Objectives. Intracellular calcium (Ca
2+
) dyshomeostasis (ICDH) has been implicated in bipolar disorder (BD) pathophysiology. We previously showed that SNP rs956572 in the B-cell CLL/lymphoma 2 ...(Bcl-2) gene associates with elevated B lymphoblast (BLCL) intracellular Ca
2+
concentrations (Ca
2+
B
) differentially in BD-I. Genome-wide association studies strongly support the association between BD and the SNP rs1006737, located within the L-type voltage-dependent Ca
2+
channel α1C subunit gene (CACNA1C). Here we investigated whether this CACNA1C variant also associates with ICDH and interacts with SNP rs956572 on Ca
2+
B
in BD-I. Methods. CACNA1C SNP rs1006737 was genotyped in 150 BD-I, 65 BD-II, 30 major depressive disorder patients, and 70 healthy subjects with available BLCL Ca
2+
B
and Bcl-2 SNP rs956572 genotype measures. Results. SNP rs1006737 was significantly associated with BD-I. The Ca
2+
B
was significantly higher in BD-I rs1006737 A compared with healthy A allele carriers and also in healthy GG compared with A allele carriers. There was no significant interaction between SNP rs1006737 and SNP rs956572 on Ca
2+
B
. Conclusions. Our study further supports the association of SNP rs1006737 with BD-I and suggests that CACNA1C SNP rs1006737 and Bcl-2 SNP rs956572, or specific causal variants in LD with these proxies, act independently to increase risk and ICDH in BD-I.
Objectives
Transient receptor potential canonical type 3 (TRPC3) channels are activated in B lymphoblast cell lines from patients with bipolar disorder (BD), and its expression is reduced by chronic ...lithium treatment, implicating TRPC3 in the intracellular calcium (Ca2+) dyshomeostasis of BD. Thrombin, via a protease‐activated receptor, moderates Ca2+ signaling and TRPC3 in astrocytes, and also cell proliferation. We examined whether lithium pretreatment attenuates thrombin‐stimulated TRPC3 expression and function in astrocytes, and levels of the calcium‐binding peptide, S100B, which is expressed mainly in these cells.
Methods
Human astroglioma, U‐87MG, cells were pretreated with 1 mmol L−1 LiCl for 1 day (acute), 3 days (subacute), and 7 days (chronic). To examine the role of TRPC3, genetically stable knockdown TRPC3 cells (TRPC3Low cells) were constructed using U‐87MG cells. Thrombin (2.0 U/mL)‐stimulated Ca2+ mobilization was measured by ratiometric fluorimetry. Changes in TRPC3 and S100B expression levels were determined by quantitative reverse transcription‐polymerase chain reaction and immunoblotting, respectively. Cell proliferation was also measured using the WST‐8 assay.
Results
In this cell model, thrombin‐stimulated Ca2+ mobilization, and both TRPC3 and S100B expression were suppressed by chronic LiCl pretreatment and the knockdown of TRPC3. Additionally, cell proliferation was attenuated in TRPC3Low cells, compared with the negative control vector‐transfected cell.
Conclusions
The reduced Ca2+ mobilization and S100B expression levels following chronic LiCl pretreatment and in TRPC3Low cells support the notion that TRPC3 modulates S100B expression and is the target of the LiCl effect. Downregulation of TRPC3 may be an important mechanism by which lithium ameliorates pathophysiological intracellular Ca2+ disturbances as observed in BD, accounting, in part, for its mood‐stabilizing effects.
Editor Highlight: Using an engineered human astroglial cell model, the authors showed that TRPC3 is yoked with S100B which is involved in reactive astrogliosis. Importantly, chronic lithium exposure suppresses both TRPC3 and S100B expression and thrombin‐stimulated calcium signaling. As presented by the authors, these findings suggest novel lithium actions and pathophysiologic targets for future therapeutics development in bipolar disorder.
