Catechol-O-methyltransferase gene regulation in rat frontal cortex

The effects of Korean Red Ginseng on stress-related neurotransmitters and gene expression: A randomized, double-blind, placebo-controlled trial

Background

Korean Red Ginseng (KRG) is an effective anti-stress treatment. In this study, we investigated the therapeutic potential effects of KRG on relieving stress in a general population using transcriptome analysis.

Methods

We conducted an 8-week clinical pilot study on 90 healthy men who reported stress. The study was completed by 43 participants in the KRG group and 44 participants in the placebo group. Participants were randomized 1:1 to the KRG and placebo groups. We evaluated the stress by stress response inventory (SRI) at baseline and 8 weeks. The main outcomes were changes in the levels of neurotransmitters (NTs) and NT-related gene expression. NTs were analyzed using automated (GC) content, and levels of gene expression were measured by reads per kilobase of transcript per million mapped reads (RPKM).

Results

The KRG group showed significantly preserved epinephrine decrease compared with placebo group at 8 weeks (changes in epinephrine, KRG vs. placebo; -1623.2 ± 46101.5 vs. -35116.3 ± 86288.2, p = 0012). Among subjects who higher SRI score, meaning stress increased compared to baseline, the KRG group showed a smaller decrease in serotonin than the placebo group (changes in serotonin, KRG vs. placebo; -2627.5 ± 5859.1 vs, -8087.4 ± 7162.4, p = 0.005) and a smaller increase in cortisol than the placebo group (changes in cortisol, KRG vs. placebo; 1912.7 ± 10097.75 vs. 8046.2 ± 8050.6 , p = 0.019) in subgroup analysis. Transcriptome findings indicated that KRG intake affects gene expression related with metabolism of choline, adrenalin, and monoamine.

Conclusion

These findings suggest that KRG has beneficial effects on the amelioration of stress response in NTs, and this effect is more prominent in stressful situations. Further clinical studies are required to confirm the anti-stress effect of KRG.

Risperidone induces long-lasting changes in the conditioned avoidance response and accumbal gene expression selectively in animals treated as adolescents

Adolescence is a period of dynamic remodeling and maturation in the brain. Exposure to psychotropic drugs during adolescence can potentially alter neural maturation in the adolescent brain subsequently altering neural function at maturity. In this regard, antipsychotic drugs (APDs) are important given a notable global increase in prescription of these APDs to adolescents for a variety of behavioural symptoms and conditions over the past twenty years. However, there is a paucity of data on the long-term consequences of APDs on the adolescent brain. In this preclinical study, we have examined whether the adolescent brain is more susceptible than the adult brain to long-term neural changes induced by risperidone, which is the APD most frequently prescribed to adolescents. Rats were chronically treated (21 days) with 1.3 mg/kg/day risperidone or vehicle either as adolescents (postnatal day (PND) 36-56)) or adults (PND80-100). Behaviour was assessed using the well-described suppression of the conditioned avoidance response (CAR) by APDs. We examined CAR after all animals had reached maturity (PND127). We show that mature rats treated with risperidone as adolescents had increased CAR suppression compared to adults when rechallenged with this same drug. In the nucleus accumbens, significant downregulation of serotonergic 5HT2A receptors and catechol-o-methyl transferase mRNA levels was observed only in the adolescent treated animals. Impaired 5HT2A receptor signaling may explain the increased CAR suppression observed in rats treated with risperidone as adolescents. Magnetic resonance imaging (MRI), however, did not detect any risperidone-induced long-term brain structural change at maturity. These findings confirm that APD administration during adolescence may produce long-term behavioural and neurochemical alterations.

The neurobiology of bipolar disorder: identifying targets for specific agents and synergies for combination treatment

Bipolar disorder (BD) is a chronic psychiatric illness described by severe changes in mood. Extensive research has been carried out to understand the aetiology and pathophysiology of BD. Several hypotheses have been postulated, including alteration in genetic factors, protein expression, calcium signalling, neuropathological alteration, mitochondrial dysfunction and oxidative stress in BD. In the following paper, we will attempt to integrate these data in a manner which is to understand targets of treatment and how they may be, in particular, relevant to combination treatment. In summary, the data suggested that BD might be associated with neuronal and glial cellular impairment in specific brain areas, including the prefrontal cortex. From molecular and genetics: (1) alterations in dopaminergic system, through catechol-O-aminotransferase; (2) decreased expression and polymorphism on brain-derived neurotrophic factor; (3) alterations cyclic-AMP responsive element binding; (4) dysregulation of calcium signalling, including genome-wide finding for voltage-dependent calcium channel α-1 subunit are relevant findings in BD. Future studies are now necessary to understand how these molecular pathways interact and their connection to the complex clinical manifestations observed in BD.

