Lifetime cannabis use and childhood trauma associated with CNR1 genetic variants increase the risk of psychosis: findings from the STREAM study

OBJECTIVES

Gene-environment interactions increase the risk of psychosis. The objective of this study was to investigate gene-gene and gene-environment interactions in psychosis, including single nucleotide variants (SNVs) of dopamine-2 receptor (D2R), N-methyl-d-aspartate receptor (NMDAR), and cannabinoid receptor type 1 (CB1R), lifetime cannabis use, and childhood trauma.

METHODS

Twenty-three SNVs of genes encoding D2R (DRD2: rs1799978, rs7131056, rs6275), NMDAR (GRIN1: rs4880213, rs11146020; GRIN2A: rs1420040, rs11866328; GRIN2B: rs890, rs2098469, rs7298664), and CB1R (CNR1: rs806380, rs806379, rs1049353, rs6454674, rs1535255, rs2023239, rs12720071, rs6928499, rs806374, rs7766029, rs806378, rs10485170, rs9450898) were genotyped in 143 first-episode psychosis patients (FEPp) and 286 community-based controls by Illumina HumanCoreExome-24 BeadChip. Gene-gene and gene-environment associations were assessed using nonparametric Multifactor Dimensionality Reduction software.

RESULTS

Single-locus analyses among the 23 SNVs for psychosis and gene-gene interactions were not significant (p > 0.05 for all comparisons); however, both environmental risk factors showed an association with psychosis (p < 0.001). Moreover, gene-environment interactions were significant for an SNV in CNR1 and cannabis use. The best-performing model was the combination of CNR1 rs12720071 and lifetime cannabis use (p < 0.001), suggesting an increased risk of psychosis.

CONCLUSION

Our study supports the hypothesis of gene-environment interactions for psychosis involving T-allele carriers of CNR1 SNVs, childhood trauma, and cannabis use.

Methylation Status of Exon IV of the Brain-Derived Neurotrophic Factor (BDNF)-Encoding Gene in Patients with Non-Diabetic Hyperglycaemia (NDH) before and after a Lifestyle Intervention

BDNF signalling in hypothalamic neuronal circuits is thought to regulate mammalian food intake. In light of this, we investigated how a lifestyle intervention influenced serum levels and DNA methylation of BDNF gene in fat tissue and buffy coat of NDH individuals. In total, 20 participants underwent anthropometric measurements/fasting blood tests and adipose tissue biopsy pre-/post-lifestyle (6 months) intervention. DNA was extracted from adipose tissue and buffy coat, bisulphite converted, and pyrosequencing was used to determine methylation levels in exon IV of the BDNF gene. RNA was extracted from buffy coat for gene expression analysis and serum BDNF levels were measured by ELISA. No differences were found in BDNF serum levels, but buffy coat mean BDNF gene methylation decreased post-intervention. There were correlations between BDNF serum levels and/or methylation and cardiometabolic markers. (i) Pre-intervention: for BDNF methylation, we found positive correlations between mean methylation in fat tissue and waist-hip ratio, and negative correlations between mean methylation in buffy coat and weight. (ii) Post-intervention: we found correlations between BDNF mean methylation in buffy coat and HbA1c, BDNF methylation in buffy coat and circulating IGFBP-2, and BDNF serum and insulin. Higher BDNF % methylation levels are known to reduce BNDF expression. The fall in buffy coat mean BDNF methylation plus the association between lower BDNF methylation (so potentially higher BDNF) and higher HbA1c and serum IGFBP-2 (as a marker of insulin sensitivity) and between lower serum BDNF and higher circulating insulin are evidence for the degree of BDNF gene methylation being implicated in insulinisation and glucose homeostasis, particularly after lifestyle change in NDH individuals.

Subchronic PCP effects on DNA methylation and protein expression of NMDA receptor subunit genes in the prefrontal cortex and hippocampus of female rats

BACKGROUND

N-methyl-d-aspartate receptor (NMDAR) dysfunction is implicated in schizophrenia, and NMDAR antagonists, such as phencyclidine (PCP), can induce behaviours that mimic aspects of the disorder.

AIMS

We investigated DNA methylation of Grin1, Grin2a and Grin2b promoter region and NR1 and NR2 protein expression in the prefrontal cortex (PFC) and hippocampus of adult female Lister-hooded rats following subchronic PCP (scPCP) administration. We also determined whether any alterations were tissue-specific.

METHODS

Rats were divided into two groups that received vehicle (0.9% saline) or 2 mg/kg PCP twice a day for 7 days (n = 10 per group). After behavioural testing (novel object recognition), to confirm a cognitive deficit, brains were dissected and NMDAR subunit DNA methylation and protein expression were analysed by pyrosequencing and ELISA. Line-1 methylation was determined as a measure of global methylation. Data were analysed using Student's t-test and Pearson correlation.

RESULTS

The scPCP administration led to Grin1 and Grin2b hypermethylation and reduction in NR1 protein in both PFC and hippocampus. No significant differences were observed in Line-1 or Grin2a methylation and NR2 protein.