Animal data indicate that the recreational drug ecstasy (3,4-methylenedioxymethamphetamine) can damage brain serotonin neurons. However, human neuroimaging measurements of serotonin transporter ...binding, a serotonin neuron marker, remain contradictory, especially regarding brain areas affected; and the possibility that structural brain differences might account for serotonin transporter binding changes has not been explored. We measured brain serotonin transporter binding using 11C N,N-dimethyl-2-(2-amino-4-cyanophenylthio) benzylamine in 50 control subjects and in 49 chronic (mean 4 years) ecstasy users (typically one to two tablets bi-monthly) withdrawn from the drug (mean 45 days). A magnetic resonance image for positron emission tomography image co-registration and structural analyses was acquired. Hair toxicology confirmed group allocation but also indicated use of other psychoactive drugs in most users. Serotonin transporter binding in ecstasy users was significantly decreased throughout all cerebral cortices (range –19 to –46%) and hippocampus (–21%) and related to the extent of drug use (years, maximum dose), but was normal in basal ganglia and midbrain. Substantial overlap was observed between control and user values except for insular cortex, in which 51% of ecstasy user values fell below the lower limit of the control range. Voxel-based analyses confirmed a caudorostral gradient of cortical serotonin transporter binding loss with occipital cortex most severely affected. Magnetic resonance image measurement revealed no overall regional volume differences between groups; however, a slight left-hemispheric biased cortical thinning was detected in methamphetamine-using ecstasy users. The serotonin transporter binding loss was not related to structural changes or partial volume effect, use of other stimulant drugs, blood testosterone or oestradiol levels, major serotonin transporter gene promoter polymorphisms, gender, psychiatric status, or self-reported hyperthermia or tolerance. The ecstasy group, although ‘grossly behaviourally normal’, reported subnormal mood and demonstrated generally modest deficits on some tests of attention, executive function and memory, with the latter associated with serotonin transporter decrease. Our findings suggest that the ‘typical’/low dose (one to two tablets/session) chronic ecstasy-polydrug user might display a highly selective mild to marked loss of serotonin transporter in cerebral cortex/hippocampus in the range of that observed in Parkinson’s disease, which is not gender-specific or completely accounted for by structural brain changes, recent use of other drugs (as assessed by hair analyses) or other potential confounds that we could address. The striking sparing of serotonin transporter-rich striatum (although possibly affected in ‘heavier’ users) suggests that serotonergic neurons innervating cerebral cortex are more susceptible, for unknown reasons, to ecstasy than those innervating subcortical regions and that behavioural problems in some ecstasy users during abstinence might be related to serotonin transporter changes limited to cortical regions.
Backgroud Aberrant intracellular calcium (Ca2+ ) signaling in patients with bipolar-I disorder (BD-I) suggests disturbed endoplasmic reticulum (ER) function in BD. We examined whether the ER stress ...response is altered in BD-I patients and the relationship to basal intracellular Ca2+ levels (Ca2+ B ), in B lymphoblasts (BLCLs) from BD-I patients. Methods Endoplasmic reticulum stress-induced X-box binding protein 1 (XBP1), C/EBP homologous protein (CHOP), and GRP78 expression in BLCLs from BD-I subjects stratified on elevated or normal Ca2+ B and control subjects were determined by real-time quantitative reverse transcription polymerase chain reaction. The XBP1 −116C/G polymorphism, which impairs the XBP1 loop in the ER stress response, were genotyped with a TaqMan-based assay. Results Compared with control subjects, thapsigargin- and tunicamycin-induced increases in XBP1 and CHOP but not GRP78 messenger RNA levels were significantly lower in BD-I patients. However, induction of these genes did not differ significantly in the two BD-I subgroups stratified on Ca2+ B . Furthermore, the attenuated XBP1 induction cannot be explained solely by differences of XBP1 −116C/G genotype frequency. Conclusions Our findings suggest that the ER stress response is impaired in BD-I patients but irrespective of altered intracellular Ca2+ homeostasis as reflected in elevated Ca2+ B . Moreover, an effect of XBP1 −116C/G polymorphism could not account for the attenuated XBP1 induction in bipolar-I disorder observed in this study.
