Aerobic Exercise versus Fluoxetine: The Effect on Depression and Cardiac M2 Muscarinic Receptors in Wistar Rats

Prolonged exposure to depression can cause heart failure. The aim of this study was to investigate the effect of endurance aerobic exercise and fluoxetine administration on depression and cardiac M2 muscarinic receptors in Wistar rats. In this experimental study, 56 Wistar rats (3 months old, mean weight of 220±15 g) were divided into 7 groups. The exercise group performed 4 weeks of endurance exercise on a treadmill with 20 m/min speed, which was equal to 65-80% VO2 max for 45 minutes per day and 6 days a week.The fluoxetine group received 5 mg of fluoxetine per kg of body weight. Intraperitoneal injection of lipopolysaccharide was used to depress the rats. The results were analyzed by dependent and independent t tests and ANOVA at the significance level of P<0.05. Level of depression in depressed-fluoxetine group did not significantly change (P=0.01). The level of depression was significantly different in the exercise-depressed group (P<0.05). There was no significant difference in the mean density of M2 muscarinic receptors between exercise and exercise-fluoxetine groups and control group (P=0.08). There was a significant difference in the mean of exercise-depressed, fluoxetine-depressed, depressed and exercise-depressed-fluoxetine groups (P=0.01). Untreated depression can worsen depression symptoms. Depression causes significant changes in the density of M2 muscarinic receptors in the heart of rats.Exercise and concomitant administration of fluoxetine can prevent significant changes in the mean density of cardiac M2 muscarinic receptors in depressed rats.