CONCLUSIONS

The scPCP treatment resulted in increased DNA methylation at promoter sites of Grin1 and Grin2b NMDAR subunits in two brain areas implicated in schizophrenia, independent of any global change in DNA methylation, and are similar to our observations in a neurodevelopmental animal model of schizophrenia - social isolation rearing post-weaning. Moreover, these alterations may contribute to the changes in protein expression for NMDAR subunits demonstrating the potential importance of epigenetic mechanisms in schizophrenia.

Changes of BDNF exon IV DNA methylation are associated with methamphetamine dependence

Aim: We investigated DNA methylation of BDNF in methamphetamine (METH) dependence in humans and an animal model. Materials & methods: BDNF methylation at exon IV was determined by pyrosequencing of blood DNA from METH-dependent and control subjects, and from rat brain following an escalating dose of METH or vehicle. Bdnf expression was determined in rat brain. Results: BDNF methylation was increased in human METH dependence, greatest in subjects with psychosis and in prefrontal cortex of METH-administered rats; rat hippocampus showed reduced Bdnf methylation and increased gene expression. Conclusion: BDNF methylation is abnormal in human METH dependence, especially METH-dependent psychosis, and in METH-administered rats. This may influence BDNF expression and contribute to the neurotoxic effects of METH exposure.

The relationship of childhood trauma and DNA methylation of NMDA receptor genes in first-episode schizophrenia

Aim: We investigated GRIN1, GRIN2A, GRIN2B and LINE-1 DNA methylation in first-episode schizophrenia patients, their nonaffected siblings and age- and sex-matched controls testing for associations between DNA methylation and exposition to childhood trauma. Materials & methods: The Childhood Trauma Questionnaire evaluated the history of childhood trauma. Genomic DNA was bisulfite converted and pyrosequencing was employed to quantify DNA methylation. Results: GRIN2A, GRIN2B and LINE-1 DNA methylation was not associated with childhood trauma in patients, siblings and controls. Siblings with childhood trauma had hypermethylation at CpG1 of GRIN1 compared with siblings without trauma. Conclusion: Childhood trauma may influence GRIN1 methylation in subjects with liability to psychosis, but not in frank schizophrenia or controls.

Circulating microRNA changes in patients with impaired glucose regulation

We analysed if levels of four miRNAs would change after a lifestyle intervention involving dietary and exercises in prediabetes. MiRNAs previously shown to be associated with diabetes (Let-7a, Let-7e, miR-144 and miR-92a) were extracted from serum pre- and post-intervention. mRNA was extracted from fat-tissue for gene expression analyses. The intervention resulted in increased Let-7a and miR-92a. We found correlations between miRNAs and clinical variables (triglycerides, cholesterol, insulin, weight and BMI). We also found correlations between miRNAs and target genes, revealing a link between miR-92a and IGF system. A lifestyle intervention resulted in marked changes in miRNAs. The association of miRNAs with insulin and the IGF system (both receptors and binding proteins) may represent a mechanism of regulating IGFs metabolic actions.

Lifestyle intervention in individuals with impaired glucose regulation affects Caveolin-1 expression and DNA methylation

Aims: We investigated whether a lifestyle intervention could influence expression and DNA methylation of diabetes-related genes in patients with impaired glucose regulation (IGR), the results were compared to bariatric surgery, considering it an intensive change. Methods: Twenty participants with IGR had adipose tissue biopsy and blood collected pre- and post-lifestyle (6 months) intervention; 12 obese patients had subcutaneous fat taken before and after bariatric surgery. RNA/DNA was extracted from all samples and underwent qPCR. DNA was bisulphite converted and 12 CpG sites of Caveolin-1 (CAV1) promoter were pyrosequenced. Results: lifestyle intervention resulted in opposite direction changes in fat tissue and blood for CAV1 expression and DNA methylation and these changes were correlated between tissues, while no significative differences were found in CAV1 expression after bariatric surgery. Conclusions: Our findings suggest a role for CAV1 in modulating adipocyte function as a consequence of lifestyle changes, as exercises and diet. These results may provide insights into new therapeutic targets for diabetes prevention.

Epigenetic-mediated N-methyl-D-aspartate receptor changes in the brain of isolated reared rats

Aim: We investigated: Grin1, Grin2a, Grin2b DNA methylation; NR1 and NR2 mRNA/protein in the prefrontal cortex (PFC); and hippocampus of male Wistar rats exposed to isolation rearing. Materials & methods: Animals were kept isolated or grouped (n = 10/group) from weaning for 10 weeks. Tissues were dissected for RNA/DNA extraction and N-methyl-D-aspartate receptor subunits were analyzed using quantitative reverse transcription (RT)-PCR, ELISA and pyrosequencing. Results: Isolated-reared animals had: decreased mRNA in PFC for all markers, increased NR1 protein in hippocampus and hypermethylation of Grin1 in PFC and Grin2b in hippocampus, compared with grouped rats. Associations between mRNA/protein and DNA methylation were found for both brain areas. Conclusion: This study indicates that epigenetic DNA methylation may underlie N-methyl-D-aspartate receptor mRNA/protein expression alterations caused by isolation rearing.

