Summary: The NPAS4 gene appears to be a key factor linking prolonged stress to a specific depressive behavior—loss of interest in normally rewarding activities (anhedonia). These results may guide the development of targeted therapies for stress-related depression.
Source: Medical University of South Carolina
Researchers at the Medical University of South Carolina (MUSC) have identified a stress-responsive gene that connects long-term stress with a particular depressive-like behavior in mice.
The team discovered that the NPAS4 gene is required for prolonged stress to cause a loss of interest in activities that were previously rewarding—an effect commonly described as anhedonia. Importantly, NPAS4 did not influence other depressive-like behaviors, such as social withdrawal or increased anxiety, indicating a selective role in this symptom.
These findings were published recently in eLife after experiments led by neuroscientists Makoto Taniguchi, Ph.D., Christopher Cowan, Ph.D., and Brandon Hughes, Ph.D. (formerly a graduate student at MUSC and now a postdoctoral fellow at the Icahn School of Medicine at Mount Sinai).
Taniguchi emphasized the therapeutic implications: identifying distinct mechanisms that underlie individual symptoms could allow treatments to target those symptoms more precisely rather than applying one-size-fits-all approaches.
Cowan, chair of the MUSC Department of Neuroscience, noted that not everyone exposed to chronic stress develops depression. “Many people recover after repeated stress,” he said, “but some go on to show persistent depressive symptoms. Understanding the neural links between stress and depression can help us create better, more targeted treatments.”
How stress alters prefrontal cortex function
Taniguchi’s lab focuses on how chronic stress affects brain circuits that regulate mood and motivation. In mice, repeated stress reduces activity in the frontal regions of the brain, particularly the medial prefrontal cortex (mPFC). Reduced frontal activity is also commonly observed in people with major depressive disorder and is thought to contribute to symptoms such as diminished motivation and pleasure.
NPAS4 is an activity-dependent transcription factor known to regulate many downstream genes in response to neuronal activity. The researchers found that chronic social defeat stress activates NPAS4 in the mPFC. When NPAS4 is induced, it changes gene expression patterns and dampens activity in reward-related circuits of the prefrontal cortex—changes that mirror patterns seen in human brains affected by mood disorders.
The team therefore hypothesized that NPAS4 might serve as a molecular bridge between prolonged stress and the emergence of depressive-like behaviors. To test this, they manipulated NPAS4 expression in the mPFC of stressed mice and monitored behavioral outcomes.
Surprisingly, manipulating NPAS4 altered anhedonia-related behaviors (such as reduced sucrose preference and lower motivation for natural rewards) but did not affect social avoidance or anxiety-like behaviors. This selective effect suggests that different depressive symptoms may arise from distinct molecular and circuit-level mechanisms.
Depression is not one-size-fits-all
The findings support the view that depression is a heterogeneous condition with multiple underlying pathways. Clinical diagnostic guides list a range of symptoms—sleep problems, low energy, difficulty concentrating, social withdrawal, and loss of pleasure—but individuals typically experience only a subset of these symptoms. The MUSC study shows that one gene, NPAS4, specifically influences the neural and behavioral changes associated with anhedonia.
This symptom-focused perspective has practical implications for treatment. If individual symptoms are driven by distinct brain mechanisms, therapies could be tailored to target the circuits relevant to a person’s particular symptom profile. For example, transcranial magnetic stimulation (TMS) is a noninvasive therapy that stimulates frontal brain regions and is used when conventional treatments fail. Insights about NPAS4 and the mPFC could help refine how TMS or other interventions are targeted to relieve specific symptoms like anhedonia.
Cowan observed that many depressive symptoms overlap with other psychiatric disorders—anxiety disorders, substance use disorders, and schizophrenia can all include features such as reduced motivation. Tailoring treatments to the specific neural causes of each symptom may improve outcomes and support more personalized mental health care.
“Depression is a mixed condition with different symptoms emerging across individuals,” Cowan said. “Clarifying the brain mechanisms tied to each symptom is a promising route toward precision medicine for mental health.”
Funding: Early-stage work was supported by pilot funding from the South Carolina Clinical & Translational Research Institute and by a NARSAD Young Investigator Grant from the Brain & Behavior Research Foundation.
About this genetics and depression research news
Author: Kimberly McGhee
Source: Medical University of South Carolina
Contact: Kimberly McGhee – Medical University of South Carolina
Image: The image is in the public domain
Original Research: Open access. “NPAS4 in the medial prefrontal cortex mediates chronic social defeat stress-induced anhedonia-like behavior and reductions in excitatory synapses” by Makoto Taniguchi et al., published in eLife.
Abstract
NPAS4 in the medial prefrontal cortex mediates chronic social defeat stress-induced anhedonia-like behavior and reductions in excitatory synapses
Chronic stress can lead to deficits in the brain’s reward system—manifested as anhedonia—and can produce neural hypofunction in the medial prefrontal cortex (mPFC). The molecular mechanisms linking sustained stress to these depressive-like states are not fully understood. This study demonstrates that NPAS4, an activity-regulated neuronal transcription factor in the mPFC, is induced by chronic social defeat stress (CSDS) and is necessary for stress-induced reductions in sucrose preference and motivation for natural rewards in mice. Notably, NPAS4 was not required for other stress-induced behaviors such as social avoidance or anxiety-like responses.
The research shows that NPAS4 in the mPFC is essential for stress-related decreases in dendritic spine density on pyramidal neurons, reductions in excitatory synaptic transmission, and diminished presynaptic function. Molecular analyses revealed that NPAS4 controls expression of many genes associated with glutamatergic synapses and ribosomal function, overlaps with genes upregulated in stress-susceptible animals, and aligns with differentially expressed genes observed in postmortem human brains from patients with various neuropsychiatric conditions, including depression.
Together, these results position NPAS4 as a critical mediator of chronic stress–induced hypofrontal states and anhedonia-like behavior, highlighting a potential target for symptom-specific interventions in stress-related mood disorders.