Different response to exogenous l-arginine in nitric oxide production between hippocampus and striatum of conscious rats: a microdialysis study.
Neurosci Lett 2004;
366:302-7. [PMID:
15288439 DOI:
10.1016/j.neulet.2004.05.055]
[Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2004] [Revised: 05/20/2004] [Accepted: 05/21/2004] [Indexed: 10/26/2022]
Abstract
We previously showed that systemic administration of a nitric oxide (NO) precursor, L-arginine (L-Arg), failed to reverse suppression by NO synthase (NOS) inhibitors of chemically induced shaking behavior in rats, leading to the hypothesis that exogenous L-Arg might be non-uniformly supplied to brain regions susceptible to NOS inhibitors. In the present study, therefore, we examined the effect of exogenous L-Arg on the extracellular levels of the oxidative nitric oxide (NO) products, nitrite (NO2-) and nitrate (NO3-), in two different brain regions, the hippocampus and the striatum, of conscious rats by means of in vivo brain microdialysis. The basal NO2- levels in the two brain regions were comparable, while the NO3- level was significantly lower in the hippocampus than the striatum. The addition of 10 mM L-Arg, but not D-Arg, to the perfusing solution significantly increased NO2- and NO3- in the hippocampus and NO2- alone in the striatum. These increases were abolished by 1 mM N(omega)-nitro-L-arginine, an NOS inhibitor. L-Arg at 1mM was able to significantly increase NO2-, but not NO3-, in the hippocampus to a level comparable with that at 10 mM L-Arg, while it had no effect in the striatum. L-Arg (500 mg/kg, i.p.) induced a significant increase in NO2- and NO3- in the hippocampus, but not in the striatum. These results suggest that the striatum may have a lower ability to enhance NO production by utilising exogenous L-Arg than the hippocampus, despite higher basal NO production.
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