Cocaine plasma concentration: relation to physiological and subjective effects in humans.

Volunteer subjects with previous histories of cocaine use were administered cocaine hydrochloride intravenously or intranasally. There was a positive relationship between peak plasma concentration, physiological and subjective responses, and dose administered. The rate of cocaine disappearance after intravenous administration paralleled the drop in physiological and subjective drug effects. After intranasal administration, blood levels remained elevated for a considerably longer period.

Subcellular and anatomical distribution in rat brain of glycoproteins that contain mannose-rich heteropolysaccharide chains.

Mannose-rich glycopeptides derived from brain glycoproteins were obtained by proteolysis of bovine brain tissue or subcellular fractions derived from rat brain tissue. The dialyzable mannose-rich glycopeptides were isolated by column electrophoresis and gel filtration. Theses glycopeptides contained, on the average, six mannose and two N-acetylglucosamine residues with variable amounts of fucose and galactose. Over 50% of the mannose-rich glycopeptides of rat brain were localized in the microsomal and synaptosomal fractions; myelin and the soluble fraction contained lesser amounts. None was recovered from the mitochondria. The amount, per mg protein, of mannose-rich oligosaccharide chains in the myelin exceeded the concentration found in the microsomal and synaptosomal fractions. The concentration of mannose-rich glycopeptides derived from glycoproteins was 50% higher in white matter than in gray. On the other hand, the non-dialyzable and acidic sialoglycopeptides showed a three-fold enrichment in gray matter compared to white. The relatively lower ratio of sialoglycopeptides to mannose-rich glycopeptides observed in white matter (2.5) compared to gray matter (6.9) is reflected in the lower value for the ratio in myelin (1.1) compared to synaptosomes (2.1). Although glycoproteins that contain mannose-rich oligosaccharide chains are present in the nerve cell and its terminals, these glycoproteins appear to be relatively enriched in myelin and/or glial membranes.

Preparation and properties of concanavalin A-binding glycopeptides derived from rat brain glycoproteins.

Mannose-rich glycopeptides derived from brain glycoproteins were recovered by affinity chromatography on Concanavalin A-Sepharose. These glycopeptides, which adsorb to the lectin and are eluted with alpha-methylmannoside, constitute about 25--30% of the total glycopeptide material recovered from rat brain glycoproteins. They contain predominately mannose and N-acetylglucosamine (mannose/N-acetylglucosamine = 3), as well as small amounts of galactose and fucose. Approx. 65% of the Concanavalin A-binding glycopeptide carbohydrate was recovered after treatment with leucine aminopeptidase, gel filtration on Biogel P-4, and ion-exchange chromatography on coupled Dowex 50-hydrogen and Dowex 1-chloride columns. The purified glycopeptide fraction contained six mannose and two N-acetylglucosamine residues per aspartic acid and possessed an apparent molecular weight of about 2000 as assessed by gel filtration and amino acid analysis. Galactose and fucose were absent. Treatment of the purified glycopeptides with alpha-mannosidase drastically reduced their affinity for Concanavalin A, suggesting the presence of one or more terminal mannose residues.

Cerebrospinal fluid and urinary biogenic amines in depressed patients and healthy controls.

The National Institute of Mental Health-Clinical Research Branch Collaborative Study investigated 132 drug-free, severely depressed patients and 80 healthy controls. Forty-five percent of the depressed patients excreted markedly elevated levels of urinary epinephrine (E) and metanephrine (MET), while only 5% of healthy controls did so. Using gaussian mixture distributions, we identified two subgroups of depressed patients: one excreting normal levels and the other excreting high levels of urinary E, MET, norepinephrine, and normetanephrine. Cerebrospinal fluid homovanillic acid levels were low in a subgroup of depressed patients. When analyzed by subgroup, the elevated E + MET group had markedly lower cerebrospinal fluid homovanillic acid levels than controls, whereas depressed patients with normal catecholamine levels did not. Since it has been postulated that there are two subgroups of depressed patients, those with low 3-methoxy-4-hydroxyphenylglycol (MHPG) levels and normal 5-hydroxyindoleacetic acid (5-HIAA) levels and those with normal MHPG levels and low 5-HIAA levels, several analyses were performed to see if such a group could be identified. Our analysis failed to find evidence of a subgroup of depressives with low MHPG and normal 5-HIAA levels or normal MHPG and low 5-HIAA levels.

