| Melatonin has been linked to a variety of physiological functions. In the process of aging, the pineal gland becomes less efficient in its production of melatonin. The characteristic drop of indole hormone has been implicated in the development of various age-related processes, including disrupted circadian rhythms, diminished immune responses leading to certain neurodegenerative diseases, and even reduced lifespans. In this study, immunohistochemistry was used to label melatonin in aged pineal glands of female rats ( Rattus rattus) for comparison against young glands. Analysis of transmission electron micrographs revealed a new aspect of the aging in pinealocytes. For the first time reported, aged pinealocytes exhibit a 23% decrease in melatonin secretory activity when compared to pinealocytes in young animals. |