and tumor necrosis factor-α) were determined. Colitis induction in ovariectomized rats resulted in a marked increase in colon mass index, ulcerative area, histopathological scoring, myeloperoxidase activity and tumor necrosis factor-α levels. These effects were ameliorated by escitalopram, even in the presence of methyllycaconitine indicating that α-7 nicotinic acetylcholine receptor does not mediate the anti-inflammatory effect of escitalopram. The present study revealed the beneficial effect of escitalopram in iodoacetamide induced colitis in ovariectomized rats and suggests that it may represent a new therapeutic agent for the treatment of inflammatory bowel disease, especially in patients with or at high risk of depressive behavior.