**6.1 Two-vessel occlusion model of forebrain ischemia**

This model is accepted widely as it mainly focuses on the extent of damage after ischemic stroke and helps understand recovery duration in animals that mimics the common condition in humans. In this model, reversible forebrain ischemia will be produced by occluding the common carotid artery and inducing hypotension to decrease blood flow to the forebrain region. Blood pressure should be reduced to 50 mm Hg by using a specific device [50]. Treatment with phentolamine or trimethaphan can help produce hypotension [51]. Cerebral blood flow (CBF) measured after 15 min shows a reduced flow to the cerebral cortex region, caudoputamen, hippocampus, midbrain, thalamus, and globus pallidus. However, there are variable differences in the CBF in the ischemic region. The two-vessel occlusion model helps understand changes in the selective structures like pyramidal neurons of the hippocampus, neocortex and caudoputamen.

Histopathological reports from studies confirm that the two-vessel occlusion model is associated with neuronal injury to hippocampal pyramidal cells within 2 min. In contrast, injury to caudoputamen happens with 8 min of ischemia and injury to the neocortex takes place in 4 min of ischemia [52]. The two-vessel occlusion model helps study energy metabolism in ischemia, neurotransmitter metabolism, phospholipids, histopathology and effects of cerebral hypothermia [53]. This model will help achieve a good outcome when the blood pressure is regulated correctly at a level of 50 mm Hg without any fluctuations. The two-vessel model has many advantages like producing efficient forebrain ischemia, ease of cerebral recirculation, low experiment failure rate. The disadvantages of two-vessel occlusion are the use of anaesthesia and hypotension induction; these can affect the resulting outcome. In this model, behavioural changes cannot be assessed immediately after occlusion.

Merits of the two-vessel occlusion model


Demerits of the two-vessel occlusion model: [55].

