The depression GWAS risk allele predicts smaller cerebellar gray matter volume and reduced SIRT1 mRNA expression in Chinese population.

Major depressive disorder (MDD) is recognized as a primary cause of disability worldwide, and effective management of this illness has been a great challenge. While genetic component is supposed to play pivotal roles in MDD pathogenesis, the genetic and phenotypic heterogeneity of the illness has hampered the discovery of its genetic determinants. In this study, in an independent Han Chinese sample (1824 MDD cases and 3031 controls), we conducted replication analyses of two genetic loci highlighted in a previous Chinese MDD genome-wide association study (GWAS), and confirmed the significant association of a single nucleotide polymorphism (SNP) rs12415800 near SIRT1. Subsequently, using hypothesis-free whole-brain analysis in two independent Han Chinese imaging samples, we found that individuals carrying the MDD risk allele of rs12415800 exhibited aberrant gray matter volume in the left posterior cerebellar lobe compared with those carrying the non-risk allele. Besides, in independent Han Chinese postmortem brain and peripheral blood samples, the MDD risk allele of rs12415800 predicted lower SIRT1 mRNA levels, which was consistent with the reduced expression of this gene in MDD patients compared with healthy subjects. These results provide further evidence for the involvement of SIRT1 in MDD, and suggest that this gene might participate in the illness via affecting the development of cerebellum, a brain region that is potentially underestimated in previous MDD studies.

Integrative analyses of major histocompatibility complex loci in the genome-wide association studies of major depressive disorder.

Recent European genome-wide association studies (GWAS) have revealed strong statistical correlations between MDD and numerous zero-to-high linked variants in the genomic region containing major histocompatibility complex (MHC) genes (MHC region), but the underlying biological mechanisms are still unclear. To better understand the roles of this genomic region in the neurobiology of MDD, we applied a convergent functional genomics approach to integrate GWAS data of MDD relevant biological phenotypes, gene-expression analyses results obtained from brain samples, and genetic analyses of independent Chinese MDD samples. We observed that independent MDD risk variants in the MHC region were also significantly associated with the relevant biological phenotypes in the predicted directions, including the emotional and cognitive-related phenotypes. Gene-expression analyses further revealed that mRNA expression levels of several MHC region genes in the human brain were associated with MDD risk SNPs and diagnostic status. For instance, a brain-enriched gene ZNF603P consistently showed lower mRNA levels in the individuals carrying MDD risk alleles and in MDD patients. Remarkably, we further found that independent MDD risk SNPs in the MHC region likely converged to affect the mRNA level(s) of the same gene(s), and Europeans and Han Chinese populations have a substantial shared genetic and molecular basis underlying MDD risk associations in the MHC region. These results highlighted several potential pivotal genes at the MHC region in the pathogenesis of MDD. Their common impacts on multiple psychiatric relevant phenotypes also implicated the neurological processes shared by different psychological processes, such as mood and/or cognition, shedding lights on their potential biological mechanisms.

Age-related intraneuronal accumulation of αII-spectrin breakdown product SBDP120 in the human cerebrum is enhanced in Alzheimer's disease.

Spectrins are a part of cytoskeletal platform that lines the intracellular side of plasma membrane, which can be proteolyzed by calcium-sensitive enzymes including calpains and caspases. Caspase-3 mediated αII-spectrin proteolysis results in the release of a 120kDa spectrin breakdown product (SBDP120), known to occur in conditions with cell death. In rodents, intraneuronal SBDP120 accumulation in the forebrain develops with age, which is enhanced in transgenic models of Alzheimer's disease (AD). The present study was set to explore age-related SBDP120 formation and its relevance to AD-type hallmark lesions in the human brains. SBDP120 immunoreactivity (IR) was detected in neuronal somata and dendrites in the cortex and hippocampal formation in postmortem brains from aged (n=10, mean age=84.2) and AD (n=10, mean age=84.8) subjects, but not mid-aged controls (n=10, mean age=58.2). The overall density of SBDP120 IR quantified in the temporal neocortex was increased in the aged and AD groups, more robust in the latter, relative to mid-aged control, while no regional, laminar or cellular association was found between SBDP120 accumulation and Aß deposition or phosphorylated-tau aggregation. In cultured rat retinal ganglion cells (RGC-5), SBDP120 elevation occurred with caspase-3 activation following oxygen as well as serum deprivation, suggestive of SBDP120 formation in stressful conditions with and without apparent neuronal death. These results confirm an age-related intraneuronal SBDP120 accumulation in the human cerebrum that is enhanced in AD. This neuronal change appears to occur independent of amyloid deposition, tau pathology and overt neuronal death.

