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Diurnal variation in plasma homovanillic acid: Not a renal phenomenon
Diurnal Variation in Plasma Homovanillic Acid: Not a Renal Phenomenon Adriana E. Stroe, Farooq Amin, Aqeel Hashmi, Dianna Densmore, Thomas Kahn, and Peter J. Knott Key Words: Dopamine, homovanillic acid, 5-hydroxyindoleacetic acid, brain, diurnal, renal, plasma BIOL PSYCHIATRY 1997;41:621--623
Introduction Plasma concentrations of homovanillic acid (HVA), a dopamine (DA) metabolite, are frequently used to assess brain DA metabolism and hence DA activity in clinical research (Amin et al 1992). An intriguing pattern of diurnal variation in plasma concentrations of HVA has been well documented with a peak during early morning and a trough during early afternoon (Sack et al 1988; Riddle et al 1987; Doran et al 1985, 1990). Although generally believed to be due to changes in brain DA activity, this diurnal variation has alternatively been hypothesized to be due to variation in the renal excretion of HVA (Potter et al 1989). Since cardiac output and renal plasma flow presumably decrease at night, and since renal plasma flow may be a determinant of the renal excretion of organic anions such as HVA, it is plausible that the nocturnal increase in plasma HVA concentrations could be caused by a possible decrease in organic anion excretion during nighttime. Renal organic anion excretion mechanism is nonspecific and is shared by many organic anions, as reviewed elsewhere (Amin et al 1992). Recently it was demonstrated that plasma concentrations of serotonin metabolite 5-hydroxyindoleacetic acid (5HIAA), another organic anion, and HVA were similarly affected by manipulations of the renal organic anion excretion, suggesting
From the Houston VA Medical Center and Baylor College of Medicine, Houston, Texas USA (AES, FA, All, DD); and Bronx VA Medical Center and Mount Sinai School of Medicine, New York, New York USA (TK, PJK). Address reprint requests to Farooq Amin, MD, Psychiatry Service (116A), Houston VA Medical Center, 2002 Holcornbe, Houston, TX 77030. Received September 24, 1996; accepted November 20, 1996.
© 1997 Society of Biological Psychiatry
that under suitable conditions plasma 5-HIAA concentrations could be used as an indicator of renal organic anion excretion (Amin et al 1995). If the diurnal variation of plasma HVA is due to changes in renal organic anion excretion, a similar diurnal variation would also be observed with plasma 5-HIAA. To investigate this we examined in two studies simultaneously measured plasma HVA and 5-HIAA concentrations during morning hours when decreasing plasma HVA concentrations are observed.
Methods
Study 1 Eight male normal volunteers participated in this study. All subjects were physically healthy as determined by medical history, physical examination, and routine laboratory tests. DSMIII-R Axis I disorders were ruled out using a structured interview. Urine toxicology screens were used on the study mornings to exclude the possibility of recent recreational drug use. Subjects observed a low monoamine diet for 72 hours prior to the study, started overnight fasting as of 6:00 PM on the evening before the study, avoided smoking and strenuous activity on study mornings, and arrived at the medical center by 8:00 AM. Blood samples were collected at 9:00 AM, 11:00 AM, 12:30 PM, and 2:00 PM through an intravenous line. During this time approximately 500 mL of 5% dextrose solution was infused while subjects remained fasting and in bed. Blood samples were collected in heparinized vacutainers, and the plasma was separated by cen0006-3223/97/$17.00 PII S0006-3223(96)00526-4
622
BIOLPSYCHIATRY
Brief Reports
1997 ;00:621 - 623
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Figure 1• Study 1: Mean plasma HVA (squares) and 5-HIAA (circles) concentrations between 9:00 AM and 2:00 PM (error bars reflect standard errors of mean). Plasma HVA significantly declined over time (repeated measures ANOVA: F = 14.52, df = 3,21, p < .0005), whereas 5-HIAA concentrations did not (F = 0.66, df = 3,21, p = ns).