Metabolic syndrome in patients taking clozapine: prevalence and influence of catechol-O-methyltransferase genotype

RATIONALE

Metabolic syndrome (MetS) has consistently been identified as an adverse effect of long-term treatment with atypical antipsychotics (AAPs) such as clozapine. Elevated serum homocysteine concentration has been found to act as an independent risk factor for MetS, and catechol-O-methyltransferase (COMT) catalyzes the homocysteine metabolism. We accordingly hypothesized that COMT dysregulation may confer the susceptibility to MetS induced by AAPs, potentially in a gender-specific manner, because the interaction effects of COMT and gender have been consistently reported.

OBJECTIVES

This study aimed at determining the prevalence and influence of COMT on MetS among a population undergoing long-term clozapine treatment.

METHODS

A total of 468 schizophrenia patients taking clozapine were divided into two groups, those experiencing MetS and non-MetS. We genotyped three functional variants (rs4633, rs4680, and rs4818) in COMT and measured the serum levels of fasting homocysteine, glucose, triglyceride (TG), and high-density lipoprotein cholesterol.

RESULTS

MetS was found in 202/468 (43.2 %) of all the patients, with 40.2 % prevalence (138/343) in males and 51.2 % (64/125) in females. Patients with MetS had notably higher metabolic parameters than those without MetS. The mean levels of homocysteine in patients with MetS were significantly higher than those without MetS. We found a positive association between the rs4680 polymorphism and the serum triglyceride levels (corrected P = 0.024). Further analysis revealed that the rs4680 Met allele was significantly associated with increased triglyceride levels among female patients (P = 0.009), but not among males (P = 0.07).

CONCLUSIONS

Our findings suggest a potential association between rs4680 in COMT and elevated TG levels, particularly among female patients.

Comparative gene expression study of the chronic exposure to clozapine and haloperidol in rat frontal cortex

Antipsychotic drugs (APDs) are effective in treating some of the positive and negative symptoms of schizophrenia. APDs take time to achieve a therapeutic effect which suggests that changes in gene expression are involved in their efficacy. We hypothesized that there would be altered expression of specific genes associated with the etiology or treatment of schizophrenia in frontal cortex of rats that received chronic treatment with a typical APD (haloperidol) vs. an atypical APD (clozapine). Rats were administered clozapine, haloperidol, or sterile saline intraperitoneally daily for 21days. Frontal cortices from clozapine-, haloperidol-, and saline-treated rats were dissected and subjected to microarray analysis. We observed a significant (1.5 fold, p<0.05) downregulation of 278 genes and upregulation of 73 genes in the clozapine-treated brains vs. controls and downregulation of 451 genes and upregulation of 115 genes in the haloperidol-treated brains vs. control. A total of 146 genes (130 downregulated and 16 upregulated) were significantly altered by both clozapine and haloperidol. These genes were classified by functional groups. qRT-PCR (quantitative real-time polymerase chain reaction) analysis verified the direction and magnitude of change for a group of nine genes significantly altered by clozapine and 11 genes significantly altered by haloperidol. Three genes verified by qRT-PCR were altered by both drugs: Bcl2-like 1 (Bcl2l1), catechol-O-methyltransferase (Comt), and opioid-binding protein/cell adhesion molecule-like (Opcml). Our results show that clozapine and haloperidol cause changes in levels of many important genes that may be involved in etiology and treatment of schizophrenia.

Erythrocytes catechol-o-methyl transferase activity is up-regulated after a 3-month treatment by entacapone in parkinsonian patients

OBJECTIVES

Entacapone is a highly potent, reversible, peripherally acting catechol-O-methyl transferase (COMT) inhibitor that is used as an adjunct to L-dopa in the treatment of patients with Parkinson disease (PD). Nevertheless, the consequence of the long-lasting inhibition of COMT by entacapone has never been investigated. We assessed the variation of the soluble red blood cell (S-RBC)-COMT activity after 3 months of chronic treatment by entacapone.

METHODS

Twelve consecutive white PD patients (3 women and 9 men; mean age, 65.7 ± 2.4 years) with L-dopa-related motor fluctuations were assessed. Entacapone 200 mg was given in combination with each scheduled L-dopa/dopa decarboxylase inhibitor dose (range, 3-5 doses daily). The S-RBC-COMT activity was determined both before entacapone administration (baseline) and twice, respectively, after 1 and 3 months treatment with entacapone, that is, on morning, after at least a 12-hour withdrawal of entacapone and L-dopa and before the following first daily administration.

