Resting-state functional magnetic resonance imaging in the adolescent rats under the combination of isoflurane and dexmedetomidine.

BACKGROUND

Resting-state functional MRI (rs-fMRI), reflecting the functional connectivity in the brain, is a useful tool for investigating the functional alteration induced by neurological diseases. In animal studies, anesthesia is essential for the acquisition of rs-fMRI data to eliminate motion artifacts. However, the optimal anesthesia protocol for adolescent rats is rarely discussed. The aim of the current study is to propose a feasible anesthesia protocol combining isoflurane and dexmedetomidine for use in adolescent rats.

MATERIAL AND

METHODS

The rs-fMRI data were acquired in ten adolescent rats (postnatal day 40) at 60 and 90 min after the bolus injection of the dexmedetomidine, respectively, to assess the different patterns of the resting-state networks. The subject-level independent component analysis (sICA) was performed to demonstrate the resting-state networks in the adolescent rats. The Z-scores, transformed from Pearson's correlation coefficients, were calculated to compare the difference of within-region functional connectivity between two time points. The functional connectivity matrix was demonstrated to show the interregional functional connectivity over the anesthesia protocol.

RESULTS

The respiratory rate of the adolescent rats returned to the baseline at around 35 min after the bolus injection, becoming stable at around 60 min. In the adolescent rats, the typical resting-state networks including the default mode network (DMN), sensory, and motor networks were observed, similar to that in adult ones under the same anesthesia protocol. The within-region functional connectivity was lower at 60 min compared to that at 90 min. The interregional functional connectivity showed the more specific network pattern at 90 min.

CONCLUSIONS

Our results demonstrated the feasibility of the anesthesia protocol with the combination of isoflurane and dexmedetomidine and highlighted its time-dependent and dosage effect in the adolescent rats.