Hypothalamic beta-endorphin concentrations are decreased in animals modelsof autoimmune disease

Complex interactions between the neuroendocrine and the immune systems are present in autoimmune diseases. The central opioid peptide beta-endorphin ( BE) has been shown to modulate peripheral immune responses in normal animal s. In the present study we analyze the hypothalamic concentrations of this peptide in two models of spontaneous autoimmune disease, the MLR lpr/lpr mo use, that develops a lupus-like autoimmune disease, and the obese strain (O S) chickens afflicted with spontaneous autoimmune thyroiditis. In both inst ances, hypothalamic concentrations of BE are significantly lower than norma l controls. In MLR lpr/lpr mice, BE is already lower at 1 month of age, whe n no clinical sign of the disease is yet present. Similarly, low levels of BE are observed in OS chickens before the onset of thyroiditis, i.e., alrea dy at the embryonic stage. Moreover, a further decrease of BE is observed i n OS chickens in correspondence with the first signs of thyroid mononuclear infiltration. Considering the immunosuppressive effects exerted by central BE, these results are suggestive of the fact that in autoimmune disease pr one animals the low hypothalamic concentrations may be one of several facto rs predisposing for the development of autoimmune disease. (C) 1999 Elsevie r Science B.V. All rights reserved.