MELATONIN PROTECTS 6-OHDA-INDUCED NEURONAL DEATH OF NIGROSTRIATAL DOPAMINERGIC SYSTEM

IN VIVO neuroprotective effects of melatonin on the nigrostriatal dopa minergic system in rats unilateral 6-hydroxydopamine (6-OHDA) lesions were tested. Two weeks after lesioning the dopamine receptor agonist, apomorphine produced rotational asymmetry. In contrast, melatonin trea tment significantly reduced the motor deficit following apomorphine ch allenge. Analysis by tyrosine hydroxylase (TH) immunocytochemistry rev ealed the loss of cell bodies in the substantia nigra (SN) and absence of terminals in the dorsolateral striatum ipsilaterally. Melatonin tr eatment also resulted in the survival of dopaminergic neurons in SN an d TH-immuoreactive terminals in the dorsolateral striatum. These behav ioral and histochemical results may indicate a neuroprotective action of melatonin and suggest a potential pharmacological role in the treat ment of Parkinson's disease. NeuroReport 9: 2387-2390 (C) 1998 Rapid S cience Ltd.