Histopathological effects of exogenous melatonin on connective tissues of thymus gland in male rats

Abstract

Background: The neurohormone namely melatonin is secreted by the pineal body in brain. It could reach all the bodily tissues and cells; affecting their function, depending on its biological level. Thymus gland is well known to be the main central immunity director, and its wellness is rather proportional to melatonin level.Aims: This work was done to study the histopathological effect of exogenous melatonin on thymic connective tissue bulk.Materials and Methods: Dietary melatonin was supplied to adult rats, for successive 30 days. Rats were divided 6 groups. Group 1 was the control, group I was the control. Group II, III, IV, V and VI were supplied with a daily measured quantity of melatonin as 125, 250, 500, and 1000 µm/kg body wt, respectively. After the last day of treatment all animals were killed then the left thymic lobe was removed under anesthesia for histopathological study.Results: No noteworthy effect of melatonin was seen on the thymic connective tissue on its normal doses, whilst it had significant effect on the connective tissue bulk with its large doses.Conclusions: The treatment of dietary melatonin had no important effects on the rat thymic connected tissues, on its little doses, but it has considerable effects when administrated in large doses.