An Investigation of the Impacts of Three Anesthetic Regimes on Task-fMRI and Functional Connectivity Resting-State fMRI in Sprague Dawley and Wistar Rats.

Aim The aim of this study was to investigate basic task-fMRI or resting-state fMRI (rs-fMRI) results on Sprague Dawley (SD) rats and Wistar rats under three anesthetic regimes. Introduction SD rats and Wistar rats are the two most commonly used rat strains in medical research and neuroimaging studies. It still lacks a direct comparison of basic task-fMRI and rs-fMRI results between the Wistar rats and SD rats under different anesthetic regimes. Methods Two rat strains and different time points were adopted to investigate task-fMRI activation and rs-fMRI functional connectivity results under three kinds of anesthetic regimes (2~2.5% Isoflurane only, Dexmedetomidine bolus combined with a continuous infusion, and Dexmedetomidine bolus combined with 0.3%-0.5% isoflurane). The electrical forepaw stimulation method and seed-based functional connectivity results were used to compare the task-fMRI brain activation and rs-fMRI functional connectivity patterns between the two rat strains. Results The results showed that Wistar rats had more robust brain activation in task fMRI experiments while exhibiting a less specific inter-hemispheric functional connectivity than that of SD rats under the two dexmedetomidine anesthetic regimes. Moreover, even low-level isoflurane could significantly affect task-fMRI and rs-fMRI results in both rat strains. Conclusions SD and Wistar rats showed different brain activation and inter-hemispheric functional connectivity pattern under the two dexmedetomidine anesthetic regimes. These results may serve as reference information for small animal fMRI studies.