Plasma norepinephrine in chronic schizophrenia

Astrocyte β-Adrenergic Receptor Activity Regulates NMDA Receptor Signaling of Medial Prefrontal Cortex Pyramidal Neurons

Glutamate spillover from the synapse is tightly regulated by astrocytes, limiting the activation of extrasynaptically located NMDA receptors (NMDAR). The processes of astrocytes are dynamic and can modulate synaptic physiology. Though norepinephrine (NE) and β-adrenergic receptor (β-AR) activity can modify astrocyte volume, this has yet to be confirmed outside of sensory cortical areas, nor has the effect of noradrenergic signaling on glutamate spillover and neuronal NMDAR activity been explored. We monitored changes to astrocyte process volume in response to noradrenergic agonists in the medial prefrontal cortex of male and female mice. Both NE and the β-AR agonist isoproterenol (ISO) increased process volume by ∼20%, significantly higher than changes seen when astrocytes had G-protein signaling blocked by GDPβS. We measured the effect of β-AR signaling on evoked NMDAR currents. While ISO did not affect single stimulus excitatory currents of Layer 5 pyramidal neurons, ISO reduced NMDAR currents evoked by 10 stimuli at 50 Hz, which elicits glutamate spillover, by 18%. After isolating extrasynaptic NMDARs by blocking synaptic NMDARs with the activity-dependent NMDAR blocker MK-801, ISO similarly reduced extrasynaptic NMDAR currents in response to 10 stimuli by 18%. Finally, blocking β-AR signaling in the astrocyte network by loading them with GDPβS reversed the ISO effect on 10 stimuli-evoked NMDAR currents. These results demonstrate that astrocyte β-AR activity reduces extrasynaptic NMDAR recruitment, suggesting that glutamate spillover is reduced.

Biomarkers in the cerebrospinal fluid of patients with psychotic disorders compared to healthy controls: a systematic review and meta-analysis

Psychotic disorders are severe mental disorders with poorly understood etiology. Biomarkers in the cerebrospinal fluid (CSF) could provide etiological clues and diagnostic tools for psychosis; however, an unbiased overview of CSF alterations in individuals with psychotic disorders is lacking. The objective of this study was to summarize all quantifiable findings in CSF from individuals with psychotic disorders compared to healthy controls (HC). Studies published before January 25th, 2023 were identified searching PubMed, EMBASE, Cochrane Library, Web of Science, ClinicalTrials.gov, and PsycINFO. Screening, full-text review, data extraction, and risk of bias assessments were performed by two independent reviewers following PRISMA guidelines. Findings in patients and healthy controls were compared and summarized using random-effects analyses and assessment of publication bias, subgroup and sensitivity analyses were performed. 145 studies, covering 197 biomarkers, were included, of which 163 biomarkers have not previously been investigated in meta-analyses. All studies showed some degree of bias. 55 biomarkers measured in CSF were associated with psychosis and of these were 15 biomarkers measured in ≥2 studies. Patients showed increased levels of noradrenaline (standardized mean difference/SMD, 0.53; 95% confidence interval/CI, 0.16 to 0.90) and its metabolite 3-methoxy-4-hydroxyphenylglycol (SMD, 0.30; 95% CI: 0.05 to 0.55), the serotonin metabolite 5-hydroxyindoleacetic acid (SMD, 0.11; 95% CI: 0.01 to 0.21), the pro-inflammatory neurotransmitter kynurenic acid (SMD, 1.58; 95% CI: 0.34 to 2.81), its precursor kynurenine (SMD,0.99; 95% CI: 0.60 to 1.38), the cytokines interleukin-6 (SMD, 0.58; 95% CI: 0.39 to 0.77) and interleukin-8 (SMD, 0.43; 95% CI: 0.24 to 0.62), the endocannabinoid anandamide (SMD, 0.78; 95% CI: 0.53 to 1.02), albumin ratio (SMD, 0.40; 95% CI: 0.08 to 0.72), total protein (SMD, 0.29; 95% CI: 0.16 to 0.43), immunoglobulin ratio (SMD, 0.45; 95% CI: 0.06 to 0.85) and glucose (SMD, 0.48; 95% CI: 0.01 to 0.94). Neurotensin (SMD, -0.67; 95% CI: -0.89 to -0.46) and γ-aminobutyric acid (SMD, -0.29; 95% CI: -0.50 to -0.09) were decreased. Most biomarkers showed no significant differences, including the dopamine metabolites homovanillic acid and 3,4-dihydroxyphenylacetic acid. These findings suggest that dysregulation of the immune and adrenergic system as well as blood-brain barrier dysfunction are implicated in the pathophysiology of psychotic disorders.

