What does a stroke look like in a rat? - briefly
In experimental models, an ischemic event in a rat commonly causes unilateral motor impairment, including weakened forelimb grip, asymmetrical gait, and facial droop on the affected side. Imaging or histological analysis shows a focal cortical or subcortical infarct that correlates with these functional deficits.
What does a stroke look like in a rat? - in detail
In experimental rodents, a cerebral ischemic event produces a recognizable set of macroscopic, microscopic, and functional alterations. Immediately after occlusion of the middle cerebral artery, the affected hemisphere becomes paler than the contralateral side due to reduced perfusion; this pallor is evident during brain extraction and persists for several hours. Within 24 hours, the infarct core develops a yellow‑white discoloration, while the surrounding penumbra retains a slightly pink hue, reflecting partial blood flow.
Neurological assessment reveals a stereotyped pattern of deficits. Rats typically display:
- Asymmetrical forelimb use, favoring the non‑affected side during spontaneous exploration.
- Decreased grip strength on the contralateral paw, measurable with a calibrated force gauge.
- Impaired balance and coordination, evident in reduced performance on a rotating rod or beam‑walking test.
- Limited spontaneous locomotion, quantified by reduced distance traveled in an open‑field arena.
Histologically, the infarct region shows:
- Early neuronal eosinophilia and loss of Nissl substance (≈6–12 h post‑injury).
- Cytoplasmic vacuolization and nuclear pyknosis progressing to coagulative necrosis (≈24–72 h).
- Infiltration of activated microglia and macrophages, identifiable by Iba1 or CD68 immunostaining.
- Reactive gliosis, marked by up‑regulation of GFAP in astrocytes surrounding the lesion.
Magnetic resonance imaging, when employed, confirms the macroscopic findings: diffusion‑weighted sequences display hyperintense signals in the ischemic zone, while T2‑weighted images reveal edema and later cavitation as the lesion matures.
Collectively, these visual, behavioral, and cellular markers constitute the detailed phenotype of an experimental stroke in a rat model.