Related Experiment Videos
Delayed institution of hypertension during focal cerebral ischemia: effect on brain edema
P M Patel1, J C Drummond, D J Cole
1Neuroanesthesia Research, University of California, San Diego, La Jolla 92093.
Abstract:
The effect of induced hypertension instituted after a 2-h delay following middle cerebral artery occlusion (MCAO) on brain edema formation and histochemical injury was studied. Under isoflurane anesthesia, the MCA of 14 spontaneously hypertensive rats was occluded. In the control group (n = 7), the mean arterial pressure (MAP) was not manipulated. In the hypertensive group (n = 7), the MAP was elevated by 25-30 mm Hg beginning 2 h after MCAO. Four hours after MCAO, the rats were killed and the brains harvested. The brains were sectioned along coronal planes spanning the distribution of ischemia produced by MCAO. Specific gravity (SG) was determined in the subcortex and in two sites in the cortex (core and periphery of the ischemic territory). The extent of neuronal injury was determined by 2,3,5-triphenyltetrazolium staining. In the ischemic core, there was no difference in SG in the subcortex and cortex in the two groups. In the periphery of the ischemic territory, SG in the cortex was greater (less edema accumulation) in the hypertensive group (1.041 +/- 0.001 vs 1.039 +/- 0.001, P less than 0.05). The area of histochemical injury (as a percent of the cross-sectional area of the hemisphere) was less in the hypertensive group (33 +/- 3% vs 21 +/- 2%, P less than 0.05). The data indicate that phenylephrine-induced hypertension instituted 2 h after MCAO does not aggravate edema in the ischemic core, that it improves edema in the periphery of the ischemic territory, and that it reduces the area of histochemical neuronal dysfunction.
Insights
Induced hypertension after middle cerebral artery occlusion (MCAO) in rats did not worsen brain edema in the core ischemic area. However, it reduced edema in the ischemic periphery and decreased neuronal injury.
Area of Science:
- Neuroscience
- Cerebrovascular Research
- Ischemic Stroke Models
Background:
- Middle cerebral artery occlusion (MCAO) is a common model for studying ischemic stroke.
- Brain edema and neuronal injury are critical consequences of ischemic stroke.
- The therapeutic window for interventions following MCAO is an area of active research.
Purpose of the Study:
- To investigate the effects of delayed induced hypertension on brain edema and histochemical neuronal injury following MCAO.
- To determine if hypertension instituted 2 hours after MCAO impacts edema in different regions of the ischemic territory.
- To assess the extent of neuronal dysfunction under these conditions.
Main Methods:
- Middle cerebral artery occlusion (MCAO) was performed on spontaneously hypertensive rats under anesthesia.
- Rats were divided into a control group and a group receiving induced hypertension (25-30 mm Hg increase in MAP) starting 2 hours post-MCAO.
- Brain edema was assessed using specific gravity (SG) measurements, and neuronal injury was quantified via 2,3,5-triphenyltetrazolium staining.
Main Results:
- No significant difference in specific gravity (edema) was observed in the ischemic core between the groups.
- A greater specific gravity (less edema) was found in the periphery of the ischemic territory in the hypertensive group (P < 0.05).
- The area of histochemical neuronal injury was significantly reduced in the hypertensive group compared to the control group (P < 0.05).
Conclusions:
- Phenylephrine-induced hypertension initiated 2 hours after MCAO does not exacerbate edema in the ischemic core.
- Delayed hypertension improves edema accumulation in the ischemic periphery.
- This therapeutic strategy effectively reduces the extent of histochemical neuronal dysfunction following MCAO.