Impact of mental disorders on the risk of heart failure among Korean patients with diabetes: a cohort study

BACKGROUND

Few studies have assessed the correlation between coexisting mental disorders in participants with diabetes mellitus (DM) and the risk of heart failure (HF). Herein, we conducted a cohort study to determine the association between the accumulation of mental disorders in participants with DM and the risk of HF.

METHODS

The Korean National Health Insurance Service records were assessed. 2,447,386 adults with DM who underwent health screening between 2009 and 2012 were analyzed. Participants with major depressive disorder, bipolar disorder, schizophrenia, insomnia, or anxiety disorders were included. In addition, participants were categorized based on the number of coexisting mental disorders. Each participant was followed until December 2018 or until the onset of HF. Cox proportional hazard modelling with confounding factors adjustment was conducted. In addition, a competing risk analysis was conducted. Subgroup analysis assessed the impact of clinical variables on the association between the accumulation of mental disorders and the risk of HF.

RESULTS

The median follow-up duration was 7.09 years. The accumulation of mental disorders was associated with a risk of HF (zero mental disorder (0), reference; 1 mental disorder, adjusted hazard ratio (aHR): 1.222, 95% confidence intervals (CI): 1.207-1.237; 2 mental disorders, aHR: 1.426, CI: 1.403-1.448; ≥3 mental disorders, aHR: 1.667, CI: 1.632-1.70. In the subgroup analysis, the strength of association was the strongest in the younger age group (< 40 years, 1 mental disorder, aHR 1.301, CI 1.143-1.481; ≥2 mental disorders, aHR 2.683, CI 2.257-3.190; 40-64 years, 1 mental disorder, aHR 1.289, CI 1.265-1.314; ≥2 mental disorders, aHR 1.762, CI 1.724-1.801; ≥65 years, 1 mental disorder, aHR 1.164, CI 1.145-1.183; ≥2 mental disorders, aHR 1.353, CI 1.330-1.377; P_inter<0.001). In addition, income, BMI, hypertension, chronic kidney disease, history of cardiovascular disease, insulin use, and duration of DM showed significant interactions.

CONCLUSIONS

Comorbid mental disorders in participants with DM are associated with an increased risk of HF. In addition, the association was stronger in a younger age group. Participants with DM and mental disorders should be monitored with increased frequency for signs of HF; for which they have a higher risk than the general population.

Trauma center admission risk conditions and the probability for developing alcohol withdrawal syndrome: A retrospective study

BACKGROUND

Because the proportion of trauma patients developing alcohol withdrawal syndrome (AWS) is low, AWS risk conditions have not been precisely delineated. We aimed to create multifactor screening strategies to assess probabilities for the likelihood of developing AWS.

METHODS

We performed a retrospective chart review of 1,011 trauma patients admitted to a Level I trauma center to investigate the associations between AWS and probable AWS risk conditions. Included patients were adults who met trauma registry inclusion criteria and had blood alcohol concentration (BAC) testing performed. Patients were excluded if they had a traumatic brain injury with a Glasgow Coma Score (GCS) ≤ 8, or no BAC testing performed. We defined heavy drinking as daily drinking or >7 per week.

