The effect of isoflurane on 18F-FDG uptake in the rat brain: a fully conscious dynamic PET study using motion compensation

Abstract

BackgroundIn preclinical positron emission tomography (PET) studies an anaesthetic is used to ensure that the animal does not move during the scan. However, anaesthesia may have confounding effects on the drug or tracer kinetics under study, and the nature of these effects is usually not known.MethodWe have implemented a protocol for tracking the rigid motion of the head of a fully conscious rat during a PET scan and performing a motion compensated list-mode reconstruction of the data. Using this technique we have conducted eight rat studies to investigate the effect of isoflurane on the uptake of 18F-FDG in the brain, by comparing conscious and unconscious scans.ResultsOur results indicate that isoflurane significantly decreases the whole brain uptake, as well as decreasing the relative regional FDG uptake in the cortex, diencephalon, and inferior colliculi, while increasing it in the vestibular nuclei. No statistically significant changes in FDG uptake were observed in the cerebellum and striata.ConclusionThe applied event-based motion compensation technique allowed for the investigation of the effect of isoflurane on FDG uptake in the rat brain using fully awake and unrestrained rats, scanned dynamically from the moment of injection. A significant effect of the anaesthesia was observed in various regions of the brain.

Optimizing clozapine for chemogenetic neuromodulation of somatosensory cortex

“…It is possible that we may have observed the increase in FDG uptake, as reported previously 32 and as we observed in electrophysiology experiments, if the animals had been anesthetized during FDG uptake. However, anesthesia is known to produce variability in glucose levels and tracer uptake, relative to the awake condition 39,40 . In particular, isoflurane anesthesia reduces glucose uptake in the cortex, thalamus, basal ganglia, etc., regions in which we wished to study off-target effects 41 .…”

Effects of isoflurane anesthesia and intravenous morphine self‐administration on regional glucose metabolism ([18F]FDG‐PET) of male Sprague‐Dawley rats

“…One emerging point of concern in preclinical [ 18 F]‐fluoro‐deoxy‐glucose (FDG)‐PET studies is the use of anesthesia during the PET scan. It has been reported that anesthesia can significantly affect the BGluM of rodents (Alkire et al ., ; Shimoji et al ., ; Mizuma et al ., ; Prieto et al ., ; Spangler‐Bickell et al ., ). These studies found that isoflurane anesthesia generally reduces BGluM in cortical regions, but its effect on sub‐cortical regions is unclear.…”

Effects of ketamine/xylazine and isoflurane on rat brain glucose metabolism measured by 18F‐fluorodeoxyglucose‐positron emission tomography

“…By comparison to the KX group, the I group showed a relative metabolic increase only in the medial vestibular nucleus. Other studies have also reported relative metabolic increases in the vestibular nucleus of animals anesthetized with isoflurane (Shimoji et al., ; Spangler‐Bickell, De Laat, Fulton, Bormans, & Nuyts, ).…”