Co-administration of melatonin reverses the tin-protoporphyrin (SnPP) induced decline of cytochrome P450 content in vivo in rats.

Melatonin (N-acetyl-5 methoxytryptamine) is a low molecular weight antioxidant and is an endogeneous defense system against the deleterious actions of the extremely reactive hydroxyl radical. Among the enzymes that participate in the antioxidant functions is cytochrome P-450, a stalwart of the detoxification system in the body. Our results revealed that tin-protoporphyrin administration brought about a marked decline in cytochrome P-450 levels. This decline was, however, reversed by the coadministration of the antioxidant, melatonin. Thus, the enhanced antioxidant status in melatonin-treated rats may act as a protective mediator of various pharmacological functions altered during tin-protoporphyrin (an antihyperbilirubemenic agent) administration to Wistar rats.