Isoflurane anesthesia is a valuable alternative for α-chloralose anesthesia in the forepaw stimulation model in rats

Isoflurane (ISO) can be a valuable alternative for α‐chloralose (ACL) anesthesia in functional MRI (fMRI) studies. Therefore, we compared the efficacy of the blood oxygen level dependent (BOLD) effect in fMRI studies during ISO and ACL anesthesia sequentially in the same animals. After non‐invasive instrumentation for ventilation and monitoring, series of T2* weighted MR images were acquired during forepaw stimulation, first under ISO, then followed by ACL anesthesia. The results demonstrated that ISO and ACL were both suitable to perform this fMRI experiment. The center of activation was at the same stereotactic position for both anesthetics and matched the primary somatosensory cortex (S1). Under the applied conditions, the BOLD response during ISO anesthesia declined in magnitude during the first stimulation period, as compared to ACL. From this study, we conclude that since ISO has several positive properties in comparison to ACL, including fast pharmacokinetics and suitability for repeated measurements, it is a valuable alternative for anesthesia in fMRI studies of rats. Copyright © 2008 John Wiley & Sons, Ltd. In this study, we compared the efficacy of the blood oxygen level dependent (BOLD) effect in fMRI studies during isoflurane (ISO) and a‐chloralose (ACL) anesthesia sequentially. We found that isoflurane and a‐chloralose were both suitable to perform this fMRI experiment. However, the BOLD response after 3 Hz electrical stimulation during isoflurane anesthesia declined in magnitude during the first of two stimulation periods, as compared to a‐chloralose. We conclude that isoflurane is a valuable alternative for anesthesia in fMRI studies of rats.