The impact of sciatic nerve injury and social interactions testing on glucocorticoid receptor expression in catecholaminergic medullary cell populations.

Paradoxically, while acute pain leads to transiently elevated corticosterone, chronic pain does not result in persistently elevated corticosterone. In the sciatic nerve chronic constriction injury (CCI) model of chronic pain, we have shown that the same nerve injury produces a range of behavioural outcomes, each associated with distinctive adaptations to the HPA-axis to achieve stable plasma corticosterone levels. We also demonstrated that CRF and GR expression in the paraventricular hypothalamus (PVH) was increased in rats that showed persistent changes to their social behaviours during Resident-Intruder testing ('Persistent Effect' rats) when compared to rats that showed no behavioural changes ('No Effect' rats).