Subchronic hypoxia pretreatment on brain pathophysiology in unilateral common carotid artery occluded albino rats

OBJECTIVE:

This study was aimed to assess the effect of unilateral common carotid artery occlusion on brain pathophysiology in rats pretreated with subchronic hypoxia.

MATERIALS AND METHODS:

Rats (200 ± 20 g) were randomized into three groups: Group 1 served as sham, Group 2 were normoxic (21% O₂ and 79% N₂), and Group 3 were hypoxia preconditioned (10% O₂ and 90% N₂) for 21 days before left common carotid artery occlusion (LCCAO). The LCCAO was done for 75 min followed by reperfusion for 12 h. Neurological scores were recorded. Serum malondialdehyde (MDA) and nitric oxide (NO) levels at pre- and 12 h post-LCCAO were measured. Brain histopathological assessments were also done.

RESULTS:

Higher neurological deficits scores in Group 2 as compared to Group 3 rats were noticed. Serum MDA and NO levels at 12 h post-LCCAO in Group 2 rats showed significant elevation as compared to preocclusion levels. Group 3 rats did not show such elevations. On histopathology of left and right cerebral hemispheres of Group 1 (sham) did not show any specific changes. In Group 2 rats, the right cerebral hemisphere (nonoccluded) showed no areas of ischemia-induced brain changes, but in the left side (occlusive), there were features of ischemic brain damage including cerebral edema. In the case of Group 3 rats, there were less ischemic damages in the left occluded side as compared to the left side of the Group 2 rats.

CONCLUSION:

This study clearly demonstrates that subchronic hypoxia pretreatment can reduce ischemic brain injury by unilateral common carotid artery occlusion in rats.

Effect of Mucuna pruriens on brain NMDA receptor and tau protein gene expression in cerebral ischemic rats

Present study aimed to assess effect of pre-treatment with Mucuna pruriens seed extract and its bioactive molecule(s) on NMDAR and Tau protein gene expression in cerebral ischemic rodent model. Methanol extract of M. pruriens seeds was characterized by HPLC, and β-sitosterol was isolated by flash chromatography. In vivo studies to observe the effect of pre-treatment (28 days) with methanol extract of M. pruriens seed and β-sitosterol on the unilateral cerebral ischemic rat model. Cerebral ischemia induced by left common carotid artery occlusion (LCCAO) for 75 min (on day 29) followed by reperfusion for 12 h. Rats (n = 48) divided into four groups. GroupI (control,Untreated + LCCAO)-No pre-treatment + cerebral ischemia; GroupII(β-sitosterol + Sham)-pre-treatment with β-sitosterol, 10 mg/kg/day + sham-operated; GroupIII(β-sitosterol + LCCAO)-pre-treatment with β-sitosterol, 10 mg/kg/day + cerebral ischemia; GroupIV(methanol extract + LCCAO)-pre-treatment with methanol extract of M. pruriens seeds, 50 mg/kg/day + cerebral ischemia. Neurological deficit score was assessed just before sacrifice. Experimental animals were sacrificed after 12 h reperfusion. Brain histopathology was performed. Gene expression of NMDAR and Tau protein of left cerebral hemisphere (occluded side) was performed by RT-PCR. Results revealed that the neurological deficit score was lower in groups III and IV compared to group I. NMDAR and tau protein mRNA expression in left cerebral hemisphere were upregulated in Group I, downregulated in groups III and IV. Histopathology of left cerebral hemisphere (occluded side) in Group I showed features of ischemic brain damage. Groups III and IV, left cerebral hemisphere showed less ischemic damage compared GroupI. Right cerebral hemisphere showed no areas of ischemia-induced brain changes. Pre-treatment with β-sitosterol and methanol extract of M. pruriens seeds may reduce ischemic brain injury following unilateral common carotid artery occlusion in rats.