The origin and development of plaques and phosphorylated tau are associated with axonopathy in Alzheimer's disease.

OBJECTIVE: The production of neurotoxic ß-amyloid and the formation of hyperphosphorylated tau are thought to be critical steps contributing to the neuropathological mechanisms in Alzheimer's disease (AD). However, there remains an argument as to their importance in the onset of AD. Recent studies have shown that axonopathy is considered as an early stage of AD. However, the exact relationship between axonopathy and the origin and development of classic neuropathological changes such as senile plaques (SPs) and neurofibrillary tangles (NFTs) is unclear. The present study aimed to investigate this relationship. METHODS: Postmortem tracing, combined with the immunohistochemical or immunofluorescence staining, was used to detect axonopathy and the formation of SPs and NFTs. RESULTS: Axonal leakage-a novel type of axonopathy, was usually accompanied with the extensive swollen axons and varicosities, and was associated with the origin and development of Aß plaques and hyperphosphorylated tau in the brains of AD patients. CONCLUSION: Axonopathy, particularly axonal leakage, might be a key event in the initiation of the neuropathological processes in AD.

Actions of bis(7)-tacrine and tacrine on transient potassium current in rat DRG neurons and potassium current mediated by K(V)4.2 expressed in Xenopus oocyte.

Bis(7)-tacrine [bis(7)-tetrahydroaminacrine] is a dimeric AChE inhibitor derived from tacrine with a potential to treat Alzheimer's disease. Actions of bis(7)-tacrine on ligand-gated ion channels and voltage-gated cation channels have been identified on neurons of both central and peripheral nervous systems. In the present study, the effect of bis(7)-tacrine was investigated on the K(V)4.2 encoded potassium currents expressed in Xenopus oocytes and the transient A-type potassium current (I(K(A))) on rat DRG neurons. Bis(7)-tacrine suppressed recombinant Kv4.2 potassium channels in a concentration-dependent manner, with IC(50) value of 0.53+/-0.13 muM. Tacrine also inhibited Kv4.2 channels, but with a much lower potency (IC(50) 74+/-15 muM).The possible mechanisms underlying the inhibition on potassium currents by bis(7)-tacrine/tacrine could be that inactivation of the transient potassium currents was accelerated and recovery of the native or Kv4.2 expressed potassium currents was suppressed by bis(7)-tacrine/tacrine.

Facial pain induces the alteration of transient receptor potential vanilloid receptor 1 expression in rat trigeminal ganglion.

OBJECTIVE: To investigate the involvement of transient receptor potential vanilloid receptor 1 (TRPV1) in the facial inflammatory pain in relation to thermal hyperalgesia and cold pain sensation. METHODS: Facial inflammatory pain model was developed by subcutaneous injection of turpentine oil (TO) into rat facial area. Head withdrawal thermal latency (HWTL) and head withdrawal cold latency (HWCL) were measured once a day for 21 d after TO treatment using thermal and cold measurement apparatus. The immunohistochemical staining, cell-size frequency analysis and the survey of average optical density (OD) value were used to observe the changes of TRPV1 expression in the neurons of the trigeminal ganglion (TG), peripheral nerve fibers in the vibrissal pad, and central projection processes in the trigeminal sensory nuclei caudalis (Vc) on day 3, 5, 7, 14, and 21 after TO injection. RESULTS: HWTL and HWCL decreased significantly from day 1 to day 14 after TO injection with the lowest value on day 5 and day 3, respectively, and both recovered on day 21. The number of TRPV1-labeled neurons increased remarkably from day 1 to day 14 with a peak on day 7, and returned back to the normal level on day 21. In control rats, only small and medium-sized TG neurons were immunoreactive (IR) to TRPV1, and the TRPV1-IR terminals were abundant in both the vibrissal pad and the Vc. Within 2 weeks of inflammation, the expression of TRPV1 in small and medium-sized TG neurons increased obviously. Also the TRPV1 stained terminals and fibers appeared more frequent and denser in both the vibrissal pad skin and throughout laminae I and the outer zone of laminae II (IIo) of Vc. CONCLUSION: Facial inflammatory pain could induce hyperalgesia to noxious heat and cold stimuli, and result in increase of the numbers of TRPV1 positive TG neurons and the peripheral and central terminals of TG. These results suggest that the phenotypic changes of TRPV1 expression in small and medium-sized TG neurons and terminals might play an important role in the development and maintenance of TO-induced inflammatory thermal hyperalgesia and cold pain sensation.

