The effect of sevoflurane and isoflurane anesthesia on single unit and local field potentials

Abstract

Volatile general anesthetics are used commonly in adults and children, yet their mechanisms of action are complex and the changes in single unit firing and synaptic activity that underlie the broad decreases in neuronal activity induced by these drugs have not been well characterized. Capturing such changes throughout the anesthesia process is important for comparing the effects of different anesthetics and gaining a better understanding of their mechanisms of action and their impact on different brain regions. Using chronically implanted electrodes in the rabbit somatosensory cortex, we compared the effects of two common general anesthetics, isoflurane and sevoflurane, on cortical neurons. Single unit activity and local field potentials (LFP) were recorded continuously before and during anesthetic delivery at 1 MAC, as well as during recovery. Our findings show that, although isoflurane and sevoflurane belong to the same class of volatile general anesthetics, their effects upon cortical single units and LFP were quite different. Overall, the suppression of neuronal firing was greater and more uniform under sevoflurane. Moreover, the changes in LFP frequency bands suggest that effect of anesthesia upon beta oscillations does not necessarily depend on the level of single unit activity, but rather on the changes in GABA/ glutamate neurotransmission induced by each drug.

Dopamine neurons in the ventral periaqueductal gray modulate isoflurane anesthesia in rats

“…According to our previous works, the suppressing effect of propofol on vPAG-DA neurons promotes presynaptic GABA release and enhances postsynaptic GABA A receptor sensitivity. Similarly, the GABA A receptor also involved in the isoflurane-induced anesthesia 19 ; hence, we investigated the role of GABA A receptors in the vPAG to isoflurane anesthesia. Our study also found that intra-vPAG injection of gabazine delayed induction and accelerated arousal, suggesting the involvement of GABAergic projections in modulating vPAG-DA neurons.…”

Normal Development of Local Neurovascular Interactions and the Diagnostic Value of Resting State Functional MRI in Neurovascular Deficiency Based on the Example of Neonatal Anesthesia Exposure

“…A larger concentration of a general anesthetic can greatly decrease or even completely abolish BOLD fMRI signal ( 40 ). Moreover, it seems that this effect might depend on the type of general anesthetic because, for example, the level of suppression of neuronal activity is very different under 1 MAC of sevoflurane and 1 MAC of isoflurane ( 41 ). Typically, local resting state activity of a majority of neurons is not visibly synchronized in the awake state.…”

Early Development of the GABAergic System and the Associated Risks of Neonatal Anesthesia

“…In animals, localized laser Doppler techniques can assess relative changes in cerebral blood flow to help investigate neurovascular coupling in vivo [ 178 ], and two-photon microscopy can represent neuronal structure in three dimensions with concurrent recording of both vasomotion and neuronal activity [ 179 ]. Moreover, classical recording of single neurons in vivo with implanted electrodes can also provide information about activity of both inhibitory and excitatory cells [ 180 , 181 ], and direct, localized brain tissue oxygen recordings with microelectrodes [ 23 ] can have the added benefit of evaluating oxygen dynamics which depend on GABAergic involvement in neurovascular coupling.…”