Objective
To establish in an exploratory neuroimaging study whether γ‐hydroxybutyrate (sodium oxybate SO), a sedative, anti‐narcoleptic drug with abuse potential, transiently inhibits striatal ...dopamine release in the human.
Methods
Ten healthy participants (30 years; 6M, 4F) and one participant with narcolepsy received a baseline positron emission tomography scan of C‐11raclopride, a D2/3 dopamine receptor radioligand sensitive to dopamine occupancy, followed approximately one week later by an oral sedative 3g dose of SO and two C‐11raclopride scans (1 h, 7 h post SO). Plasma SO levels and drowsiness duration were assessed.
Results
No significant changes were detected in C‐11raclopride binding in striatum overall 1 or 7 h after SO, but a small non‐significant increase in C‐11raclopride binding, implying decreased dopamine occupancy, was noted in limbic striatal subdivision at one hour (+6.5%; p uncorrected = 0.045; +13.2%, narcolepsy participant), returning to baseline at 7 h. A positive correlation was observed between drowsiness duration and percent change in C‐11raclopride binding in limbic striatum (r = 0.73; p = 0.017).
Conclusions
We did not find evidence in this sample of human subjects of a robust striatal dopamine change, as was reported in non‐human primates. Our preliminary data, requiring extension, suggest that a 3g sedative SO dose might cause slight transient inhibition of dopamine release in limbic striatum.
Despite much evidence that lithium and valproate, two commonly used mood stabilizers, exhibit neuroprotective properties against an array of insults, the pharmacological relevance of such effects is ...not clear because most of these studies examined the acute effect of these drugs in supratherapeutic doses against insults which were of limited disease relevance to bipolar disorder. In the present study, we investigated whether lithium and valproate, at clinically relevant doses, protects human neuroblastoma (SH-SY5Y) and glioma (SVG and U87) cells against oxidative stress and endoplasmic reticulum stress in a time-dependent manner. Pretreatment of SH-SY5Y cells for 7 days, but not 1 day, with 1 mM of lithium or 0.6 mM of valproate significantly reduced rotenone and H
2O
2-induced cytotoxicity, cytochrome
c release and caspase-3 activation, and increased Bcl-2 levels. Conversely, neither acute nor chronic treatment of SH-SY5Y cells with lithium or valproate elicited cytoprotective responses against thapsigargin-evoked cell death and caspase-3 activation. Moreover, inhibitors of glycogen synthase kinase-3 (GSK-3), kenpaullone and SB216763, abrogated rotenone-induced, but not H
2O
2-induced, cytotoxicity. Thus the cytoprotective effects of lithium and valproate against H
2O
2-induced cell death is likely independent of GSK-3 inhibition. On the other hand, chronic lithium or valproate treatment did not ameliorate cytotoxicity induced by rotenone, H
2O
2, and thapsigargin in SVG astroglial and U87 MG glioma cell lines. Our results suggest that lithium and valproate may decrease vulnerability of human neural, but not glial, cells to cellular injury evoked by oxidative stress possibly arising from putative mitochondrial disturbances implicated in bipolar disorder.
B cell CLL/lymphoma 2 protein, bcl-2, is an important anti-apoptotic factor that has been implicated in lithium's neuroprotective effect. However, most studies have focused on assessing the effects ...of lithium in neurons, ignoring examination of bcl-2 in astrocytes, which also influence neuronal survival and are affected in bipolar disorder. The aim of this study was to evaluate whether chronic lithium treatment also elevates bcl-2 expression in astrocytes compared with neuronal and mixed neuron-astrocyte cultures.