Figure 2. Study 2: Mean plasma HVA (squares) and 5-HIAA (circles) concentrations at 9:30, 10:00, and 10:30 AM (error bars reflect standard errors of mean). Plasma HVA significantly declined over time (repeated measures ANOVA: F = 18.31, df = 2,34, p < .0005), whereas 5-HIAA concentrations did not (F = 1.36, df = 2,34, p = ns). A log transformation of plasma 5-HIAA was used to normalize data in this study.
trifuging at 2000 g for 15 min at 10°C and stored immediately at -80°C until assayed. Plasma HVA was assayed using highperformance liquid chromatography (HPLC) with coulometric detection (Knott et al 1990) with intra- and interassay coefficients of variation estimated at 2.4 and 6.0%, respectively. Plasma 5-HIAA was assayed by HPLC with electrochemical detection (Tagari et al 1984) with intra- and interassay coefficients of variation estimated at 3.2 and 7.9%, respectively.
Study 2 Eighteen normal volunteers (7 female and 11 male) participated in this study. Subject preparation, blood sample collection, processing, storage, and assay procedures were identical to those of study 1, except that only three blood samples were collected at 9:00, 10:00, and 10:30 AM using the hep-lock procedure.
Results In study 1, a statistically significant decline in plasma HVA concentrations was observed over time [repeated measures analysis of variance (ANOVA): F = 14.52, df = 3,21, p < .0005], whereas plasma 5-HIAA concentrations did not change significantly over time (F = 0.66, df = 3,21, p = ns) (Figure 1). Similarly, in study 2, only plasma HVA concentrations declined significantly over time (repeated measures ANOVA: F = 18.31, df = 2,34, p < .0005), but not plasma 5-HIAA concentrations (F = 1.36, df = 2,34, p = ns) (Figure 2).
Discussion In each of the two studies presented here, only plasma HVA concentrations significantly declined over time during morning
hours, whereas no such change was observed for plasma 5-HIAA concentrations. These data support the view that the diurnal variation in plasma HVA is not largely due to changes in the excretion of HVA, but rather due to changes in its production. Under fasting conditions, plasma HVA is ultimately derived from two main sources: DA neurons and noradrenergic (NA) neurons (Amin et al 1992). Since plasma MHPG (3-methoxy-4hydroxy-phenylglycol) concentrations, an indicator of NA metabolism, do not show a diurnal pattern similar to that of plasma HVA under controlled conditions (Sack et al 1988; Amin et al unpublished data), it is unlikely that the diurnal variation of plasma HVA is due to its NA component. These data are consistent with the notion that the diurnal variation of plasma HVA is due to changes in brain DA activity• This view is also supported by the finding that the majority of neuroleptic-induced dystonic reactions (presumably reflecting DA blockade) occur in the afternoon and evening hours, and relatively few occur during morning hours (Mazurek and Rosebush 1996). Similarly, patients with Parkinson's disease frequently report less severe symptoms in the morning and worsening symptoms as the day progresses (Struck et al 1990). These lines of evidence are compatible with the view that the brain DA activity may have a diurnal variation. Renal plasma clearance (RPC) of HVA has been proposed as a useful measure (Potter et al 1989), and in one study diurnal changes in RPC of HVA were reported (Whelton et al 1993) and interpreted as evidence that diurnal changes in plasma HVA are due to renal mechanisms; however, RPC is calculated by dividing the amount of a substance excreted in urine by its plasma concentration. When plasma HVA concentrations rise due to increased production, RPC of HVA would correspondingly decrease despite unchanged renal excretion• Therefore, the use-
Brief Reports
fulness of RPC is limited when production rates are not constant, and the diurnal changes in RPC of HVA may be due to changes in plasma HVA concentrations per se and not necessarily reflect a renal mechanism.
BIOL PSYCHIATRY 1997;00:621-623
623
This work is based on support provided to Dr. Farooq Amin by Medical Research Service of Department of Veterans Affairs.
