norepinephrine ratios in thalami of schizophrenic brains

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Elevated Dopamine/Norepinephrine Ratios in Thalami of Schizophrenic Brains A.F. Oke, R.N. Adams, B. Winblad, and L. von Knorring

Introduction Abnormalities in sensory processing long have been considered to be important features of schizophrenic behavior (Wynne et al. 1978; Spohn and Patterson 1979; Neuchterlein and Dawson 1984; Torrey 1985; Freedman et al. 1983; Schwartz et al. 1983; Siegel et al. 1984; Adler et al. 1985; Braff and Saccuzzo 1985). The neuroanatomical locus and mechanism of such disturbances are as yet unknown. The thalamus, with its major role in sensory integration, is a possible site where even minor abnormalities might produce widespread disturbances in the final expression of sensory functioning. In the schizophrenic literature, the thalamus rarely has been implicated as a potential source of such dysfunctions (Hassler 1982). As reported earlier, the human thalamus normally contains very little dopamine (DA), ordinarily less than 20% of the endogenous norepinephrine (NE) content (Oke et al. 1978). In this article, we replicate this finding and, in addition, report that thalami of brains from schizophrenic patients show a striking elevation in DA without any apparent changes in NE con-

From the Departments of Chemistry (A.F.O., R.N.A.) and Psychiatry (R.N.A.) and the Center for Bioanalytical Research, University of Kansas, Lawrence, KS, and the Departments of Geriatric Medicine and Pathology, (B.W.) and Psychiatry (L.v.K). University of Ume&, UmeP, Sweden. Suppotted in part by NIH NS08740, tbe Scottish Rite Schizophrenia Research Program, and funds from the Kansas Families for Mental Health. Address reprint requests to Dr. Ralph N. Adams, Department of Chemistry, University of Kansas. Lawrence, KS 66045. Received Febmary 28, 1987; revised August 5, 1987.

0 1988 Society of Biological

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tent. The results are given in terms of the percent ratio of endogenous amounts, i.e., (DA/ NE) x 100.

Methods Frozen whole brains were obtained from the brain bank, Department of Pathology, UmeP, Sweden, and from routine autopsies in the United States. The series included 14 control brains from subjects who never had been treated for a psychiatric disorder of a psychotic dimension, as well as 7 brains from patients who had been hospitalized under the diagnosis of schizophrenia according to the ICD criteria (WHO, 1965). All available records were reanalyzed for research diagnoses according to strict criteria. All but two subjects fulfilled the DSM-III criteria for schizophrenia. One had a major depressive episode at the onset of the disease. He was later hospitalized for 43 years, and the clinical picture was dominated by auditory hallucinations and ideas of reference. No mood swings were recorded during the years. The other subject fulfilled the DSM-III criteria except for the age of onset. He was hospitalized at the age of 52 due to a paranoid schizophrenia. The clinical picture was dominated by auditory hallucinations and paranoid ideas. It is probable that symptoms of the psychosis had been present already before the age of 45, but it was not documented. Except for the last subject, the total hospitalization for each patient was at least 30 years. Causes of death in the schizophrenic group were myocardial infarction, pulmonary 0006-3223/88/$03.50

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edema, bronchopneumonia, pyelonephritis, and carcinoma-all of which were also represented in the control group. The mean age of the controls was 62 years and that of the schizophrenics was 68 years. Death-to-autopsy time did not differ significantly between either group, with mean times of 20 hr and 26 hr for controls and schizophrenics, respectively. Following removal. all brains were maintained at -70°C. During transit, they were always kept under dry ice conditions (ca. - 70°C). Dissection was accomplished by warming the brains from their storage temperature to - 20°C and slicing 3-mm coronal sections on a mechanical slicer equipped with a smooth blade. The slices were placed on a cold plate overlaying dry ice within a nitrogen-filled chamber built after the design of Kanazawa (1983). A 3 x 3 mm grid was etched on the surface of each slice over the structure of the thalamus. Thalamic boundaries were limited laterally by the internal capsule and ventrally by such myelinated landmarks as Forels field anteriorly, the capsule of the red nucleus and dorsal ridge of the subthalamic nucleus midthalamically, and superior colliculus and geniculate bodies more posteriorly. The etched pattern was photographed. then segments were removed, weighed, and stored in plastic vials at - 70°C until assay. Analysis was accomplished using standard methods of highperformance liquid chromatography with electrochemical detection (Mefford 198 1). This quantitative assay of DA, NE, and metabolites was automated, and integrator readout of endogenous concentrations was free of operator bias. Analysts were not informed of the nature of the samples, but in some cases, high DA levels or an extraneous chromatographic peak gave rise to discussions that indicated the nature of the sample source. Figure 1 shows that the thalami from control brains contain a mean of 14.8% DA when compared to NE. Conversely, thalami from schizophrenic brains show DA content to be significantly elevated to 53.2% that of NE (t = 5. I, p < 0.001). Both the absolute levels of DA as well as the DA/NE ratios are higher in the schizophrenic thalami. It is significant to note