CACNA1C methylation: association with cortisol, perceived stress, rs1006737 and childhood trauma in males

Aim: We investigated morning cortisol, stress, rs1006737 and childhood trauma relationship with CACNA1C methylation. Materials & methods: Morning cortisol release, childhood trauma and perceived stress were collected and genotyping for rs1006737 conducted in 103 adult males. Genomic DNA extracted from saliva was bisulphite converted and using pyrosequencing methylation determined at 11 CpG sites within intron 3 of CACNA1C. Results: A significant negative correlation between waking cortisol and overall mean methylation was found and a positive correlation between CpG5 methylation and perceived stress. Conclusion: CACNA1C methylation levels may be related to cortisol release and stress perception. Future work should evaluate the influence of altered CACNA1C methylation on stress reactivity to investigate this as a potential mechanism for mental health vulnerability.

Association of the leptin receptor Q223R (rs1137101) polymorphism with obesity measures in Sri Lankans

Objective

The role of genetic factors in the development of obesity is largely unreported in Sri Lankans. The Q223R (rs1137101) single nucleotide polymorphism (SNP) of the leptin receptor (LEPR) gene has been associated with obesity measures in various ethnicities. We investigated the association of the Q223R polymorphism with obesity related anthropometric measures and biochemical parameters fasting blood glucose and lipid profile in a sample of 530 Sri Lankan adult subjects (age 18–70 years) representing both urban and rural areas of residence.

Results

The LEPR Q223R variant G allele frequency was 0.54. The polymorphism was associated with body mass index (p = 0.04) and waist circumference (p = 0.02) measures in overweight and obese (BMI ≥ 25 kgm⁻²) subjects with the variant allele conferring a greater risk of adiposity. Residency in urban areas eliminated the protective effect of the non-risk genotype (AA) in the development of obesity.

Neurotransmitter selection by monoamine oxidase isoforms, dissected in terms of functional groups by mixed double mutant cycles

Double mutant cycles were constructed using neurotransmitters and synthetic substrates that measure their selective binding to one monoamine oxidase (MAO) enzyme isoform over another as a function of structural change. This work measures a reduction in selectivity for the MAOB isoform of 3 to 9.5 kJ mol^-1 upon the addition of hydroxy functional groups to a phenethylamine scaffold. Replacement of hydroxy functional groups on the phenethylamine scaffold by hydrophobic substituents measures an increase in selectivity for MAOB of -1.1 to -6.9 kJ mol^-1. The strategies presented here can be applied to the development of competitive reversible inhibitors of MAO enzymes and other targets with structurally related isoforms.

Association of SLC1A2 and SLC17A7 polymorphisms with major depressive disorder in a Thai population

Background

Major depressive disorder (MDD) is a common psychiatric disorder with high prevalence and high risk of suicide. Genetic variation of glutamate transporters may associate with MDD and suicide attempt.

Objectives

To evaluate polymorphisms of excitatory amino acid transporter 2 gene (SLC1A2; rs752949, rs1885343, rs4755404, and rs4354668) and vesicular glutamate transporter 1 gene (SLC17A7; rs1043558, rs2946848, and rs11669017) in patients with MDD with and without suicide attempt, and determine the association of these polymorphisms with age of onset and severity of MDD.

Methods

DNA was extracted from blood taken from patients with MDD (n = 100; including nonsuicidal [n = 50] and suicidal [n = 50] subgroups) and controls (n = 100). Genotyping was conducted using TaqMan single-nucleotide polymorphism (SNP) genotyping.

Results

We found a significant difference in SLC17A7 rs2946848 genotype distribution between patients in the MDD and control groups (P = 0.016). Moreover, significant differences in SLC1A2 rs752949 (P = 0.022) and SLC17A7 rs2946848 (P = 0.026) genotype distributions were observed between patients in the nonsuicidal MDD and suicidal MDD groups. SLC1A2 rs1885343 A allele carriers showed significantly lower age of onset than GG genotype (P = 0.049). Furthermore, the severity of MDD indicated by the Hamilton Depression Rating Scale (HDRS) score of G allele carriers of SLC1A2 rs4755404 was significantly greater than the CC genotype (P = 0.013).

Conclusions

Polymorphisms of SLC1A2 and SLC17A7 may contribute to the risk of MDD and/or suicide attempt. An association of an SLC1A2 polymorphism with the severity of MDD was apparent.

Adjunctive Lurasidone Suppresses Food Intake and Weight Gain Associated with Olanzapine Administration in Rats

Objective

Lurasidone is an antipsychotic drug that shows a relative lack of weight gain common to many antipsychotics. Aripiprazole and ziprasidone also show little weight gain and can reduce olanzapine-induced food intake and weight gain in animals, paralleling some clinical findings. We hypothesized that lurasidone would have similar actions.

