Endocrine Abstracts

Adriamycin (ADR) is a potent chemotherapeutic agent, effective in treatment of leukemias, lymphomas and of many solid tumours. However, its clinical usage is often limited by cardiotoxicity, induced by oxygen radical damage of membrane lipids.

Melatonin (MEL), is a well-known antioxidant. It has been shown that melatonin can scavenge free radicals, both directly or indirectly, stimulating the activity of antioxidative enzyme, e.g., glutathione peroxidase (GSH-Px).

The aim of the study was to examine the effect of Mel on the GSH-Px activity in serum, erythrocytes and the heart after adriamycin.

Materials and Methods: Wistar rats were divided into the 3 groups: pinealectomized (PX), sham-operated (Sham-PX) and control animals (Intact). Each of the groups was divided into 4 subgroups, injected with: 1 – saline, 2 – MEL, 3 – ADR and 4 – MEL + ADR. ADR was administered 2 months after PX as a single dose (15 mg/kg, i.p.), 1 hour after the fourth melatonin injection. Melatonin (5 mg/kg, i.p.) was administered for 4 days before and 4 days after ADR. After 8 days of treatment the rats were killed by decapitation. Their hearts and blood were collected for measurements.

Results: The activity of GSH-Px in the heart increased significantly in all the examined groups after ADR injections. On the contrary, in serum, GSH-Px activity decreased in all the groups after ADR. In erythrocytes, GSH-Px decreased after ADR in Px-animals. Mel did not change GSH-Px activity after ADR.

Conclusion: MEL did not influence the activity of GSH-Px, either in normal or in pinealectomized rats after ADR.

Grant No 502-11-293 of the Medical University of Łódź.