5-HT2A receptor gene promoter polymorphism in relation to abdominal obesity and cortisol

Body mass index (BMI) does not predict responses to psilocybin

BACKGROUND

Psilocybin is a serotonin type 2A (5-HT2A) receptor agonist and naturally occurring psychedelic. 5-HT2A receptor density is known to be associated with body mass index (BMI), however, the impact of this on psilocybin therapy has not been explored. While body weight-adjusted dosing is widely used, this imposes a practical and financial strain on the scalability of psychedelic therapy. This gap between evidence and practice is caused by the absence of studies clarifying the relationship between BMI, the acute psychedelic experience and long-term psychological outcomes.

METHOD

Data were pooled across three studies using a fixed 25 mg dose of psilocybin delivered in a therapeutic context to assess whether BMI predicts characteristics of the acute experience and changes in well-being 2 weeks later. Supplementing frequentist analysis with Bayes Factors has enabled for conclusions to be drawn regarding the null hypothesis.

RESULTS

Results support the null hypothesis that BMI does not predict overall intensity of the altered state, mystical experiences, perceptual changes or emotional breakthroughs during the acute experience. There was weak evidence for greater 'dread of ego dissolution' in participants with lower BMI, however, further analysis suggested BMI did not meaningfully add to the combination of the other covariates (age, sex and study). While mystical-type experiences and emotional breakthroughs were strong predictors of improvements in well-being, BMI was not.

CONCLUSIONS

These findings have important implications for our understanding of pharmacological and extra-pharmacological contributors to psychedelic-assisted therapy and for the standardization of a fixed therapeutic dose in psychedelic-assisted therapy.

The impact of pre-pregnancy BMI on maternal depressive and anxiety symptoms during pregnancy and the postpartum period: A systematic review and meta-analysis

BACKGROUND

Studies have reported conflicting results on the association between maternal pre-pregnancy weight and adverse mental health outcomes during pregnancy and the postpartum period. This systematic review and meta-analysis aim to provide the current state of evidence concerning the association between maternal pre-pregnancy BMI and the risk of antenatal and postnatal depressive and anxiety symptoms.

METHODS

PubMed, EMBASE, Web of Science and Scopus databases were searched from their inception through August 31, 2020. Observational studies assessing the association between maternal pre-pregnancy BMI and risk of depression and/anxiety during pregnancy and the postpartum period were included. We used random-and quality-effects meta-analyses to estimate risks. Subgroup, sensitivity and meta-regression analyses were performed.

RESULTS

Pre-pregnancy obesity was associated with a 33% increased risk of antenatal depressive symptoms (pooled OR = 1.33 [95% CI; 1.20-1.48]). The pooled ORs for the association between underweight, overweight and obesity and postnatal depressive symptoms were 1.71 [95% CI; 1.27 - 2.31], 1.14 [95% CI; 1.0 - 1.30] and 1.39 [95% CI; 1.23 - 1.57], respectively. Low to moderate level of between-study heterogeneity was noted. The association between pre-pregnancy BMI and perinatal anxiety symptoms remain uncertain.

CONCLUSIONS

Pre-pregnancy obesity was associated with an increased risk of maternal depressive symptoms both in pregnancy and the postpartum period. The findings suggest that women with both high and low pre-pregnancy weight may benefit from receiving mental health screening and interventions during prenatal care.

Early Life Stress and the Onset of Obesity: Proof of MicroRNAs' Involvement Through Modulation of Serotonin and Dopamine Systems' Homeostasis

Healthy persons hold a very complex system for controlling energy homeostasis. The system functions on the interconnected way between the nutritional, endocrine, neural, and epigenetic regulation, which includes the microRNAs (miRNAs). Currently, it is well accepted that experiences of early life stress (ELS) carry modification of the central control of feeding behavior, one of the factors controlling energy homeostasis. Recently, studies give us a clue on the modulation of eating behavior, which is one of the main factors associated with the development of obesity. This clue connected the neural control through the serotonin (5HT) and dopamine (DA) systems with the fine regulation of miRNAs. The first pieces of evidence highlight the presence of the miR-16 in the regulation of the serotonin transporter (SERT) as well as the receptors 1a (5HT1A) and 2a (5HT2A). On the other hand, miR-504 is related to the dopamine receptor D2 (DRD2). As our knowledge advance, we expected to discover other important pathways for the regulation of the energy homeostasis. As both neurotransmission systems and miRNAs seem to be sensible to ELS, the aim of this review is to bring new insight about the involvement of miRNAs with a central role in the control of eating behavior focusing on the influences of ELS and regulation of neurotransmission systems.

Association between serotonin 2A receptor (HTR2A) genetic variations and risk of hypertension in a community-based cohort study

Background

Hypertension is one of the risk factors for obesity-related cardiovascular diseases. We investigated whether genetic variations in serotonin 2A receptor (HTR2A) were associated with hypertension.

Methods

We carried out a cross-sectional study in cohorts A (Ansan-Ansung cohort, N = 6039) and B (Wonju-Pyengchang cohort, N = 7524). Several genetic variants in HTR2A including rs7330636, rs9590999, rs2183057, and rs4942595 were selected and genotyped.

Results

In hypertensive participants in cohort A, the baseline systolic blood pressure and body mass index were 141.80 ± 17.20 mg/dL and 24.48 ± 4.75 kg/m², respectively, which were higher than in those without hypertension (p < 0.001). rs4942595TC genotype was associated with hypertension in cohort A (OR = 0.739), after adjusting for variables. Subjects with rs4942578AA genotype had a decreased risk of hypertension after adjusting for clinical factor (OR = 0.735) in cohort B, and an elevated risk of hypertension in cohort A (OR = 1.562). The logistic regression analysis showed that participants with rs4941573TC genotype were 1.327 times more likely to have a higher blood pressure than those with TT genotype (95% CI 1.101–1.599) in cohort B. Whereas, the OR for developing hypertension in subjects with rs17069883CC genotype compared to those with AA genotype was 1.447 (95% CI 1.018–2.056; p for trend = 0.040) in cohort A.

Conclusions

HTR2A genetic variations were associated with hypertension risk in our study.

RNA-Seq Analysis Reveals a Positive Role of HTR2A in Adipogenesis in Yan Yellow Cattle

In this study, we performed high throughput RNA sequencing at the primary bovine preadipocyte (Day-0), mid-differentiation (Day-4), and differentiated adipocyte (Day-9) stages in order to characterize the transcriptional events regulating differentiation and function. The preadipocytes were isolated from subcutaneous fetal bovine adipose tissues and were differentiated into mature adipocytes. The adipogenic characteristics of the adipocytes were detected during various stages of adipogenesis (Day-0, Day-4, and Day-9). We used RNA sequencing (RNA-seq) to investigate a comprehensive transcriptome information of adipocytic differentiation. Compared to the pre-differentiation stage (Day-0), 2510 genes were identified as differentially expressed genes (DEGs) at the mid-differentiation stage (Day-4). We found 2446 DEGs in the mature adipocytic stage relative to the mid-differentiation stage. Some adipogenesis-related transcription factors, CCAAT-enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ) were differentially expressed at Day-0, Day-4, and Day-9. We further investigated the adipogenic function of 5-hydroxytryptamine receptor 2A (HTR2A) in adipogenesis. Overexpression of HTR2A stimulated the differentiation of preadipocytes, and knockdown of HTR2A had opposite effects. Furthermore, functional enrichment analysis of DEGs revealed that the PI3K-Akt signaling pathway was the significantly enriched pathway, and HTR2A regulated adipogenesis by activating or inhibiting phosphorylation of phospho-AKT (Ser473). In summary, the present study provides the first comparative transcription of various periods of adipocytes in cattle, which presents a solid foundation for further study into the molecular mechanism of fat deposition and the improvement of beef quality in cattle.

