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Background Severe neonatal hyperbilirubinemia has been known to cause the clinical syndrome of kernicterus and a milder one the syndrome of bilirubin-induced neurologic dysfunction (BIND). BIND clinically manifests itself after the neonatal period as developmental delay, cognitive impairment, and related behavioral and psychiatric disorders. The complete picture of BIND is not clear. Methods The Gunn rat is a mutant strain of the Wistar rat with the BIND phenotype, and it demonstrates abnormal behavior. We investigated serotonergic dysfunction in Gunn rats by pharmacological analyses and ex vivo neurochemical analyses. Results Ketanserin, the 5-HT2AR antagonist, normalizes hyperlocomotion of Gunn rats. Both serotonin and its metabolites in the frontal cortex of Gunn rats were higher in concentrations than in control Wistar rats. The 5-HT2AR mRNA expression was downregulated without alteration of the protein abundance in the Gunn rat frontal cortex. The TPH2 protein level in the Gunn rat raphe region was significantly higher than that in the Wistar rat. Conclusions It would be of value to be able to postulate that a therapeutic strategy for BIND disorders would be the restoration of brain regions affected by the serotonergic dysfunction to normal operation to prevent before or to normalize after onset of BIND manifestations. Impact We demonstrated serotonergic dysregulation underlying hyperlocomotion in Gunn rats. This finding suggests that a therapeutic strategy for bilirubin-induced neurologic dysfunction (BIND) would be the restoration of brain regions affected by the serotonergic dysfunction to normal operation to prevent before or to normalize after the onset of the BIND manifestations. Ketanserin normalizes hyperlocomotion of Gunn rats. To our knowledge, this is the first study to demonstrate a hyperlocomotion link to serotonergic dysregulation in Gunn rats.

Background: Fibroblast growth factor (FGF) 2 (also referred to as basic FGF) is a multifunctional growth factor that plays a pivotal role in the pro-survival, pro-migration and pro-differentiation of neurons. Method: Because alterations in FGF2 levels are suggested to contribute to the pathogenesis schizophrenia, we investigated serum levels of FGF2 in the Gunn rat, a hyperbilirubinemia animal model of schizophrenic symptoms. Results: The enzyme-linked immunosorbent assay showed that the serum levels of FGF2 in Gunn rats were 5.09 ± 0.236 pg/mL, while those in the normal strain Wistar rats were 11.90 ± 2.142 pg/mL. The serum FGF2 levels in Gunn rats were significantly lower than those in Wistar rats. We also measured serum levels of unconjugated bilirubin (UCB) and found a significant negative correlation between UCB and FGF2 at serum levels in all the rats studied. Conclusion: Since it is known that FGF2 regulates dopaminergic neurons and have anti-neuroinflammatory effects, our finding suggests that low FGF2 levels may contribute to the pathogenesis of schizophrenia, in which disbalanced dopamin-ergic signaling and neuroinflammation are supposed to play certain roles.

Background Although growing evidence indicates that ECT affects astrocytes, the exact mechanisms of the therapeutic effect of ECT are still unknown. Astrocytic endfeet express the water channel aquaporin (AQP) 4 abundantly and ensheath brain blood vessels to form gliovascular units. It has been shown that the coverage of blood vessels by AQP4-immunostained endfeet is decreased in the prefrontal cortex (PFC) of patients with major depression. This study was made to determine whether ECT restores the astrocytic coverage of blood vessels with amelioration of depressive symptoms. Methods After electroconvulsive shock (ECS) administration to rats, the forced swimming test (FST) and Y-maze test were performed. Subsequently, immunofluorescence analysis was conducted to measure the coverage of blood vessels by astrocytic endfeet in the PFC and hippocampus by using the endothelial cell marker lectin and anti-AQP4 antibody. We also performed Western blot to examine the effects of ECS on the hippocampal expression of AQP4 and the tight junction molecule claudin-5. Results Gunn rats showed learned helplessness and impaired spatial working memory, compared to normal control Wistar rats. ECS significantly improved the depressive-like behavior. Gunn rats showed a decrease in astrocytic coverage of blood vessels, that was significantly increased by ECS. ECS significantly increased expression of AQP4 and claudin-5 in Gunn rats. Conclusions ECS increased the reduced coverage of blood vessels by astrocytic endfeet in the mPFC and hippocampus with amelioration of depressive-like behavior. Therefore, therapeutic mechanism of ECT may involve restoration of the impaired gliovascular units by increasing the astrocytic-endfoot coverage of blood vessels.

Introduction: Recent studies imply that glial activation plays a role in the pathogenesis of psychiatric disorders, such as schizophrenia and major depression. We previously demonstrated that Gunn rats with hyperbilirubinemia show congenital gliosis and schizophrenia-like behavior. Methods: As it has been suggested that major depression involves glial activation associated with neuroinflammation, we examined whether Gunn rats show depression-like behavior using the forced swimming test (FST) and the tail suspension test (TST). In addition, we quantitatively evaluated both microgliosis and astrogliosis in the hippocampus of Gunn rats using immunohistochemistry analysis of the microglial marker ionized calcium-binding adaptor molecule (Iba) 1 and the astrocytic marker S100B. Results: Both the FST and TST showed that immobility time of Gunn rats was significantly longer than that of normal control Wistar rats, indicating that Gunn rats are somewhat helpless, a sign of depression-like behavior. In the quantification of immunohistochemical analysis, Iba1immunoreactivity in the dentate gyrus (DG), cornu ammonis (CA) 1, and CA3 and the number of Iba1-positive cells in the CA1 and CA3 were significantly increased in Gunn rats compared to Wistar rats. S100B immunoreactivity in the DG, CA1, and CA3 and the number of S100B-positive cells in the DG and CA3 were significantly increased in Gunn rats compared to Wistar rats. Conclusion: Our findings suggest that both microglia and astrocyte are activated in Gunn rats and their learned helplessness could be related to glial activation.