Methods

Female Lister-hooded rats received intraperitoneal injection either 2× vehicle (saline), lurasidone (3 mg/kg) and vehicle, olanzapine (1 mg/kg) and vehicle, or olanzapine and lurasidone. Following drug administration food intake was measured for 60min. A further series of rats underwent a seven-day regime of once-daily administration of the above doses and free access to food and water. Weight gain over the course of the study was monitored.

Results

Olanzapine induced a significant increase in food intake while lurasidone showed no significant effect. Co-administration of lurasidone with olanzapine suppressed the increase in food intake. Repeated dosing showed an increase in body weight after seven days with olanzapine, and no significant effect observed with lurasidone, while repeated administration of lurasidone with olanzapine reduced the effect of olanzapine on the increase in body weight.

Conclusion

These findings support our hypotheses in that lurasidone, in addition to a lack of effect on acute food intake and short term weight gain, can reduce olanzapine-induced food intake and weight gain in rats. This indicates the drug to have an active anti-hyperphagic mechanism, rather than solely the absence of a drug-induced weight gain that is such a severe limitation of drugs such as olanzapine.

Neuromyelitis optica spectrum disorder in three generations of a Chinese family

Neuromyelitis optica spectrum disorder is an inflammatory demyelinating disease that is largely sporadic. Familial disease has been reported in one or two generations, although its basis remains unknown. We report here three subjects meeting diagnostic criteria for NMOSD in one family: a father and son, and the maternal aunt of the father. Anticipation, of 27 years, was apparent in transmission from father to son. Aquaporin-4 antibodies were observed in the aunt but not the father and son, nor in other family members. A putative pathogenic mutation in the NECL2 gene was not found in this pedigree. This first report of NMOSD in three generations of one family underlines the heterogeneity of familial NMOSD.

Recapitulating Parkinson's disease pathology in a three-dimensional human neural cell culture model

Extensive loss of dopaminergic neurons and aggregation of the protein α-synuclein into ubiquitin-positive Lewy bodies represents a major neuropathological hallmark of Parkinson's disease (PD). At present, the generation of large nuclear-associated Lewy bodies from endogenous wild-type α-synuclein, translationally regulated under its own promoter in human cell culture models, requires costly and time-consuming protocols. Here, we demonstrate that fully differentiated human SH-SY5Y neuroblastoma cells grown in three-dimensional cell culture develop Lewy-body-like pathology upon exposure to exogenous α-synuclein species. In contrast to most cell- and rodent-based PD models, which exhibit multiple diffuse α-synuclein aggregates throughout the cytoplasm, a single large nuclear inclusion that is immunopositive for α-synuclein and ubiquitin is rapidly obtained in our model. This was achieved without the need for overexpression of α-synuclein or genetic modification of the cell line. However, phosphorylation of α-synuclein within these inclusions was not observed. The system described here provides an ideal tool to screen compounds to therapeutically intervene in Lewy body formation, and to investigate the mechanisms involved in disease progression in synucleinopathies.

Editor's choice: This study describes a novel 3D cell culture model that recapitulates key features of neuropathology in synucleinopathies, including large, nuclear-associated α-synuclein and ubiquitin-positive inclusions.

GRIN2B promoter methylation deficits in early-onset schizophrenia and its association with cognitive function

Aim: We investigated GRIN1 and GRIN2B promoter methylation in first-episode schizophrenia patients compared with siblings and controls, testing for correlations between DNA methylation, cognitive performance and clinical variables. Materials & methods: Blood-derived DNA from all groups underwent bisulfite conversion and pyrosequencing to determine methylation at CpG sites within the GRIN1 and GRIN2B promoters and results were compared with the measure of global methylation LINE-1.Results: We found hypomethylation among all CpGs analyzed within GRIN2B promoter in patients and greater LINE-1 methylation in patients and siblings. CpG4 was correlated to a measure of intellectual function. Conclusion: Changes in GRIN2B promoter methylation may represent an environmental influence contributing to glutamatergic dysfunction in psychosis and relate to lower cognitive performance in subjects with first-episode schizophrenia.

Parvalbumin Promoter Methylation Altered in Major Depressive Disorder

Aims: To determine the extent of DNA methylation of parvalbumin gene (PVALB) promoter in major depressive disorder (MDD) patients with and without suicide attempt in comparison with healthy controls. Methods: The extracted DNA from dried blood spots of MDD patients (n = 92) including non-suicidal MDD and suicidal-MDD subgroups (n = 45 and n = 47, respectively) and age-matched control subjects (n = 95) was used for DNA methylation analysis at four CpG sites in the promoter sequence of PVALB by pyrosequencing. Results: The PVALB methylation was significantly increased at CpG2 and decreased at CpG4 in the MDD group compared to the control group, while there was no difference between non-suicidal MDD and suicidal-MDD subgroups. A significant inverse correlation of severity of MDD was indicated only for CpG4. Conclusion: This study provides the first evidence of abnormalities of PVALB promoter methylation in MDD and its correlation with MDD severity indicating a role for epigenetics in this psychiatric disorder.