RESULTS

Mean baseline S-RBC-COMT activity was 0.72 ± 0.09 pmol/min per milligram (range, 0.30-1.29 pmol/min per milligram) of protein. After 3 months, the level increased significantly in all PD patients from 0.72 ± 0.09 pmol/min per milligram (range, 0.30-1.29 pmol/min per milligram) to 1.19 ± 0.13 pmol/min per milligram (range, 0.58-2.14 pmol/min per milligram) of protein (P < 0.01), which corresponds to a mean increase of 72.9 ± 9.2% (range, 24%-146%).

CONCLUSIONS

Our findings suggest that a long-lasting inhibition of the COMT may limit the efficacy of entacapone by development of a tolerance. Moreover, one may assume that an abrupt withdrawal of the treatment will be followed by a dramatic worsening of motor disability.

The catechol-O-methyltransferase gene: its regulation and polymorphisms

The catechol-O-methyltransferase (COMT) gene is of significant interest to neuroscience, due to its role in modulating dopamine function. COMT is dynamically regulated; its expression is altered during normal brain development and in response to environmental stimuli. In many cases the underlying molecular basis for these effects is unknown; however, in some cases (e.g., estrogenic regulation in the case of sex differences) regulatory mechanisms have been identified. COMT contains several functional polymorphisms and haplotypes, including the well-studied Val158Met polymorphism. Here I review the regulation of COMT and the functional polymorphisms within its sequence with respect to brain function.

The role of lithium in modulation of brain genes: relevance for aetiology and treatment of bipolar disorder

Bipolar disorder is a debilitating disorder of the brain with a lifetime prevalence of 1.0% for bipolar I, 1.1% for bipolar II disorder and 2.4-4.7% for subthreshold bipolar disorder. Medications, including lithium, have demonstrated efficacy in the treatment of bipolar disorder, but their molecular targets and mode of action are largely unknown. A few studies have begun to shed light on potential targets of lithium treatment that may be involved in lithium's therapeutic effect. We have recently conducted a microarray study of rat frontal cortex following chronic treatment (21 days) with lithium. Chronic treatment with lithium led to a significant (at least 1.5-fold) down-regulation of 151 genes and up-regulation of 57 genes. We discuss our results in the context of previous microarray studies involving lithium and gene-association studies to identify key genes associated with chronic lithium treatment. A number of genes associated with bipolar disorder, including Comt (catechol-O-methyltransferase), Vapa (vesicle-associated membrane protein-associated protein A), Dtnb (dystrobrevin beta) and Pkd1 (polycystic kidney disease 1), were significantly altered in our microarray dataset along with genes associated with synaptic transmission, apoptosis and transport among other functions.

The role of cerebellar genes in pathology of autism and schizophrenia

Schizophrenia and autism are neurodevelopmental diseases that have genetic as well as environmental etiologies. Both disorders have been associated with prenatal viral infection. Brain imaging and postmortem studies have found alterations in the structure of the cerebellum as well as changes in gene expression. Our laboratory has developed an animal model using prenatal infection of mice with human influenza virus that has demonstrated changes in behavior, pharmacology, structure, and gene expression in the brains of exposed offspring. In the current communication we describe altered expression of cerebellar genes associated with development of brain disorder in a mouse model for schizophrenia and autism and correlate these changes with those involved in the pathology of these two disorders.

The neurodevelopmental hypothesis of schizophrenia, revisited

While multiple theories have been put forth regarding the origin of schizophrenia, by far the vast majority of evidence points to the neurodevelopmental model in which developmental insults as early as late first or early second trimester lead to the activation of pathologic neural circuits during adolescence or young adulthood leading to the emergence of positive or negative symptoms. In this report, we examine the evidence from brain pathology (enlargement of the cerebroventricular system, changes in gray and white matters, and abnormal laminar organization), genetics (changes in the normal expression of proteins that are involved in early migration of neurons and glia, cell proliferation, axonal outgrowth, synaptogenesis, and apoptosis), environmental factors (increased frequency of obstetric complications and increased rates of schizophrenic births due to prenatal viral or bacterial infections), and gene-environmental interactions (a disproportionate number of schizophrenia candidate genes are regulated by hypoxia, microdeletions and microduplications, the overrepresentation of pathogen-related genes among schizophrenia candidate genes) in support of the neurodevelopmental model. We relate the neurodevelopmental model to a number of findings about schizophrenia. Finally, we also examine alternate explanations of the origin of schizophrenia including the neurodegenerative model.