Summary: Researchers report that a single dose of alcohol can cause lasting changes in synapse structure and mitochondrial behavior in neurons.
Source: University of Cologne
A collaborative research team from the University of Cologne, the University of Mannheim, and the University of Heidelberg has demonstrated that a single exposure to ethanol produces persistent alterations in neuronal morphology.
The study, led by Professor Dr. Henrike Scholz with contributions from Michèle Tegtmeier and Michael Berger, shows that even one episode of intoxication changes the physical structure of synapses and disrupts mitochondrial dynamics. Using the genetic model Drosophila melanogaster (fruit flies) alongside mouse experiments, the researchers linked these cellular changes to modified behavior, including an increased tendency for later alcohol consumption.
Although most alcohol research focuses on the effects of long-term drinking—especially on the hippocampus—this project set out to identify acute, ethanol-dependent molecular events that could underlie lasting cellular changes after a single intoxication, particularly when that first exposure occurs early in life.
“We looked for molecular alterations triggered by ethanol that could translate into stable cellular remodeling after a single acute intoxication,” explained Scholz. “We examined outcomes at the molecular, cellular, and behavioral levels to understand how a single drinking episode might create a lasting positive association with alcohol.”
Their cross-species approach revealed two main categories of ethanol-induced change: disrupted mitochondrial trafficking within axons and altered synaptic balance and morphology. Mitochondria are essential for neuronal energy supply and must move within axons to meet local energy demands. The researchers observed that ethanol impaired the normal movement of mitochondria in treated neurons. Additionally, they detected shifts in the balance and structure of synapses that persisted well beyond the acute exposure.
These cellular alterations were reflected in behavior. Both mice and fruit flies that experienced a single ethanol exposure later showed increased alcohol consumption and a higher likelihood of relapse-like behavior, suggesting that the cellular changes contribute to enduring ethanol-related reward learning.
Neuronal remodeling—changes in spine shape, synapse number, and axonal structure—is a well-established basis for learning and memory. The team proposes that some of the ethanol-dependent morphological changes they observed may facilitate the formation of associative memories tied to drug reward. Coupled with altered mitochondrial migration, which affects synaptic transmission and plasticity, these mechanisms likely contribute to the emergence of addictive behaviors after a single ethanol exposure.
“It is striking that cellular processes linked to complex reward behaviors are conserved across species, which suggests they may play a similar role in humans,” Scholz noted. She emphasized that identifying persistent ethanol-dependent cellular changes is a critical step toward understanding how an initial drinking episode can evolve into chronic alcohol misuse.
The findings also align with epidemiological observations that an early first intoxication is a major risk factor for later problematic alcohol use. By mapping molecular and cellular effects of a single ethanol dose, the study provides a mechanistic framework that helps explain why early exposures carry disproportionate risk.
About this neuroscience research news
Author: Press Office
Source: University of Cologne
Contact: Press Office – University of Cologne
Image: The image is in the public domain
Original Research: Closed access.
Title: “Single-dose ethanol intoxication causes acute and lasting neuronal changes in the brain” by Johannes Knabbe et al. PNAS
Abstract
Single-dose ethanol intoxication causes acute and lasting neuronal changes in the brain
Early-age alcohol intoxication increases the risk of developing addictive behaviors. To identify neuronal and molecular correlates of an acute ethanol event, the authors applied stable-isotope labeling in mice combined with quantitative mass spectrometry to analyze more than 2,000 hippocampal proteins. They found 72 proteins whose synaptic abundance changed by up to twofold after ethanol exposure, including mitochondrial proteins and proteins involved in neuronal morphology such as MAP6 and ankyrin-G.
Following these candidate proteins, the study uncovered acute and lasting molecular, cellular, and behavioral outcomes after a single intoxication in alcohol-naïve mice. Immunofluorescence revealed shortening of the axon initial segment, while longitudinal two-photon in vivo imaging documented increased synaptic dynamics and enhanced mitochondrial trafficking in axons. In Drosophila, knockdown of mitochondrial trafficking in dopaminergic neurons eliminated conditioned alcohol preference, implicating mitochondrial movement in reward learning.
This research highlights mitochondrial trafficking as a cellular process involved in reward-related learning and demonstrates how high-resolution proteomics can identify mechanisms relevant to addictive behavior.