An acute bout of cycling does not induce compensatory responses in pre-menopausal women not using hormonal contraceptives

There is a clear need to improve understanding of the effects of physical activity and exercise on appetite control. Therefore, the acute and short-term effects (three days) of a single bout of cycling on energy intake and energy expenditure were examined in women not using hormonal contraceptives. Sixteen active (n = 8) and inactive (n = 8) healthy pre-menopausal women completed a randomised crossover design study with two conditions (exercise and control). The exercise day involved cycling for 1 h (50% of maximum oxygen uptake) and resting for 2 h, whilst the control day comprised 3 h of rest. On each experimental day participants arrived at the laboratory fasted, consumed a standardised breakfast and an ad libitum pasta lunch. Food diaries and combined heart rate-accelerometer monitors were used to assess free-living food intake and energy expenditure, respectively, over the subsequent three days. There were no main effects or condition (exercise vs control) by group (active vs inactive) interaction for absolute energy intake (P > 0.05) at the ad libitum laboratory lunch meal, but there was a condition effect for relative energy intake (P = 0.004, η_p² = 0.46) that was lower in the exercise condition (1417 ± 926 kJ vs. 2120 ± 923 kJ). Furthermore, post-breakfast satiety was higher in the active than in the inactive group (P = 0.005, η_p² = 0.44). There were no main effects or interactions (P > 0.05) for mean daily energy intake, but both active and inactive groups consumed less energy from protein (14 ± 3% vs. 16 ± 4%, P = 0.016, η_p² = 0.37) and more from carbohydrate (53 ± 5% vs. 49 ± 7%, P = 0.031, η_p² = 0.31) following the exercise condition. This study suggests that an acute bout of cycling does not induce compensatory responses in active and inactive women not using hormonal contraceptives, while the stronger satiety response to the standardised breakfast meal in active individuals adds to the growing literature that physical activity helps improve the sensitivity of short-term appetite control.

Parvalbumin promoter hypermethylation in postmortem brain in schizophrenia

Deficits of brain parvalbumin (PV) are a consistent finding in schizophrenia and models of psychosis. We investigated whether this is associated with abnormal PV gene (PVALB) methylation in the brain in schizophrenia. Bisulfite pyrosequencing was used to determine cytosine (CpG) methylation in a PVALB promoter sequence. Greater PVALB methylation was found in schizophrenia hippocampus, while no differences were observed in prefrontal cortex. LINE-1 methylation, a measure of global methylation, was also elevated in both regions in schizophrenia, although the PVALB change was independent of this effect. These results provide the first evidence that PVALB promoter methylation is abnormal in schizophrenia and suggest that this epigenetic finding may relate to the reduction of PV expression seen in the disease.

Increased DNA methylation in the parvalbumin gene promoter is associated with methamphetamine dependence

Aim: The parvalbumin (PV)-containing subgroup of GABAergic neurons is particularly affected in schizophrenia and animal models of psychosis, including after methamphetamine (METH) administration. We investigated whether METH dependence and METH-induced psychosis may involve an effect on DNA methylation of the PVALB promoter. Materials & methods: The methylation of a PVALB promoter sequence was determined in 100 METH-dependent and 102 control subjects using pyrosequencing. Results: A significant increase in PVALB methylation was observed in METH dependence and METH-induced psychosis. No significant effect on long interspersed nucleotide element-1 methylation, a measure of global DNA methylation, was observed. Conclusion: These results demonstrate a specific association between elevated PVALB methylation and METH-induced psychosis. This finding may contribute to the GABAergic deficits associated with METH dependence.

Copper Binding and Subsequent Aggregation of α-Synuclein Are Modulated by N-Terminal Acetylation and Ablated by the H50Q Missense Mutation

The Parkinson's disease-associated protein α-synuclein exhibits significant conformational heterogeneity. Bacterially expressed α-synuclein is known to bind to copper, resulting in the formation of aggregation-prone compact conformations. However, in vivo, α-synuclein undergoes acetylation at its N-terminus. Here the effect of this modification and the pathological H50Q mutation on copper binding and subsequent conformational transitions were investigated by electrospray ionization-ion mobility spectrometry-mass spectrometry. We demonstrate that acetylation perturbs the ability of α-synuclein to bind copper and that the H50Q missense mutation in the presence of N-terminal acetylation prevents copper binding. These modifications and mutations prevent the formation of the most compact conformations and inhibit copper-induced aggregation.

Subchronic administration of phencyclidine produces hypermethylation in the parvalbumin gene promoter in rat brain

AIM

A deficit in parvalbumin neurons is found in schizophrenia and several animal models of the disease. In this preliminary study, we determined whether one such model, phencyclidine (PCP) administration, results in changes in DNA methylation in the rat Pvalb promoter.

MATERIALS & METHODS

DNA from hippocampus and prefrontal cortex from rats, which 6 weeks previously received either 2 mg/kg PCP or vehicle for 7 days, underwent bisulphite pyrosequencing to determine methylation.

