Cyclooxygenase-2-Derived Prostaglandins Mediate Cerebral Microcirculation in a Juvenile Ischemic Rat Model.

Abstract : BACKGROUND AND PURPOSE: We previously showed that the selective neuronal nitric oxide synthase inhibitor 7-nitroindazole (7-NI) increases cerebral microcirculation in a juvenile ischemic rat model. We address the roles of cyclooxygenase (COX)-elaborated prostaglandins in collateral recruitment and blood supply. METHODS: Fourteen-day-old rats were subjected to ischemia-reperfusion and treated with either PBS or 7-NI (25 mg/kg) at the reperfusion onset. Six-keto-prostaglandin F1α was measured using ELISA. COX-1 and COX-2 and prostaglandin terminal synthesizing enzymes were evaluated using reverse-transcriptase polymerase chain reaction and immunofluorescence. Microvascular blood flow indexes (artery diameter and capillaries number) were measured using sidestream dark-field videomicroscopy in PBS- and 7-NI-treated ischemic rats in the absence or presence of the COX-2 inhibitor NS-398 (5 mg/kg). Cell death was measured with the TUNEL (terminal transferase dUTP nick end labeling) assay and cleaved-caspase-3 immunostaining. RESULTS: Six-keto-prostaglandin F1α and COX-2, associated with a prostaglandin E synthase, were significantly increased in PBS- and 7-NI-treated animals 15 minutes and 1 hour after ischemia-reperfusion, respectively. In contrast and as compared with PBS, 7-NI significantly decreased prostacyclin synthase and cytosolic prostaglandins E synthase mRNA. Selective COX-2 inhibition significantly decreased blood flow indexes and significantly reversed the effects of 7-NI, including the number of TUNEL+- and cleaved-caspase-3+-nuclei. CONCLUSIONS: These results show that the juvenile rat brains mostly respond to ischemia by a COX-2-dependent prostaglandins production and suggest that the transcriptional responses observed under 7-NI facilitate and reorient COX-2-dependent prostaglandins production.
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Stroke, American Heart Association, 2016, 47 (12), pp.3048-3052. 〈10.1161/STROKEAHA.116.015095〉
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Pierre-Louis Leger, Julien Pansiot, Valérie Besson, Bruno Palmier, Sylvain Renolleau, et al.. Cyclooxygenase-2-Derived Prostaglandins Mediate Cerebral Microcirculation in a Juvenile Ischemic Rat Model.. Stroke, American Heart Association, 2016, 47 (12), pp.3048-3052. 〈10.1161/STROKEAHA.116.015095〉. 〈inserm-01415571〉

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