[Changes of cyclin D1 expression following human brain contusion].

OBJECTIVE: To study the relationships of Cyclin D1 expression with the posttraumatic intervals (PTI) following the cerebra, brainstem or cerebella contusion in human. METHODS: 88 cases of brain contusions of the closed head injury were investigated with pathological and Cyclin D1 immunohistochemistry methods. The results were analyzed by image analysis technique (IAT). RESULTS: The immunoreactivity of Cyclin D1 was almost disappeared in the core cells of the brain contusion. Cyclin D1-positive cells started to increase in the boundary of the brain contusion in the 1h group. Cyclin D1-positive cells were increased significantly in the 3 h-30 d groups and maintained at a high level in the boundary of the brain contusion of those groups. It is suggested that the Cyclin D1-positive cells were primarily origin from microglia and other glia. A few neurons expressed Cyclin D1. CONCLUSION: Cyclin D1 can express in several kinds of brain cells following the contusion, especially in the glia cells. Cyclin D1-positive cells were increased obviously and rapidly after injury, so it could be used as a reference marker for early stage brain injury.

Characterization of three types of ATP-activated current in relation to P2X subunits in rat trigeminal ganglion neurons.

In the present study, ATP-activated currents (I(ATP)s) recorded from rat trigeminal ganglion (TG) neurons using whole-cell patch clamp technique are classified into three types (F, I and S) based on the characteristics of their activation and desensitization. The time of rising phase (R(10-90)) of types F, I and S of I(ATP) is measured to be 33.6+/-4.5, 62.2+/-9.9 and 302.1+/-62.0 ms respectively, and positively correlated to cell size. The time of decaying phases (D(10-90)) of types F and S is 399.4+/-58.2 and >1500 ms, respectively. The dose-response curves for the three types of I(ATP) show that their EC(50) values are close (3.44 x 10(-5), 4.89 x 10(-5) and 4.14 x 10(-5) M for types F, I and S respectively, P>0.05). Their reversal potentials are basically the same, varying from +4 to +10 mV. In addition, using whole-cell patch clamp technique in combination with single cell immunohistochemical staining for P2X receptor subunits, our results suggest that the type distinction of ATP-activated current was associated with cell size and P2X receptor subunits: small-sized cells with type F of I(ATP) express only P2X1 and/or P2X3 subunits, while cells with types S and I of I(ATP) express P2X2 or P2X4 in addition to P2X1 and P2X3.

[Relationship between expression of nestin in experimental brain contusion and injury time].

OBJECTIVE: To observe the alteration of nestin intervals in the experimental traumatic brain injury and investigate its relation to the injury intervals. METHODS: The rat brain contusion was conducted by falling impact injury. After various survival interval (0.5, 6, 12 h and 1, 3, 7, 14, 28 d), immunohistochemical SP method was used for observing the expression of nestin in the cortex, hippocampal dentate gyrus and the corpus callosum on injury side. RESULTS: Expression of nestin positive cells increased at 0.5 h and reached the maximum level in 7 d after brain contusion, then the expression decreased gradually. The intensity of nestin staining in the the cortex and the hippocampal dentate gyrus decreased to normal on 28 d. As to the corpus callosum of injury side it remained weak on 28 d. CONCLUSION: The changes of nestin immunohistochemical staining can be used as an index for forensic estimation of early injury time.

Electroacupuncture modulates cortical activities evoked by noxious somatosensory stimulations in human.

