Anti-glucocorticoid effects of melatonin on adult rats.

To extend our previous experiment on anti-glucocorticoid effects of melatonin which was performed under a very special condition using young rats, we have carried out another experiment of long term administration of pineal hormone melatonin to adult female rats which were conditioned by overdose glucocorticoid. The results clearly demonstrated significant protection, by melatonin, from the injurious effects of a glucocorticoid, dexamethasone: decrease of body weight gain, atrophy of the thymus and adrenals, and elevation of the level of total cholesterol in blood. Thus, it has been clarified that anti-glucocorticoid effects of melatonin could be shown experimentally not only in young rats but also in adults, and also, could be really seen not only in short term experiment but also in longer ones. Anti-glucocorticoid effects of melatonin seem to be of considerably wide range, not being limited to occur under a special condition, including the age of animals, in experiments.