Septic encephalopathy. Evidence for altered phenylalanine metabolism and comparison with hepatic encephalopathy.

We elected to test the hypothesis that the metabolic encephalopathy associated with systemic sepsis may have a pathogenesis that is similar to hepatic encepathology, ie, as the consequence of hepatic dysfunction that induces alterations in synthesis of catecholic and noncatecholic neurotransmitters. Eleven patients with septic encephalopathy were compared with nine patients with septic encephalopathy and nine normal controls with respect to blood and cerebrospinal fluid (CSF) amino acid profile, phenylethylamine and its metabolite phenylacetic acid, and blood ammonia. Blood and CSF levels of phenylacetic acid increased markedly in septic and hepatic encephalopathy while CSF phenylethylamine levels were not increased in either condition, presumably due to rapid turnover. The CSF concentrations of all the aromatic amino acids were increased in hepatic encephalopathy, whereas in the patients with sepsis, only phenylalanine levels were increased. Evidence of stimulated neutral amino acid transport into brain was demonstrated in hepatic not septic encephalopathy and appeared to correlate with the CSF glutamine concentration. Blood ammonia levels were increased in hepatic but not in septic encephalopathy. Our data support the hypothesis that metabolites of phenylethylamine contribute to encephalopathy in systemic sepsis and hepatic failure; however, the entities differ in other respects.

Homovanillic acid in the cerebrospinal fluid: patterns of response after four weeks of neuroleptic treatment.

Lumbar cerebrospinal fluid (CSF) homovanillic acid (HVA) concentrations were measured before and after 4 weeks of neuroleptic treatment in schizophrenic (n = 15) and schizoaffective (n = 4) patients. Neuroleptic treatment induced a nonsignificant (17%) increase in CSF HVA group mean levels. For the total group, no correlations were found between pretreatment CSF HVA and clinical measures, or between changes in HVA and clinical response. An alternative interpretation was attempted by defining "tolerant" and "nontolerant" subgroups. A "tolerant" response was defined as a reduction in posttreatment HVA values below pretreatment levels, whereas a "nontolerant" response was characterized by posttreatment values above pretreatment levels. When thus defined, nontolerant patients had a significantly inferior clinical response to neuroleptics, in contrast to their tolerant counterparts. Further, although there was no difference in pretreatment CSF HVA values between these two groups, pretreatment clinical profiles did differ significantly. Also, in a retrospective analysis, nontolerant patients were found to have a significantly earlier age of illness onset, a greater number of prior psychiatric hospitalizations, and more time spent in psychiatric hospitals.

Pretreatment plasma homovanillic acid in schizophrenia and schizoaffective disorder: the influence of demographic variables and the inpatient drug-free period.

BACKGROUND: The relationship between plasma homovanillic acid (pHVA) and schizophrenic symptoms has not been conclusively determined. We reexamine pHVA levels in a new sample of patients with emphasis on demographic variables and the drug-free period. METHODS: Plasma HVA levels were studied in 54 schizophrenic and schizoaffective-disordered, drug-free inpatients suffering from a psychotic exacerbation. RESULTS: A significant correlation was observed between pHVA levels and the number of inpatient drug-free days in the total sample, as well as the schizophrenic patient subsample. Further, pHVA was significantly and positively correlated with the duration of illness in the schizophrenic patient subsample. Plasma HVA correlations with behavior, as measured by Brief Psychiatric Rating Scale factors (anxiety/depression and hostility/suspiciousness), emerged only when considering schizophrenic patients drug-free for more than 2 weeks. No correlation was found between pHVA and the age of illness onset or the duration of the delay of treatment of the first psychotic episode. CONCLUSIONS: The effects of antipsychotic withdrawal on levels of pHVA in clinical populations may have to be examined and controlled for in future studies attempting to study the relationship between this metabolite and behavior in acutely ill, drug-free schizophrenic patients.

