Age-related changes in tissue and plasma zinc levels: modulation by exogenously administered melatonin.

Melatonin (MEL) is synthesized mainly in the pineal gland and derived from 5-hydroxytryptophan (5-HTP). Zinc (Zn) is one of the most important trace elements in the body. Zn and MEL levels are changed with aging. The aim of this study was to investigate the age-related changes of tissue and plasma Zn levels and effect of MEL administration on these parameters. Male wistar rats received for 3 weeks subcutaneous injection of MEL (10 mg/kg). Kidney and pancreas Zn levels in old rats were significantly lower than middle-aged group. Spleen, small intestine, and plasma Zn levels were not different in middle-aged and old rats. On the other hand, MEL treatment increased Zn levels of small intestine and plasma in middle-aged rats. However, kidney, spleen, and pancreas Zn levels were unaffected by MEL treatment.