To measure opiate receptor sensitivity, the effects of naloxone on beta-endorphin and cortisol serum levels were determined before and after 3 weeks of clomipramine treatment (75 mg/day i.v.) in 12 patients with major depressive disorder. The opiate antagonist significantly increased both hormonal levels. The only significant endocrine differences between pre- and post-treatment were basal and maximal cortisol levels, which were elevated before antidepressant therapy. The rise in the cortisol or beta-endorphin serum level after naloxone injection was not affected by clomipramine treatment. There was no significant relationship between depression score and basal or stimulated endocrine variables. These data do not indicate a distinct effect of antidepressants on opiate receptor sensitivity.
