Comparison of the effect of topical and systemic melatonin administration on delayed wound healing in rats that underwent pinealectomy.

Objectives. Melatonin is a hormone which has many systemic effects in addition to its strong antioxidant properties. The aim of the present study was to investigate the difference between sytemic and topical administration of melatonin by forming a chronic wound model in rats whose release of basal melatonin was supressed by pinealectomy. Material and methods. Experimental animals used in the study were divided into four equal groups: (i) a group of normal animals with wound formation (control), (ii) a group of animals who underwent pinelaectomy and wound formation (PINx), (iii) a group that underwent PINx + systemic melatonin administration, and (iv) a group that underwent PINx + topical melatonin administration. Fifteen days after pinealectomy, a bipediculed flap was formed on the back of the rats under anesthesia and then six excisional skin wounds were produced in all groups. Following the treatment that lasted 7 days, on day 8 the wound surface areas were measured and wound tissues were removed under anesthesia. In these tissues the levels of malondialdehit (MDA) and hydroxyproline (OH-proline) and the activities of superoxide dismutase(SOD) and glutathion peroxidase (GSH-Px) were measured. Results. In the PINx group, OH-prolin levels decreased significantly compared to the control group and wound surface areas increased. MDA levels increased compared to the control group, and SOD and GSH-Px decreased accordingly. Conversely, in two melatonin groups in which melatonin was administered systemically or topically MDA decreased while SOD ve GSH-Px enzymes increased. Conclusion. In conclusion, in the present study it was shown that wound healing was prolonged in experimental animals deprived of melatonin through pinealectomy. Melatonin exerts positive effects on wound healing, whether it is administered topically or systemically. [ABSTRACT FROM AUTHOR]