Hydroxy-indole-o-methyltransferase activity in human pineals: a comparison of controls and schizophrenics

The activity of hydroxy-indole-o-methyltransferase (HIOMT) has been assayed in pineal glands from fifteen controls and twenty-three schizophrenics. There was no significant difference between the two groups in HIOMT activity and no significant effect of age, sex or neuroleptic treatment on the activity of the enzyme. A diurnal rhythm was not discernible in HIOMT activity and it is suggested that this may be the result of terminal illness. It is concluded that HIOMT activity in pineals of schizophrenics is unlikely to differ from controls.