References Amin F, Davidson M, Davis KL (1992): Homovanillic acid measurement in clinical research: A review of methodology. Schizophr Bull 18:123-148. Amin F, Kahn T, Knott P, Davidson M (1995): Control of renal factors affecting plasma HVA measurement [abstract]. 34th
Annual Meeting of American College of Neuropsychopharmacology, p 175. Doran AR, Pickar D, Labarca R, et al (1985): Evidence for a daily rhythm of plasma HVA in normal controls but not in schizophrenic patients. Psychopharmacol Bull 21:694-697. Doran AR, Labarca R, Wolkowitz OM, Roy A, Douillet P, Pickar D (1990): Circadian variation of plasma homovanillic acid levels is attenuated by fluphenazine in patients with schizophrenia. Arch Gen Psychiatry 47:558-563. Knott PJ, Yang RK, Cbeng H, et al (1990): An improved, sensitive method for measurement of plasma homovanillic acid by HPLC with coulometric detection [abstract]. 14th
International Symposium on Column Liquid Chromatography. Mazurek MF, Rosebush PI (1996): Circadian pattern of acute, neuroleptic-induced dystonic reactions. Am J Psychiatry 153: 708-710.
Potter WZ, Hsiao JK, Goldman SM (1989): Effects of renal clearance on plasma concentrations of homovanillic acid. Methodologic cautions. Arch Gen Psychiatry 46:558-562. Riddle MA, Leckman JF, Anderson GM, et al (1987): Plasmafree homovanillic acid: Within- and across-day stability in children and adults with Tourette's syndrome. Life Sci 40: 2145-2151. Sack DA, James SP, Doran AR, Sherer MA, Linnoila M, Wehr TA (1988): The diurnal variation in plasma homovanillic acid level persists but the variation in 3-methoxy-4-hydroxyphenylglycol level is abolished under constant conditions. Arch Gen Psychiatry 45:162-166. Struck LK, Rodnitzky RL, Dobson JK (1990): Circadian fluctuations of contrast sensitivity in Parkinson's disease. Neurology 40:467-470. Tagari PC, Boullin DJ, Davies CL (1984): Simplified determination of serotonin in plasma by liquid chromatography with electrochemical detection. Clin Chem 30:131-135. Whelton CL, Gupta RN, Cleghorn JM, Ballagh SR (1993): Influence of renal clearance on peripheral homovanillic acid measurements in healthy subjects and schizophrenic patients. Schizophr Res 11:33-40.
Introduction Plasma concentrations of homovanillic acid (HVA), a dopamine (DA) metabolite, are frequently used to assess brain DA metabolism and hence DA activity in clinical research (Amin et al 1992). An intriguing pattern of diurnal variation in plasma concentrations of HVA has been well documented with a peak during early morning and a trough during early afternoon (Sack et al 1988; Riddle et al 1987; Doran et al 1985, 1990). Although generally believed to be due to changes in brain DA activity, this diurnal variation has alternatively been hypothesized to be due to variation in the renal excretion of HVA (Potter et al 1989). Since cardiac output and renal plasma flow presumably decrease at night, and since renal plasma flow may be a determinant of the renal excretion of organic anions such as HVA, it is plausible that the nocturnal increase in plasma HVA concentrations could be caused by a possible decrease in organic anion excretion during nighttime. Renal organic anion excretion mechanism is nonspecific and is shared by many organic anions, as reviewed elsewhere (Amin et al 1992). Recently it was demonstrated that plasma concentrations of serotonin metabolite 5-hydroxyindoleacetic acid (5HIAA), another organic anion, and HVA were similarly affected by manipulations of the renal organic anion excretion, suggesting
From the Houston VA Medical Center and Baylor College of Medicine, Houston, Texas USA (AES, FA, All, DD); and Bronx VA Medical Center and Mount Sinai School of Medicine, New York, New York USA (TK, PJK). Address reprint requests to Farooq Amin, MD, Psychiatry Service (116A), Houston VA Medical Center, 2002 Holcornbe, Houston, TX 77030. Received September 24, 1996; accepted November 20, 1996.