RESULTS

PCP administration induced significantly greater methylation at one of two Pvalb CpG sites in both prefrontal cortex and hippocampus, while no significant difference was found in long interspersed nucleotide element-1, a global measure of DNA methylation.

CONCLUSION

Subchronic PCP administration results in a specific hypermethylation in the Pvalb promoter which may contribute to parvalbumin deficits in this animal model of psychosis.

Pharmacogenomics in psychiatry: the relevance of receptor and transporter polymorphisms

The treatment of severe mental illness, and of psychiatric disorders in general, is limited in its efficacy and tolerability. There appear to be substantial interindividual differences in response to psychiatric drug treatments that are generally far greater than the differences between individual drugs; likewise, the occurrence of adverse effects also varies profoundly between individuals. These differences are thought to reflect, at least in part, genetic variability. The action of psychiatric drugs primarily involves effects on synaptic neurotransmission; the genes for neurotransmitter receptors and transporters have provided strong candidates in pharmacogenetic research in psychiatry. This paper reviews some aspects of the pharmacogenetics of neurotransmitter receptors and transporters in the treatment of psychiatric disorders. A focus on serotonin, catecholamines and amino acid transmitter systems reflects the direction of research efforts, while relevant results from some genome-wide association studies are also presented. There are many inconsistencies, particularly between candidate gene and genome-wide association studies. However, some consistency is seen in candidate gene studies supporting established pharmacological mechanisms of antipsychotic and antidepressant response with associations of functional genetic polymorphisms in, respectively, the dopamine D2 receptor and serotonin transporter and receptors. More recently identified effects of genes related to amino acid neurotransmission on the outcome of treatment of schizophrenia, bipolar illness or depression reflect the growing understanding of the roles of glutamate and γ-aminobutyric acid dysfunction in severe mental illness. A complete understanding of psychiatric pharmacogenomics will also need to take into account epigenetic factors, such as DNA methylation, that influence individual responses to drugs.

Binding of Dopamine to Alpha-Synuclein is Mediated by Specific Conformational States

Parkinson's disease is the second most common neurodegenerative disorder, in which both alpha-synuclein (α-syn) and dopamine (DA) have a critical role. α-Syn is known to be natively unstructured in equilibrium with subpopulations of more compact structures. It is these compact structures that are thought to be linked to amyloid formation. In the presence of DA, α-syn yields a diverse range of SDS-resistant, non-amyloid oligomers, however the precursor state conformation has not been established. Here, three DA molecules have been observed to bind per α-syn monomer by electrospray-ionization-ion mobility spectrometry-mass spectrometry (ESI-IMS-MS). Each of these DA molecules binds exclusively to the extended conformation of α-syn, and binding is not observed in the compact state of the protein. Measurements of collisional cross sectional areas show that the incremental uptake of DA pushes the protein towards a highly extended population, becoming fully populated upon the binding of three DA ligands. Tyrosine (Tyr) as a closely related structural analog, exhibited limited binding to the protein as compared with DA, with a maximum of two ligands being observed. Those Tyr ligands that do bind were observed as adducts to the extended conformation akin to DA. These findings suggest DA is able to modulate α-syn self-assembly by inducing the population of a highly extended state.

Phospholipid fatty acids and neurotoxicity in human neuroblastoma SH-SY5Y cells

The fatty acid composition of phospholipids from differentiated human neuroblastoma SH-SY5Y cells, human and rat brain tissue and rat brain synaptosomes was determined using high pressure liquid chromatography. Comparison of the fatty acid composition of the cells with that derived from brain tissue identified differences in the cells including a profound deficit of docosahexaenoic acid and an elevation of arachidonic acid. The phospholipid fatty acid content could be modified by addition of free fatty acids to the growth medium, and this was shown to influence the susceptibility of the SH-SY5Y cells to the cell death induced by a mitochondrial toxin, 3-nitropropionic acid.

Brain neurotransmitter deficits in mice transgenic for the Huntington's disease mutation

Huntington's disease (HD) is associated with an expansion in the CAG repeat sequence of a gene on chromosome 4, resulting in a neurodegenerative process particularly affecting the striatum and with profound but selective changes in content of various neurotransmitters. Recently, transgenic mice expressing a fragment of the human HD gene containing a large CAG expansion have been generated; these mice exhibit a progressive neurological phenotype that includes motor disturbances, as well as neuronal deficits. To investigate their underlying neurotransmitter pathology, we have determined concentrations of GABA, glutamate, and the monoamine neurotransmitters in several brain regions in these mice and control animals at times before and after the emergence of the behavioural phenotype. In contrast to the findings in HD, striatal GABA was unaffected, although a deficit was observed in the cerebellum, consistent with a dysfunction of Purkinje cells. Losses of the monoamine transmitters were observed, some of which are not seen in HD. Thus, 5-hydroxytryptamine and, to a greater extent, 5-hydroxyindoleacetic acid levels were diminished in all brain regions studied, and noradrenaline was particularly affected in the hippocampus. Dopamine was decreased in the striatum in older animals, parallelling evidence for diminished dopaminergic activity in HD.

