CHRONIC VARIED STRESS MODULATES EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS IN WISTAR RATS

Stress disturbs homeostasis by altering the equilibrium of various hor mones which have a significant impact on immune responses. Few studies have examined the influence of stressors on autoimmune disease in ani mal models. In our work, we studied the effects of long-term exposure (14 days) to chronic varied stress (CVS) in a model of experimental au toimmune encephalomyelitis (EAE) in Wister rats. We studied whether th e exposure to CVS before or after the immune challenge would correlate with differences in the clinical course of the disease. We also exami ned whether the CVS would modulate the magnitude of the cellular or th e humoral immune response. We observed opposite effects on the clinica l signs in animals stressed before or after the immune challenge. The clinical signs of the disease were attenuated in animals stressed befo re but not after the immune challenge. Relationships were found in the modulation of the clinical severity related to the time of exposure t o the CVS, the histological alterations and the proliferative results. Stressed animals with milder clinical signs presented an exacerbated humoral response against myelin antigens while stressed animals with m ore severe clinical symptoms exhibited a significantly diminished one. Besides, we detected thr presence of specific IgG1 associated with th e exposure to CVS before the induction of EAE. Our results show that, depending on the timing of the exposure of Wistar rats to the CVS, the neuroendocrine disbalance favors a more pronounced humoral or cellula r profile of the response. (C) 1998 Academic Press.