Relationship between DRD4 polymorphism and lipid metabolism: what is the role of novelty seeking?

Network Pharmacology and Molecular Docking Analysis on Targets and Mechanisms of Berberine in Atypical Antipsychotic-Induced Metabolic Syndrome

Berberine (BBR), an isoquinoline alkaloid, possesses multiply pharmacological effects as a potential therapeutic drug for antipsychotic-induced metabolic syndrome (MetS). However, the underlying therapeutic mechanisms have not been fully elucidated. In this study, we aim to investigate the possible mechanisms by identifying the key targets and biological pathways through network pharmacology and molecular docking analysis. A total of 23 overlapping targets in the intersection set among BBR, atypical antipsychotic drugs (AADs), and MetS were determined. PPI network analysis showed that 22 out of the 23 overlapping targets closely interacted with the others. The following pathway enrichment analysis and molecular docking indicated a central role of peroxisome proliferator-activated receptor-γ (PPARG) as the key target of BBR against AAD-induced MetS by acting on the PPAR signaling pathway, lipid and atherosclerosis, and AMP activated protein kinase (AMPK) signaling pathway. In addition, cytochrome P-450 2D6 (CYP2D6) could be considered as another target of BBR in ameliorating antipsychotic-induced metabolic side effects. Collectively, this study investigated the central targets and biological pathways of BBR against AAD-induced MetS from a systematic perspective, and thus brings novel insights into further understanding of the protective effects of BBR.

Association of APOE E2 and low-density lipoprotein with depressive symptoms in Chinese senile schizophrenia inpatients: A cross-sectional study

Background

Schizophrenia is considered to occur due to both environmental and genetic factors. Depressive symptoms and apolipoprotein E (APOE) gene polymorphisms are involved in the pathogenesis of schizophrenia. However, the effect of APOE gene polymorphism on depressive symptoms has never been investigated among Chinese elderly schizophrenia patients.

Objective

This cross-sectional study aimed to determine the effect of APOE gene polymorphism on blood lipid metabolism and depressive symptoms among elderly schizophrenia patients.

Method

A total of 301 elderly schizophrenia patients (161 males, age ranges from 60 to 92 years, with an average age of 67.31 ± 6.667) were included in the study. Depressive symptoms were assessed using the Geriatric Depression Scale (GDS). APOE gene polymorphisms were determined by polymerase chain reaction (PCR). Correlations between GDS and serum low-density lipoprotein (LDL) levels with APOE genotypes were assessed.

Results

The concentration of LDL in the APOE E2 group was significantly lower than those in the APOE E3 and APOE E4 groups, and the GDS scores in the APOE E2 and APOE E3 groups were higher than those in the APOE E4 group. Using partial correlation analysis and controlling the duration of disease and hyperlipidemia, we found that GDS scores were significantly correlated with LDL (r = −0.179, p = 0.025).

Conclusions

The APOE E2 genotype is associated with more depressive symptoms and lower serum LDL in elderly Chinese schizophrenia patients, and there is a negative correlation between depressive symptoms and LDL.

Association between apolipoprotein E gene polymorphism and depression

We performed an updated meta-analysis to obtain a more precise estimation of the relationship between apolipoprotein E (ApoE) gene polymorphism and susceptibility to depression, as previous reports have been inconsistent. Twenty studies with 2286 depression patients and 3845 controls were included. Odds ratios (OR) with 95% confidence intervals (CI) were calculated to assess the association between ApoE gene polymorphism and depression using a random effects model. Results showed a significant association between ApoE gene polymorphism and susceptibility to depression in the overall population (ε2/ε3 genotype versus ε3/ε3: OR 0.76, 95% CI 0.59-0.99). Subgroup analyses indicated an association in the Caucasian population (ε2 allele versus ε3: OR 0.75, 95% CI 0.58-0.97) as well as in late-life depression (LLD) patients (ε3/ε4 genotype versus ε3/ε3: OR 1.34, 95% CI 1.07-1.68, and ε4 allele versus ε3: OR 1.30, 95% CI 1.06-1.59). We concluded that the ε2/ε3 genotype likely provided a protective effect against depression in the overall population and the ε2 allele acted as a protective factor for depression in the Caucasian population while the ε4 allele and ε3/ε4 genotype were associated with an increased risk of depression in the LLD subjects.