RESULTS

AWS had univariate associations with heavy drinking history, Injury Severity Score (ISS) ≥15, psychiatric disorders, liver disease, smoking history, in-hospital bronchodilator administration, age ≥45, male sex, Intensive Care Unit (ICU) admission, serum aspartate aminotransferase (AST) ≥40 U/L, and cognitive preservation (GCS ≥13 with BAC ≥100 mg/dL) (all, p < 0.05). ICU admission, AST ≥40 U/L, cognitive preservation, male sex, and age ≥45 had associations with ISS ≥15 or alcohol misuse (all, p < 0.0001). For patients with age ≥45 and heavy drinking history or age <45 and heavy drinking history with ISS ≥15 and ICU admission, the AWS proportion (15.3%) was greater in comparison to other patients (0.3%). The AWS risk score was the sum of the following nine conditions, assigned a zero when the condition was absent and one when present (range 0-9): ISS ≥15, psychiatric disorders, liver disease, smoking history, in-hospital bronchodilator administration, age ≥45, male sex, AST ≥40 U/L, and cognitive preservation. The AWS proportion was greater with a risk score of 5-9 (16.8%) than of 0-4 (1.2%; p < 0.0001).

CONCLUSIONS

AWS in the setting of traumatic injury is associated with multiple risk conditions. The presence of multiple risk conditions might have additive effects that could contribute toward a clinical manifestation of AWS. The identified risk conditions may be associated with a hyperadrenergic state.

Association of working memory and elevated overnight urinary norepinephrine in patients with schizophrenia

INTRODUCTION

Norepinephrine has both central and peripheral origins and is known to influence cognitive processes in attention, learning, and working memory, but the research regarding the impact of norepinephrine on cognition in schizophrenia remains sparse, and mainly focuses on centrally regulated noradrenergic effects. This study examined the relationship between cumulative overnight norepinephrine levels in the urine and working memory in patients with schizophrenia and healthy controls.

METHODS

Urinary catecholamines were collected overnight in patients with schizophrenia (n = 75) and healthy controls (n = 33). Working memory was assessed using the digit sequencing task.

RESULTS

Patients showed significantly higher average levels of overnight norepinephrine (t(103.10) = -3.16, p = 0.002) and reduced working memory performance (t(90) = 3.87, p = 0.001) compared with healthy individuals. There was a significant negative correlation between norepinephrine and working memory in patients (r = -0.38, p = 0.005), but not in controls (r = 0.08, p = 0.67). After controlling for age, sex, antipsychotic medications, and serotonin-norepinephrine reuptake inhibitor-based antidepressants, the correlation remained significant (r = -0.41, p = 0.004).

CONCLUSIONS

High peripheral overnight levels of urinary norepinephrine are associated with lower working memory performance in patients with schizophrenia. These results parallel previous studies suggesting that high levels of central norepinephrine may result in working memory impairments. As norepinephrine rapidly breaks down and usually does not pass through the blood-brain barrier, the potential effect of peripheral cumulative norepinephrine on working memory is intriguing, and needs to be further investigated.

Atypical Antipsychotics and Metabolic Syndrome: From Molecular Mechanisms to Clinical Differences

Atypical antipsychotics (AAPs) are commonly prescribed medications to treat schizophrenia, bipolar disorders and other psychotic disorders. However, they might cause metabolic syndrome (MetS) in terms of weight gain, dyslipidemia, type 2 diabetes (T2D), and high blood pressure, which are responsible for reduced life expectancy and poor adherence. Importantly, there is clear evidence that early metabolic disturbances can precede weight gain, even if the latter still remains the hallmark of AAPs use. In fact, AAPs interfere profoundly with glucose and lipid homeostasis acting mostly on hypothalamus, liver, pancreatic β-cells, adipose tissue, and skeletal muscle. Their actions on hypothalamic centers via dopamine, serotonin, acetylcholine, and histamine receptors affect neuropeptides and 5'AMP-activated protein kinase (AMPK) activity, thus producing a supraphysiological sympathetic outflow augmenting levels of glucagon and hepatic glucose production. In addition, altered insulin secretion, dyslipidemia, fat deposition in the liver and adipose tissues, and insulin resistance become aggravating factors for MetS. In clinical practice, among AAPs, olanzapine and clozapine are associated with the highest risk of MetS, whereas quetiapine, risperidone, asenapine and amisulpride cause moderate alterations. The new AAPs such as ziprasidone, lurasidone and the partial agonist aripiprazole seem more tolerable on the metabolic profile. However, these aspects must be considered together with the differences among AAPs in terms of their efficacy, where clozapine still remains the most effective. Intriguingly, there seems to be a correlation between AAP's higher clinical efficacy and increase risk of metabolic alterations. Finally, a multidisciplinary approach combining psychoeducation and therapeutic drug monitoring (TDM) is proposed as a first-line strategy to avoid the MetS. In addition, pharmacological treatments are discussed as well.