5-HT2A receptor deficiency alters the metabolic and transcriptional, but not the behavioral, consequences of chronic unpredictable stress

Chronic stress enhances risk for psychiatric disorders, and in animal models is known to evoke depression-like behavior accompanied by perturbed neurohormonal, metabolic, neuroarchitectural and transcriptional changes. Serotonergic neurotransmission, including serotonin_2A (5-HT_2A) receptors, have been implicated in mediating specific aspects of stress-induced responses. Here we investigated the influence of chronic unpredictable stress (CUS) on depression-like behavior, serum metabolic measures, and gene expression in stress-associated neurocircuitry of the prefrontal cortex (PFC) and hippocampus in 5-HT_2A receptor knockout (5-HT2A−/−) and wild-type mice of both sexes. While 5-HT2A−/− male and female mice exhibited a baseline reduced anxiety-like state, this did not alter the onset or severity of behavioral despair during and at the cessation of CUS, indicating that these mice can develop stress-evoked depressive behavior. Analysis of metabolic parameters in serum revealed a CUS-evoked dyslipidemia, which was abrogated in 5-HT2A−/− female mice with a hyperlipidemic baseline phenotype. 5-HT2A−/− male mice in contrast did not exhibit such a baseline shift in their serum lipid profile. Specific stress-responsive genes (Crh, Crhr1, Nr3c1, and Nr3c2), trophic factors (Bdnf, Igf1) and immediate early genes (IEGs) (Arc, Fos, Fosb, Egr1-4) in the PFC and hippocampus were altered in 5-HT2A−/− mice both under baseline and CUS conditions. Our results support a role for the 5-HT_2A receptor in specific metabolic and transcriptional, but not behavioral, consequences of CUS, and highlight that the contribution of the 5-HT_2A receptor to stress-evoked changes is sexually dimorphic.

Is there a bi-directional relationship between depression and obesity among adult men and women? Systematic review and bias-adjusted meta analysis

The rapidly increasing prevalence of both obesity and depression represent two major public health concerns worldwide. But the evidence regarding the direction and strength of the association between these two disorders, for both adult men and women, are remain inconclusive. We systematically reviewed publications from five different databases: Pubmed, Embase, BIOSIS, CINAHL and PsychINFO. A total of 21 articles were included for the systematic review and 19 of them for the meta-analysis using a bias-adjusted (quality effect) model. This resulted in the inclusion of approximately 226,063 (33.7% men) participants. Those who were depressed had a 37% (RR: 1.37, 95% CI: 1.17, 1.48) increased risk of being obese, and who were obese had an 18% increased risk of being depressed (RR: 1.18, 95% CI: 1.04, 1.35). Those who were depressed had a 2% (RD: 0.02, 95% CI: 0.01, 0.03) excess risk of obesity, however, the reciprocal associations were not significant. The association between overweight and depression was not found significant in either direction. Both men and women were at risk of obesity and depression bi-directionally. In sensitivity analyses bi-directional associations were more pronounced among young and middle aged adults and in studies with longer follow-up. The findings of this study suggest that the strength of the association is greater for the direction leading from depression to obesity and this link was more pronounced for young and middle aged women.

5-HT2A and 5-HT2C receptors as hypothalamic targets of developmental programming in male rats

Although obesity is a global epidemic, the physiological mechanisms involved are not well understood. Recent advances reveal that susceptibility to obesity can be programmed by maternal and neonatal nutrition. Specifically, a maternal low-protein diet during pregnancy causes decreased intrauterine growth, rapid postnatal catch-up growth and an increased risk for diet-induced obesity. Given that the synthesis of the neurotransmitter 5-hydroxytryptamine (5-HT) is nutritionally regulated and 5-HT is a trophic factor, we hypothesised that maternal diet influences fetal 5-HT exposure, which then influences development of the central appetite network and the subsequent efficacy of 5-HT to control energy balance in later life. Consistent with our hypothesis, pregnant rats fed a low-protein diet exhibited elevated serum levels of 5-HT, which was also evident in the placenta and fetal brains at embryonic day 16.5. This increase was associated with reduced levels of 5-HT2CR, the primary 5-HT receptor influencing appetite, in the fetal, neonatal and adult hypothalamus. As expected, a reduction of 5-HT2CR was associated with impaired sensitivity to 5-HT-mediated appetite suppression in adulthood. 5-HT primarily achieves effects on appetite by 5-HT2CR stimulation of pro-opiomelanocortin (POMC) peptides within the arcuate nucleus of the hypothalamus (ARC). We show that 5-HT2ARs are also anatomically positioned to influence the activity of ARC POMC neurons and that mRNA encoding 5-HT2AR is increased in the hypothalamus ofin uterogrowth-restricted offspring that underwent rapid postnatal catch-up growth. Furthermore, these animals at 3 months of age are more sensitive to appetite suppression induced by 5-HT2AR agonists. These findings not only reveal a 5-HT-mediated mechanism underlying the programming of susceptibility to obesity, but also provide a promising means to correct it, by treatment with a 5-HT2AR agonist.

Serotonin, a possible intermediate between disturbed circadian rhythms and metabolic disease

It is evident that eating in misalignment with the biological clock (such as in shift work, eating late at night and skipping breakfast) is associated with increased risk for obesity and diabetes. The biological clock located in the suprachiasmatic nucleus dictates energy balance including feeding behavior and glucose metabolism. Besides eating and sleeping patterns, glucose metabolism also exhibits clear diurnal variations with higher blood glucose concentrations, glucose tolerance and insulin sensitivity prior to waking up. The daily variation in plasma glucose concentrations in rats, is independent of the rhythm in feeding behavior. On the other hand, feeding itself has profound effects on glucose metabolism, but differential effects occur depending on the time of the day. We here review data showing that a disturbed diurnal eating pattern results in alterations in glucose metabolism induced by a disrupted circadian clock. We first describe the role of central serotonin on feeding behavior and glucose metabolism and subsequently describe the effects of central serotonin on the circadian system. We next explore the interaction between the serotonergic system and the circadian clock in conditions of disrupted diurnal rhythms in feeding and how this might be involved in the metabolic dysregulation that occurs with chronodisruption.

