Elevated opioid activity in sera of chronic schizophrenics.

The effect of native serum samples from schizophrenic and control patients on the electrically induced contractions of the isolated mouse vas deferens (MVD) preparations was investigated. It was demonstrated that only the samples of schizophrenic origin elicited a naloxone dependent inhibition on the contractions of the MVD preparations, while sera from healthy individuals and those from non schizophrenic but mentally ill patients proved to be ineffective in this respect. By using ultrafiltration and gel chromatographic techniques, four fractions disclosing MVD related biological activity could be separated from schizophrenic samples. Chemical analysis revealed an elevated quantity of ninhydrin and Lowry positive materials as well as of unidentified carbohydrate components in the active fractions. Molecular mass of the serum ingredients carrying opioid activity was found to range between 0.5 and 5.0 KD. It is speculated that new appearance or the accumulation in the sera of several, and partly at least, unknown peptides and glycopeptides disclosing opioid activity might be characteristic of schizophrenia.