HUMAN POST‐MORTEM PINEAL ENZYME ACTIVITY

Abstract

The synthetic enzymes for melatonin production, serotonin-N-acetyltransferase (SNAT) and hydroxy-indole-O-methyltransferase (HIOMT), were measured in postmortem pineal organs from 88 men and women. The activity of each enzyme was correlated with age and sex. No difference was seen in either parameter when the maximum or minimum activities were measured in the death time periods of the diurnal rhythm established earlier. However, an annual bimodal rhythm was seen in HIOMT activity with maximal values occurring in Jan. and July, and minimum activities in March and Oct. The SNAT and HIOMT enzymes have previously been shown to be stable, when measured in pineal organs held under the usual postmortem conditions. Pineal HIOMT has also been measured in 21 psychotic individuals. While the schizophrenic group showed significantly increased values, the schizophrenic-like group had normal values. The results were not affected by antemortem or postmortem states, or by drug treatment. Any clinical interpretation of pineal dysfunction in disease states need not, therefore, take into consideration age, or possibly sex; however, awareness of the normal diurnal rhythm and the bimodal annual rhythm should be considered.