Neocortical serotonin2A receptor binding predicts quetiapine associated weight gain in antipsychotic-naive first-episode schizophrenia patients

Antipsychotic-induced weight gain is of major clinical importance since it is associated with severe metabolic complications and increased mortality. The serotonin2A receptor system has been suggested to be implicated in weight gain and obesity. However, no previous in vivo imaging data have related serotonin2A receptor binding to weight gain before and after antipsychotic monotherapy. Fifteen antipsychotic-naive first-episode schizophrenia patients were included and investigated before and after six months of quetiapine treatment. We examined the relationship between serotonin2A receptor binding as measured with positron emission tomography (PET) and [18F]altanserin and change in body mass index (BMI). Quetiapine was chosen because it is characterized by a moderately high affinity for the serotonin2A receptor and a fast dissociation rate from the dopamine D2 receptor. At baseline the mean BMI was 24.2 kg/m2, range 18-36 kg/m2. After six months of quetiapine treatment (mean dose: 383 mg/day) the BMI had, on average, increased by 6.7%, corresponding to an average weight gain of 5.0 kg. We found a significant positive correlation both between neocortical serotonin2A receptor binding prior to treatment and subsequent increase in BMI (rho=0.59, p=0.022). At follow-up, the serotonin2A receptor occupancy was positively correlated with BMI increase (rho=0.54, p=0.038). To our knowledge, these are the first in vivo receptor imaging data in initially antipsychotic-naive first-episode schizophrenia patients to show that the cerebral serotonin2A receptor is associated with antipsychotic-induced weight gain.

A functional polymorphism in the 5HTR2C gene associated with stress responses also predicts incident cardiovascular events

Previously we have shown that a functional nonsynonymous single nucleotide polymorphism (rs6318) of the 5HTR2C gene located on the X-chromosome is associated with hypothalamic-pituitary-adrenal axis response to a stress recall task, and with endophenotypes associated with cardiovascular disease (CVD). These findings suggest that individuals carrying the rs6318 Ser23 C allele will be at higher risk for CVD compared to Cys23 G allele carriers. The present study examined allelic variation in rs6318 as a predictor of coronary artery disease (CAD) severity and a composite endpoint of all-cause mortality or myocardial infarction (MI) among Caucasian participants consecutively recruited through the cardiac catheterization laboratory at Duke University Hospital (Durham, NC) as part of the CATHGEN biorepository. Study population consisted of 6,126 Caucasian participants (4,036 [65.9%] males and 2,090 [34.1%] females). A total of 1,769 events occurred (1,544 deaths and 225 MIs; median follow-up time =  5.3 years, interquartile range  = 3.3–8.2). Unadjusted Cox time-to-event regression models showed, compared to Cys23 G carriers, males hemizygous for Ser23 C and females homozygous for Ser23C were at increased risk for the composite endpoint of all-cause death or MI: Hazard Ratio (HR)  = 1.47, 95% confidence interval (CI)  = 1.17, 1.84, p  = .0008. Adjusting for age, rs6318 genotype was not related to body mass index, diabetes, hypertension, dyslipidemia, smoking history, number of diseased coronary arteries, or left ventricular ejection fraction in either males or females. After adjustment for these covariates the estimate for the two Ser23 C groups was modestly attenuated, but remained statistically significant: HR  = 1.38, 95% CI = 1.10, 1.73, p = .005. These findings suggest that this functional polymorphism of the 5HTR2C gene is associated with increased risk for CVD mortality and morbidity, but this association is apparently not explained by the association of rs6318 with traditional risk factors or conventional markers of atherosclerotic disease.

No evidence of association between the serotonin 2A receptor −1438G/A promoter polymorphism and childhood obesity in a Spanish population: A case-parent study and a matched case-control study

Serotonin has been related to feeding behaviour and body weight control through its suppressive effect on appetite. Conflicting results have been published in the literature regarding the association between the - 1438 G/A promoter polymorphism of the 5HT2A gene with obesity-related variables. The aim of this study was to assess the association between the--1438 G/A polymorphism of the 5HT2A gene with childhood obesity in a Spanish population. A total of 136 cases aged 6-16 years with BMI above the 97th percentile of the Spanish BMI reference data for age and gender were matched by gender and age (+/- 6 months) with 136 controls. Additionally, 43 obese children and their parents were selected for a family-based association study (case-parent study). Genotyping was carried out by polymerase chain reaction and restriction enzyme analysis. Conditional logistic regression and transmission/disequilibrium test were used to assess genotype-obesity association. In the matched case-control study, the crude and adjusted odds ratios for the association between 5HT2A--1438 G/A genotypes were nonsignificant. Likewise, no association is suggested by the case-parent study. In conclusion, it is unlikely that the--1438 G/A polymorphism of 5HT2A gene may influence obesity in a Spanish children population.

Genetic association analysis of 30 genes related to obesity in a European American population

OBJECTIVE

Obesity, which is frequently associated with diabetes, hypertension and cardiovascular diseases, is primarily the result of a net excess of caloric intake over energy expenditure. Human obesity is highly heritable, but the specific genes mediating susceptibility in non-syndromic obesity remain unclear. We tested candidate genes in pathways related to food intake and energy expenditure for association with body mass index (BMI).

METHODS

We reanalyzed 355 common genetic variants of 30 candidate genes in seven molecular pathways related to obesity in 1982 unrelated European Americans from the New York Cancer Project. Data were analyzed by using a Bayesian hierarchical generalized linear model. The BMIs were log-transformed and then adjusted for covariates, including age, age(2), gender and diabetes status. The single-nucleotide polymorphisms (SNPs) were modeled as additive effects.

RESULTS

With the stipulated adjustments, nine SNPs in eight genes were significantly associated with BMI: ghrelin (GHRL; rs35683), agouti-related peptide (AGRP; rs5030980), carboxypeptidase E (CPE; rs1946816 and rs4481204), glucagon-like peptide-1 receptor (GLP1R; rs2268641), serotonin receptors (HTR2A; rs912127), neuropeptide Y receptor (NPY5R;Y5R1c52), suppressor of cytokine signaling 3 (SOCS3; rs4969170) and signal transducer and activator of transcription 3 (STAT3; rs4796793). We also found a gender-by-SNP interaction (rs1745837 in HTR2A), which indicated that variants in the gene HTR2A had a stronger association with BMI in males. In addition, NPY1R was detected as having a significant gene effect even though none of the SNPs in this gene was significant.

CONCLUSION

Variations in genes AGRP, CPE, GHRL, GLP1R, HTR2A, NPY1R, NPY5R, SOCS3 and STAT3 showed modest associations with BMI in European Americans. The pathways in which these genes participate regulate energy intake, and thus these associations are mechanistically plausible in this context.

N(ε)-Carboxymethyllysine (CML), a Maillard reaction product, stimulates serotonin release and activates the receptor for advanced glycation end products (RAGE) in SH-SY5Y cells

Maillard reaction products, which are formed in highly thermally treated foods, are commonly consumed in a Western diet. In this study, we investigated the impact of N(ε)-carboxymethyllysine (CML), a well-characterized product of the Maillard reaction, on the gene regulation of the human neuroblastoma cell line SH-SY5Y. Pathway analysis of data generated from customized DNA microarrays revealed 3 h incubation with 50 μM and 500 μM CML to affect serotonin receptor expression. Further experiments employing qRT-PCR showed an up-regulation of serotonin receptors 2A, 1A and 1B after 0.25 h and 3 h. In addition, 500 μM CML increased serotonin release, thus showing effects of CML not only at a genetic, but also at a functional level. Intracellular calcium mobilization, which mediates serotonin release, was increased by CML at concentrations of 0.05-500 μM. Since calcium mobilization has been linked to the activation of the receptor for advanced glycation end products (RAGE), we further investigated the effects of CML on RAGE expression. RAGE was found to be up-regulated after incubation with 500 μM CML for 0.25 h. Co-incubation with the calcium blocker neomycin for 0.25 h blocked the up-regulation of RAGE and the serotonin receptors 2A, 1A and 1B. These results indicate a possible link between a CML-induced calcium-mediated serotonin release and RAGE.

