β-endorphin and β-lipotropin plasma levels in chronic schizophrenia, primary affective disorders and secondary affective disorders

Plasma levels of β-endorphin (β-EP), β-lipotropin (β-LPH) and ACTH were assayed in 15 chronic schizophrenics, nine patients with primary affective disorders (PAD) and seven patients with secondary affective disorders (SAD). Patients received no therapy for 10 days prior to study. All subjects were studied once; eight schizophrenics were studied again after 10 days of Haloperidol therapy, at a dose of 0.1 mg/kg body weight. β-LPH levels were significantly higher in the schizophrenics without hallucinations and in the PAD and SAD patients in comparison to the controls; β-EP levels were higher in the schizophrenics and SAD patients compared to the controls; and ACTH concentrations were significantly lower in the SAD than in the PAD patients. Haloperidol therapy failed to induce significant changes in β-LPH, β-EP or ACTH plasma levels.

Statistical evaluation by multiple linear regression confirmed the significant positive correlations among β-LPH, β-EP and ACTH in the controls, schizophrenics with hallucinations, and PAD and SAD patients, while inverse correlations between β-LPH and the other two peptides were found in the schizophrenics without hallucinations. The same analysis revealed that, while in the PAD patients equimolar amounts of the three peptides occurred, the SAD patients were characterized by ACTH/β-LPH and ACTH/β-EP molar ratios of 0.5.

Although these results are preliminary, they seem to indicate that β-LPH, β-EP and ACTH secretion patterns in chronic schizophrenia, PAD and SAD may help in revealing specific groups of patients with different biochemical substrates.