Summary: Male and female rodents show different behavioral and brain changes associated with both PTSD and alcohol use disorder. After trauma, males display increased GABA receptor function while females show elevated GABA release.
Source: Scripps Research Institute
Researchers at Scripps Research have conducted careful, sex-aware experiments that reveal specific brain changes that may drive alcohol misuse in people with post-traumatic stress disorder (PTSD).
Using a rodent model, the team demonstrated that males and females develop distinct symptoms and neural signatures when PTSD and alcohol use disorder (AUD) occur together. These sex-specific differences are rarely addressed in many laboratory studies but could be crucial for improving clinical treatments.
Published in Molecular Psychiatry, the work also introduces a translational model that helps identify biomarkers predicting which individuals with PTSD are at increased risk of developing alcohol use disorder.
“PTSD substantially raises the risk of alcohol use disorder because many people use alcohol to cope with intense stress and anxiety. Yet the biological mechanisms behind these comorbid conditions remain poorly understood,” says Dean Kirson, PhD, a postdoctoral fellow in neurophysiology in Marisa Roberto’s lab and a co-lead author alongside Michael Steinman, PhD. “By pinpointing sex-specific brain changes, we hope to guide the development of more targeted, effective treatments.”
PTSD affects roughly 7–8 percent of people at some point in their lives, according to estimates from public health agencies. Traumatic causes range from combat and physical abuse to serious accidents and other life-threatening events. Alcohol use disorder is also widespread, affecting millions of people, and individuals with PTSD often face greater risk of alcohol misuse, more severe withdrawal, and higher relapse rates.
“Most people will know someone affected by PTSD, AUD, or both. Despite the prevalence of these conditions, effective treatments remain limited,” Roberto says. “Our lab has long studied addiction and stress separately. By partnering with the Zorrilla lab, we applied a new, clinically relevant behavioral model to examine the biological changes that arise when these disorders co-occur.”
The collaborative study, led by Roberto and Eric Zorrilla, PhD, assessed behavior, sleep patterns, immune signaling, and levels of the inhibitory neurotransmitter GABA (gamma-aminobutyric acid), which is closely tied to anxiety regulation and alcohol dependence.
Across sexes, traumatic stress combined with alcohol exposure amplified core PTSD-like behaviors in rats, including social avoidance, exaggerated startle responses, and defensive actions. Animals identified as “drinking-vulnerable” prior to trauma showed particularly strong avoidance of locations associated with the traumatic event.
Crucially, the researchers observed sex-dependent differences in both behavior and GABAergic signaling. Males tended to show increased GABA receptor function in the central amygdala, whereas females displayed increased presynaptic GABA release. These divergent mechanisms point to different therapeutic targets in males and females.
“Recognizing that medications may act differently in male and female patients is growing in importance,” Steinman explains. “Understanding the biological basis for those differences should help improve treatment outcomes.”
The team also identified an immune-related biomarker profile in males: specific circulating cytokines—small signaling proteins released by immune cells—were associated with vulnerability to alcohol use disorder. This cytokine signature was not observed in females, indicating that different biomarkers may be needed for each sex.
“We found distinct cytokine patterns, many of which were not previously linked to stress-related behavior, that strongly correlated with poorer drinking outcomes in males,” Zorrilla says. “These markers could have clinical or mechanistic relevance, but because they were unique to males, further work is needed to discover comparable biomarkers in females.”
Going forward, the Roberto and Zorrilla laboratories will pursue additional research to clarify the mechanisms behind these sex-specific changes and to test which neural systems can be targeted to treat both PTSD and alcohol misuse. They will also continue investigating the immune system’s role in these comorbid conditions, with the goal of developing biomarker-driven, sex-specific interventions.
Funding: This research was supported by the National Institute on Alcohol Abuse and Alcoholism (grants AA027700, AA013498, P60 AA006420, AA017447, AA021491, AA015566, K99 AA026638, T32 AA007456), the National Institute on Drug Abuse (R21 DA046865), and the Pearson Center for Alcoholism and Addiction Research.
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Source: Scripps Research Institute
Contact: Press Office – Scripps Research Institute
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Original Research: Closed access. “Importance of sex and trauma context on circulating cytokines and amygdalar GABAergic signaling in a comorbid model of posttraumatic stress and alcohol use disorders” by Dean Kirson et al., published in Molecular Psychiatry.
Abstract
Importance of sex and trauma context on circulating cytokines and amygdalar GABAergic signaling in a comorbid model of posttraumatic stress and alcohol use disorders
Alcohol use disorder and anxiety disorders frequently co-occur and share neural mechanisms that could serve as therapeutic targets. To support mechanistic investigation, the authors adapted an inhibitory-avoidance “two-hit” rat model of PTSD-like stress and identified predictors and biomarkers of comorbid ethanol/PTSD-like outcomes. Stressed Wistar rats received two footshocks: the first when entering a dark chamber and the second 48 hours later in either a familiar or a novel context. Rats then had four weeks of two-bottle choice ethanol access. During abstinence, PTSD-like behaviors, GABAergic synaptic function in the central amygdala, and circulating cytokines were measured. Familiar and novel stress contexts differentially increased ethanol drinking in males and females, respectively. Stressed males—particularly drinking-vulnerable individuals—showed fear overgeneralization in novel settings, elevated central amygdala GABAergic transmission, and a cytokine profile (including G-CSF, GM-CSF, IL-13, IL-6, IL-17a, leptin, and IL-4) that distinguished stress context. Drinking-resilient males displayed the highest levels of some cytokines such as G-CSF, IL-13, and leptin. Stressed females exhibited increased acoustic startle, impaired sleep maintenance (signs of hyperarousal), and increased central amygdala GABAergic signaling in the novel context. This model reproduces key PTSD features—hyperarousal, fear generalization, avoidance, and sleep disturbance—alongside comorbid ethanol intake in a sex-specific manner that mirrors clinical patterns more closely than existing models, and it highlights distinct GABAergic and cytokine-related biomarkers that could inform targeted treatments.