Could the Sasang constitution itself be a risk factor of abdominal obesity?

Background

Abdominal obesity (AO) is a medical condition in which excess body fat accumulates in the abdomen. It may cause adverse effects on health and result in reduced life expectancy or increased health problems. While various genetic approaches have explained the risks of AO in Western society, the Sasang constitution (SC) has been identified as a risk factor in Korean medicine. Different SC types are associated with different fat distribution, body shapes and susceptibility to diseases. We evaluated whether the SC type could be a risk for AO in a cross-sectional study among Koreans.

Methods

In total, 2,528 subjects aged over 30 years were recruited from 23 medical clinics. We collected waist circumference (WC), weight, height, and some clinical information for AO from the subjects. A Chi-square test and a one-way ANOVA were performed according to SC type (p < .05), while multiple logistic regression was used to produce odds ratios (ORs).

Results

The rates of AO in Tae-eumin (TE), Soeumin (SE), and Soyangin (SY) types were 63.7%, 14.7%, and 32.8% in males and 84.8%, 41.7%, and 52.8% in females, respectively. The TE type was associated with increased AO prevalence compared with the SE and SY types in males (OR 1.79; 95% CI 1.02–3.15, p = 0.044 and OR 1.74; 95% CI 1.18–2.58, p = 0.006, respectively) and females (OR 1.51; 95% CI 1.03–2.23, p = 0.037 and OR 1.88; 95% CI 1.32–2.68, p < 0.001, respectively) after adjusting for age, BMI, hypertension, diabetes mellitus, hypertriglyceridemia, and low HDL cholesterol.

Conclusions

This study suggested that SC, particularly the TE type, might be significantly and independently associated with AO and could be considered a risk factor in predicting AO.

Genetic variations in the serotoninergic system contribute to body-mass index in Chinese adolescents

OBJECTIVE

Obesity has become a worldwide health problem in the past decades. Human and animal studies have implicated serotonin in appetite regulation, and behavior genetic studies have shown that body mass index (BMI) has a strong genetic component. However, the roles of genes related to the serotoninergic (5-hydroxytryptamine,5-HT) system in obesity/BMI are not well understood, especially in Chinese subjects.

SUBJECTS AND DESIGN

With a sample of 478 healthy Chinese volunteers, this study investigated the relation between BMI and genetic variations of the serotoninergic system as characterized by 136 representative polymorphisms. We used a system-level approach to identify SNPs associated with BMI, then estimated their overall contribution to BMI by multiple regression and verified it by permutation.

RESULTS

We identified 12 SNPs that made statistically significant contributions to BMI. After controlling for gender and age, four of these SNPs accounted for 7.7% additional variance of BMI. Permutation analysis showed that the probability of obtaining these findings by chance was low (p = 0.015, permuted for 1000 times).

CONCLUSION

These results showed that genetic variations in the serotoninergic system made a moderate contribution to individual differences in BMI among a healthy Chinese sample, suggesting that a similar approach can be used to study obesity.

Serotonin Receptor 2A (HTR2A) Gene Polymorphisms Are Associated with Blood Pressure, Central Adiposity, and the Metabolic Syndrome

BACKGROUND

Although the etiology of the metabolic syndrome remains unclear, recent evidence suggests that dysregulation of brain serotonergic activity may partly underlie the covariation of risk factors comprising the syndrome. In addition, prior studies have shown polymorphisms in the serotonin 2A receptor (HTR2A) gene to be associated with two syndrome components, hypertension and central adiposity. We conducted a study to confirm associations of HTR2A polymorphisms with elevated blood pressure and central adiposity and tested for association between these polymorphisms and the metabolic syndrome.

METHODS

The study sample included 934 unrelated individuals of European ancestry. We tested for association of two HTR2A polymorphisms, one in the promoter: (-1438[G/A]) and one in the first intron (2416 [C/T]), individually and as a diplotype, with elevated blood pressure, central adiposity, elevated fasting glucose, triglycerides, high density lipoprotein (HDL) cholesterol and presence of the metabolic syndrome, as defined by the American Heart Association/National Heart, Lung and Blood Institute (AHA/NHLBI) Scientific Statement Executive Summary.

RESULTS

Confirming previous reports, elevated blood pressure (>130/85 mm Hg) was associated with both the -1438 GG and 2416 TT genotypes and the GG/TT diplotype (ORs = 1.39-1.76); high waist circumference was associated with -1438 GG genotype only (OR = 1.57). In addition, both the -1438 GG and 2416 TT genotypes, and the GG/TT diplotype, predicted presence of the metabolic syndrome (ORs = 1.44-1.77). Fasting glucose, triglyceride and HDL cholesterol were not associated with either polymorphism.

CONCLUSIONS

Elevated blood pressure, central adiposity, and the metabolic syndrome are associated with polymorphisms in HTR2A gene.

The Human Obesity Gene Map: The 2003 Update

This is the tenth update of the human obesity gene map, incorporating published results up to the end of October 2003 and continuing the previous format. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, quantitative trait loci (QTLs) from human genome-wide scans and animal crossbreeding experiments, and association and linkage studies with candidate genes and other markers is reviewed. Transgenic and knockout murine models relevant to obesity are also incorporated (N = 55). As of October 2003, 41 Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. QTLs reported from animal models currently number 183. There are 208 human QTLs for obesity phenotypes from genome-wide scans and candidate regions in targeted studies. A total of 35 genomic regions harbor QTLs replicated among two to five studies. Attempts to relate DNA sequence variation in specific genes to obesity phenotypes continue to grow, with 272 studies reporting positive associations with 90 candidate genes. Fifteen such candidate genes are supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. Overall, more than 430 genes, markers, and chromosomal regions have been associated or linked with human obesity phenotypes. The electronic version of the map with links to useful sites can be found at http://obesitygene.pbrc.edu.

The Human Obesity Gene Map: The 2004 Update

This paper presents the eleventh update of the human obesity gene map, which incorporates published results up to the end of October 2004. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTLs) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2004, 173 human obesity cases due to single-gene mutations in 10 different genes have been reported, and 49 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 166 genes which, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 221. The number of human obesity QTLs derived from genome scans continues to grow, and we have now 204 QTLs for obesity-related phenotypes from 50 genome-wide scans. A total of 38 genomic regions harbor QTLs replicated among two to four studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably with 358 findings of positive associations with 113 candidate genes. Among them, 18 genes are supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. Overall, >600 genes, markers, and chromosomal regions have been associated or linked with human obesity phenotypes. The electronic version of the map with links to useful publications and genomic and other relevant sites can be found at http://obesitygene.pbrc.edu.