The role of norepinephrine in the pathophysiology of schizophrenia

Several lines of evidence have suggested for decades a role for norepinephrine (NE) in the pathophysiology and treatment of schizophrenia. Recent experimental findings reveal anatomical and physiological properties of the locus coeruleus-norepinephrine (LC-NE) system and its involvement in brain function and cognition. Here, we integrate these two lines of evidence. First, we review the functional and structural properties of the LC-NE system and its impact on functional brain networks, cognition, and stress, with special emphasis on recent experimental and theoretical advances. Subsequently, we present an update about the role of LC-associated functions for the pathophysiology of schizophrenia, focusing on the cognitive and motivational deficits. We propose that schizophrenia phenomenology, in particular cognitive symptoms, may be explained by an abnormal interaction between genetic susceptibility and stress-initiated LC-NE dysfunction. This in turn, leads to imbalance between LC activity modes, dysfunctional regulation of brain network integration and neural gain, and deficits in cognitive functions. Finally, we suggest how recent development of experimental approaches can be used to characterize LC function in schizophrenia.

Discrete forebrain neuronal networks supporting noradrenergic regulation of sensorimotor gating

Prepulse inhibition (PPI) refers to the reduction in the startle response when a startling stimulus is preceded by a weak prestimulus, and is an endophenotype of deficient sensorimotor gating in several neuropsychiatric disorders. Emerging evidence suggests that norepinephrine (NE) regulates PPI, however, the circuitry involved is unknown. We found recently that stimulation of the locus coeruleus (LC), the primary source of NE to the forebrain, induces a PPI deficit that is a result of downstream NE release. Hence, this study sought to identify LC-innervated forebrain regions that mediate this effect. Separate groups of male Sprague-Dawley rats received a cocktail solution of the α1-NE receptor agonist phenylephrine plus the β-receptor agonist isoproterenol (equal parts of each; 0, 3, 10, and 30 μg) into subregions of the medial prefrontal cortex (mPFC), nucleus accumbens (NAcc), extended amygdala, mediodorsal thalamus (MD-thalamus), or the dorsal hippocampus (DH) before PPI testing. NE agonist infusion into the posterior mPFC, NAcc shell, bed nucleus of the stria terminalis, basolateral amygdala, and the MD-thalamus disrupted PPI, with particularly strong effects in MD-thalamus. Sites in which NE receptor stimulation did not disrupt PPI (anterior mPFC, NAcc core, central amygdala, and DH) did support PPI disruptions with the dopamine D2 receptor agonist quinpirole (0, 10 μg). This pattern reveals new pathways in the regulation of PPI, and suggests that NE transmission within distinct thalamocortical and ventral forebrain networks may subserve the sensorimotor gating deficits that are seen in disorders such as schizophrenia, Tourette syndrome, and post-traumatic stress disorder.

Disruption of prepulse inhibition after stimulation of central but not peripheral alpha-1 adrenergic receptors