Behavioral and biochemical effects of methylphenidate in schizophrenic and nonschizophrenic patients.

The authors examined the specific behavioral and biochemical effects of intravenous methylphenidate in a sample of schizophrenic and nonschizophrenic patients. Twenty drug-free patients participated in a double-blind, placebo randomized study of methylphenidate, with multiple samples of plasma homovanillic acid (HVA) and serum growth hormone (GH) obtained during the infusion procedure. Methylphenidate caused a significant increase in positive symptoms that was relatively specific to the schizophrenic patients and was evident even in those with otherwise dormant symptomatology. When behavioral response was correlated with the biochemical responses (i.e., changes in plasma HVA and GH), there was a significant positive relationship between the increase in the BPRS-positive symptoms as well as the hostility/suspiciousness factor, and the increase in GH. These results suggest that the expression of psychotic symptoms may be associated with increased dopaminergic postsynaptic sensitivity, although the nonspecific nature of methylphenidate's actions discourages a stronger interpretation of the results.

Peripheral benzodiazepine receptors are decreased during cocaine withdrawal in humans.

In the present study, homovanillic acid in plasma (pHVA) and benzodiazepine receptors (3H-PK11195 binding) in neutrophil membranes were determined in blood obtained from cocaine-dependent (DSM-III-R) adult male inpatients at baseline-(within 72 hr of last cocaine use) and after 3 weeks of cocaine abstinence, and normal controls. The mean (+/- SEM) pHVA at baseline (10.3 ng/ml +/- 1.1) was similar to normals and did not change after 3 weeks of cocaine abstinence. Similarly, the binding indices of benzodiazepine receptors in cocaine-dependent subjects as a group were not significantly different than in normal controls. In 10 cocaine-dependent subjects, however, where both blood samples were available, the number of 3H-PK11195 binding sites was significantly (p < 0.05) decreased after 3 weeks of cocaine abstinence (mean +/- sem: Bmax = 6371 +/- 657 fmol/mg protein) compared with baseline (Bmax = 7553 +/- 925 fmol/mg protein), although there were no differences in the binding affinity (mean +/- sem: KD = 8.6 +/- 1.2 nmol/L after 3 weeks of abstinence compared with 8.1 +/- 1.0 nmol/L at baseline). These preliminary results suggest that peripheral benzodiazepine receptors may play an important role in the pathophysiology of cocaine withdrawal in cocaine-dependent human subjects.

The methylphenidate test for differentiating desipramine-responsive from nortriptyline-responsive depression.

Monitoring tricyclic antidepressant concentrations in the plasma of 43 patients with major depressive disorders indicated that some responded to imipramine or desipramine but not to amitriptyline or nortriptyline, or vice versa, even though plasma levels were within therapeutic ranges. Mood elevation by methylphenidate predicted marked improvement from treatment with imipramine or desipramine but not with amitriptyline or nortriptyline. When methylphenidate failed to improve mood, patients responded to amitriptyline or nortriptyline but not to desipramine. These results suggest differential drug responses with different tricyclic antidepressants, the clinical utility of the methylphenidate test, and the heterogeneity of depressions. The authors question the mechanism of action of nortriptyline via blockade of norepinephrine reuptake.

Platelet MAO inhibition, urinary MHPG, and leukocyte beta-adrenergic receptors in depressed patients treated with phenelzine.

The authors investigated three biochemical indices of peripheral catecholamine activity in 36 depressed inpatients treated with the monoamine oxidase (MAO) inhibitor phenelzine. Platelet MAO activity, urinary excretion of 3-methoxy-4-hydroxyphenylglycol (MHPG), and leukocyte beta-adrenergic receptor functions were measured before and during the 4th week of phenelzine treatment. There were significant reductions in platelet MAO activity, urinary MHPG excretion, and depressive symptoms in all of the patients. Responders had the same decrease in MHPG as nonresponders. There were no changes in leukocyte beta-receptor function in a small subgroup of the patients.