5-HT2A receptor antagonism by MDL 11,939 during inescapable stress prevents subsequent exaggeration of acoustic startle response and reduced body weight in rats

Activation of central 5-HT(2A) receptor signaling and its subsequent alterations have been implicated in the pathophysiological response to stress and the pathogenesis of stress-associated psychiatric disorders. To further examine the association between alterations in central 5-HT(2A) receptor signaling and the occurrence of stress-induced psychiatric symptoms, the present study, utilizing a learned helplessness stress model in rats, determined whether 5-HT(2A) receptor signaling blockade during stress could prevent the occurrence of stress-induced physical and behavioral abnormalities. Rats subjected to restraint/tail shock for three days developed long-lasting elevated acoustic startle response (ASR) and reduced body weight, compared to non-stressed control animals. However, administration of the selective 5-HT(2A) receptor antagonist, MDL 11,939 (α-phenyl-1-(2-phenylethyl)-4-piperidinemethanol), 30 min prior to exposure of the animals to the stress protocol prevented the subsequent occurrence of elevated ASR and reduced body weight in a dose-dependent manner in stressed subjects. Administration of MDL 11,939 to the animals immediately after exposure to the stress protocol also prevented the occurrence of exaggerated ASR, but was not able to normalize body weight. These findings suggest a critical role of the central 5-HT(2A) receptor activation in developing the pathophysiology associated with elevated ASR and reduced body weight during stress. The differential effects of MDL 11,939 on startle response and body weight and its potential clinical significance are discussed.

Gene-gene interaction between serotonin transporter (SLC6A4) and CLOCK modulates the risk of metabolic syndrome in rotating shiftworkers

Serotonergic neurotransmission and the master circadian CLOCK gene are physiological modulators of the circadian system. In addition, both are involved in the physiopathology of metabolic syndrome (MS). The authors sought to examine the potential effect of the gene-gene interaction between the functional 44-bp insertion/deletion polymorphism in the promoter region (serotonin-transporter-linked promoter region polymorphism or 5-HTTLPR) of the serotonin transporter gene (SLC6A4) and common variants of the gene CLOCK on the genetic risk underlying MS of shift-workers. To test this hypothesis, 856 men were studied; 518 dayworkers were compared with 338 rotating shiftworkers. Medical history, health examination including anthropometric and arterial blood pressure measurements, a questionnaire on health-related behaviors, and biochemical determinations were obtained from every participant. 5-HTTLPR genotypes were determined using polymerase chain reaction followed by gel electrophoresis. Six tag single-nucleotide polymorphisms (SNPs) in the CLOCK gene with a minor allele frequency >10 % (rs1554483 C/G, rs11932595 A/G, rs4580704 C/G, rs6843722 A/C, rs6850524 C/G, and rs4864548 A/G), encompassing 117 kb of chromosome 4 and representing 115 polymorphic sites (r(2) > .8), were genotyped. A significant interaction between the 5-HTTLPR variant and the haplotype rs1554483-rs4864548 of the CLOCK gene was detected for diastolic (p = .0058) and systolic blood pressure (p = .0014), arterial hypertension (p = .033), plasma triglycerides levels (p = .033), and number of MS components (p = .01). In all these cases, the higher values were observed in rotating shiftworkers homozygous for the SLC6A4 S allele and carrying the haplotype composed by the CLOCK rs1554483 G and rs4864548 A variants. In conclusion, these data suggest a potential interaction (epistatic effect) of serotonin transporter and CLOCK gene variation on the genetic susceptibility to develop MS by rotating shiftworkers.

Depression and obesity: do shared genes explain the relationship?

BACKGROUND

Studies have found a modest association between depression and obesity, especially in women. Given the substantial genetic contribution to both depression and obesity, we sought to determine whether shared genetic influences are responsible for the association between these two conditions.

METHODS

Data were obtained from 712 monozygotic and 281 dizygotic female twin pairs who are members of the community-based University of Washington Twin Registry. The presence of depression was determined by self-report of doctor-diagnosed depression. Obesity was defined as body mass index of > or =30 kg/m(2), based on self-reported height and weight. Generalized estimating regression models were used to assess the age-adjusted association between depression and obesity. Univariate and bivariate structural equation models estimated the components of variance attributable to genetic and environmental influences.

RESULTS

We found a modest phenotypic association between depression and obesity (odds ratio=1.6, 95% confidence interval=1.2-2.1). Additive genetic effects contributed substantially to depression (57%) and obesity (81%). The best-fitting bivariate model indicated that 12% of the genetic component of depression is shared with obesity.

CONCLUSIONS

The association between depression and obesity in women may be in part due to shared genetic risk for both conditions. Future studies should examine the genetic, environmental, social, and cultural mechanisms underlying the relationship between this association.

Polymorphisms of serotonin receptor 2A and 2C genes and COMT in relation to obesity and type 2 diabetes

BACKGROUND

Candidate genes of psychological importance include 5HT2A, 5HT2C, and COMT, implicated in the serotonin, noradrenaline and dopamine pathways, which also may be involved in regulation of energy balance. We investigated the associations of single nucleotide polymorphisms (SNPs) of these genes with obesity and metabolic traits.

METHODOLOGY/PRINCIPAL FINDINGS

In a population of 166 200 young men examined at the draft boards, obese men (n = 726, BMI> or =31.0 kg/m(2)) and a randomly selected group (n = 831) were re-examined at two surveys at mean ages 46 and 49 years (S-46, S-49). Anthropometric, physiological and biochemical measures were available. Logistic regression analyses were used to assess age-adjusted odds ratios. No significant associations were observed of 5HT2A rs6311, 5HT2C rs3813929 and COMT rs4680 with obesity, except that COMT rs4680 GG-genotype was associated with fat-BMI (OR = 1.08, CI = 1.01-1.16). The SNPs were associated with a number of physiological variables; most importantly 5HT2C rs3813929 T-allele was associated with glucose (OR = 4.56, CI = 1.13-18.4) and acute insulin response (OR = 0.65, CI = 0.44-0.94) in S-49. COMT rs4680 GG-genotype was associated with glucose (OR = 1.04, CI = 1.00-1.09). Except for an association between 5HT2A rs6311 and total-cholesterol at both surveys, significant in S-46 (OR = 2.66, CI = 1.11-6.40), no significant associations were observed for the other phenotypes. Significant associations were obtained when combined genotype of 5HT2C rs3813929 and COMT rs4680 were examined in relation to BMI (OR = 1.12, CI = 1.03-1.21), fat-BMI (OR = 1.22, CI = 1.08-1.38), waist (OR = 1.13, CI = 1.04-1.22), and cholesterol (OR = 5.60, CI = 0.99-31.4). Analyses of impaired glucose tolerance (IGT) and type 2 diabetes (T2D) revealed, a 12.3% increased frequency of 5HT2C rs3813929 T-allele and an 11.6% increased frequency of COMT rs4680 GG-genotype in individuals with IGT or T2D (chi(2), p = 0.05 and p = 0.06, respectively). Examination of the combined genotypes of 5HT2C and COMT showed a 34.0% increased frequency of IGT or T2D (chi(2), p = 0.01).

CONCLUSIONS

The findings lend further support to the involvement of serotonin, noradrenaline and dopamine pathways on obesity and glucose homeostasis, in particular when combined genotype associations are explored.

Role of shared genetic and environmental factors in symptoms of depression and body composition

BACKGROUND

Both obesity and lean mass have been correlated with symptoms of depression.

OBJECTIVE

To investigate the contribution of genetic and environmental factors in the co-occurrence of obesity and lean mass with symptoms of depression.

METHODS

Individuals were 2383 participants of the Erasmus Rucphen Family study. Symptoms of depression were assessed using the Center for Epidemiologic Studies Depression Scale and the Hospital Anxiety and Depression Scale. Anthropometric and dual-energy X-ray absorptiometry total body scans were obtained for the assessment of body composition. The role of shared genetic and shared environmental factors was quantified by estimating genetic and environmental correlations between symptoms of depression and measures of body composition.

