Multiple sclerosis is associated with alterations in hypothalamic-pituitary-adrenal axis function

In the LEW/N rat model, a decreased hypothalamic-pituitary-adrenal (HPA) axis response to inflammatory and immune mediators confers susceptibility to the development of a variety of inflammatory and immune diseases, including experimental allergic encephalomyelitis. In humans with optic neuritis, early intervention with steroids is associated with a decrease in the number of patients who go on to develop multiple sclerosis (MS). The current study was designed to determine whether patients with MS show evidence of a hypoactive HPA axis. Thirteen patients with MS were studied at baseline and with provocative tests of HPA axis function [ovine CRH, arginine vasopressin (AVP), and ACTH stimulation]. Compared to matched controls, patients with MS had significantly higher plasma cortisol levels at baseline. Despite this hypercortisolism and in contrast to patients with depression who had similar elevations in plasma cortisol levels, patients with MS showed normal, rather than blunted, plasma ACTH responses to ovine CRH, suggesting that the pathophysiology of hypercortisolism in MS is different from that in depression. Patients with MS also showed blunted ACTH responses to AVP stimulation and normal cortisol responses to high and low dose ACTH stimulation. Taken together, these findings are compatible with data from studies of experimental animals exposed to chronic inflammatory stress, which showed mild increased activation of the HPA axis with increased relative activity of AVP in the regulation of the pituitary-adrenal axis. These data do not support a role for hypocortisolism in MS once the disease is established.