Striatal application of nicotine, but not of lobeline, attenuates dopamine release in freely moving rats.

We investigated the physiological role of native low- and high-affinity nicotinic acetylcholine receptors (nAChRs) in regulating dopamine (DA) release from striatal DA terminals. To evaluate the functional interactions of the two receptor subtypes, nicotine (which interacts with both high- and low-affinity nAChRs) and lobeline (which selectively interacts with high-affinity nAChRs) were perfused through a microdialysis probe implanted into the striatum of freely moving rats. The DA content of successive dialysates was quantified by HPLC with an electrochemical detector. A short-lasting (1-min) perfusion of nicotine or lobeline dose-dependently increased the DA content of striatal dialysates. A second application of the same dose of nicotine resulted in an attenuated DA increase, compared with the increase elicited by the first application; however, the DA increase elicited by a second application of lobeline was similar to that of the first lobeline application. The nicotine-induced response was not attenuated when it followed a lobeline perfusion; in contrast, if the nicotine perfusion preceded that of lobeline, the lobeline-induced response was attenuated. In the presence of mecamylamine (a noncompetitive nAChR antagonist), the increase in DA content of striatal dialysate samples induced by either nicotine or lobeline was attenuated. However, in the presence of methyllycaconitine (a preferential antagonist for low-affinity alpha7 homomeric nAChRs), the nicotine response was attenuated but that of lobeline was unaffected. These results suggest that the functional inactivation of striatal nAChRs requires the simultaneous activation of both low- and high-affinity nAChRs. Since lobeline is devoid of reinforcing properties, one might infer that the reinforcing properties of nicotine require the simultaneous activation of high- and low-affinity brain nAChRs.

Expression and function of striatal nAChRs differ in the flinders sensitive (FSL) and resistant (FRL) rat lines.

Rats of Flinders Sensitive (FSL) and Flinders Resistant lines (FRL) differ in their susceptibility to physiological and associated behavioral responses elicited by nicotine. In the present study, we measured dopamine (DA) content in striatal dialysates to investigate the sensitivity of FSL and FRL rats to nicotine delivered locally through a microdialysis probe placed in the striatum. We also measured the expression density of striatal high-affinity nicotinic acetylcholine receptors (nAChRs), and that of mRNAs encoding for alpha3, alpha4, alpha7 and beta2 nAChR subunits in both lines. The DA content of dialysates was measured before and after a 1-min perfusion of nicotine (6, 10 or 20 nmoles/min) and the resulting DA increase was taken as a measure of the alkaloid's intrinsic activity for nAChRs involved in the release of DA. The nicotine-induced increase of striatal DA release was greater in FSL than in FRL rats for all concentrations of nicotine, suggesting that the intrinsic activity of nicotine was greater in the FSL than in the FRL rats. This was further supported by our finding that the density of high-affinity nAChRs in the striatum of FSL rats was 44% greater than in the FRL rats, whereas affinity (K(D)) was virtually the same in the two lines of rats. Also the expression of mRNAs encoding for alpha(4), alpha(7), and beta(2) subunits in the striatum was greater in FSL than in FRL rats (attomol/microg total RNA, alpha(4):98+/-10 vs. 77+/-7; alpha(7):279+/-16 vs. 184+/-16; beta(2):310+/-19 vs. 201+/-12). We hypothesize that the difference in nicotine-induced DA release in the striatum of FSL and FRL rats depends on the difference in nAChR subunit expression in the striatum between the two lines. The Flinders rats could be used as a model for nicotine self-administration studies to evaluate the susceptibilities of FSL and FRL rats to nicotine dependence.

alpha 1-acid glycoprotein involvement in high affinity binding of tricyclic antidepressants to human plasma.