RESULTS

Phenotypic correlations between body composition and symptoms of depression ranged from -0.08 to 0.08. Heritability estimates for body composition ranged from 0.40 to 0.46 (P<0.001) in women and from 0.35 to 0.51 (P<0.001) in men, and heritability estimates for depression scores were higher in women (0.34 and 0.37) than in men (0.13 and 0.21). No consistent genetic correlations between measures of body composition and symptoms of depression were found. We did find a significant consistent environmental correlation between depression scores and lean mass index (environmental correlation=-0.23 for Center for Epidemiologic Studies Depression Scale and -0.31 for Hospital Anxiety and Depression Scale).

CONCLUSION

In our study, there is no evidence that the co-occurrence of symptoms of depression and body composition result from a common genetic pathway.

Genes implicated in serotonergic and dopaminergic functioning predict BMI categories

OBJECTIVE

This study addressed the hypothesis that variation in genes associated with dopamine function (SLC6A3, DRD2, DRD4), serotonin function (SLC6A4, and regulation of monoamine levels (MAOA) may be predictive of BMI categories (obese and overweight + obese) in young adulthood and of changes in BMI as adolescents transition into young adulthood. Interactions with gender and race/ethnicity were also examined.

METHODS AND PROCEDURES

Participants were a subsample of individuals from the National Longitudinal Study of Adolescent Health (Add Health), a nationally representative sample of adolescents followed from 1995 to 2002. The sample analyzed included a subset of 1,584 unrelated individuals with genotype data. Multiple logistic regressions were conducted to evaluate the associations between genotypes and obesity (BMI > 29.9) or overweight + obese combined (BMI > or = 25) with normal weight (BMI = 18.5-24.9) as a referent. Linear regression models were used to examine change in BMI from adolescence to young adulthood.

RESULTS

Significant associations were found between SLC6A4 5HTTLPR and categories of BMI, and between MAOA promoter variable number tandem repeat (VNTR) among men and categories of BMI. Stratified analyses revealed that the association between these two genes and excess BMI was significant for men overall and for white and Hispanic men specifically. Linear regression models indicated a significant effect of SLC6A4 5HTTLPR on change in BMI from adolescence to young adulthood.

DISCUSSION

Our findings lend further support to the involvement of genes implicated in dopamine and serotonin regulation on energy balance.

Polymorphism of the 5-HT(2A) receptor gene: association with stress-related indices in healthy middle-aged adults

Past research has concentrated on the stress system and personality in order to explain the variance found in cognitive performance in old age. A growing body of research is starting to focus on genetic polymorphism as an individual difference factor to explain the observed heterogeneity in cognitive function. While the functional mechanism is still under investigation, polymorphism of the 5-HT(2A) receptor gene (-1438A/G) has been linked to certain behavioral and physiological outcomes, including cortisol secretion, the expression of certain personality traits, and memory performance. It was the goal of the present study to investigate the association between the -1438A/G polymorphism and stress hormone secretion, stress-related psychological measures, and cognitive performance in a group of adults between the ages of 50 and 65. To examine these associations, 101 middle-aged adults were recruited, completed a battery of psychological questionnaires and were administered a battery of cognitive tasks that assess frontal lobe and hippocampal function. Basal and stress-reactive salivary cortisol levels were collected, at home and in the laboratory. Analyses on psychological measures showed that participants with the GG genotype reported significantly higher levels of neuroticism compared to the AG group and higher levels of depression and more emotion-based coping strategies compared to both the AG and AA group. In terms of cortisol secretion, the AA genotype was related to a significantly higher awakening cortisol response (ACR) compared to the AG and GG group and the GG genotype group displayed a greater increase in cortisol secretion following a psychosocial stressor compared to the two other groups. On measures of cognitive performance, the AA genotype group performed significantly better on a test of declarative memory and selective attention compared to the other two groups. Together, these results suggest that carriers of the GG genotype are more susceptible to low mood and display a greater potential for an overactive stress system, which may influence cognitive function in later years.

Impact of the -1438G>a polymorphism in the serotonin 2A receptor gene on anthropometric profile and obesity risk: a case-control study in a Spanish Mediterranean population

Research into the genetic factors that regulate food intake is arousing great interest. The polymorphism -1438G>A in the serotonin 2A receptor or 5-hydroxytriptamine (5-HT) type 2A receptor (5-HTR2A) gene has been associated with alterations in food intake such as anorexia and bulimia. However, its association with obesity has not been studied to the same extent. Our aim, therefore, was to estimate the association between the -1438G>A polymorphism and obesity risk and related anthropometric variables in a Spanish Mediterranean population. A case-control study including 303 cases and 606 controls paired by gender and age was undertaken. The association between the -1438G>A polymorphism and obesity and other anthropometric measures was studied. No association with obesity risk was observed. However, when only the obese group was analyzed, it was observed that AA subjects presented a lower body mass index (BMI) than G allele carriers (35.2+/-5.3 kg/m2 vs 37.5+/-7.8 kg/m2; P=0.039). Moreover, significant differences were also obtained in waist perimeter that was lower in AA subjects compared to G allele carriers (105+/-11 cm vs 112+/-17 cm; P=0.011). In conclusion, although the -1438G>A polymorphism is not a relevant marker for obesity risk, this variant may play a role in determining BMI in obese subjects.

The human obesity gene map: the 2005 update

This paper presents the 12th update of the human obesity gene map, which incorporates published results up to the end of October 2005. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTL) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2005, 176 human obesity cases due to single-gene mutations in 11 different genes have been reported, 50 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 244 genes that, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 408. The number of human obesity QTLs derived from genome scans continues to grow, and we now have 253 QTLs for obesity-related phenotypes from 61 genome-wide scans. A total of 52 genomic regions harbor QTLs supported by two or more studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably, with 426 findings of positive associations with 127 candidate genes. A promising observation is that 22 genes are each supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. The electronic version of the map with links to useful publications and relevant sites can be found at http://obesitygene.pbrc.edu.

Bioefficacy of a novel calcium-potassium salt of (-)-hydroxycitric acid

Obesity is associated with cardiovascular disease, diabetes and certain forms of cancer. Popular strategies on weight loss often fail to address many key factors such as fat mass, muscle density, bone density, water mass, their inter-relationships and impact on energy production, body composition, and overall health and well-being. (-)-Hydroxycitric acid (HCA), a natural plant extract from the dried fruit rind of Garcinia cambogia, has been reported to promote body fat loss in humans without stimulating the central nervous system. The level of effectiveness of G. cambogia extract is typically attributed solely to HCA. However, other components by their presence or absence may significantly contribute to its therapeutic effectiveness. Typically, HCA used in dietary weight loss supplement is bound to calcium, which results in a poorly soluble (<50%) and less bioavailable form. Conversely, the structural characteristics of a novel Ca2+/K+ bound (-)-HCA salt (HCA-SX or Super CitriMax) make it completely water soluble as well as bioavailable. An efficacious dosage of HCA-SX (4500 mg/day t.i.d.) provides a good source of Ca2+ (495 mg, 49.5% of RDI) and K+ (720 mg, 15% of RDI). Ca2+ ions are involved in weight management by increasing lipid metabolism, enhancing thermogenesis, and increasing bone density. K+, on the other hand, increases energy, reduces hypertension, increases muscle strength and regulates arrhythmias. Both Ca and K act as buffers in pH homeostasis. HCA-SX has been shown to increase serotonin availability, reduce appetite, increase fat oxidation, improve blood lipid levels, reduce body weight, and modulate a number of obesity regulatory genes without affecting the mitochondrial and nuclear proteins required for normal biochemical and physiological functions.

