Plasma endogenous opioids and dexamethasone suppression test in depression.

Plasma levels of beta-endorphin plus beta-lipotropin were determined in 35 hospital patients with depression and in 23 controls before and after administration of 1 mg of dexamethasone (dxm). Dxm suppressed opioid secretion in both groups. The opioid levels of the patients were significantly higher than those of the controls both before and after dxm. All the controls were cortisol suppressors. Among the patients the post-dxm opioid levels of cortisol nonsuppressors (n = 14) were higher than those of cortisol suppressors (n = 21). A significant correlation between the opioid and cortisol levels was found in the patients. There was a significant association between the use of neuroleptics and high opioid levels, but the difference between the patients and the controls was not explained by the effect of any single class of drugs. The results support the concept of hypersecretion of corticotropin-releasing factor in depression.