Serum antibodies to nicotinic acetylcholine receptors in schizophrenic patients.

Although elevated serum levels of antibodies to the nicotinic acetylcholine receptor (nAChR) have been reported in neuroleptic treated patients with tardive dyskinesia, such antibodies have not been determined in comparable nondyskinetic patients. Using a toxin-binding inhibition assay, we examined serum anti-nAChR antibody levels in 17 DSM-III-R chronic schizophrenic patients, seven of whom had persistent tardive dyskinesia, and 10 normal controls. On the average, anti-nAChR antibody levels were significantly higher in schizophrenic patients than in normal controls, but but not differ between patients with and without tardive dyskinesia and was not related to age, sex, or duration of illness in patients.

Plasma cholinesterase isozymes and REM latency in schizophrenia.

The relation between electroencephalographic sleep parameters and plasma cholinesterase isozymes was examined in a group of 19 unmedicated schizophrenic patients. Rapid eye movement (REM) latency was found to be significantly inversely correlated with isozyme 3 (mainly acetylcholinesterase). The results are discussed in relation to cholinergic involvement in the regulation of REM sleep and in the pathophysiology of schizophrenia.

Quantitative analyses of plasma cholinesterase isozymes in haloperidol-treated rats.

We describe a quantitative slab gel electrophoresis procedure that allows quantitative determination of plasma levels of discrete cholinesterase isozymes. Using this method, the effects of haloperidol treatment on plasma cholinesterase isozyme levels were examined in normal rats. Eight isozymes were detected by enzymatic reaction with either of two substrates (alpha-naphthyl acetate, NA; acetylthiocholine iodide, AcTCh), and then quantified using densitometric scanning. With AcTCh substrate, the activities of two major isozymes (1 and 2) were found to be linear with increasing quantities of applied plasma. With NA as substrate, Iso-OMPA (a pseudocholinesterase inhibitor) inhibited activities of all isozymes, except isozymes 2 and 8. With either substrate, BW284C51 (acetylcholinesterase inhibitor) inhibited 100% and 13% of activity of isozymes 2 and 8, respectively, and with AcTCh substrate, 37% of isozyme 1. Based on the differential patterns of substrate specificity and action of inhibitors, and the reproducibility of patterns, we propose that these isozymes represent distinct molecular species. Short-term (14 days) and long-term (45 days) haloperidol treatment both resulted in altered levels of specific cholinesterase (ChE) isozymes. On the average, with AcTCh substrate, haloperidol treatment increased levels of isozymes 1 and 2 by 30% and 8%, respectively, after 14 days, and by 50% and 30%, respectively, after 45 days. Isozymes 3 through 8 showed minor changes. Plasma levels of isozymes 1 and 2 returned to baseline pretreatment values after a 40-day drug-free period. No significant change was observed after either short- or long-term treatment with clozapine, imipramine, or saline, or after an acute (less than 5 days) haloperidol treatment. No change was noted in RBC-ChE levels as function of treatment. These findings indicate that, in the rat, chronic haloperidol treatment results in differential changes in the plasma levels of discrete ChE isozymes. We have suggested that these changes reflect an alteration of central dopaminergic-cholinergic balance.

GM1 ganglioside protects nucleus basalis from excitotoxin damage: reduced cortical cholinergic losses and animal mortality.

Ten days after bilateral injections of ibotenic acid into the nucleus basalis, rats injected daily (i.m.) with ganglioside GM1 were protected from anterograde degeneration of cholinergic projections to the fronto-lateral cortex. This protection was reflected by reduced losses (associated with ibotenic acid lesions) of cortical acetylcholinesterase, choline acetyltransferase, and lowered animal mortality.

Haloperidol alters rat CNS cholinergic system: enzymatic and morphological analyses.

