February 1988

The Diurnal Variation in Plasma Homovanillic Acid Level Persists but the Variation in 3-Methoxy-4-hydroxyphenylglycol Level Is Abolished Under Constant Conditions

Author Affiliations

From the Clinical Psychobiology Branch, National Institute of Mental Health (Drs Sack, James, and Wehr), the National Institute of Drug Abuse (Dr Sherer), and the Laboratory of Clinical Studies, Division of Intramural and Biological Research, National Institute on Alcohol Abuse and Alcoholism (Dr Linnoila), National Institutes of Health, Washington, DC; and University of California, Davis (Dr Doran). Dr Sack is now with Los Altos Hospital, Los Altos, Calif.

Arch Gen Psychiatry. 1988;45(2):162-166. doi:10.1001/archpsyc.1988.01800260076010

• Plasma concentrations of homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) were determined every two hours for two consecutive days in seven depressed patients and seven matched normal controls. On the first day subjects followed their regular ward routine. On the second day they were placed on a regimen in which activity, posture, diet, and wakefulness were held constant. There were significant diurnal variations in both MHPG and HVA concentrations on the baseline day, whereas on the constant routine, a diurnal variation was present only in HVA. We conclude that diurnal variations in plasma MHPG are evoked by changes in physical activity, posture, or other factors controlled on the constant routine, and that a major component of the diurnal variation in plasma HVA concentrations is regulated by a circadian oscillator that is independent of sleep or activity.