Prepulse inhibition (PPI) refers to the attenuation of startle when a weak prestimulus precedes the startling stimulus. PPI is deficient in several psychiatric illnesses involving poor sensorimotor gating. Previous studies indicate that alpha1 adrenergic receptors regulate PPI, yet the extent to which these effects are mediated by central vs peripheral receptors is unclear. The present studies compared the effects of intracerebroventricular (ICV) vs intraperitoneal (IP) delivery of several alpha1 receptor agonists on PPI. Male Sprague-Dawley rats received either cirazoline (0, 10, 25, 50 microg/5 microl), methoxamine (0, 30, 100 microg/5 microl), or phenylephrine (0, 3, 10, 30 microg/5 microl) ICV immediately before testing. Separate groups received either cirazoline (0, 0.25, 0.50, 0.75 mg/kg), methoxamine (0, 2, 5, 10 mg/kg), or phenylephrine (0, 0.1, 2.0 mg/kg) IP 5 min before testing. PPI, baseline startle responses, and piloerection, an index of autonomic arousal, were measured. Cirazoline disrupted PPI; effective ICV doses were approximately six times lower than effective IP doses. Methoxamine disrupted PPI after ICV infusion but failed to affect PPI with IP doses that were up to 30-fold higher than the effective ICV dose. Phenylephrine disrupted PPI with ICV administration, but did not alter PPI after IP injection of even a 20-fold higher dose. None of the ICV treatments altered baseline startle magnitude, but phenylephrine and methoxamine lowered startle after administration of high systemic doses. Piloerection was induced by cirazoline via either route of administration, and by IP methoxamine and phenylephrine, but not by ICV infusion of methoxamine or phenylephrine. These findings indicate that alpha1 receptor-mediated PPI disruption occurs exclusively through stimulation of central receptors and is dissociable from alterations in baseline startle or autonomic effects.

Effects of pharmacological doses of 2-deoxyglucose on plasma catecholamines and glucose levels in patients with schizophrenia

RATIONALE

Several lines of evidence suggest that the pathophysiology of schizophrenia may be associated with altered noradrenergic and glucoregulatory function.

OBJECTIVE

The aim of this study was to investigate these alterations during a perturbed homeostatic state.

METHODS

Fifteen patients with schizophrenia and 13 healthy individuals were given a glucose deprivation challenge through administration of pharmacological doses of 2-deoxyglucose (2DG; 40 mg/kg), and their plasma was assayed over the next 60 min for concentrations of norepinephrine (NE), the intraneuronal NE metabolite dihydroxyphenylglycol (DHPG), epinephrine and glucose.

RESULTS

2DG induced significant increases in plasma NE, epinephrine and glucose levels in both groups with significantly greater NE and glucose increments in patients than in controls. For DHPG, 2DG produced increases in patients and decreases in the control subjects. NE responses correlated positively and significantly with the DHPG and glucose responses in schizophrenics, but not in controls.

CONCLUSIONS

These findings suggest that patients with schizophrenia have exaggerated NE and glucose responses to an acute metabolic perturbation.

Group II mGlu receptor activation suppresses norepinephrine release in the ventral hippocampus and locomotor responses to acute ketamine challenge

Group II mGlu receptor agonists (eg LY379268 and LY354740) have been shown to reverse many of the behavioral responses to PCP as well as glutamate release elicited by PCP and ketamine. In the present set of experiments, we used in vivo microdialysis to show that, in addition to reversing PCP- and ketamine-evoked glutamate release, group II mGlu receptor stimulation also prevents ketamine-evoked norepinephrine (NE) release. Pretreating animals with the mixed 2/3 metabotropic glutamate (mGlu2/3) receptor agonist LY379268 (0.3-10 mg/kg) dose-dependently inhibited ketamine (25 mg/kg)-evoked NE release in the ventral hippocampus (VHipp). Ketamine hyperactivity was also reduced in a similar dose range. Following our initial observation on NE release, we conducted a series of microinjection experiments to reveal that the inhibitory effects of LY379268 on VHipp NE release may be linked to glutamate transmission within the medial prefrontal cortex. Finally, we were able to mimic the inhibitory effects of LY379268 on ketamine-evoked NE release by using a novel mGlu2 receptor selective positive modulator. (+/-) 2,2,2-Trifluoroethyl [3-(1-methyl-butoxy)-phenyl]-pyridin-3-ylmethyl-sulfonamide (2,2,2-TEMPS, characterized through in vitro GTPgammaS binding) at a dose of 100 mg/kg significantly reduced the NE response. Together, these results demonstrate a novel means to suppress noradrenergic neurotransmission (ie by activating mGlu2 receptors) and may, therefore, have important implications for neuropsychiatric disorders in which aberrant activation of the noradrenergic system is thought to be involved.

