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Gene–environment (GxE) interactions may comprise an important part of the aetiology of depression, and childhood maltreatment (CM), a significant stressor, has consistently been linked to depression. Hence, in this systematic review, we aimed to investigate the interaction between hypothalamus–pituitary–adrenal axis (HPA-axis) genes and CM in depression.
We conducted a literature search using the Pubmed, Embase, and PsychINFO databases in adherence with the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. We included studies investigating GxE interactions between HPA-axis genes [Angiotensin Converting Enzyme (ACE), Arginine Vasopressin (AVP), Corticotrophin Releasing Hormone (CRH), Corticotrophin Releasing Hormone Receptor 1 (CRHR1), Corticotrophin Releasing Hormone Receptor 2 (CRHR2), FK506 binding protein (FKBP5), Nuclear Receptor subfamily 3 group C member 1 (NR3C1), Nuclear Receptor subfamily 3 group C member 2 (NR3C2)] and CM in depression.
The literature search identified 159 potentially relevant studies. Following screening, 138 of these were excluded. Thus, 21 studies, investigating a total of 51 single nucleotide polymorphisms, were included in the final study. The most prevalent genes in the current study were CRHR1 and FKBP5. Significant GxE interactions were reported in seven of eight studies for CRHR1:rs110402 and CM, and in five of eight studies for FKBP5:rs1360780 and CM. In summary, our results suggest possible GxE interactions between CRHR1, FKBP5, NR3C1, and NR3C2 and CM, respectively. For the remaining genes, no relevant literature emerged.
We find that genetic variation in four HPA-axis genes may influence the effects of CM in depression.
Accumulating evidence from preclinical and clinical studies indicates that prenatal exposure to stress impairs the development of the offspring brain and facilitates the emergence of mental illness. This study aims to describe the impact of prenatal restraint stress on cognition and exploration to an unfamiliar environment at adulthood in an outbred strain of mice.
Late pregnant mice were exposed to restraint stress and adult offspring (60 days of age) behaviours were assessed in the object recognition task and open field test.
Prenatal stress (PNS) impaired new object recognition in male and female mice. Importantly, the learning deficits in female PNS mice were linked to their estrous cycle. Actually, PNS females in metestrus/diestrus but not in proestrus/estrus phases displayed recognition deficits compared to controls. Concerning locomotion in an unfamiliar environment, male but not female PNS mice displayed significant increase, but showed no differences in the distance travelled within the centre zone of the arena.
Present findings support the view that maternal restraint-stress during late pregnancy impairs recognition memory in both male and female offspring, and in females, this cognitive deficit is dependent on the estrous cycle phase. Ultimately, these data reinforce that PNS is an aetiological component of psychiatric disorders associated with memory deficits.
Abnormalities in neurotransmission via N-methyl-d-aspartic acid receptor (NMDAR) play a role in the pathophysiology of neuropsychiatric disorders. The impact of repetitive transcranial magnetic stimulation (rTMS) on NMDAR-related amino acids remains unknown. We aim to investigate the effects of rTMS on NMDAR-related amino acids in serum of post-stroke patients.
Ninety-five consecutive post-stroke patients with upper limb hemiparesis were recruited. In 27 patients, the Beck Depression Inventory (BDI) score was 10 or higher. Twelve depressed patients underwent rehabilitation in combination with rTMS and 15 non-depressed patients underwent rehabilitation only without rTMS for 14 days. 1 Hz rTMS was applied to the primary motor area in the non-lesional hemisphere. BDI was conducted before and after treatment. Serum glutamine, glutamate, glycine, l-serine, and d-serine levels were measured before and after treatment.
There were no differences between depressed patients and non-depressed patients in clinical characteristics, levels of the five amino acids in serum, and the ratio of amino acids. However, in 27 depressed patients, there was a significant correlation between levels of glutamate in serum and BDI (ρ = 0.428, p = 0.026). BDI decreased significantly in depressed patients after treatment with or without rTMS. d-serine decreased in the rehabilitation with rTMS group, but increased in the rehabilitation without rTMS group. l-serine increased in the rehabilitation with rTMS group, but decreased in the rehabilitation without rTMS group.
The results suggest that rTMS can modulate NMDAR-related amino acids in blood, producing beneficial effects.
Peripheral gene expression of several molecular pathways has been studied in major depressive disorder (MDD) with promising results. We sought to investigate some of these genes in a treatment-free Latino sample of Mexican descent.
Material and Methods:
The sample consisted of 50 MDD treatment-free cases and 50 sex and age-matched controls. Gene expression of candidate genes of neuroplasticity (BDNF, p11, and VGF), inflammation (IL1A, IL1B, IL4, IL6, IL7, IL8, IL10, MIF, and TNFA), the canonical Wnt signaling pathway (TCF7L2, APC, and GSK3B), and mTOR, was compared in cases and controls. RNA was obtained from blood samples. We used bivariate analyses to compare subjects versus control mean mRNA quantification of target genes and lineal regression modelling to test for effects of age and body mass index on gene expression.
Most subjects were female (66%) with a mean age of 26.7 (SD 7.9) years. Only GSK3B was differentially expressed between cases and controls at a statistically significant level (p = 0.048). TCF7L-2 showed the highest number of correlations with MDD-related traits, yet these were modest in size.
GSK3B encodes a moderator of the canonical Wnt signaling pathway. It has a role in neuroplasticity, neuroprotection, depression, and other psychiatric phenotypes. We found that adding population diversity has the potential to elicit distinct peripheral gene expression markers in MDD and MDD-related traits. However, our results should only be considered as hypothesis-generating research that merits further replication in larger cohorts of similar ancestry.
To investigate the association of prenatal alcohol exposure (PAE) and early neurodevelopment in the first 2 years of life, adjusting for maternal socio-demographic and psychosocial factors, in the Drakenstein Child Health Study (DCHS), a South African birth cohort study.
The DCHS comprises a population-based birth cohort of 1143 children, of which a subsample completed the Bayley Scales of Infant Development-III (BSID-III) at 6 (n = 260) and 24 months of age (n = 734). A subset of alcohol-exposed and -unexposed children was included in this analysis at age 6 (n = 52 exposed; n = 104 unexposed) and 24 months (n = 92 exposed; n = 184 unexposed). Multiple hierarchical regression was used to explore the associations of PAE with motor and language development.
PAE was significantly associated with decreased gross motor [odds ratio (OR) = 0.16, 95% confidence interval (CI) = 0.06–0.44, p = 0.001] or fine motor (OR = 0.16, 95% CI = 0.06–0.46, p = 0.001) functioning after adjusting for maternal socio-demographic and psychosocial factors at 6 months of age only. No significant effects were found in either receptive or expressive communication and cognitive outcomes at either time points.
PAE has potentially important consequences for motor development in the first 2 years of life, a period during which the most rapid growth and maturation occur. These findings highlight the importance of identifying high-risk families in order to provide preventive interventions, particularly in antenatal clinics and early intervention services.
We provide a closer look at the result of a randomised, placebo-controlled, active-reference (quetiapine XR), flexible-dose, 6-week study of brexpiprazole in schizophrenia, which did not meet its primary endpoint – change from baseline in Positive and Negative Syndrome Scale (PANSS) total score. We also investigate potential expectancy bias from the well-known side-effect profile of the active reference that could have affected the study outcome.
Pre-specified sensitivity analyses of the primary end point were performed using analysis of covariance (ANCOVA) last observation carried forward (LOCF) and observed cases (OC). Post hoc analyses of change from baseline in PANSS total score were performed using the mixed model for repeated measures approach with treatment groups split by having typical adverse events with potential for functional unblinding, for example, somnolence, increase in weight, dizziness, dry mouth and sedation.
Pre-specified sensitivity analyses showed separation from placebo for brexpiprazole at week 6: LOCF, ANCOVA: −4.3 [95% CI (−8.0, −0.5), p = 0.0254]. OC, ANCOVA: −3.9 [95% CI (−7.3, −0.5), p = 0.0260]. Patients treated with brexpiprazole experiencing typical adverse events with potential for functional unblinding before or at Week 2 had a least square (LS) mean PANSS change of −29.5 (improvement), with a difference in change from baseline to Week 6 in PANSS total score between brexpiprazole and placebo of −13.5 [95% CI (−23.1, −4.0), p = 0.0057], and those who did not had an LS mean change of −18.9 and a difference between brexpiprazole and placebo of −2.9 [95% CI (−7.2, 1.4), p = 0.1809].
Pre-specified sensitivity analyses showed separation from placebo for brexpiprazole at Week 6. A post hoc analysis suggested a potential confounding of efficacy rating towards symptom improvement in patients who experience known side effects of quetiapine XR.
Although the assessment of expression of serotonin-related genes in experimental animals has become a common strategy to shed light on variations in brain serotonergic function, it remains largely unknown to what extent the manipulation of serotonin levels causes detectable changes in gene expression. We therefore chose to investigate how sub-acute depletion or elevation of brain serotonin influences the expression of a number of serotonin-related genes in six brain areas.
Male Wistar rats were administered a serotonin synthesis inhibitor, para-chlorophenylalanine (p-CPA), or a serotonin reuptake inhibitor, paroxetine, for 3 days and then sacrificed. The expression of a number of serotonin-related genes in the raphe nuclei, hypothalamus, amygdala, striatum, hippocampus and prefrontal cortex was investigated using real-time quantitative PCR (rt-qPCR).
While most of the studied genes were uninfluenced by paroxetine treatment, we could observe a robust downregulation of tryptophan hydroxylase-2 in the brain region where the serotonergic cell bodies reside, that is, the raphe nuclei. p-CPA induced a significant increase in the expression of Htr1b and Htr2a in amygdala and of Htr2c in the striatum and a marked reduction in the expression of Htr6 in prefrontal cortex; it also enhanced the expression of the brain-derived neurotrophic factor (Bdnf) in raphe and hippocampus.
With some notable exceptions, the expression of most of the studied genes is left unchanged by short-term modulation of extracellular levels of serotonin.