© 1997 Society of Biological Psychiatry
that under suitable conditions plasma 5-HIAA concentrations could be used as an indicator of renal organic anion excretion (Amin et al 1995). If the diurnal variation of plasma HVA is due to changes in renal organic anion excretion, a similar diurnal variation would also be observed with plasma 5-HIAA. To investigate this we examined in two studies simultaneously measured plasma HVA and 5-HIAA concentrations during morning hours when decreasing plasma HVA concentrations are observed.
Methods
Study 1 Eight male normal volunteers participated in this study. All subjects were physically healthy as determined by medical history, physical examination, and routine laboratory tests. DSMIII-R Axis I disorders were ruled out using a structured interview. Urine toxicology screens were used on the study mornings to exclude the possibility of recent recreational drug use. Subjects observed a low monoamine diet for 72 hours prior to the study, started overnight fasting as of 6:00 PM on the evening before the study, avoided smoking and strenuous activity on study mornings, and arrived at the medical center by 8:00 AM. Blood samples were collected at 9:00 AM, 11:00 AM, 12:30 PM, and 2:00 PM through an intravenous line. During this time approximately 500 mL of 5% dextrose solution was infused while subjects remained fasting and in bed. Blood samples were collected in heparinized vacutainers, and the plasma was separated by cen0006-3223/97/$17.00 PII S0006-3223(96)00526-4
622
BIOLPSYCHIATRY
Brief Reports
1997 ;00:621 - 623
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• 65
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Time of Day
Figure 1• Study 1: Mean plasma HVA (squares) and 5-HIAA (circles) concentrations between 9:00 AM and 2:00 PM (error bars reflect standard errors of mean). Plasma HVA significantly declined over time (repeated measures ANOVA: F = 14.52, df = 3,21, p < .0005), whereas 5-HIAA concentrations did not (F = 0.66, df = 3,21, p = ns).
Figure 2. Study 2: Mean plasma HVA (squares) and 5-HIAA (circles) concentrations at 9:30, 10:00, and 10:30 AM (error bars reflect standard errors of mean). Plasma HVA significantly declined over time (repeated measures ANOVA: F = 18.31, df = 2,34, p < .0005), whereas 5-HIAA concentrations did not (F = 1.36, df = 2,34, p = ns). A log transformation of plasma 5-HIAA was used to normalize data in this study.
trifuging at 2000 g for 15 min at 10°C and stored immediately at -80°C until assayed. Plasma HVA was assayed using highperformance liquid chromatography (HPLC) with coulometric detection (Knott et al 1990) with intra- and interassay coefficients of variation estimated at 2.4 and 6.0%, respectively. Plasma 5-HIAA was assayed by HPLC with electrochemical detection (Tagari et al 1984) with intra- and interassay coefficients of variation estimated at 3.2 and 7.9%, respectively.
Study 2 Eighteen normal volunteers (7 female and 11 male) participated in this study. Subject preparation, blood sample collection, processing, storage, and assay procedures were identical to those of study 1, except that only three blood samples were collected at 9:00, 10:00, and 10:30 AM using the hep-lock procedure.
Results In study 1, a statistically significant decline in plasma HVA concentrations was observed over time [repeated measures analysis of variance (ANOVA): F = 14.52, df = 3,21, p < .0005], whereas plasma 5-HIAA concentrations did not change significantly over time (F = 0.66, df = 3,21, p = ns) (Figure 1). Similarly, in study 2, only plasma HVA concentrations declined significantly over time (repeated measures ANOVA: F = 18.31, df = 2,34, p < .0005), but not plasma 5-HIAA concentrations (F = 1.36, df = 2,34, p = ns) (Figure 2).
