Role of Aspirin and Dexamethasone against Experimentally Induced Depression in Rats

A large number of current studies indicate that inflammatory mediators may contribute to depression in experimental models as well as in human beings. Nevertheless, the subject, whether anti-inflammatory treatments can prevent depression still remains controversial. In the present study, a chronic mild stress (CMS) model of male Sprague Dawley rats was used to investigate the role of anti-inflammatory drugs in the treatment of depression. All the animals in different groups, except the normal control group, were exposed to CMS procedure for 28 days and concurrently treated with aspirin (10 mg/kg, p.o.), dexamethasone (1 mg/kg p.o.) and amitriptyline (10 mg/kg p.o., reference standard), respectively. Amitriptyline was also used in combination with aspirin and dexamethasone to inspect any synergistic effects. Tests performed towards the end of the study included sucrose preference test, behavioural tests like forced swim test, elevated plus-maze, light/dark box, locomotor activity and biochemical estimations like serum cortisol and brain neurotransmitters. Disease control group (CMS-treated) produced significant depressive behaviour in rats. The animals treated with aspirin showed increased sucrose preference, decreased immobility time in forced swim test, decreased serum cortisol and increased brain serotonin levels signifying antidepressant action. In contrast, there was aggravation of depressive behaviour in rats treated with dexamethasone. Together, these findings suggest that aspirin can serve as a potential antidepressant both individually and as adjunctive agent in the treatment of depression. Inhibition of the inflammatory mediators during stress procedures or any other potential physiological and biochemical mechanisms may be involved in its antidepressant effect.