Alterations in function of the brain dopamine (DA) system have been implicated in the pathophysiology of schizophrenia and in the therapeutic action of neuroleptic drugs. Detailed understanding of these changes in brain DA function has been limited by the absence of an accurate easily repeatable measure of brain DA activity in man. Plasma levels of the DA metabolite homovanillic acid (HVA) may be such a measure. In animals, plasma levels of HVA (pHVA) accurately reflect changes in the brain DA system. These results have been intially difficult to replicate in a clinical setting. In man, """"""""extraneous"""""""" variables such as diet and activity can substantially alter pHVA. Only by understanding and eliminating the effects of these variables is pHVA likely to be a useful clinical index of brain DA function. Therefore, the focus of this proposal is to develop techniques in man to maximize the degree to which pHVA reflects brain DA function. Three strategies will be utilized. First, """"""""extraneous"""""""" factors that can alter pHAV levels are systematically studied and techniques for controlling their effects are developed. These factors include diet, activity, cigarette smoking, and circadian rhythm. Second, two pharmacologic agents are tested which can produce a direct inhibition of peripheral production of HVA, thereby increasing the degree to which pHVA reflects brain DA activity: debrisoquin and carbidopa. The third strategy is to examine the response of pHVA to pharmacologic """"""""probes"""""""" which produce major changes in brain DA function. Drugs examined are apomorphine, haloperidol, tyrosine and 1-dopa. The results of these studies will form the basis for the rational design and interpretation of studies utilizing pHVA as a measure of brain DA function in neuropsychiatric illness. The ability to repeatedly and accurately measure brain DA function may produce major new insights into the pathophysiology of schizophrenia and the mode of action of neuroleptic drugs.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
5R01MH037922-03
Application #
3376412
Study Section
(PCBB)
Project Start
1983-09-15
Project End
1986-08-31
Budget Start
1985-09-01
Budget End
1986-08-31
Support Year
3
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Mount Sinai School of Medicine
Department
Type
Schools of Medicine
DUNS #
City
New York
State
NY
Country
United States
Zip Code
10029
Stern, R G; Kahn, R S; Davidson, M et al. (1994) Early response to clozapine in schizophrenia. Am J Psychiatry 151:1817-8
Serper, M R; Davidson, M; Harvey, P D (1994) Attentional predictors of clinical change during neuroleptic treatment in schizophrenia. Schizophr Res 13:65-71
Davidson, M; Kahn, R S; Stern, R G et al. (1993) Treatment with clozapine and its effect on plasma homovanillic acid and norepinephrine concentrations in schizophrenia. Psychiatry Res 46:151-63
Stern, R G; Kahn, R S; Harvey, P D et al. (1993) Early response to haloperidol treatment in chronic schizophrenia. Schizophr Res 10:165-71
Kahn, R S; Davidson, M; Hirschowitz, J et al. (1992) Nocturnal growth hormone secretion in schizophrenic patients and healthy subjects. Psychiatry Res 41:155-61
Keefe, R S; Lobel, D S; Mohs, R C et al. (1991) Diagnostic issues in chronic schizophrenia: kraepelinian schizophrenia, undifferentiated schizophrenia, and state-independent negative symptoms. Schizophr Res 4:71-9
Harvey, P D; Davidson, M; Powchik, P et al. (1991) Time course and clinical predictors of treatment response in schizophrenia. Schizophr Res 5:161-6
Davis, K L; Kahn, R S; Ko, G et al. (1991) Dopamine in schizophrenia: a review and reconceptualization. Am J Psychiatry 148:1474-86
Davidson, M; Kahn, R S; Knott, P et al. (1991) Effects of neuroleptic treatment on symptoms of schizophrenia and plasma homovanillic acid concentrations. Arch Gen Psychiatry 48:910-3
Harvey, P D; Putnam, K M; Davidson, M et al. (1991) Brief neuroleptic discontinuation and clinical symptoms in Kraepelinian and non-Kraepelinian chronic schizophrenic patients. Psychiatry Res 38:285-92

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