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Hyperglycaemia does not increase perfusion deficits after focal cerebral ischaemia in male Wistar rats.

ABSTRACT: Background:Hyperglycaemia is associated with a worse outcome in acute ischaemic stroke patients; yet the pathophysiological mechanisms of hyperglycaemia-induced damage are poorly understood. We hypothesised that hyperglycaemia at the time of stroke onset exacerbates ischaemic brain damage by increasing the severity of the blood flow deficit. Methods:Adult, male Wistar rats were randomly assigned to receive vehicle or glucose solutions prior to permanent middle cerebral artery occlusion. Cerebral blood flow was assessed semi-quantitatively either 1?h after middle cerebral artery occlusion using 99mTc-D, L-hexamethylpropyleneamine oxime (99mTc-HMPAO) autoradiography or, in a separate study, using quantitative pseudo-continuous arterial spin labelling for 4?h after middle cerebral artery occlusion. Diffusion weighted imaging was performed alongside pseudo-continuous arterial spin labelling and acute lesion volumes calculated from apparent diffusion coefficient maps. Infarct volume was measured at 24?h using rapid acquisition with refocused echoes T2-weighted magnetic resonance imaging. Results:Glucose administration had no effect on the severity of ischaemia when assessed by either 99mTc-HMPAO autoradiography or pseudo-continuous arterial spin labelling perfusion imaging. In comparison to the vehicle group, apparent diffusion coefficient-derived lesion volume 2-4?h post-middle cerebral artery occlusion and infarct volume 24?h post-middle cerebral artery occlusion were significantly greater in the glucose group. Conclusions:Hyperglycaemia increased acute lesion and infarct volumes but there was no evidence that the acute blood flow deficit was exacerbated. The data reinforce the conclusion that the detrimental effects of hyperglycaemia are rapid, and that treatment of post-stroke hyperglycaemia in the acute period is essential but the mechanisms of hyperglycaemia-induced harm remain unclear.

SUBMITTER: Thow LA

PROVIDER: S-EPMC7058243 | biostudies-literature | 2018 Jan-Dec

REPOSITORIES: biostudies-literature

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Hyperglycaemia does not increase perfusion deficits after focal cerebral ischaemia in male Wistar rats.

Thow Lisa A LA MacDonald Kathleen K Holmes William M WM Muir Keith W KW Macrae I Mhairi IM Dewar Deborah D

Brain and neuroscience advances 20180101

<h4>Background</h4>Hyperglycaemia is associated with a worse outcome in acute ischaemic stroke patients; yet the pathophysiological mechanisms of hyperglycaemia-induced damage are poorly understood. We hypothesised that hyperglycaemia at the time of stroke onset exacerbates ischaemic brain damage by increasing the severity of the blood flow deficit.<h4>Methods</h4>Adult, male Wistar rats were randomly assigned to receive vehicle or glucose solutions prior to permanent middle cerebral artery occl ...[more]

PMID: 32166145

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Project description:Background and purposeRapamycin is a clinically approved mammalian target of rapamycin inhibitor that has been shown to be neuroprotective in animal models of stroke. However, the mechanism of rapamycin-induced neuroprotection is still being explored. Our aims were to determine if rapamycin improved leptomeningeal collateral perfusion, to determine if this is through eNOS (endothelial nitric oxide synthase)-mediated vessel dilation and to determine if rapamycin increases immediate postreperfusion blood flow.MethodsWistar and spontaneously hypertensive rats (≈14 weeks old, n=22 and n=15, respectively) were subjected to ischemia by middle cerebral artery occlusion (90 and 120 minutes, respectively) with or without treatment with rapamycin at 30-minute poststroke. Changes in middle cerebral artery and collateral perfusion territories were measured by dual-site laser Doppler. Reactivity to rapamycin was studied using isolated and pressurized leptomeningeal anastomoses. Brain injury was measured histologically or with triphenyltetrazolium chloride staining.ResultsIn Wistar rats, rapamycin increased collateral perfusion (43±17%), increased reperfusion cerebral blood flow (16±8%) and significantly reduced infarct volume (35±6 versus 63±8 mm3, P<0.05). Rapamycin dilated leptomeningeal anastomoses by 80±9%, which was abolished by nitric oxide synthase inhibition. In spontaneously hypertensive rats, rapamycin increased collateral perfusion by 32±25%, reperfusion cerebral blood flow by 44±16%, without reducing acute infarct volume 2 hours postreperfusion. Reperfusion cerebral blood flow was a stronger predictor of brain damage than collateral perfusion in both Wistar and spontaneously hypertensive rats.ConclusionsRapamycin increased collateral perfusion and reperfusion cerebral blood flow in both Wistar and comorbid spontaneously hypertensive rats that appeared to be mediated by enhancing eNOS activation. These findings suggest that rapamycin may be an effective acute therapy for increasing collateral flow and as an adjunct therapy to thrombolysis or thrombectomy to improve reperfusion blood flow.

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Hyperglycaemia does not increase perfusion deficits after focal cerebral ischaemia in male Wistar rats.

Publications

Hyperglycaemia does not increase perfusion deficits after focal cerebral ischaemia in male Wistar rats.

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