Discussion In each of the two studies presented here, only plasma HVA concentrations significantly declined over time during morning
hours, whereas no such change was observed for plasma 5-HIAA concentrations. These data support the view that the diurnal variation in plasma HVA is not largely due to changes in the excretion of HVA, but rather due to changes in its production. Under fasting conditions, plasma HVA is ultimately derived from two main sources: DA neurons and noradrenergic (NA) neurons (Amin et al 1992). Since plasma MHPG (3-methoxy-4hydroxy-phenylglycol) concentrations, an indicator of NA metabolism, do not show a diurnal pattern similar to that of plasma HVA under controlled conditions (Sack et al 1988; Amin et al unpublished data), it is unlikely that the diurnal variation of plasma HVA is due to its NA component. These data are consistent with the notion that the diurnal variation of plasma HVA is due to changes in brain DA activity• This view is also supported by the finding that the majority of neuroleptic-induced dystonic reactions (presumably reflecting DA blockade) occur in the afternoon and evening hours, and relatively few occur during morning hours (Mazurek and Rosebush 1996). Similarly, patients with Parkinson's disease frequently report less severe symptoms in the morning and worsening symptoms as the day progresses (Struck et al 1990). These lines of evidence are compatible with the view that the brain DA activity may have a diurnal variation. Renal plasma clearance (RPC) of HVA has been proposed as a useful measure (Potter et al 1989), and in one study diurnal changes in RPC of HVA were reported (Whelton et al 1993) and interpreted as evidence that diurnal changes in plasma HVA are due to renal mechanisms; however, RPC is calculated by dividing the amount of a substance excreted in urine by its plasma concentration. When plasma HVA concentrations rise due to increased production, RPC of HVA would correspondingly decrease despite unchanged renal excretion• Therefore, the use-
Brief Reports
fulness of RPC is limited when production rates are not constant, and the diurnal changes in RPC of HVA may be due to changes in plasma HVA concentrations per se and not necessarily reflect a renal mechanism.
BIOL PSYCHIATRY 1997;00:621-623
623
This work is based on support provided to Dr. Farooq Amin by Medical Research Service of Department of Veterans Affairs.
References Amin F, Davidson M, Davis KL (1992): Homovanillic acid measurement in clinical research: A review of methodology. Schizophr Bull 18:123-148. Amin F, Kahn T, Knott P, Davidson M (1995): Control of renal factors affecting plasma HVA measurement [abstract]. 34th
Annual Meeting of American College of Neuropsychopharmacology, p 175. Doran AR, Pickar D, Labarca R, et al (1985): Evidence for a daily rhythm of plasma HVA in normal controls but not in schizophrenic patients. Psychopharmacol Bull 21:694-697. Doran AR, Labarca R, Wolkowitz OM, Roy A, Douillet P, Pickar D (1990): Circadian variation of plasma homovanillic acid levels is attenuated by fluphenazine in patients with schizophrenia. Arch Gen Psychiatry 47:558-563. Knott PJ, Yang RK, Cbeng H, et al (1990): An improved, sensitive method for measurement of plasma homovanillic acid by HPLC with coulometric detection [abstract]. 14th
International Symposium on Column Liquid Chromatography. Mazurek MF, Rosebush PI (1996): Circadian pattern of acute, neuroleptic-induced dystonic reactions. Am J Psychiatry 153: 708-710.
Potter WZ, Hsiao JK, Goldman SM (1989): Effects of renal clearance on plasma concentrations of homovanillic acid. Methodologic cautions. Arch Gen Psychiatry 46:558-562. Riddle MA, Leckman JF, Anderson GM, et al (1987): Plasmafree homovanillic acid: Within- and across-day stability in children and adults with Tourette's syndrome. Life Sci 40: 2145-2151. Sack DA, James SP, Doran AR, Sherer MA, Linnoila M, Wehr TA (1988): The diurnal variation in plasma homovanillic acid level persists but the variation in 3-methoxy-4-hydroxyphenylglycol level is abolished under constant conditions. Arch Gen Psychiatry 45:162-166. Struck LK, Rodnitzky RL, Dobson JK (1990): Circadian fluctuations of contrast sensitivity in Parkinson's disease. Neurology 40:467-470. Tagari PC, Boullin DJ, Davies CL (1984): Simplified determination of serotonin in plasma by liquid chromatography with electrochemical detection. Clin Chem 30:131-135. Whelton CL, Gupta RN, Cleghorn JM, Ballagh SR (1993): Influence of renal clearance on peripheral homovanillic acid measurements in healthy subjects and schizophrenic patients. Schizophr Res 11:33-40.