Psychotropic drugs, cardiac arrhythmia, and sudden death

A variety of drugs targeted towards the central nervous system are associated with cardiac side effects, some of which are linked with reports of arrhythmia and sudden death. Some psychotropic drugs, particularly tricyclic antidepressants (TCAs) and antipsychotic agents, are correlated with iatrogenic prolongation of the QT interval of the electrocardiogram (ECG). In turn, this is associated with the arrhythmia (TdP). This review discusses the association between psychotropic agents, arrhythmia and sudden death and, focusing on TCAs and antipsychotics, considers their range of cellular actions on the heart; potentially pro-arrhythmic interactions between psychotropic and other medications are also considered. At the cellular level TCAs, such as imipramine and amitriptyline, and antipsychotics, such as thioridazine, are associated with inhibition of potassium channels encoded by In many cases this cellular action correlates with ECG changes and a risk of TdP. However, not all psychotropic agents that inhibit HERG at the cellular level are associated equally with QT prolongation in patients, and the potential for QT prolongation is not always equally correlated with TdP. Differences in risk between classes of psychotropic drugs, and between individual drugs within a class, may result from additional cellular effects of particular agents, which may influence the consequent effects of inhibition of repolarizing potassium current.

Catecholamines and opioid peptides increase in plasma in humans during possession trances

Naturally induced possession trances have been observed in healthy people of many societies. The neurophysiological basis of this phenomenon remains unknown, however, because of the difficulty in accessing subjects in trances due to their sacred context. In the present study, we measured the plasma levels of several neuroactive substances from subjects exhibiting or lacking possession trance characteristics during Balinese dedicatory dramas under natural conditions. The trance group exhibited significant increases in plasma concentrations of noradrenaline, dopamine and beta-endorphin, compared with controls who performed the same actions as the trance group. The present finding suggests that catecholamines and opioid peptides are involved in possession trances.

Alpha-1-adrenergic receptors mediate sensorimotor gating deficits produced by intracerebral dizocilpine administration in rats

Prepulse inhibition refers to the inhibition by a weak prepulse of the startle response to an intense stimulus. Prepulse inhibition is thought to provide an operational measure of sensorimotor gating, a putative central inhibitory process by which an organism filters information from its environment. Prepulse inhibition deficits are observed in schizophrenia patients and in rats treated with psychotomimetic compounds, such as the non-competitive N-methyl-D-aspartate antagonists phencyclidine or dizocilpine maleate. In rats, phencyclidine-induced prepulse inhibition deficits are blocked by clozapine, olanzapine and quetiapine, which are multireceptor antagonists and atypical antipsychotics, or by prazosin, which is a selective alpha1-adrenergic antagonist. The dorsal hippocampus and amygdala are two of the brain regions shown to contribute to the disruption of prepulse inhibition produced by non-competitive N-methyl-D-aspartate antagonists. The present study tested the hypotheses that quetiapine or prazosin would prevent deficits in prepulse inhibition produced by dizocilpine infusion into the dorsal hippocampus or amygdala. In separate groups of rats, either quetiapine (0 or 5.0 mg/kg, s.c.) or prazosin (0 or 1.0 mg/kg, i.p.) was administered 15 min prior to bilateral infusion of dizocilpine (0 or 6.25 microg/0.5 microl/side) into either the dorsal hippocampus or amygdala. Rats were placed into startle chambers immediately after intracerebral drug infusion and prepulse inhibition was assessed. Confirming previous studies, prepulse inhibition was decreased after either intra-dorsal hippocampus or intra-amygdala infusions of dizocilpine. Both quetiapine and prazosin blocked the prepulse inhibition deficits produced by intracranial dizocilpine administration. Startle reactivity was increased by dizocilpine infusion into either region; these effects were not blocked by either quetiapine or prazosin. These results indicate that non-competitive N-methyl-D-aspartate antagonists may disrupt sensorimotor gating via actions within the dorsal hippocampus or amygdala, and that alpha1-adrenergic receptors distal to these sites might mediate this effect.