The binding of the tricyclic antidepressants imipramine (IMI) and desmethylimipramine (DMI) to human plasma and individual proteins was studied by equilibrium dialysis. Both drugs bound extensively to plasma, albumin, and alpha 1-acid glycoprotein, while there was very little binding to the gamma-globulin fraction. The binding of both IMI and DMI to alpha 1-acid glycoprotein was high affinity (association constant K, 9.2 X 10(4)/M and 4.7 X 10(4)/M respectively) and low capacity (number of binding sites, n = 1 for both IMI and DMI), whereas the binding to albumin was low affinity (K for IMI, 2.3 X 10(2)/M and for DMI, 3 X 10(2)/M) and high capacity (n = 7). The binding of IMI to a mixture of human serum albumin and alpha 1-acid glycoprotein revealed two sets of binding sites; a high affinity binding site corresponding to alpha 1-acid glycoprotein and a low affinity binding site corresponding to albumin. The binding affinity and/or number of binding sites for IMI binding to albumin decreased with increasing albumin concentrations. The free fraction in plasma of nineteen normal, male controls was significantly correlated with the concentration of alpha 1-acid glycoprotein (r = 0.601, P less than 0.01), although there was no correlation with albumin or free fatty acid concentrations in plasma.

Clinical studies on the phenylethylamine hypothesis of affective disorder: urine and blood phenylacetic acid and phenylalanine dietary supplements.

To test the hypothesis that 2-phenylethylamine (PEA) modulates affect, plasma levels and urinary excretion of its main metabolite, phenylacetic acid (PAA), were studied in depressed and manic subjects, and the mood-elevating effects of its precursor, L-phenylalanine, were studied in depressed subjects. Mean total plasma PAA concentrations were 491.83 +/- 232.84 ng/ml in 12 healthy volunteers and 300.33 +/- 197.44 ng/ml in 23 drug-free patients with major depression. The 24-hour urinary PAA excretion was also measured in 48 healthy volunteers (141.1 +/- 10.2 mg PAA/24 hr) and in 144 patients with major depression (78.2 +/- 41.0 mg PAA/24 hr). The results suggest that low plasma and urinary PAA may be state markers for depression and are compatible with the PEA hypothesis. In further support, phenylalanine elevated mood in 31 of 40 depressives.

Fluphenazine pharmacokinetics and therapeutic response.

We conducted a double-blind study of therapeutic outcome versus mean steady-state levels in 29 newly admitted schizophrenic and schizoaffective patients who were treated with a constant dose of fluphenazine HCI over a 2-week period. both an upper and lower end of the therapeutic window were suggested by three nonresponders whose plasma levels were above 2.8 ng per ml and by two nonresponders and one partial responder whose plasma levels were below 0.2 ng per ml. The mean terminal half-life of fluphenazine (+ or - SD) was 16.4 + or - 13.3 h. We found that concomitant use of benztropn mesylate during the initial 4 weeks of fluphenazine treatment did not significantly alter fluphenazine plasma levels.

Plasma levels of fluphenazine during fluphenazine decanoate treatment in schizophrenia.

The authors measured plasma fluphenazine levels in 20 schizophrenic patients receiving 25 or 50 mg fluphenazine decanoate (FPZ-D) by IM injection every 2 weeks. The plasma levels were determined by a sensitive gas-liquid chromatographic (GLC) assay with a nitrogen detector device developed in their laboratory. Using this chemical assay method, they replicated the finding of a sharp initial plasma peak within 24 h after the injection followed by a low but rather stable plasma level as previously reported by nonchemical assay methods. The interval plasma levels (averages of day 4-10 after injection) ranged from 0.17-0.61 ng/ml in 10 patients who received 25 mg; and 0.20-0.93 ng/ml in 7 patients who received 50 mg FPZ-D every 2 weeks. This four-fold variation in plasma levels during FPZ-D injection was smaller than previously reported levels achieved with oral antipsychotic drug treatment. Based on the study of plasma levels achieved with FPZ-D injection and oral FPZ-H (fluphenazine HC1) in 6 patients, the dosage requirement of FPZ-D appeared to be difficult to predict from the oral dosage of FPZ-H in the same patient. Two weeks past injection, fluphenazine was undetectable in approximately half the samples with the GLC method. Thus, radioimmunoassay or radioreceptor assay, which also measures metabolites, might be more suitable for the study of plasma levels in patients receiving FPZ-D injection.

