E A Del Bel1, F S Guimarães. 1. Department of Physiology, School of Odontology, FORP, Ribeirão Preto, SP, Brazil. eadelbel@usp.br
Abstract
RATIONALE: NG-nitro-L-arginine (L-NOARG), an inhibitor of nitric-oxide synthase (NOS), induces catalepsy in mice. This effect undergoes rapid tolerance, showing a significant decrease after 2 days of sub-chronic L-NOARG treatment. Nitric oxide (NO) has been shown to influence dopaminergic neurotransmission in the striatum. Neuroleptic drugs such as haloperidol, which block dopamine receptors, also cause catalepsy in rodents. OBJECTIVES: To investigate the effects of subchronic L-NOARG treatment in haloperidol-induced catalepsy and the number of NOS neurons in areas related to motor control. METHODS: Male albino Swiss mice were treated sub-chronically (twice a day for 4 days) with L-NOARG (40 mg/kg i.p.) or haloperidol (1 mg/kg i.p.). Catalepsy was evaluated at the beginning and the end of the treatments. Reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry was also employed to visualize NOS as an index of enzyme expression in mice brain regions related to motor control. RESULTS: L-NOARG sub-chronic administration produced tolerance of L-NOARG and of haloperidol-induced catalepsy. It also induced an increase in the number of NADPH-d-positive cells in the dorsal part of the caudate and accumbens nuclei compared with haloperidol and in the pedunculopontine tegmental nucleus compared with saline. In contrast, there was a decrease in NADPH-d neuron number in the substantia nigra, pars compacta in both haloperidol-treated and L-NOARG-treated animals. CONCLUSIONS: The results give further support to the hypothesis that NO plays a role in motor behavior control and suggest that it may take part in the synaptic changes produced by antipsychotic treatment.
RATIONALE: NG-nitro-L-arginine (L-NOARG), an inhibitor of nitric-oxide synthase (NOS), induces catalepsy in mice. This effect undergoes rapid tolerance, showing a significant decrease after 2 days of sub-chronic L-NOARG treatment. Nitric oxide (NO) has been shown to influence dopaminergic neurotransmission in the striatum. Neuroleptic drugs such as haloperidol, which block dopamine receptors, also cause catalepsy in rodents. OBJECTIVES: To investigate the effects of subchronic L-NOARG treatment in haloperidol-induced catalepsy and the number of NOS neurons in areas related to motor control. METHODS: Male albino Swiss mice were treated sub-chronically (twice a day for 4 days) with L-NOARG (40 mg/kg i.p.) or haloperidol (1 mg/kg i.p.). Catalepsy was evaluated at the beginning and the end of the treatments. Reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry was also employed to visualize NOS as an index of enzyme expression in mice brain regions related to motor control. RESULTS:L-NOARG sub-chronic administration produced tolerance of L-NOARG and of haloperidol-induced catalepsy. It also induced an increase in the number of NADPH-d-positive cells in the dorsal part of the caudate and accumbens nuclei compared with haloperidol and in the pedunculopontine tegmental nucleus compared with saline. In contrast, there was a decrease in NADPH-d neuron number in the substantia nigra, pars compacta in both haloperidol-treated and L-NOARG-treated animals. CONCLUSIONS: The results give further support to the hypothesis that NO plays a role in motor behavior control and suggest that it may take part in the synaptic changes produced by antipsychotic treatment.
Authors: E A Del Bel; F S Guimarães; M Bermúdez-Echeverry; M Z Gomes; A Schiaveto-de-souza; F E Padovan-Neto; V Tumas; A P Barion-Cavalcanti; M Lazzarini; L P Nucci-da-Silva; D de Paula-Souza Journal: Cell Mol Neurobiol Date: 2005-03 Impact factor: 5.046