A noninvasive high-resolution imaging technique of cerebral electric activities has been developed to directly link scalp potential measurement with the magnetic resonance images of the subjects, which is very helpful for the elucidation of the cortical processing following various stimulations. Here, we used a 64-channel Neuroscan ESI-128 system to explore the specific cortical activities elicited by electroacupuncture (EA) acupoint in normal volunteers and the modulatory effect of EA on cortical activities evoked by noxious somatosensory stimulation. A specific later-latency somatosensory-evoked potential (SEP, P150) located in bilateral anterior cingulated cortex was observed after EA acupoint but not non-acupoint. Two pain-specific SEP components (P170 and N280), located in bilateral suprasylvian operculum and anterior cingulated cortex respectively were observed following painful median nerve stimulation. Binding EA acupoint with painful median nerve stimulation, the amplitudes of P170 and N280 appeared to be attenuated significantly, 2D topography exhibited tremendous decrease of cortical activation between 120 ms and 296 ms in latency, and visual analogue scale (VAS) changes also showed a similar pattern to the change of amplitude. The bilateral anterior cingulated cortex recruited following acupoint stimuli might, to some extent, suggest that EA has the specific physiological effects. Decrease of pain-induced cortical activation by EA acupoint was considered to be mainly due to an interaction of the signals in anterior cingulated cortex ascending from the pain stimulation and EA.

The comparisons on total RNA from different source-original neurons applied in LMPC.

Objective To compare the quality and quantity of total RNA from different source-original neurons applied in LMPC technique. Methods (1) Aglient 2100 bioanalyzer and RT-PCR were used to check the concentration and fragmentation of total RNA from unfixed, temporal fixed and fixed 12 h hypothalamus sections; (2) Different neurons of PVN and SON were collected by LMPC, CRH, TRH, AVP, OT mRNA level were measured by RT-PCR; (3) Labeled neurons by injecting CTB into stomach and non-labeled neurons in DMV collected by LMPC were checked for house keeping genes by RT-PCR. Results (1) Unfixed section had higher concentration and better quality of total RNA compared with fixed sections applied in LMPC; relative short amplicons such as GAPDH, NSE, MCH and MC4R were successfully obtained from fixed and unfixed and long amplicon of GR can only be obtained from unfixed material; (2) In mangocellular PVN and SON the expressions of AVP and OT were more special than those in the parvocellular PVN. Oppositely, the expressions of CRH, TRH in the parvocellular were more special than the other two; (3) The expressions of house keeping genes had no significant difference between labeled and non-labeled DMV neurons. Conclusion The quality and quantity of total RNA from unfixed brain tissues were better than fixed tissues applied in LMPC and the CTB tracer which may differentiate neurons had no significant effect on physiology of the neurons applied in LMPC. The results showed that the LMPC technique is suitable for the qualitative and quantitative study on individual neurons at mRNA level.

Effects of tanshinone on neuropathological changes induced by amyloid beta-peptide(1-40) injection in rat hippocampus.

AIM: To investigate the effect of tanshinone (Tan) on the neuropathological changes induced by amyloid beta-peptide1-40 (Abeta1-40) injection in hippocampus in rats. METHODS: Abeta1-40 10 microg was injected bilaterally into the dorsal blade of the dentate gyrus in the hippocampus. The level of acetylcholinesterase (AChE) in hippocampus was evaluated by histochemistry. The expressions of neuronal nitric oxide synthase (nNOS) and inducible form of NOS (iNOS) were detected by immunohistochemistry and Western blot. Abeta1-40-injected rats were treated ig with Tan, the major active ingredient from Salvia miltiorrhiza of Chinese herb extract. RESULTS: The level of AChE positive fibers of each subfield in Abeta1-40-injected hippocampus decreased significantly compared with those of control (P<0.01). The expression of nNOS was down-regulated whereas the iNOS was up-regulated. After treatment with Tan (50 mg/kg, ig), the changes mentioned above were significantly improved. Moreover, the correlation analysis revealed a significant negative correlation between the area percentage of AChE positive fibers and the number of iNOS positive neural cells in CA1, CA2 to CA3 (CA2-3), and dentate gyrus (DG) subfields (P<0.01). CONCLUSION: Tan can protect the neuropathological changes induced by Abeta1-40 injection in hippocampus.