Summary: Ever wondered why you rarely notice an itch during intense, high-pressure moments? Researchers have now mapped a brain circuit that explains this effect. Their work shows how a group of neurons in the lateral hypothalamus acts like a biological “mute button” for itch during acute stress, and how prolonged stress can reverse that protection and worsen chronic itch conditions.
The team behind this study identified a discrete population of stress-responsive neurons in the lateral hypothalamic area (LHA). These neurons suppress scratching behavior when activated by short-term stress. However, in models of chronic inflammation resembling psoriasis, the same neurons become hyperexcitable and lose their ability to suppress itch, suggesting a mechanism for why long-term stress aggravates chronic pruritus.
Key Facts
- Stress-triggered suppression: Acute stress engages LHA neurons that reduce the urge to scratch, effectively lowering itch perception in the moment.
- Necessary and sufficient circuit: Artificial activation of these neurons blocks itching even without stress, while inhibiting them prevents stress from alleviating itch—showing they are both necessary and sufficient for this effect.
- Chronic stress changes the circuit: In psoriasis-like chronic inflammation, the stress-sensitive neurons become more excitable and fail to suppress scratching, which helps explain how persistent stress can make chronic itch worse.
- Central target for therapy: Current itch treatments largely focus on the skin and immune system; this research highlights the brain—especially emotional and stress-regulating centers—as a promising target for managing chronic itch.
- Sensory prioritization: The study clarifies how the brain prioritizes different sensations—pain triggers withdrawal while itch triggers scratching—and how stress selectively dampens itch-related signals.
Source: IISC
Researchers at the Indian Institute of Science (IISc) have mapped a neural circuit that links stress and itch in the brain. Their findings, published in Cell Reports, show how specific stress-responsive neurons in the lateral hypothalamic area regulate itch behavior.
Itch and pain are distinct but related sensations: both signal irritation or harm, yet they drive different responses—pain typically causes withdrawal, while itch motivates scratching. Emotional states such as stress and anxiety are known to influence these sensations. While the neural basis of stress and pain has been extensively studied, how stress affects itch has remained less clear until now.
Focusing on the lateral hypothalamic area (LHA)—a brain region involved in stress, motivation, and emotion—the IISc team used genetically engineered mouse models to identify LHA neurons that activate during acute stress. They then tested whether these stress-activated neurons directly affect itch.
“In pilot experiments, we observed that acute stress could unexpectedly suppress acute itch,” says Jagat Narayan Prajapati, a PhD student at the Centre for Neuroscience (CNS), IISc, and first author of the study. When the researchers artificially activated these neurons, scratching behavior decreased in both short-term chemically induced itch and in a psoriasis-like chronic itch model. Conversely, silencing the neurons blocked the itch-suppressing effects of stress. These results demonstrate that this neuronal population is both necessary and sufficient for the suppression of itch during acute stress.
“We show that a specific circuit in the lateral hypothalamus can suppress itch during acute stress, revealing a direct link between emotional state and sensory perception,” explains Arnab Barik, Assistant Professor at CNS and corresponding author. “By pinpointing this circuit, we open the possibility of targeting brain mechanisms to better manage chronic itch that worsens with stress.”
The study, conducted in collaboration with PhD student Aynal Haque and Giriraj Sahu from the Molecular Biophysics Unit, also examined differences between acute and chronic itch. In mice with psoriasis-like chronic inflammation, these stress-sensitive LHA neurons displayed increased activity and became more responsive during scratching. This altered excitability suggests a mechanism by which chronic stress disrupts the normal itch-suppressing function of the circuit.
Chronic itch affects millions worldwide and is a major cause of discomfort and reduced quality of life. Most current therapies focus on peripheral targets—the skin and immune system—but these results emphasize the central nervous system’s role in shaping itch. Understanding the brain circuits that mediate stress-related changes in itch could enable the development of treatments that address central causes rather than just peripheral symptoms.
The researchers note that their experiments examined a specific type of acute stress and that additional circuits likely contribute to how different stressors affect itch. Future work will aim to characterize the molecular identity of the involved neurons and to map how these circuits evolve over extended periods, particularly in chronic disease states.
Key Questions Answered:
A: This likely reflects an evolutionary survival strategy. During urgent “fight or flight” situations, the brain prioritizes immediate survival over minor irritations, temporarily muting itch signals so attention and action can focus on the threat.
A: Acute and chronic stress have opposite effects. Short-term stress suppresses itch, while long-term, chronic stress makes the same neurons hyperexcitable and can amplify itch over time, which helps explain increased itching during prolonged worry.
A: That is the goal. By identifying a specific hypothalamic “switch” that links stress to itch, researchers hope to develop therapies that target these central circuits to relieve chronic itch without widespread systemic effects.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was provided by editorial staff.
About this itching and stress research news
Author: Office of Communications
Source: IISC
Contact: Office of Communications – IISC
Image: The image is credited to Neuroscience News
Original Research: Open access. “Lateral hypothalamus directs stress-induced modulation of acute and psoriatic itch” by Jagat Narayan Prajapati, Aynal Hoque, Manojeet Pattanayak, Giriraj Sahu, and Arnab Barik. Cell Reports
DOI: 10.1016/j.celrep.2026.117025
Abstract
Stress influences itch in opposing ways: acute stress suppresses pruritus while chronic stress can worsen it. The neural basis for this modulation was previously unclear. Using activity-dependent genetic labeling and chemogenetic manipulation, this study targeted a stress-responsive population of LHA neurons (LHAstress-TRAP neurons). Transient activation of these cells produced anxiety-like behavior and place aversion while suppressing both acute (chloroquine-induced) and chronic (psoriatic) itch; inhibition of these neurons enhanced itch responses. Although these neurons were not activated by acute itch alone, they correlated with scratching behavior in psoriatic mice and showed increased intrinsic excitability ex vivo. Tracing studies revealed projections from these LHA neurons to brainstem regions involved in itch modulation—such as the periaqueductal gray (PAG), rostral ventromedial medulla (RVM), and lateral parabrachial nucleus (LPBN)—with projection-specific manipulations indicating a predominant role for the PAG in itch suppression. Together, these results define a central stress-itch circuit centered on LHA neurons and their brainstem targets.