A novel method of detecting rCBF with laser-Doppler flowmetry without cranial window through the skull for a MCAO rat model

Abstract

Background and purpose: In a rat model of middle cerebral artery occlusion (MCAO) with intraluminal technique, lesion volume and its reproducibility vary among laboratories. Although laser-Doppler flowmetry (LDF) is useful to optimize the reliability, conventional methods require a craniotomy and special apparatus. The purpose of this study was to evaluate a novel approach for LDF monitoring of rCBF through lateral aspect of the skull without a craniotomy.

Methods: SD rats were subjected to 45 min of MCAO using an intraluminal thread. MCAO was achieved by an examiner who had been trained 4 weeks for making the model with no LDF monitoring (Group-1, n = 12), while in the other group, the same examiner induced MCAO using a novel approach of LDF monitoring (Group-2, n = 12). rCBF was detected through an LDF probe attached to the lateral aspect of the skull. The survival rate and the infarct volume were estimated for comparison between the two groups 2 days after MCAO.

Results: The mortality rate was 25% in Group-1 and 0% in Group-2. The lesion volume of the cortex in Group-2 was 167.21 +/− 48.54 mm³ (mean +/− SD), which was larger than that in Group-1 (112.77 +/− 36.03 mm³, P = 0.026). The coefficient variation of the lesion volume was smaller in Group-2 (29%) than in Group-1 (35%), indicating better reproducibility of the lesion volume in Group-2 than in Group-1.

Conclusions: The approach of LDF monitoring through the lateral aspect of skull was useful for making large consistent infarct with reducing intraanimal variability and unexpected animal death for rat MCAO model.