Metalloproteinases and tissue inhibitor of metalloproteinase 1 (TIMP-1) in endometrial flushings from pre- and post-menopausal women and from women with endometrial adenocarcinoma

The presence of metalloproteinase activity in endometrial flushings obtained from premenopausal women, during the proliferative and secretory phases of the menstrual cycle, control post-menopausal women and women with post-menopausal bleeding (PMB) with or without adenocarcinoma was analysed by zymography. In addition, quantitative measurements of matrix metalloproteinase 2 (MMP-2), MMP-3, MMP-9 and tissue inhibitor of metalloproteinase 1 (TIMP-1) in the flushings were obtained by ELISA. The zymography results showed eight bands of activity, with molecular weights ranging from 51 to 208 kDa in the flushings from pre-menopausal women and post-menopausal women, particularly those with adenocarcinoma. Both zymography and ELISA showed that MMP-2 and MMP-9 were the major metalloproteinases found in the flushings and only low concentrations of MMP-3 were found. Concentrations of MMP-2 in pre-menopausal women were higher in flushings obtained during the secretory phase of the menstrual cycle than those obtained in the proliferative phase (P < 0.05), suggesting that it may play a role in embryo implantation. Concentrations of MMP-2 (P < 0.001), MMP-9 (P < 0.05) and TIMP-1 (P < 0.001) in the flushings from post-menopausal control women were lower than those from pre-menopausal women. Concentrations of MMP-2 (P < 0.05) and TIMP-1 (P < 0.05) were higher in flushings from women with PMB without carcinoma compared with post-menopausal controls and concentrations of MMP-9 (P < 0.01) and TIMP-1 (P < 0.05) in flushings from women with adenocarcinoma were higher than in post-menopausal controls. Among subjects with PMB, concentrations of MMP-9 in women with adenocarcinoma were higher than those without carcinoma (P < 0.05). Our results show that concentrations of MMP-2, MMP-9 and TIMP-1, but not MMP-3, are associated with endometrial activity and, therefore, may have a role in the breakdown of endometrial tissue. In addition, the increased concentrations of MMP-9 in flushings of women with adenocarcinoma indicate that this particular proteinase is associated with the presence of endometrial neoplastic cells.

Endometrial protein PP14 and CA-125 in recurrent miscarriage patients; correlation with pregnancy outcome

The concentrations of endometrial proteins PP14 and CA-125 were measured in uterine flushings taken on days LH+10 and LH+12 (10 and 12 days after luteinizing hormone surge) of the menstrual cycle from 15 normal, fertile women and 49 women who suffered recurrent miscarriage. The concentration of PP14 was significantly lower in the flushings from the recurrent miscarriage patients than in those from fertile controls on both day LH+10 (median: 1300, range: 3-10 300 ng/ml versus median: 13 933, range: 2174-40 404 ng/ml; P < 0.01) and LH+12 (median: 1560, range: 820-12 100 ng/ml versus median: 14 047, range 1402-62 108 ng/ml; P < 0.05). Similarly concentrations of CA-125 were significantly lower in flushings from recurrent miscarriage women compared to controls on both day LH + 10 (median: 1555, range: 47-6710 U/ml versus median: 6385.5, range 2884-27 731 U/ml, P < 0.01) and LH+12 (median: 2892, range: 956-9974 U/ml versus median: 7127.5, range: 1591-21 343 U/ml; P < 0.05). In contrast there was no significant difference in the concentration of PP14 in plasma samples taken on the same days as the flushings from recurrent miscarriage patients and fertile controls. The concentrations of PP14 in uterine flushings obtained on day LH + 10 or LH + 12 from recurrent miscarriage women during a pre-pregnancy investigative cycle were significantly lower (P < 0.05) in patients who went on to miscarry (median: 1000, range: 9-2900 ng/ml) than those who went on to have a live birth (median: 1440, range: 4-12 100 ng/ml) during a subsequent pregnancy. In contrast there was no significant difference in uterine CA-125 or plasma PP14 concentrations between these two groups of recurrent miscarriage patients. The results suggest that measurements of uterine PP14 and CA-125 may be useful in the assessment of endometrial development in recurrent miscarriage patients and suggest the importance of PP14 in preparing the endometrium for embryo implantation. In addition pre-pregnancy uterine PP14 measurements may be useful in predicting subsequent pregnancy outcome.

Is the measurement of placental protein-14 and CA-125 in plasma and uterine flushings useful in the evaluation of peri-menopausal and post-menopausal bleeding?

