Work

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

Year: 2025

Type: article

Abstract: 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. The rs-fMRI data were acquired in ten adolescent rats (postnatal day 40) at 60 and 90 minutes 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. The respiratory rate of the adolescent rats returned to the baseline at around 35 minutes after the bolus injection, becoming stable at around 60 minutes. 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 minutes compared to that at 90 minutes. The interregional functional connectivity showed the more specific network pattern at 90 minutes. 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. ● The well-established anesthesia protocol with the combination of isoflurane and dexmedetomidine, used in adult rats, is feasible for adolescent rats. ● While functional connectivity in the adolescent brain is observed at 60 minutes, the within-region connectivity is stronger at 90 minutes in the anesthesia protocol. ● Functional connectivity within the destined resting-state network becomes more specific over the course of the anesthesia protocol.

Source: Brain Research Bulletin

DOI: 10.1016/j.brainresbull.2025.111600

Authors: Ying-Wei Sung, Chia-Feng Lu, Bao-Yu Hsieh, Chao-Ching Huang, Yu-Chieh Jill Kao