Plasma 3-methoxy-4-hydroxyphenylglycol and homovanillic acid measurements in deficit and nondeficit forms of schizophrenia

BACKGROUND

Discrepancies in the biochemical research on negative symptoms in schizophrenia may be ascribed to the lack of differentiation into primary and secondary negative symptoms. We have used Carpenter's criteria to define the deficit syndrome of schizophrenia as the presence of enduring and primary negative symptoms and measured catecholaminergic parameters in deficit as compared with nondeficit schizophrenics.

METHODS

We have investigated plasma homovanillic acid (pHVA) and 3-methoxy-4-hydroxyphenylglycol (pMHPG) concentrations in 34 DSM-III-R neuroleptic-treated schizophrenic patients who were classified into deficit (n = 14) and nondeficit (n = 20) forms of schizophrenia. All these patients were in a stable clinical and therapeutic status for the preceding 12 months.

RESULTS

The 14 deficit schizophrenic patients had lower plasma levels of pHVA and higher plasma concentrations of pMHPG from 9 AM to 12 AM as compared with the 20 nondeficit schizophrenic patients. The two groups did not differ on any demographic, therapeutic, or clinical variable considered.

CONCLUSIONS

Our data are consistent with the postulated distinct pathophysiological basis for the deficit syndrome of schizophrenia and suggest that opposite alterations in the pHVA or pMHPG levels may reflect specific changes in noradrenergic and dopaminergic functions in these deficit patients.

First-episode neuroleptic-free schizophrenics: concentrations of monoamines and their metabolites in plasma and their correlations with clinical responses to haloperidol treatment

Thirty-two first-episode neuroleptic-free schizophrenics were treated with neuroleptics for 8 weeks. The monoamines and their metabolites, dopamine, norepinephrine, serotonin, homovanillic acid (HVA), 3-methoxy-4-hydroxy-phenylglycol(MHPG), and 5-hydroxyindoleacetic acid (5-HIAA) in plasma were measured to examine the association with treatment responses and psychopathology assessed according to the brief psychiatry rating scale (BPRS). No differences were noted in the pretreatment concentrations of monoamines and their metabolites between patients and healthy controls; however, during treatment the concentrations of HVA and MHPG were significantly reduced only in the schizophrenics who responded to treatment. Moreover, the HVA and MHPG reductions correlated significantly with improvements in BPRS scores. Since their plasma levels reflect to some extent central dopaminergic and noradrenergic activities, respectively, the present findings suggest the involvement of these systems in the pathogenesis of schizophrenia as well as the usefulness of such measurements as predictors of responsiveness to neuroleptics.

CSF of neuroleptic-naive first-episode schizophrenic patients: levels of biogenic amines, substance P, and peptides derived from chromogranin A (GE-25) and secretogranin II (secretoneurin)

Lumbar cerebrospinal fluid (CSF) was collected from controls and neuroleptic-naive patients with their first acute schizophrenic episode. The CSF was analyzed for several biogenic amines and their metabolites [dopamine,dihydroxyphenylacetic acid (DOPAC), noradrenaline, 5-hydroxytryptamine (5-HT), 5-hydroxyindolacetic acid (5-HIAA)]. For these transmitters, which are stored and secreted from synaptic vesicles, there was no significant difference between controls and schizophrenic patients. As constituents of large dense-core vesicles substance P (SP) and GE-25 (derived from chromogranin A)-and secretoneurin (derived from secretogranin 11)-immunoreactivities were determined. SP-like immunoreactivity levels did not differ between controls and patients; however, GE-25 was elevated and especially the GE-25/secretoneurin ratio was significantly (p < .001) higher in patients. Characterization of the immunoreactivities by high-performance liquid chromatography did not reveal any difference between patients (n = 3) and controls in the processing of the two proproteins chromogranin A and secretogranin II. These data indicate that proteolytic processing of the two widespread constituents of large dense-core vesicles, i.e., chromogranin A and secretogranin II, is not altered in schizophrenic patients. The increase in the chromogranin A /secretoneurin ratio in schizophrenic patients deserves further investigation in order to elucidate its possible pathogenetic significance.