Chemical and morphological changes in cholinergic marker enzymes, acetylcholinesterase (AChE), and choline acetyltransferase (ChAT) of striatum, hippocampus, and cerebral cortex were studied following haloperidol treatment of rats. After short-term (7-21 days) haloperidol treatment, the levels of both enzymes (AChE and ChAT) were increased in striatum and hippocampus (greater than 25%), but not in cortex. After long-term (+40 days) haloperidol treatment, the level of AChE activity returned to control levels in all brain areas, whereas the levels of striatal and hippocampal ChAT decreased by 26% and 29%, respectively. No change in levels of both enzymes was detected after acute treatment (single dose) of haloperidol or chronic treatment with either clozapine or imipramine. Morphological analysis of cholinergic neurons and their processes using monoclonal antibody to ChAT showed two types of changes following 40 days of haloperidol treatment. First, parallel to the observed decrease in the levels of ChAT activity there was a visual decrease in the immunoreactivity in neurons as well as in their processes in striatum and hippocampus. Second, there was an apparent reduction in the size and number of stained neurons and their processes. No changes were seen in immunoreactivity after an acute treatment with haloperidol. These results indicate that the chronic haloperidol treatment in rats causes changes in central cholinergic systems that may be relevant to the pathophysiology of schizophrenia and its treatment.

Distribution of six synaptic membrane antigens in subcellular fractions of rat brain cortex.

The subcellular distribution in rat brain cortex of six synaptic membrane antigens (56K, 58K, 62K, 63K, 64K, 66K) was studied by rocket immunoelectrophoresis, using antiserum to a highly purified synaptic plasma membrane fraction. Initial analysis of the insoluble portion of subcellular fractions showed that these antigens were also present in smooth microsomes, rough microsomes, and synaptic vesicles; that only traces were present in synaptic junctions; and that none was present in nuclei, mitochondria, and myelin. A trace amount of activity was also present in synaptic vesicle cytosol, but none in whole brain cytosol. Quantitative measurements of synaptic plasma membranes, smooth microsomes, and synaptic vesicles showed that all six antigens were present in synaptic plasma membranes and smooth microsomes, but that the 66K antigen was absent from synaptic vesicles. The 56K, 58K, 62, 63K, and 64K antigens were present in highest concentration in synaptic plasma membranes, whereas the 66K antigen content was highest in smooth microsomes. Only the 58K, 62K, and 63K antigen were detectable in the membrane fraction of whole brain. Their enrichments in synaptic plasma membranes were 10.9, 5.4, and 5.9, respectively. We conclude that the 56K, 58K, 62K, 63K and 64K antigens are primary components of synaptic plasma membranes. The presence of synaptic plasma membrane antigens in smooth microsomes and synaptic vesicles probably represents material being actively transported, consistent with the hypothesis that proteins of synaptic plasma membranes and synaptic vesicles are hypothesis that proteins of synaptic plasma membranes and synaptic vesicles are transported via smooth endoplasmic reticulum.

Synaptic membrane antigens: detection and characterization.

Analysis of the antigenic components of synaptic membranes presents several problems caused by detergents required to solubilize the proteins. These problems involve detection of the reaction between antibodies and proteins in the detergent extract as well as characterization of the individual antigens after further purification. We found a satisfactory solution for analysis of rat synaptic membranes by using rocket immunoelectrophoresis with an intermediate gel containing 0.5% berol to sequester sodium dodecyl sulfate (SDS) and an antibody gel containing 0.1% berol to maintain the solubility of the proteins. With antiserum prepared against a highly purified synaptic membrane fraction, these conditions gave rocket heights proportional to protein concentration (for the major rocket) and showed no reactions with membrane extracts of liver, kidney and spleen. By separation on gradient slab gels containing SDS, 4 antigenic polypeptides were found in Berol extracts of synaptic membrane, having apparent molecular sizes of 56,000, 58,000, 62,000 and 66,000 daltons. The SDS extract of the berol insoluble residue contained 3 antigenic polypeptides (12,500; 15,000, 16,500 daltons). The combined use of gradient slab gel electrophoresis in SDS and rocket immunoelectrophoresis with an intermediate gel to remove SDS provides a sensitive and rapid method for definitive identification of individual antigenic components in detergent extracts of membrane and for further purification of these antigens.