In this prospective study, we examined the possible diagnostic value of the measurement of two endometrial proteins, placental protein-14 (PP14) and CA-125, in the evaluation of pre- and post-menopausal bleeding. Concentrations of these two proteins were measured in plasma and uterine flushings obtained from 139 pre- and post-menopausal women with bleeding problems, and 26 normal post-menopausal control women without bleeding. Endometrial biopsy samples were also obtained for histological study. Concentrations of PP14 in both the plasma and uterine flushings in post-menopausal women were significantly lower (P < 0.001) than those of control pre-menopausal women. In post-menopausal women, the concentrations of PP14 (mean +/- SEM) in both plasma and flushing were significantly higher (P < 0.001) in women with endometrial adenocarcinoma (46.9+/-7.5 ng/ml plasma; 3350+/-1711 ng/ml flushing) than in the controls (7.6+/-1.3 ng/ml plasma; 125+/-27 ng/ml flushing) or in women with post-menopausal bleeding and atrophic endometrium (20.4+/-2.1 ng/ml plasma; 453+/-167 ng/ml flushing). In contrast CA-125 concentrations in plasma and flushings were similar in post-menopausal and pre-menopausal women. Plasma concentrations of CA-125 were higher in post-menopausal women with adenocarcinoma (29.1+/-7.4 IU/ml) than in those with post-menopausal bleeding and atrophic endometrium (21.8+/-2 IU/ml) (P < 0.05) or control post-menopausal subjects (16.1+/-2.1 IU/ml) (P < 0.01). CA-125 concentrations in uterine flushings were not significantly different in any group of post-menopausal women. The results show that concentrations of PP14 are correlated more strongly to endometrial histopathology than those of CA-125 in pre- and post-menopausal women. Elevated PP14 concentrations are also associated with the presence of endometrial adenocarcinoma and may have a potential to be used as a marker for this disease.

The production of leukaemia inhibitory factor by human endometrium: presence in uterine flushings and production by cells in culture

The concentration of leukaemia inhibitory factor (LIF) was measured in uterine flushings obtained from normal fertile women, from women with unexplained infertility and from women who suffered recurrent miscarriage. In normal fertile women, LIF was not detected in flushings obtained on days luteinizing hormone (LH)+0 to LH+6 of the cycle, but concentrations gradually increased from day LH+7 to a maximum at day LH+12. The amount of LIF in flushings obtained from women with unexplained infertility was significantly lower than in those from normal fertile women on day LH+10 (P < 0.05). The production of LIF by cultured human epithelial and stromal cells was also investigated. LIF was not detectable in the supernatants of cultured stromal cells. Basal LIF production by epithelial cells varied according to the stage in the cycle at which the biopsy was taken. Significantly more LIF was produced by epithelial cells from late proliferative and early secretory endometrium compared with amounts produced by cells from early proliferative (P < 0.001) and late secretory (P < 0.01) endometrium. High doses of progesterone and oestradiol caused a small decrease in epithelial cell LIF production: the combined effect of progesterone and oestradiol (P < 0.01) was greater than the effect of either steroid alone (P < 0.05). The results show, for the first time, the capability of human endometrium to produce LIF in vivo. The fact that maximum LIF concentrations are present at implantation and that decreased concentrations occur in women with unexplained infertility suggest the importance of this cytokine in embryo implantation.

The measurement of CA 125 and placental protein 14 in uterine flushings in women with recurrent miscarriage; relation to endometrial morphology

The concentrations of CA 125 and placental protein 14 (PP14) were measured in uterine flushings obtained throughout the luteal phase of the cycle from eight normal fertile women. The concentrations of both proteins increased in a similar pattern throughout the luteal phase of the cycle, with the most dramatic increase occurring 6 days after their luteinizing hormone surge (day LH +6). However, a greater variation in CA 125 concentrations was seen compared to that seen for PP14. The concentrations were compared to those obtained on day LH +7 of the cycle from a group (n = 35) of women with recurrent miscarriage. The ranges in concentration of PP14 and CA 125 in the flushings of fertile and recurrent miscarriage patients were very similar. However, a greater proportion of women with recurrent miscarriage (55%) had low concentrations (< 5 ng/ml) of PP14 than in the control group (12.5%) and the concentrations of PP14 in the uterine flushings were significantly less (P < 0.05) in women with recurrent miscarriage compared to the normal fertile group. There was no significant difference in the concentration of CA 125 in the uterine flushings between the two groups. Histological observation of the endometrial biopsy samples from recurrent miscarriage patients gave menstrual cycle datings that ranged from day LH +2.5 to LH +6.5 with retarded endometrium (< day LH +5) in 12 of 35 (34%) patients. Of these 12 patients, 10 (83%) had low PP14 concentrations and six (50%) had low CA 125 concentrations in their uterine flushings. In the recurrent miscarriage patients with histologically normal (> or = day LH +5) endometrial development, 10 out of 23 (43%) also had low PP14 concentrations and 8 out of 23 (35%) had low CA 125 in their uterine flushings. The results suggest that PP14 is better than CA 125 as a marker for endometrial function in this group of women. In some cases (52%) the low concentrations of PP14 in the uterine flushings could be explained by retarded endometrial development but for the others the reduction in PP14 concentration in the uterine flushing was not associated with retardation of endometrial development.