In 2007, a multifaceted syndrome, associated with anti-NMDA receptor autoantibodies (NMDAR-AB) of immunoglobulin-G isotype, has been described, which variably consists of psychosis, epilepsy, cognitive decline and extrapyramidal symptoms. Prevalence and significance of NMDAR-AB in complex neuropsychiatric disease versus health, however, have remained unclear. We tested sera of 2817 subjects (1325 healthy, 1081 schizophrenic, 263 Parkinson and 148 affective-disorder subjects) for presence of NMDAR-AB, conducted a genome-wide genetic association study, comparing AB carriers versus non-carriers, and assessed their influenza AB status. For mechanistic insight and documentation of AB functionality, in vivo experiments involving mice with deficient blood-brain barrier (ApoE(-/-)) and in vitro endocytosis assays in primary cortical neurons were performed. In 10.5% of subjects, NMDAR-AB (NR1 subunit) of any immunoglobulin isotype were detected, with no difference in seroprevalence, titer or in vitro functionality between patients and healthy controls. Administration of extracted human serum to mice influenced basal and MK-801-induced activity in the open field only in ApoE(-/-) mice injected with NMDAR-AB-positive serum but not in respective controls. Seropositive schizophrenic patients with a history of neurotrauma or birth complications, indicating an at least temporarily compromised blood-brain barrier, had more neurological abnormalities than seronegative patients with comparable history. A common genetic variant (rs524991, P=6.15E-08) as well as past influenza A (P=0.024) or B (P=0.006) infection were identified as predisposing factors for NMDAR-AB seropositivity. The >10% overall seroprevalence of NMDAR-AB of both healthy individuals and patients is unexpectedly high. Clinical significance, however, apparently depends on association with past or present perturbations of blood-brain barrier function.

Amyotrophic lateral sclerosis (ALS) is the collective term for a fatal motoneuron disease of different etiologies, with oxidative stress as a common molecular denominator of disease progression. Melatonin is an amphiphilic molecule with a unique spectrum of antioxidative effects not conveyed by classical antioxidants. In preparation of a possible future clinical trial, we explored the potential of melatonin as neuroprotective compound and antioxidant in: (1) cultured motoneuronal cells (NSC-34), (2) a genetic mouse model of ALS (SOD1(G93A)-transgenic mice), and (3) a group of 31 patients with sporadic ALS. We found that melatonin attenuates glutamate-induced cell death of cultured motoneurons. In SOD1(G93A)-transgenic mice, high-dose oral melatonin delayed disease progression and extended survival. In a clinical safety study, chronic high-dose (300 mg/day) rectal melatonin was well tolerated during an observation period of up to 2 yr. Importantly, circulating serum protein carbonyls, which provide a surrogate marker for oxidative stress, were elevated in ALS patients, but were normalized to control values by melatonin treatment. This combination of preclinical effectiveness and proven safety in humans suggests that high-dose melatonin is suitable for clinical trials aimed at neuroprotection through antioxidation in ALS.

Common sequence variants have recently joined rare structural polymorphisms as genetic factors with strong evidence for association with schizophrenia. Here we extend our previous genome-wide association study and meta-analysis (totalling 7 946 cases and 19 036 controls) by examining an expanded set of variants using an enlarged follow-up sample (up to 10 260 cases and 23 500 controls). In addition to previously reported alleles in the major histocompatibility complex region, near neurogranin (NRGN) and in an intron of transcription factor 4 (TCF4), we find two novel variants showing genome-wide significant association: rs2312147[C], upstream of vaccinia-related kinase 2 (VRK2) [odds ratio (OR) = 1.09, P = 1.9 × 10(-9)] and rs4309482[A], between coiled-coiled domain containing 68 (CCDC68) and TCF4, about 400 kb from the previously described risk allele, but not accounted for by its association (OR = 1.09, P = 7.8 × 10(-9)).

Recombinant human erythropoietin (EPO) improves cognitive performance in neuropsychiatric diseases ranging from schizophrenia and multiple sclerosis to major depression and bipolar disease. This consistent EPO effect on cognition is independent of its role in hematopoiesis. The cellular mechanisms of action in brain, however, have remained unclear. Here we studied healthy young mice and observed that 3-week EPO administration was associated with an increased number of pyramidal neurons and oligodendrocytes in the hippocampus of ~20%. Under constant cognitive challenge, neuron numbers remained elevated until >6 months of age. Surprisingly, this increase occurred in absence of altered cell proliferation or apoptosis. After feeding a 15N-leucine diet, we used nanoscopic secondary ion mass spectrometry, and found that in EPO-treated mice, an equivalent number of neurons was defined by elevated 15N-leucine incorporation. In EPO-treated NG2-Cre-ERT2 mice, we confirmed enhanced differentiation of preexisting oligodendrocyte precursors in the absence of elevated DNA synthesis. A corresponding analysis of the neuronal lineage awaits the identification of suitable neuronal markers. In cultured neurospheres, EPO reduced Sox9 and stimulated miR124, associated with advanced neuronal differentiation. We are discussing a resulting working model in which EPO drives the differentiation of non-dividing precursors in both (NG2+) oligodendroglial and neuronal lineages. As endogenous EPO expression is induced by brain injury, such a mechanism of adult neurogenesis may be relevant for central nervous system regeneration.