Rat primary astrocyte, neuronal, and mixed neuron-astrocyte cultures were prepared from the cerebral cortices of 18-day embryos. The cell cultures were treated with lithium (1 mM) or vehicle for 24 h or 7 days. Thereafter, bcl-2 mRNA and protein levels were determined by RT-PCR and ELISA, respectively.
Chronic, but not acute, lithium treatment significantly increased bcl-2 protein levels in the astrocyte cultures compared with the vehicle-treated cultures. While lithium treatment increased bcl-2 protein levels in both neuronal and mixed neuron-astrocyte cultures, the elevations fell short of statistical significance compared with the respective vehicle-treated cultures. However, neither acute nor chronic lithium treatment affected bcl-2 mRNA levels in any of the three cell types studied.
Increased bcl-2 levels in rat primary astrocyte cultures following chronic lithium treatment suggest astrocytes are also a target of lithium's action. In light of the evidence showing decreased numbers of glial cells in the post-mortem brain of patients bipolar disorder with and increased glial numbers following lithium treatment, the findings of this study indicate that lithium's action on astrocytes may account, at least in part, for its therapeutic effects in bipolar disorder.
Oxidative stress has been implicated in psychiatric disorders, including posttraumatic stress disorder (PTSD). Currently, the status of glutathione (GSH), the brain's most abundant antioxidant, in ...PTSD remains uncertain. Therefore, the current study investigated brain concentrations of GSH and peripheral concentrations of blood markers in individuals with PTSD vs. Healthy Controls (HC).
GSH spectra was acquired in the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC) using MEGA-PRESS, a J-difference-editing acquisition method. Peripheral blood samples were analyzed for concentrations of metalloproteinase (MMP)-9, tissue inhibitors of MMP (TIMP)-1,2, and myeloperoxidase (MPO).
There was no difference in GSH between PTSD and HC in the ACC (
= 30 PTSD,
= 20 HC) or DLPFC (
= 14 PTSD,
= 18 HC). There were no group differences between peripheral blood markers (
> 0.3) except for (non-significantly) lower TIMP-2 in PTSD. Additionally, TIMP-2 and GSH in the ACC were positively related in those with PTSD. Finally, MPO and MMP-9 were negatively associated with duration of PTSD.
We do not report altered GSH concentrations in the ACC or DLPFC in PTSD, however, systemic MMPs and MPO might be implicated in central processes and progression of PTSD. Future research should investigate these relationships in larger sample sizes.
Microglia are immune brain cells implicated in stress-related mental illnesses including posttraumatic stress disorder (PTSD). Their role in the pathophysiology of PTSD, and on neurobiological ...systems that regulate stress, is not completely understood. We tested the hypothesis that microglia activation, in fronto-limbic brain regions involved in PTSD, would be elevated in participants with occupation-related PTSD. We also explored the relationship between cortisol and microglia activation. Twenty participants with PTSD and 23 healthy controls (HC) completed positron emission tomography (PET) scanning of the 18-kDa translocator protein (TSPO), a putative biomarker of microglia activation using the probe
FFEPPA, and blood samples for measurement of cortisol.
FFEPPA V
was non-significantly elevated (6.5-30%) in fronto-limbic regions in PTSD participants.
FFEPPA V
was significantly higher in PTSD participants reporting frequent cannabis use compared to PTSD non-users (44%, p = 0.047). Male participants with PTSD (21%, p = 0.094) and a history of early childhood trauma (33%, p = 0.116) had non-significantly higher
FFEPPA V
. Average fronto-limbic
FFEPPA V
was positively related to cortisol (r = 0.530, p = 0.028) in the PTSD group only. Although we did not find a significant abnormality in TSPO binding in PTSD, findings suggest microglial activation might have occurred in a subgroup who reported frequent cannabis use. The relationship between cortisol and TSPO binding suggests a potential link between hypothalamic-pituitary-adrenal-axis dysregulation and central immune response to trauma which warrants further study.
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