Shared genetic factors in the co-occurrence of symptoms of depression and cardiovascular risk factors

BACKGROUND

We aim to investigate the extent to which shared genetic and shared environmental factors play a role in the co-occurrence of symptoms of depression and cardiovascular risk factors.

METHODS

The analyses included 2383 individuals from a genetically isolated population in the Netherlands (mean age 48.7 years (standard deviation 15.1), percentage of women 56.9%). Symptoms of depression were assessed using the Center for Epidemiology Studies Depression Scale (CES-D) and the Depression subscale of the Hospital Anxiety and Depression Scale (HADS-D). Assessment of cardiovascular risk factors included systolic and diastolic blood pressure, plasma, glucose levels, high and low density lipoprotein (HDL, LDL) and total cholesterol levels.

RESULTS

Overall, we found that HADS-D was significantly correlated to total cholesterol levels (correlation coefficient [rho]=0.05), and inversely associated to HDL (rho=-0.06). Statistically significant genetic correlations (rho(G)) were found between CES-D scores and total plasma cholesterol (rho(G)=0.30), LDL (rho(G)=0.31) and total cholesterol/HDL ratios (rho(G)=0.25). For HADS-D scores, a significant genetic correlation was found with total cholesterol/HDL ratios (rho(G)=0.27). Environmental correlations (rho(E)) with an opposite direction were found between CES-D and both total cholesterol (rho(E)=-0.16) and LDL (rho(E)=-0.15).

LIMITATION

By adjusting for sibship, we are taking into account environmental effects, however we cannot exclude dominance variance.

CONCLUSIONS

Our study shows that there is evidence for shared genetic factors contributing to the co-occurrence of symptoms of depression and lipid levels. This finding suggests a joint genetic pathogenesis. Future research is encouraged to assess susceptibility genes for mood disorders to be studied for cardiovascular disorders and vice versa.

Association of the dopamine D4 receptor (DRD4) gene and approach-related personality traits: meta-analysis and new data

BACKGROUND

Two variants in the dopamine D4 receptor (DRD4) gene have been reported to be associated with human approach-related traits such as novelty seeking and extraversion. However, the strength of evidence for this association remains uncertain.

METHODS

We conducted a meta-analysis of published studies of the association between the DRD4 gene variable number of tandem repeats (VNTR) and C-521T polymorphisms and human approach-related personality traits, including novelty seeking, extraversion, and impulsivity, restricted to adult samples recruited from nonpsychiatric populations, and extended on this literature by attempting to confirm any evidence of association in a replication sample (n = 309) selected for extreme scores on the extraversion subscale of the Eysenck Personality Questionnaire from a large (n = 40,090) population-based sample.

RESULTS

Our initial meta-analysis supported the association of the DRD4 C-521T polymorphism, but not the VNTR polymorphism, with approach-related traits. This conclusion was qualified by evidence of significant publication bias and the failure to detect association in a replication sample comprising individuals at the extremes of the trait distribution. The association of the C-521T polymorphism observed in our initial meta-analysis was robust to the inclusion of these new data, but our revised meta-analysis indicated that the association was present for measures of novelty seeking and impulsivity but not for measures of extraversion.

CONCLUSIONS

The DRD4 gene may be associated with measures of novelty seeking and impulsivity but not extraversion. The association of the C-521T variant with these measures, if genuine, may account for up to 3% of phenotypic variance.

Smoking cessation, weight gain, and DRD4 -521 genotype

We investigated change in body mass index following long-term smoking cessation in a representative cohort of treatment-seeking heavy smokers in the United Kingdom, to determine the extent of long-term weight gain in successful quitters versus continuing smokers. We further investigated whether DRD4 genotype moderated any weight gain in either group. Smoking cessation was associated with an increase in BMI, and persisted up to 8 years after smoking cessation. Ex-smokers at 8-year follow-up weighed over 2.5 kg/m(3) more on average than they did at baseline, while participants who were smokers at both baseline and 8-year follow-up did not demonstrate any change in BMI. We did not observe an interaction between smoking status and DRD4 genotype. However, independently of the weight gain among those who stopped smoking during the course of the study, DRD4 genotype was significantly associated with BMI, with possession of the -521 C-allele associated with increased BMI. The magnitude of increase in BMI following smoking cessation, and the persistence of this change at 8-year follow-up, suggests that health benefits associated with smoking cessation may to some extent be negated by the detrimental effects on health of associated weight gain. Smoking cessation programmes should therefore consider incorporating follow-up support to promote weight loss among those who successfully stop smoking.