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that these elevated DA/NE ratios are not caused by low NE endogenous content. The mean NE values of 140 t 9.4 nglg and 129 + 5.7 nglg (SEM) for control and schizophrenic thalami. respectively, are not significantly different. The detailed patterns of these high DA/NE ratios within the thalami will be presented elsewhere. This brief report concerns only the totality of all individual samples analyzed.

Discussion There have been many studies of endogenous DA content in the caudate, putamen, and nucleus accumbens of brains from schizophrenic patients. Reports addressing the issue of DA elevation have been inconsistent (Bird et al. 1979; Crow et al. 1979; Winblad et al. 1979; Farley et al. 1980; Wyatt et al. 1981). According to a recent study, elevated DA in these regions may be found in a subpopulation of patients whose illness had an early onset (Mackay et al. 1982). In addition, the amygdala has recently been reported to contain a large unilateral DA increase in the left hemisphere (Reynolds 1983). This is the first report of elevated DA/NE ratios in the thalami of schizophrenic patients. The 14% DA/NE ratio found in this study for controls compares favorably with a 7%-15% DA-NE content relationship found for two nuclear regions of the human thalamus in earlier work (Moses and Robins 1975). The self-consistency of the DA/NE ratios in the control thalami makes it appear that the elevated values found in the schizophrenic cases are not related to age, death-to-autopsy time, nor agonal states prior to death. Furthermore, our control brains were not all “normals” by postmortem chemical analysis standards (Jellinger 1985). Our controls included brains from persons with diagnoses of alcoholism (3) and possible organic brain syndrome (2). Yet none of these 14 control thalami showed elevated DA/NE ratios comparable to those of the schizophrenic group. All subjects had been on major tranquilizers. The last 6 months before death, one subject was on flupenthixol (5 mg/day), two subjects were on levomepromazine (10 mg/day), two subjects

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were on levomepromazine (50-125 mg/day) in combination with trifluoperazine (3 mg/day) or perfenazin (12 mg/day). At least one subject was completely without major tranquilizers the last 6 months before death, yet the thalamus had a high DA/NE ratio (42.7%, shown in Figure 1). In any event, two recent studies concluded that neuroleptic medication has no obvious effect on DA levels in nucleus accumbens and caudate (Crow et al. 1980; MacKay et al. 1982). If ineffective in such DA-rich areas, it seems unlikely that neuroleptics would alter endogenous levels of a DA-impoverished area such as the thalamus. Whether the elevated thalamic DA is functional, e.g., exists in nerve terminals and has synaptic actions and corresponding receptor sites, or whether it is “misplaced” DA is not known at this time. Indeed, such questions are premature until the abnormal DA/NE ratios can be validated further in a larger range of samples

Figure 1. Mean DA/NE values x 100 for thalamus from control (C; n = 14) and schizophrenic (SCZ; n = 7) patients. Values for each brain represent a mean of all samples analyzed for that thalamus. Comparison was made by onetailed Student’s t-test. Vertical line extension represents -C SEM.

with detailed diagnostic and case history data. These studies are ongoing, and we hope independent checking from other laboratories will be forthcoming. Despite the obvious difficulties of dealing with chemical analysis of postmortem tissue, if the present limited results hold up to such investigations, they could constitute a new direction for research in biochemical studies of schizophrenia. We wish to acknowledge P. Nyberg, K. Mills, L. McKay, and W. Ayetey for technical assistance and T. Kent for valuable discussions in this work.

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