Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6262860 | Brain Research | 2015 | 20 Pages |
â¢NOS inhibitors, 7-NI and l-NAME induced catalepsy in 6-OHDA-lesioned rats.â¢Chronic l-DOPA induces robust contralateral rotations in 6-OHDA-lesioned rats.â¢nNOS inhibitor 7-NI prolonged duration of l-DOPA-induced rotations.â¢L-NAME did not change the time course of l-DOPA-evoked rotations.â¢7-NI but not l-NAME increased the level of l-DOPA-derived DA in the striatum and SN.
Reciprocal interactions between nitrergic and dopaminergic systems play a key role in the control of motor behavior. In the present study, we performed a comparative analysis of motor behavior (locomotor activity, catalepsy, rotational behavior) and monoamine metabolism in the striatum and substantia nigra of unilaterally sham-operated and 6-OHDA-lesioned rats treated with the preferential neuronal nitric oxide synthase (nNOS) inhibitor 7-nitroindazole (7-NI) or the non-selective one NG-nitro-l-arginine methyl ester (l-NAME), alone or in combination with l-DOPA. Each NOS inhibitor given alone (50Â mg/kg) induced a distinct catalepsy 30Â min after injection but only 7-NI impaired spontaneous locomotion after 10Â min. In 6-OHDA-lesioned rats, chronic l-DOPA (25Â mg/kg) induced 2.5-h long contralateral rotations. 7-NI (30 and 50Â mg/kg) markedly reduced the intensity of l-DOPA-induced contralateral rotations while extending their duration until 4.5Â h whereas l-NAME (50 and 100Â mg/kg) only tended to attenuate their intensity without affecting the duration. 7-NI but not l-NAME significantly increased endogenous tissue DA levels in the nigrostriatal system of both sham-operated and 6-OHDA-lesioned rats. In l-DOPA-treated group, 7-NI significantly enhanced the l-DOPA-derived tissue DA content in this system and decreased the level of the intracellular DA metabolite DOPAC produced by monoamine oxidase (MAO). In contrast to 7-NI, l-NAME decreased markedly DA content and did not affect DOPAC level in the ipsilateral striatum. It means that the differences in 7-NI and l-NAME-mediated modulation of l-DOPA-induced behavioral and biochemical effects resulted not only from the inhibition of NOS activity but also from differences in their ability to inhibit MAO.