A study of enzymes involved in catecholamine metabolism in parents of patients with schizophrenia

The concentrations of serum homovanillic acid (HVA), norepinephrine (NE), tyrosine (Tyr), phenylalanine (Phe) and tryptophan (Trp), and the activities of serum dopamine-beta-hydroxylase (DBH), platelet monoamine oxidase (MAO), and erythrocyte catechol-O-methyl transferase (COMT) were measured in 68 healthy parents who had schizophrenic offspring. The results show a significant correlation between the parents of schizophrenic patients in serum HVA (r=0.38, n=34, p<0.05), NE (r=0.40, n=33, p<0.02), Phe (r=0.44, n=34, p<0.0l), Tyr (r=0.43, n = 34, p <0.02) and DBH activity (r=0.51, n = 30, p <0.005), but do not show a significant correlation in erythrocyte COMT (r=0.01, n=27), platelet MAO (r=0.04, n=23) or serum Trp (r=0.10, n=34). There were no significant correlations in these measurements between randomly matched parents. The present study suggests that both parental sides of schizophrenic patients are likely to have similar alleles associated with the catecholamine pathway, and their ill offspring may possess a double dose of the schizophrenogenic alleles.

Positron emission tomography and plasma biochemistry findings in schizophrenic patients before and after electroconvulsive therapy

The clinical effects of electroconvulsive therapy (ECT) on the morbidity of paranoid schizophrenic patients were assessed by positron emission tomography (PET) and plasma biochemistry studies before and after ECT. The present study included five patients whose average age was 41.4 years. The average duration of illness was 23.0 years. To avoid any effect of changes in drugs on PET, no changes were made in the medication of any of the five patients during the study period. ECT improved the clinical symptoms in every patient. Regional cerebral blood flow (rCBF) on PET in both temporal lobes and the left cerebellum was higher in paranoid schizophrenia before ECT than in normal subjects, and rCBF after ECT in both frontal lobes, the right temporal lobe and the right putamen was lower than before ECT as mental symptoms improved. These findings suggest high cerebral blood flow volume in paranoid schizophrenia. Plasma biochemistry studies revealed a lower level of 3-methoxy-4-hydroxyphenylglycol (MHPG) after ECT than before ECT, but a higher level of prolactin existed.

Noradrenergic and dopaminergic interrelation in schizophrenia

Growth hormone (GH) and prolactin (PRL) responses to the acute administration of clonidine (150 micrograms) and apomorphine (0.5 mg) were investigated in parallel in 20 drug-free subchronic and chronic schizophrenic patients and in nine control subjects. Neither basal levels of the two hormones nor their mean responses to both stimuli differed significantly between the two groups. However, eight patients had blunted GH responses to clonidine and seven to apomorphine; only two patients showed blunted GH responses to both stimuli. The blunted GH response to apomorphine correlated with the chronicity of the disorder. A greater than normal GH response to clonidine stimulation was observed in paranoid patients. Significant correlations were observed between negative symptoms and GH responses to clonidine (negative), between negative symptoms and PRL responses to apomorphine (positive), and between positive symptoms and PRL responses to apomorphine (negative).

Acute effects of neuroleptics on unmedicated schizophrenic patients and controls

Acute administration of haloperidol (0.2 mg/kg) produced many more side effects in normal controls than in unmedicated schizophrenic patients. Prior to the neuroleptic challenge, both groups were on the peripheral monoamine oxidase inhibitor, debrisoquin, for at least 1 week, in order to enhance the relative contribution of CNS catecholamine metabolites to those measured in both plasma and urine. The patient group had higher plasma levels of methoxyhydroxyphenylglycol (MHPG) and homovanillic acid (HVA) and higher urinary MHPG output than controls, but there were no effects of haloperidol challenge, compared to placebo challenge. In both groups there were significant declines in plasma HVA levels from 8:30 AM to 12 NOON. These declines were unaffected by the haloperidol challenge. Explanations for the marked differences in behavioral effects of haloperidol on patients and controls include the possibility that dopamine receptor numbers were increased in the brains of the schizophrenic patients.