BackgroundErythropoietin (EPO) improves cognition of human subjects in the clinical setting by as yet unknown mechanisms. We developed a mouse model of robust cognitive improvement by EPO to obtain the first clues of how EPO influences cognition, and how it may act on hippocampal neurons to modulate plasticity.ResultsWe show here that a 3-week treatment of young mice with EPO enhances long-term potentiation (LTP), a cellular correlate of learning processes in the CA1 region of the hippocampus. This treatment concomitantly alters short-term synaptic plasticity and synaptic transmission, shifting the balance of excitatory and inhibitory activity. These effects are accompanied by an improvement of hippocampus dependent memory, persisting for 3 weeks after termination of EPO injections, and are independent of changes in hematocrit. Networks of EPO-treated primary hippocampal neurons develop lower overall spiking activity but enhanced bursting in discrete neuronal assemblies. At the level of developing single neurons, EPO treatment reduces the typical increase in excitatory synaptic transmission without changing the number of synaptic boutons, consistent with prolonged functional silencing of synapses.ConclusionWe conclude that EPO improves hippocampus dependent memory by modulating plasticity, synaptic connectivity and activity of memory-related neuronal networks. These mechanisms of action of EPO have to be further exploited for treating neuropsychiatric diseases.

The PGAS allows identification of marker-associated clinical/biological traits. Current cognitive performance in schizophrenic patients is modified by CPLX2 variants modulating posttranscriptional gene expression.

In humans, neurotrauma is suspected to cause brain atrophy and accelerate slowly progressive neurodegenerative disorders, such as Alzheimer's disease or schizophrenia. However, a direct link between brain injury and subsequent delayed global neurodegeneration has remained elusive. Here we show that juvenile (4-week-old) mice that are given a discrete unilateral lesion of the parietal cortex, develop to adulthood without obvious clinical symptoms. However, when monitored 3 and 9 months after lesioning, using high-resolution three-dimensional MRI and behavioural testing, the same mice display global neurodegenerative changes. Surprisingly, erythropoietin, a haematopoietic growth factor with potent neuroprotective activity, prevents behavioural abnormalities, cognitive dysfunction and brain atrophy when given for 2 weeks after acute brain injury. This demonstrates that a localized brain lesion is a primary cause of delayed global neurodegeneration that can be efficiently counteracted by neuroprotection.

Central nervous and hematopoietic systems share developmental features. We report that thrombopoietin (TPO), a stimulator of platelet formation, acts in the brain as a counterpart of erythropoietin (EPO), a hematopoietic growth factor with neuroprotective properties. TPO is most prominent in postnatal brain, whereas EPO is abundant in embryonic brain and decreases postnatally. Upon hypoxia, EPO and its receptor are rapidly reexpressed, whereas neuronal TPO and its receptor are down-regulated. Unexpectedly, TPO is strongly proapoptotic in the brain, causing death of newly generated neurons through the Ras-extracellular signal-regulated kinase 1͞2 pathway. This effect is not only inhibited by EPO but also by neurotrophins. We suggest that the proapoptotic function of TPO helps to select for neurons that have acquired targetderived neurotrophic support.astrocytes ͉ erythropoietin ͉ neurons ͉ differentiation ͉ development I n the hematopoietic system, survival, proliferation, and differentiation of cells are regulated by a plethora of growth factors (1-4). The effect of erythropoietin (EPO) on the generation of red blood cells is well known. The hematopoietic growth factor thrombopoietin (TPO) stimulates megakaryopoiesis and thrombocyte formation (1-3, 5, 6). During hematopoiesis, EPO and TPO can interact in a synergistic and an antagonistic fashion (1-3, 7).EPO and TPO exhibit significant homology in their receptorbinding domain (20% identity and 25% similarity). Likewise, they bind to receptors, erythropoietin receptor (EPOR) and thrombopoietin receptor (TPOR), respectively, that belong to the same cytokine receptor superfamily (1)(2)(3)(8)(9)(10). Previous studies reported a neurotrophin-like motif in the N-terminal receptor binding region of the TPO molecule, with conflicting data about the presence of TPO in the brain (5,6,(11)(12)(13).For EPO, it is well established that the gene is expressed in the embryonic CNS. EPO has a marked effect as a survival factor for neurons and their progenitors (14, 15), presumably to overcome phases of physiological hypoxia (16, 17). The widespread but rather ''unspecific'' neuroprotective potential of EPO is regained in the adult CNS upon distress or injury. This finding has been confirmed in rodent models of cerebral ischemia (18-23), brain trauma (18), and neurodegenerative disease (18), as well as in a clinical study with stroke patients (24).Here we show that TPO plays a previously unrecognized proapoptotic role in the brain. Materials and MethodsAll experiments were approved by and conducted in accordance with the regulations of the local Animal Care and Use Committee. For detailed information on all methods see Supporting Materials and Methods, which is published as supporting information on the PNAS web site.Cell Culture. Primary hippocampal neuronal cultures were prepared from newborn Wistar-Imamichi rats, cultured under serum-free conditions (25, 26), and used for experiments after five days (purity: Ͼ95% neurons). Neuronal cell number and viability was assessed by try...