The prolactin response to fenfluramine in schizophrenia is associated with negative symptoms.

We examined the serotonergic system in drug-free inpatients [schizophrenia (n=28) and schizoaffective (n=7)] by administering a challenge dose of oral dl-fenfluramine (fenfluramine) in a controlled angiocatheter study. Seventeen of these patients were also randomized to a placebo condition in addition to receiving fenfluramine. Response to fenfluramine as reflected by changes in serum prolactin and cortisol were examined by repeated measures ANOVA, as well as Area Under the Curves (AUCs). The prolactin response, but not the cortisol response, was significantly correlated with measures of negative symptoms.

Clinical pharmacokinetics of antipsychotics.

The antipsychotics are a chemically diverse group of heterocyclic compounds, which ameliorate many symptoms of schizophrenia. Most of the antipsychotics are very lipophilic and cross lipoidal membranes freely. When administered orally, they are well absorbed and undergo substantial pre-systemic elimination (bioavailability: 10-70%), are highly bound to plasma proteins (75-99%) and tissues, and are extensively distributed (VD: 100-1000 L). Primary route of elimination for most of antipsychotics is hepatic metabolism and biotransformation produces active metabolites. There is no linear relationship between the concentration of parent compound and different metabolites, and clinical relevance of pharmacologically active metabolites is not well understood. There are wide interindividual variabilities in pharmacokinetics, which result in large differences in steady-state plasma concentrations on the same dose regimen. The existence of optimal therapeutic ranges for most antipsychotics remains controversial. One of the major problems is the lack of well-designed studies that involve sufficient numbers of patients to clearly establish a therapeutic range for these drugs and is further complicated by the presence of a large number of pharmacologically active metabolites. However, the pronounced interindividual kinetic variabilities, combined with problems of noncompliance and drug interactions, and the delayed onset of clinical response in relation to initiation of treatment with antipsychotics are reasons why drug monitoring in conjunction with clinical status of the patient can be useful. Indications for antipsychotic drug monitoring include lack of response, non-compliance, toxicity, and drug interactions when other drugs are coadministered.

Nicotine-induced behavioral sensitization is associated with extracellular dopamine release and expression of c-Fos in the striatum and nucleus accumbens of the rat.

It is well known that repeated injections of nicotine produce progressively larger increases in locomotor activity, an effect referred to as behavioral sensitization. This study was carried out to investigate the neural mechanisms underlying nicotine-induced behavioral sensitization using in vivo microdialysis and Fos-like immunohistochemistry (FLI). Rats were given repeated injections of saline or nicotine (0.4 mg/kg s.c., twice daily for 7 days) followed by one challenge injection on the 4th day after the last daily injection. Systemic challenge with nicotine produced a much larger increase in locomotor activity in nicotine-pretreated rats (659.1+/-94.9 counts/2 h) than in saline-pretreated rats (218.1+/-61 counts/2 h). A direct local challenge of nicotine (1 or 5 mM) via a microdialysis probe in the nucleus accumbens or striatum induced a much greater dose-dependent increase of dopamine (DA) output in nicotine-pretreated rats than in saline-pretreated rats. Furthermore, in parallel with the behavioral and biochemical data, systemic challenge with nicotine produced marked Fos-like immunohistochemistry in the nucleus accumbens and the striatum in the nicotine-pretreated rats. Taken together, this study demonstrates that behavioral sensitization is clearly associated with an increase in DA release and activation of Fos-like immunoreactive cells in the striatum and the nucleus accumbens produced by repeated nicotine treatment. Our results strongly suggest that the striatum and the nucleus accumbens may play a major role in nicotine-induced behavioral sensitization. The present results are discussed in terms of the development and expression of nicotine-induced behavioral sensitization.