Proenkephalin neurons in the adBNST mitigate stress-induced anxiety and estrous cycle disruption in female mice

Chronic stress is a major risk factor for anxiety disorders and is often accompanied by disruptions in female reproductive cyclicity, but the stress-responsive neural populations that shape these comorbid behavioral and physiological outcomes remain poorly defined. The bed nucleus of the stria terminalis (BNST) is a major node for sustained anxiety and stress integration, yet the contribution of genetically defined BNST neurons to restraint stress is not fully resolved in females. Here, we identify proenkephalin-expressing neurons in the anterior dorsal BNST (adBNST^PENK) as a restraint-responsive population that constrains anxiety-like behaviors and modulates cytology-based estrous cycle organization. Acute chemogenetic inhibition of adBNST^PENK neurons produced anxiety-like behaviors in females, whereas activation attenuated acute restraint stress (ARS)-induced anxiety-like behaviors. Female mice subjected to chronic restraint stress (CRS) exhibited both anxiety-like avoidance and disrupted estrous-cycle organization, which can be mitigated by sustained activation of adBNST^PENK neurons. These findings suggest that adBNST^PENK neurons form a stress-recruited limbic circuit node that buffers stress-induced anxiety-like behaviors and is associated with improved vaginal cytology-based estrous-cycle organization under chronic stress.