**9. Photochemical stroke model**

This model is widely accepted as it helps understand the extent of damage to the brain region by measuring the size of infarcts, which could help estimate human stroke. In this model, rats weighing around 350 g will be selected and anaesthetized using 3% halothane and are maintained with 1.5–2% halothane, 70% nitrous oxide and oxygen. The scalp covering the left hemisphere will be exposed, and the focal infarct would be introduced in rats using the photochemical method. The photosensitizing dye rose bengal (1 mg in 0.133 ml of saline per 100 g body wt) will be injected intravenously, and the rat will be restrained using the stereotactic frame. Light emerging from xenon arc lamp at 560 nm will be focused on to the skull. The light would be focused for a period of 120 sec, and the intensity of light used will be 0.58 W/cm2 . Light penetrating the brain interacts with intravascular photosensitive dye, resulting in oxygen free radicals highly reactive within the blood vessels. These free radicals cause injury to the endothelial cells and initiate the process of platelet aggregation. Once the procedure is completed, animals would be placed back into cages. After 7 days, animals were sacrificed for histopathological evaluation and measuring infarct size. This model is mainly used to study regional cerebral blood flow and to measure infarct size [69].

Merits of focal thrombotic stroke model:


Demerits of focal thrombotic stroke:

