Met carriers of the BDNF Val66Met polymorphism show reduced Glx/NAA in the pregenual ACC in two independent cohorts

BDNF rs6265 Met carriers with alcohol use disorder show greater age-related decline of N-acetylaspartate in left dorsolateral prefrontal cortex

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is implicated in neuronal and glial cell growth and differentiation, synaptic plasticity, and apoptotic mechanisms. A single-nucleotide polymorphism of the BDNF rs6265 gene may contribute to the pattern and magnitude of brain metabolite abnormalities apparent in those with an Alcohol Use Disorder (AUD). We predicted that Methionine (Met) carriers would demonstrate lower magnetic resonance spectroscopy (MRS) measures of N-acetylaspartate level (NAA) and greater age-related decline in NAA than Valine (Val) homozygotes.

METHODS

Veterans with AUD (n=95; 46±12 years of age, min = 25, max = 71) were recruited from VA Palo Alto residential treatment centers. Single voxel MRS, at 3 Tesla, was used to obtain NAA, choline (Cho) and creatine (Cr) containing compounds from the left dorsolateral prefrontal cortex (DLPFC). Metabolite spectra were fit with LC Model and NAA and Cho were standardized to total Cr level and NAA was also standardized to Cho.

RESULTS

Val/Met (n=35) showed markedly greater age-related decline in left DLPFC NAA/Cr level than Val/Val (n=60); no differences in mean metabolite levels were observed between Val/Met and Val/Val. Val/Met demonstrated greater frequency of history of MDD and higher frequency of cannabis use disorder over 12 months prior to study.

CONCLUSIONS

The greater age-related decline in left DLPFC NAA/Cr and the higher frequency of MDD history and Cannabis Use disorder in BDNF rs6265 Met carriers with AUD are novel and may have implications for non-invasive brain stimulation targeting the left DLFPC and other psychosocial interventions typically utilized in the treatment of AUD.

Association of BDNF gene missense polymorphism rs6265 (Val66Met) with three quantitative traits, namely, intelligence quotient, body mass index, and blood pressure: A genetic association analysis from North India

Background

Brain-derived neurotrophic factor (BDNF), a neurotransmitter modulator, plays a significant role in neuronal survival and growth and participates in neuronal plasticity, thus being essential for learning, memory, and the development of cognition. Additionally, it is crucial for appetite, weight, and metabolic control and plays a pivotal role in the cardiovascular system. The Val66Met polymorphism (rs6265) of the BDNF gene causes a decrease in BDNF secretion and plays a role in impairments in cognition, energy homeostasis, and cardiovascular events. The present study aimed to evaluate the association of polymorphism (rs6265) of the BDNF gene with three quantitative traits simultaneously, namely, intelligence quotient (IQ), body mass index (BMI), and blood pressure (BP).

Methods

Psychometric, morphometric, and physiometric data of the total participants (N = 246) were collected. WASI-II^INDIA was used to measure cognitive ability. Genotyping was carried out using allele-specific PCR for the rs6265 polymorphism (C196T), and genotypes were determined. Statistical analyses were performed at p < 0.05 significance level using MS-Excel and SigmaPlot. The odds ratio models with a 95% confidence interval were used to test the associations. The used models are co-dominant, recessive, dominant, over-dominant, and additive.

Results

The allelic frequencies of alleles C and T were 72 and 28%, respectively. Under the dominant genetic model, a significant susceptible association of minor allele T was observed with a lower average verbal comprehensive index (OR = 2.216, p = 0.003, CI (95%) =1.33-3.69), a lower average performance reasoning index (OR = 2.634, p < 0.001, CI (95%) = 1.573-4.41), and a lower average full-scale IQ-4 (OR = 3.159, p < 0.001, CI (95%) = 1.873-5.328). Carriers of Met-alleles were found to have an increased body mass index (OR = 2.538, p < 0.001, CI (95%) = 1.507-4.275), decreased systolic blood pressure (OR = 2.051, p = 0.012, CI (95%) = 1.202-3.502), and decreased diastolic blood pressure (OR = 2.162, p = 0.006, CI (95%) = 1.278-3.657). Under the recessive genetic model, several folds decrease in IQ and BP and an increase in BMI with the presence of the T allele was also detected.

Conclusion

This novel study may improve our understanding of genetic alterations to the traits and hence be helpful for clinicians and researchers to investigate the diagnostic and prognostic value of this neurotrophic factor.

BDNF rs6265 differentially influences neurometabolites in the anterior cingulate of healthy and bipolar disorder subjects

Brain-derived neurotrophic factor (BDNF) is the most abundant brain neurotrophin and plays a critical role in neuronal growth, survival and plasticity, implicated in the pathophysiology of Bipolar Disorders (BD). The single-nucleotide polymorphism in the BDNF gene (BDNF rs6265) has been associated with decreased hippocampal BDNF secretion and volume in met carriers in different populations, although the val allele has been reported to be more frequent in BD patients. The anterior cingulate cortex (ACC) is a key center integrating cognitive and affective neuronal connections, where consistent alterations in brain metabolites such as Glx (Glutamate + Glutamine) and N-acetylaspartate (NAA) have been consistently reported in BD. However, little is known about the influence of BDNF rs6265 on neurochemical profile in the ACC of Healthy Controls (HC) and BD subjects. The aim of this study was to assess the influence of BDNF rs6265 on ACC neurometabolites (Glx, NAA and total creatine- Cr) in 124 euthymic BD type I patients and 76 HC, who were genotyped for BDNF rs6265 and underwent a 3-Tesla proton magnetic resonance imaging and spectroscopy scan (¹ H-MRS) using a PRESS ACC single-voxel (8cm³) sequence. BDNF rs6265 polymorphism showed a significant two-way interaction (diagnosis × genotype) in relation to NAA/Cr and total Cr. While met carriers presented increased NAA/Cr in HC, BD-I subjects with the val allele revealed higher total Cr, denoting an enhanced ACC metabolism likely associated with increased glutamatergic metabolites observed in BD-I val carriers. However, these results were replicated only in men. Therefore, our results support evidences that the BDNF rs6265 polymorphism exerts a complex pleiotropic effect on ACC metabolites influenced by the diagnosis and sex.

NAA/Glu Ratio Associated with Suicidal Ideation in Pilot Sample of Autistic Youth and Young Adults

Suicidality is increased in autism spectrum disorder (ASD), yet effective interventions are lacking. Developing biologically based approaches for preventing and treating suicidality in ASD hinges on the identification of biomarkers of suicidal ideation (SI). Here, we assessed magnetic resonance spectroscopy (MRS) markers of glutamatergic neurotransmission in ASD youth and young adults. Twenty-eight ASD participants (16-33 years) underwent 1H-MRS, and metabolites were quantified using LCModel. N-acetylaspartate (NAA), glutamate (Glu), and the NAA/Glu ratio from the left dorsolateral prefrontal cortex were compared between ASD SI+ (n = 13) and ASD SI- (n = 15) participants. We found that ASD SI+ participants had a higher NAA/Glu ratio compared ASD SI- participants. The NAA/Glu ratio also predicted SI and significantly discriminated between ASD SI+/SI- participants. All analyses including NAA and Glu alone were non-significant. Here, we provide preliminary evidence for the importance of NAA/Glu in ASD with SI, with implications for biomarker discovery. Further mechanistic research into risk and interventional approaches to address SI in ASD are needed.

Optimization of spectrally selective 180° radiofrequency pulse timings in J-difference editing (MEGA) of lactate

PURPOSE

J-Difference editing (MEGA) provides an effective spectroscopic means of selectively measuring low-concentration metabolites having weakly coupled spins. The fractional inphase and antiphase coherences are determined by the radiofrequency (RF) pulses and inter-RF pulse intervals of the sequence. We examined the timings of the spectrally selective editing 180° pulses (E180) in MEGA-PRESS to maximize the edited signal amplitude in lactate at 3T.

METHODS

The time evolution of the lactate spin coherences was analytically and numerically calculated for non-volume localized and single-voxel localized MEGA sequences. Single-voxel localized MEGA-PRESS simulations and phantom experiments were conducted for echo time (TE) 60-160 ms and for all possible integer-millisecond timings of the E180 pulses. Optimized E180 timings of 144, 103, and 109 ms TEs, tailored with simulation and phantom data, were tested in brain tumor patients in vivo. Lactate signals, broadened to singlet linewidths (~6 Hz), were compared between simulation, phantom, and in vivo data.

RESULTS

Theoretical and experimental data indicated consistently that the MEGA-edited signal amplitude and width are sensitive to the E180 timings. In volume-localized MEGA, the lactate peak amplitudes in E180-on and difference spectra were maximized at specific E180 timings for individual TEs, largely due to the chemical-shift displacement effects. The E180 timings for maximum lactate peak amplitude were different from those of maximum inphase coherence in in vivo linewidth situations.

CONCLUSION

In in vivo MEGA editing, the E180 pulse timings can be effectively used for manipulating the inphase and antiphase coherences and increasing the edited signal amplitude, following TE optimization.

BDNF blood serum linkage with BDNF gene polymorphism (rs6265) in thyroid pathology patients in the West-Ukrainian population

Objective. Brain-derived neurotrophic factor (BDNF) is identified as an important growth factor involved in learning and memory. Patients with Hashimoto's thyroiditis can suffer from cognitive dysfunction, whereas BDNF is directly regulated by thyroid hormones. It seems reasonable to propose that changes in BDNF expression underlie some of the persistent neurological impairments associated with hypothyroidism. Methods. The study involved a total of 153 patients with various forms of thyroid pathology. BDNF levels in the sera of the patients and healthy individuals were quantified using enzyme-linked immunosorbent assay with highly sensitive Human BDNF ELISA Kit. Genotyping of the BDNF (rs6265) gene polymorphism using TaqMan probes and TaqMan Genotyping Master Mix (4371355) on CFX96™Real-Time PCR Detection System. Polymerase chain reaction (PCR) for TaqMan genotyping was carried out according to the kit instructions. Results. Distribution rs6265 variants in the patients depending on the different types of thyroid pathology showed no significant difference in the relative frequency of BDNF polymorphic variants. Presence of hypothyroidism, regardless of its cause (autoimmune or postoperative), there was a decrease in the serum BDNF levels in all genotypes carriers compared with the control group. The analysis of the correlation between BDNF levels and the levels of thyroid-stimulating hormone (TSH), thyroxine (T4), anti-thyroglobulin (anti-Tg), and anti-thyroid peroxidase (anti-TPO) antibodies showed a significant inverse relationship between BDNF and TSH levels (p<0.001), a direct correlation between BDNF and T4 levels in the blood (p<0.001), and a weak direct relationship between anti-Tg and BDNF levels (p=0.0157). Conclusion. The C allele presence is protective and associates with the lowest chances for reduced serum BDNF levels in thyroid pathology patients in the West-Ukrainian population. However, the T-allele increases the risk of low BDNF levels almost 10 times in observed subjects.

A pilot spectroscopy study of adversity in adolescents

Background

Childhood adversity is a global health problem affecting 25-50% of children worldwide. Few prior studies have examined the underlying neurochemistry of adversity in adolescents. This cross-sectional study examined spectroscopic markers of trauma in a cohort of adolescents with major depressive disorder (MDD) and healthy controls. We hypothesized that historical adversity would have a negative relationship with spectroscopic measures of glutamate metabolites in anterior cingulate cortex.

Methods

Adolescent participants (aged 13-21) underwent a semi-structured diagnostic interview and clinical assessment, which included the self-report Childhood Trauma Questionnaire (CTQ), a 28-item assessment of childhood adversity. Proton magnetic resonance spectroscopy (1H-MRS) scans at 3 Tesla of an anterior cingulate cortex (ACC) voxel (8 cm3) encompassing both hemispheres were collected using a 2-dimensional J-averaged sequence to assess N-acetylaspartate (NAA), Glx (glutamate+glutamine) and [NAA]/[Glx] concentrations. Generalized linear models assessed the relationships between CTQ scores and metabolite levels in ACC.

Results

Thirty-nine participants (17 healthy controls, 22 depressed participants) underwent 1H-MRS and completed the CTQ measures. There were decrements in [NAA]/[Glx] ratio in the ACC of participants with childhood adversity while no significant relationship between CTQ total score and any of the ACC metabolites was found in the combined sample. Exploratory results revealed a positive association between Glx levels and CTQ scores in depressed participants. Conversely the [NAA]/[Glx] ratio had a negative association with total CTQ scores in the depressed participants. Emotional Abuse Scale showed a significant negative relationship with [NAA]/[Glx] ratio in the combined sample when adjusted for depression severity.

Conclusions

Our findings suggest that childhood adversity may impact brain neurochemical profiles. Further longitudinal studies should examine neurochemical correlates of childhood adversity throughout development and in populations with other psychiatric disorders.

Brain-derived neurotrophic factor produced long-term synaptic enhancement in the anterior cingulate cortex of adult mice

Previous studies have demonstrated that brain-derived neurotrophic factor (BDNF) is one of the diffusible messengers for enhancing synaptic transmission in the hippocampus. Less information is available about the possible roles of BDNF in the anterior cingulate cortex (ACC). In the present study, we used 64-electrode array field recording system to investigate the effect of BDNF on ACC excitatory transmission. We found that BDNF enhanced synaptic responses in a dose-dependent manner in the ACC in C57/BL6 mice. The enhancement was long-lasting, and persisted for at least 3 h. In addition to the enhancement, BDNF also recruited inactive synaptic responses in the ACC. Bath application of the tropomyosin receptor kinase B (TrkB) receptor antagonist K252a blocked BDNF-induced enhancement. L-type voltage-gated calcium channels (L-VGCC), metabotropic glutamate receptors (mGluRs), but not NMDA receptors were required for BDNF-produced enhancement. Moreover, calcium-stimulated adenylyl cyclase subtype 1 (AC1) but not AC8 was essential for the enhancement. A selective AC1 inhibitor NB001 completely blocked the enhancement. Furthermore, BDNF-produced enhancement occluded theta burst stimulation (TBS) induced long-term potentiation (LTP), suggesting that they may share similar signaling mechanisms. Finally, the expression of BDNF-induced enhancement depends on postsynaptic incorporation of calcium-permeable AMPA receptors (CP-AMPARs) and protein kinase Mζ (PKMζ). Our results demonstrate that cortical BDNF may contribute to synaptic potentiation in the ACC.