Polymorphism of the 5-HT2A receptor gene and food intakes in children and adolescents: the Stanislas Family Study

BACKGROUND

Serotonin (5-hydroxytryptamine; 5-HT) is a key mediator in the control of food intake and is probably involved in the etiology of anorexia nervosa. An association between a polymorphism of the 5-HT receptor (5-HT2A) gene promoter (-1438G/A) and anorexia nervosa has been reported.

OBJECTIVE

We investigated the relation between the -1438G/A polymorphism of the 5-HT(2A) gene and the energy and macronutrient intakes of children and adolescents.

DESIGN

This cross-sectional study included 370 children and adolescents aged 10-20 y (176 boys and 194 girls from 251 families) drawn from the Stanislas Family Study. Energy and macronutrient intakes were assessed by using 3-d food records. The -1438G/A polymorphism was analyzed by polymerase chain reaction and then by Hpa II digestion.

RESULTS

In the overall group, after adjustment for age, sex, weight, height, and family correlation, the A allele was significantly associated with lower energy (P for trend = 0.045) and with total, monounsaturated, and saturated fat intakes expressed in g/d (P for trend = 0.007, 0.005, and 0.006, respectively). Subjects with the GA genotype had intermediate values. In addition, genotype x sex and genotype x age interactions were not significant.

CONCLUSIONS

The 5-HT2A gene polymorphism in the promoter region is associated with energy and fat intakes in young people. This could be explained by the role of the serotonergic system as a determinant of food intakes and eating behavior.

Interaction between obesity-susceptibility loci in chromosome regions 2p25-p24 and 13q13-q21

One of the chief complexities of genetic influences on human obesity appears to be gene-gene interactions. Here, we employed model-free approaches to look for gene-gene interaction effects in human obesity using genome scan data from 260 European American families. We found consistent evidence for statistical interaction between 2p25-p24 (18-38 cM) and 13q13-q21 (26-47 cM). For discrete traits, the positive correlations were significant at P<0.0001 (P</=0.0023 after correction for multiple tests) in both IBD-based and NPL-based analyses for BMI>/=40 kg/m(2). Other analytic approaches gave consistent, supportive results. For quantitative traits, interaction effects were significant for BMI (P=0.0012), percent fat (P=0.0265) and waist circumference (P=0.0023) in a Haseman-Elston regression model, and for BMI (P=0.0043) in variance component analysis. Our findings suggest that obesity-susceptibility loci in chromosome regions 2p25-p24 and 13q13-21 may interact to influence extreme human obesity. The identification of gene-gene interactions may prove crucial to understanding the contributions of genes, which, by themselves, have relatively small effects on obesity susceptibility and resistance.

A psychobiological perspective on genetic determinants of hypothalamus-pituitary-adrenal axis activity

From the perspective of psychobiological stress research we present a brief overview of findings documenting a significant impact of genetic factors on the activity of the hypothalamus-pituitary-adrenal (HPA) axis. Quantitative genetic studies in twins as well as association studies, primarily on polymorphisms in the glucocorticoid receptor gene, are depicted. Recent findings suggest that the collaboration of psychobiology and molecular genetics is a promising interdisciplinary approach that will significantly contribute to the understanding of the mechanisms underlying the link between stress, the HPA axis, and HPA-related clinical states.

Comparison of Gene Expression in Intra-Abdominal and Subcutaneous Fat: A Study of Men with Morbid Obesity and Nonobese Men Using Microarray and Proteomics

Extent of intra-abdominal fat had significant linear relations with six metabolic coronary risk factors: systolic and diastolic blood pressure, fasting blood concentrations of glucose, high density lipoprotein (HDL) cholesterol, triglyceride, and plasminogen activator inhibitor-1. Tumor necrosis factor-alpha and adiponectin can be biological mediators from the intra-abdominal fat to the metabolic coronary risk factors. Complementarily, we describe a new study that will analyze the gene expression in intra-abdominal and subcutaneous fat on mRNA and protein level using high throughput methods. The study will elucidate further whether intra-abdominal obesity is the common denominator for the different components of the metabolic syndrome.

Analysis of 5-hydroxytryptamine 2c receptor gene promoter variants as alcohol-dependence risk factors

AIMS

To examine whether polymorphic variants of the HTR2C gene are associated with diagnosis of alcohol dependence.

METHODS

We compared allele frequencies of five HTR2C promoter polymorphisms in a Nordic population of alcohol dependent individuals (Males: n = 309; Females: n = 127) and ethnically matched controls (Males: n = 83; Females: n = 190) in whom alcohol dependence was established, or any diagnosis of substance disorder was excluded, respectively. Patients were further subtyped into Type I (late onset) and Type II (early onset) alcoholics.

RESULTS

None of the individual polymorphisms indicated significant association with alcohol dependence. A common promoter haplotype (GAGG) exhibited different distribution frequencies between males and females (Type I), however on Bonferroni's multiple-testing correction, this observation proved to be insignificant.

CONCLUSIONS

Although we report a lack of association between alcohol dependence and five common promoter polymorphisms, and the constituted haplotypes, the analysis tends to indicate gender and sub-type differences. We suggest that a follow up study with larger sample numbers should be performed to improve the power to detect the genetic influences of HTR2C in alcohol dependence.

Association of the -1438 G/A and 102 T/C polymorphism of the 5-Ht2A receptor gene with irritable bowel syndrome 5-Ht2A gene polymorphism in irritable bowel syndrome

GOALS

The aim of this study is to investigate whether there were any association between the 102 T/C and -1438 G/A polymorphisms of the 5-HT2A receptor gene and IBS, and abdominal pain, anxiety and depression.

BACKGROUND

Genes involved in serotonin (5-HT) metabolism are good candidates for the pathogenesis of irritable bowel syndrome (IBS). Recently, a silent polymorphism in the 5-HT2A receptor gene was identified that is defined by a T to C transition at position 102. Also, a novel G to A base change at position -1438 of the promoter region has been detected in 5-HT2A receptor gene.

STUDY

Fifty-four patients with IBS diagnosed according to the Rome 1 criteria and 107 healthy individuals were included in the study. PCR was used to amplify a 468-bp (G-->A) and 342-bp (T-->C) fragment of genomic DNA containing the polymorphism. Hospital anxiety and depression scale was used to assess the risk of depression and anxiety. Severity of chronic abdominal pain was determined by visual analogue scale (VAS).

RESULTS

It was shown that there was a high incidence of homozygote C allele of the 102T/C polymorphism (%22.2; OR: 7.89, P = 0.04) and homozygote A allele of the -1438 G/A promoter region (%%37; OR: 11.14, P = 0.01) in patients with IBS. The risk of having an anxiety disorder was 83.3% in patients with C/C genotype, which was higher than other allele carrying patients, and overall mean (%52.7). (chi = 8.56, P = 0.014). The patients with T/T genotype had a VAS score of 54.93 +/- 2.59 mm, which was significantly higher than that of the patients with other genotypes (p1 = 0.02, p2 = 0.001).

