Plasticity of intrinsic excitability across the estrous cycle in hypothalamic CRH neurons

Stress responses are highly plastic and vary across physiological states. The female estrous cycle is associated with a number of physiological changes including changes in stress responses, however, the mechanisms driving these changes are poorly understood. Corticotropin-releasing hormone (CRH) neurons are the primary neural population controlling the hypothalamic-pituitary-adrenal (HPA) axis and stress-evoked corticosterone secretion. Here we show that CRH neuron intrinsic excitability is regulated over the estrous cycle with a peak in proestrus and a nadir in estrus. Fast inactivating voltage-gated potassium channel (I-A) currents showed the opposite relationship, with current density being lowest in proestrus compared to other cycle stages. Blocking I-A currents equalized excitability across cycle stages revealing a role for I-A in mediating plasticity in stress circuit function over the female estrous cycle.

Automated summary

Research shows that the excitability of CRH neurons is regulated over the estrous cycle, with peak excitability in proestrus and lowest in estrus. Additionally, the relationship between I-A currents and excitability is opposite, and blocking I-A currents can equalize excitability across cycle stages, indicating a role for I-A in mediating plasticity in stress circuit function over the female estrous cycle.