Effects of electrolytic and 6-hydroxydopamine lesions of rat nigrostriatal pathway on nitric oxide synthase and nicotinamide adenine dinucleotide phosphate diaphorase

The aim of the present study was to assess degenerative changes in the nitric oxide (NO) system of basal ganglia in animals with experimentally induced Parkinson's disease. In one procedure, rats were stereotaxically injected with 6-hydroxydopamine (6-OHDA) in the right medial forebrain bundle; in a second procedure, electrodes were implanted in the right substantia nigra. pars compacta (SNc). After 15 and 30 days animals were tested for rotational asymmetry induced by apomorphine. Apomorphine induced rotation in lesioned animals, towards the ipsilateral side after electrolytic lesion and towards contralateral side in 6-OHDA animals. Structural deficits in basal ganglia were quantified by nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemistry and by nitric oxide synthase (NOS) immunoreactivity. 6-OHDA and electrolytic lesions induced a significant decrease in the number of NADPH-d/NOS positive cells in the lesion ipsilateral to SNc, in contrast with cell number increase in the ipsilateral dorsal striatum. By contrast, 6-OHDA-treated animals showed a decrease in the number of NOS immunoreactive cells in the contralateral nucleus accumbens. We conclude that populations of NO-synthesizing neurons are differentially regulated in Parkinson's disease induced by different experimental procedures. (C) 2003 Elsevier Inc. All rights reserved.