Early NO-donor treatment improves acute perfusion deficit and brain damage after experimental subarachnoid hemorrhage in rats

A lack of nitric oxide (NO) may be a possible factor in the pathogenesis of an acute decrease of cerebral blood flow (CBF) after subarachnoid hemorrhage (SAH). This study was conducted to investigate whether early therapy with an NO-donor can improve CBF and offer neuroprotection after experimental SAH in rats. Male Sprague-Dawley rats were subjected to SAH by the endovascular filament model and treated with 1.5 μg/kg/min of intravenous sodium nitroprusside (SNP) or vehicle (n = 10) starting 15 min after induction of SAH until 180 min thereafter. SNP caused a moderate decrease of arterial blood pressure and cerebral perfusion pressure. Conversely, CBF measured by laser-Doppler flowmetry increased significantly in SNP-treated animals. The rate of injured neurons in the hippocampal CA1-field was significantly reduced in SNP-treated animals (10.5 ± 5%) compared to controls (14.2 ± 7%), as well as the number of Caspase-3 positive neurons. Low-dose treatment with SNP can attenuate an early perfusion deficit after SAH and reduce neuronal damage in spite of a hypotensive side effect. This may reflect the reversal of an early NO-deficit. In the clinical setting, the moderate hypotensive effect may be welcome since SAH-patients frequently present with elevated blood pressure.