A self-limiting orexin–habenula circuit for stress resilience

Abstract Resilience requires neural systems that mobilise active coping during stress while limiting its persistence to preserve homeostasis under sustained challenge1–4. Here we identify a self-limiting orexin–habenula circuit in which lateral hypothalamic orexin neurons engage aromatic L-amino acid decarboxylase-expressing D-neurons (encoded by Ddc) in the lateral habenula via orexin receptor type 2 (OX2R)5–7. Activation of this pathway increased nucleus accumbens dopamine and promoted active coping and positive valence. Optotagging revealed rapid stress-evoked recruitment followed by post-stress suppression. In lateral habenula neurons, orexin peptides exerted dissociable effects: orexin-A engaged an OX2R-dependent inhibitory programme superimposed on a parallel inward current, whereas orexin-B did not reproduce this inhibitory profile and instead exerted a distinct membrane effect. Chronic stress disrupted this buffering system through coordinated inflammatory activation, promoter methylation and erosion of D-neuron identity and orexin responsiveness. Restoring orexin-A reversed behavioural and molecular deficits through OX2R-dependent suppression of nuclear factor kappa B signalling, preservation of Tet2 expression, and demethylation-linked maintenance of the Ddc programme. Together, these findings define a self-limiting orexin–habenula resilience circuit that enables adaptive coping while constraining stress-induced vulnerability. Competing Interest Statement The authors have declared no competing interest.