RESUMEN
Recent advances in immunology revolutionized the approach of management of infectious diseases by the use of immunomodulators or immunostimulators. Since melatonin, the neuroendocrine hormone, is found to have direct immunomodulatory effects in many biological models including human, it may be possible to utilize this feature for the improvement of immune responses against infections. This study designed to evaluate the effects of various pharmacological doses of melatonin alone or in combination with antibiotics in the treatment of experimentally induced infected lesions in rabbits Methods: Infected lesions were induced in the skin of 36 rabbits with pathogenic strain of Staphylococcus aureus. Healing time, lesion size, and immunoglobulin production were measured during the period of treatment with different doses [2, 5, 10 mg kg[-1]] of melatonin alone or in combination with antibiotics [25 mg kg[-1] ampicillin and cloxacillin]. Dose dependent effect for melatonin was observed in the improvement of the immune responses of animals against the bacterial infection, revealed as reduction in the healing time, and lesion size with significant increase in immunoglobulin production compared to controls. Meanwhile, combination of melatonin in pharmacological doses with antibiotics synergizes their effects in improving all the studied parameters. These results provide experimental evidences for the immunomodulatory effects of melatonin in the improvement of the resistance against infectious burden; in addition to the synergistic effect with antibiotics in vivo