CONCLUSION

This study suggests that the patients with homozygote C allele of the 102 T/C polymorphisms or homozygote A allele of the -1438 G/A polymorphism of the 5-HT2A receptor gene, have a high risk of IBS. On the other hand, T/T genotype of 102 T/C polymorphism may be associated with more severe pain in patient with IBS.

A database of [18F]-altanserin binding to 5-HT2A receptors in normal volunteers: normative data and relationship to physiological and demographic variables

This study presents the results of an analysis of 5-hydroxytryptamine (5-HT)(2A) receptors in 52 healthy subjects. Thirty men and twenty-two women aged between 21 and 79 years were investigated with magnetic resonance imaging (MRI) and [(18)F]-altanserin positron emission tomography (PET). The distribution volumes of specific tracer binding (DV(3)') was calculated for 15 brain regions using either cerebellum or pons as reference regions and correlations between DV(3)' and physiological and demographic variables were made. The regional distribution of [(18)F]-altanserin binding in the healthy human brain was in agreement with existing in vitro post-mortem human 5-HT(2A) data. Apart from nonspecific cerebellar binding (DV(2)), there was no gender difference in 5-HT(2A) binding. A positive correlation between cerebellar binding and age was observed and negative correlations between age and DV(3)' were found in all cortical regions, except occipital cortex, corresponding to a decrease in DV(3)' of 6% or 4% per decade with cerebellum or pons as reference regions, respectively. In several temporal and frontal cortical regions, positive correlations were found between body mass index (BMI) and DV(3)'. Our findings provide a resource to aid design of clinical studies of the 5-HT(2A) receptors. [(18)F]-altanserin binding appears to be unaffected by gender, but the effects of ageing must be considered for clinical studies. The correlations between different cortical regions' 5-HT(2A) binding and BMI should be explored in future studies.

Body weight and abdominal fat gene expression profile in response to a novel hydroxycitric acid-based dietary supplement

Obesity is a global public health problem, with about 315 million people worldwide estimated to fall into the WHO-defined obesity categories. Traditional herbal medicines may have some potential in managing obesity. Botanical dietary supplements often contain complex mixtures of phytochemicals that have additive or synergistic interactions. The dried fruit rind of Garcinia cambogia, also known as Malabar tamarind, is a unique source of (-)-hydroxycitric acid (HCA), which exhibits a distinct sour taste and has been safely used for centuries in Southeastern Asia to make meals more filling. Recently it has been demonstrated that HCA-SX or Super Citrimax, a novel derivative of HCA, is safe when taken orally and that HCA-SX is bioavailable in the human plasma as studied by GC-MS. Although HCA-SX has been observed to be conditionally effective in weight management in experimental animals as well as in humans, its mechanism of action remains to be understood. We sought to determine the effects of low-dose oral HCA-SX on the body weight and abdominal fat gene expression profile of Sprague-Dawley rats. We observed that at doses relevant for human consumption dietary HCA-SX significantly contained body weight growth. This response was associated with lowered abdominal fat leptin expression while plasma leptin levels remained unaffected. Repeated high-density microarray analysis of 9960 genes and ESTs present in the fat tissue identified a small set (approximately 1% of all genes screened) of specific genes sensitive to dietary HCA-SX. Other genes, including vital genes transcribing for mitochondrial/nuclear proteins and which are necessary for fundamental support of the tissue, were not affected by HCA-SX. Under the current experimental conditions, HCA-SX proved to be effective in restricting body weight gain in adult rats. Functional characterization of HCA-SX-sensitive genes revealed that upregulation of genes encoding serotonin receptors represent a distinct effect of dietary HCA-SX supplementation.

Nonpeptide corticotropin-releasing hormone receptor type 1 antagonists and their applications in psychosomatic disorders

Overproduction of corticotropin-releasing hormone (CRH) and stress system abnormalities are seen in psychiatric diseases such as depression, anxiety, eating disorders, and addiction. Investigations of CRH type 1 receptor (CRHR1) nonpeptide antagonists suggest therapeutic potential for treatment of these and other neuropsychiatric diseases. However, overproduction of CRH in the brain and on its periphery and disruption of the hypothalamic-pituitary-adrenal axis are also found in 'somatic' disorders. Some rare forms of Cushing's disease and related pituitary/adrenal disorders are obvious applications for CRHR1 antagonists. In addition, however, these antagonists may also be effective in treating more common somatic diseases. Patients with obesity and metabolic syndrome who often have subtle, but chronic hypothalamic-pituitary-adrenal hyperactivity, which may reflect central dysregulation of CRH and consequently glucocorticoid hypersecretion, could possibly be treated by administration of CRHR1 antagonists. Hormonal, autonomic, and immune aberrations are also present in chronic inflammatory, autoimmune, and allergic diseases, with considerable evidence linking CRH with the observed abnormalities. Furthermore, autonomic dysregulation is a prominent feature of common gastrointestinal disorders, such as irritable bowel syndrome and peptic ulcer disease. Patients with irritable bowel syndrome and other gastrointestinal disorders frequently develop altered pain perception and affective symptoms. CRH acts peripherally to modulate bowel activity both directly through the autonomic system and centrally by processing viscerosensory and visceromotor neural signals. This review presents clinical and preclinical evidence for the role of CRH in the pathophysiology of these disorders and for potential diagnostic and therapeutic applications of CRHR1 antagonists. Recognition of a dysfunctional stress system in these and other diseases will alter the understanding and treatment of 'psychosomatic' disorders.

Association studies of genetic polymorphisms in central obesity: a critical review

During the past decade, mutations affecting liability to central obesity have been discovered at a phenomenal rate, and despite few consistently replicated findings, a number of intriguing results have emerged in the literature. Association studies have been proposed to identify the genetic determinants of complex traits such as central obesity. The advantages of the association method include its relative robustness to genetic heterogeneity and the ability to detect much smaller effect sizes than is detectable using feasible sample sizes in linkage studies. However, the current literature linking central obesity to genetic variants is teeming with reports of associations that either cannot be replicated or for which corroboration by linkage has been impossible to find. Explanations for this lack of reproducibility are well rehearsed, and typically include poor study design, incorrect assumptions about the underlying genetic architecture, and simple overinterpretation of data. These limitations create concern about the validity of association studies and cause problems in establishing robust criteria for undertaking association studies. In this article, the current status of the literature of association studies for genetic dissection of central obesity is critically reviewed.

The human obesity gene map: the 2002 update

This is the ninth update of the human obesity gene map, incorporating published results through October 2002 and continuing the previous format. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, quantitative trait loci (QTLs) from human genome-wide scans and various animal crossbreeding experiments, and association and linkage studies with candidate genes and other markers is reviewed. For the first time, transgenic and knockout murine models exhibiting obesity as a phenotype are incorporated (N = 38). As of October 2002, 33 Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and the causal genes or strong candidates have been identified for 23 of these syndromes. QTLs reported from animal models currently number 168; there are 68 human QTLs for obesity phenotypes from genome-wide scans. Additionally, significant linkage peaks with candidate genes have been identified in targeted studies. Seven genomic regions harbor QTLs replicated among two to five studies. Attempts to relate DNA sequence variation in specific genes to obesity phenotypes continue to grow, with 222 studies reporting positive associations with 71 candidate genes. Fifteen such candidate genes are supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. More than 300 genes, markers, and chromosomal regions have been associated or linked with human obesity phenotypes. The electronic version of the map with links to useful sites can be found at http://obesitygene.pbrc.edu.