In Vivo Quantification of Ethanol Kinetics in Rat Brain

Abstract

Proton magnetic resonance spectroscopy was used at 3T to measure the uptake and clearance of brain ethanol in rats after bolus intraperitoneal (i.p.) or intragastric (i.g.) alcohol injection, and to estimate the effects of acute alcohol on brain metabolites. The observation duration was 1-1.5 h with temporal resolution of alcohol sampling ranging from 4 s-4 min. The observed time course of alcohol brain concentration followed a consistent pattern characterized by a rapid absorption, an intermediate distribution, and a slower clearance that approached a linear decay. In a sample of eight healthy Wistar rats, the intercept of the linear clearance term, extrapolated back to the time of injection, correlated well with the administered dose per unit of lean body mass. Alcohol concentration estimation based on spectroscopically measured clearance was compared with blood alcohol levels from blood samples at the end of observation, and were in good agreement with the administered dose. Serial proton spectroscopy measurements provide a valid in vivo method for quantifying brain alcohol uptake and elimination kinetics in real time.

Direct monitoring of ethanol in the brain

“…Even though ethanol equilibrates within brain tissue in minutes, unlike the other techniques, the 13 C-labelled ethanol, is commonly used to directly detect not only ethanol but also its metabolites in the brain, in particular 13 C-acetate, which is largely used to study cerebral metabolism, neurotransmission and neuronal-glial interactions in both humans and animals 36 .…”

“…The proton MR spectra show different peaks along the x-axis, labelled in parts per million (ppm), while the amplitude of the resonances is measured on the y-axis, generally using an arbitrary scale 29 . MRS has been largely used to measure brain alcohol levels in vivo [30][31][32] , and its added benefit is the ability to monitor alcohol-induced changes in the spectroscopically-visible brain metabolites 13 . Ethanol is detectable by MRS via the methyl protons and can be identified by a distinctive triplet at 1.3 ppm.…”

“…These methods use spectroscopic techniques, such as magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) 13,14 or positron emission tomography (PET), which are principally used to monitor ethanol metabolites 15 . The aim of this review is to show and critically discuss all the techniques used to monitor brain ethanol and highlight their strengths and weaknesses.…”

The Density Difference of Cupula and Endolymph Changes the Mechanics of Semicircular Canals

“…"The expected brain concentration of alcohol after i.p. injection is governed primarily by absorption in the first 5-10 min, followed by a combination of absorption, metabolism and elimination, and after 30 min, primarily elimination" (Adalsteinsson et al 2006).…”

Dépendance aux drogues : avancées de la neurobiologie et perspectives thérapeutiques

“…L'éthanol a des propriétés très particulières : en effet, il est soluble à la fois dans l'eau et les lipides, et se distribue très rapidement dans le cytoplasme et dans les lipides des membranes de l'ensemble des cellules de l'organisme, y compris les alvéoles pulmonaires. La résonance magnétique nucléaire a montré in vivo, chez l'animal et chez l'homme que l'alcool est présent dans le cerveau quelques minutes après sa consommation [30,31]. L'alcool en aigu s'intercale entre les phospholipides des membranes cellulaires et entraîne une augmentation de la fluidité membranaire, alors que la consommation chronique d'alcool modifie la composition lipidique des membranes et le fonctionnement des protéines qui y sont incorporées.…”