Transversely oriented lobules and longitudinally arrayed stripes of Purkinje cell subsets subdivide the cerebellar cortex into multiple compartments that are involved in diverse functions. In the mammalian cerebellum, anterior, and posterior lobules, which are involved in somatosensorimotor function, show an alternation of aldolase C (zebrin II) -positive and -negative stripes, whereas the central lobules (lobules VIb-VII and crus I), which are implicated in nonmotor functions, show a laterally expanded arrangement solely of aldolase C-positive stripes. To understand the developmental process of this compartmental pattern, we identified groups of Purkinje cell subsets in the entire mouse cerebellum at embryonic day (E) 14.5 by staining Purkinje cell subset markers. We then tracked four major domains of Protocadherin 10 (Pcdh10)-positive Purkinje cell subsets (medial, dorsal, central, and mid-lateral subsets), which were clearly demarcated during E14.5-17.5. These domains of Purkinje cell subsets shifted predominantly in the longitudinal direction to be positioned in the anterior and posterior lobules. However, a particular portion of the medial and mid-lateral domains, and the whole of the central domain shift in the lateral direction to be positioned in the central lobules. The results indicate that while the longitudinal shift of domains of Purkinje cell subsets forms the longitudinally striped compartments in the anterior and posterior cerebellum, the lateral shift of particular domains of Purkinje cell subsets underlies the laterally expanded arrangement of stripes in central lobules. Thus, the rearrangement of Purkinje cell subsets in the embryonic cerebellum is critically related to the compartmental organization in the mammalian cerebellum.

Vocalizations of common marmoset (Callithrix jacchus ) were examined under experimental situations related to fear or anxiety. When marmosets were isolated in an unfamiliar environment, they frequently vocalized “tsik-egg” calls, which were the combination calls of ‘tsik’ followed by several ‘egg’. Tsik-egg calls were also observed after treatment with the anxiogenic drug FG-7142 (20 mg/kg, sc). In contrast, when marmosets were exposed to predatory stimuli as fear-evoking situations, they frequently vocalized tsik solo calls as well as tsik-egg calls. These results suggest that marmosets dissociate the vocalization of tsik-egg and tsik calls under conditions related to fear/anxiety; tsik-egg solo vocalizations were emitted under anxiety-related conditions (e.g., isolation and anxiogenic drug treatment), whereas a mixed vocalization of tsik-egg and tsik was emitted when confronted with fear-provoking stimuli (i.e., threatening predatory stimuli). Tsik-egg call with/without tsik can be used as a specific vocal index of fear/anxiety in marmosets, which allows us to understand the neural mechanism of negative emotions in primate.

The rostromedial caudate (rmCD) of primates is thought to contribute to reward value processing, but a causal relationship has not been established. Here we use an inhibitory DREADD (Designer Receptor Exclusively Activated by Designer Drug) to repeatedly and non-invasively inactivate rmCD of macaque monkeys. We inject an adeno-associated viral vector expressing the inhibitory DREADD, hM4Di, into the rmCD bilaterally. To visualize DREADD expression in vivo, we develop a non-invasive imaging method using positron emission tomography (PET). PET imaging provides information critical for successful chemogenetic silencing during experiments, in this case the location and level of hM4Di expression, and the relationship between agonist dose and hM4Di receptor occupancy. Here we demonstrate that inactivating bilateral rmCD through activation of hM4Di produces a significant and reproducible loss of sensitivity to reward value in monkeys. Thus, the rmCD is involved in making normal judgments about the value of reward., Processing the value of reward is thought to involve the rostromedial caudate (rmCD), but a causal demonstration is lacking in primates. Here the authors use chemogenetics and PET imaging to show that inactivation of rmCD leads to impairments in reward value judgments.

We examined the usefulness of commercially available DNA methylation arrays designed for the human genome (Illumina HumanMethylation450 and MethylationEPIC) for high-throughput epigenome analysis of the common marmoset, a nonhuman primate suitable for research on neuropsychiatric disorders. From among the probes on the methylation arrays, we selected those available for the common marmoset. DNA methylation data were obtained from genomic DNA extracted from the frontal cortex and blood samples of adult common marmosets as well as the frontal cortex of neonatal marmosets. About 10% of the probes on the arrays were estimated to be useful for DNA methylation assay in the common marmoset. Strong correlations existed between human and marmoset DNA methylation data. Illumina methylation arrays are useful for epigenome research using the common marmoset.

Epidemiological studies have shown that maternal infection during early pregnancy increases the risk of neurodevelopmental disorders (i.e., schizophrenia or autism) in offspring. Recently, diagnostic/stratification biomarkers for the maternal immune activation background in patients with neurodevelopmental disorders have been energetically searched for in the patient blood. Here, we report a novel serologic marker candidate for the disorders found in the maternal immune activation (MIA) rat model. Serum proteome analysis of the MIA rat showed that the immunoglobulin (Ig) light chain is reproducibly augmented. The Ig light chain in sera takes two forms — free form or bound to the Ig heavy chain. Only the former is an inflammatory disease marker, but pro-inflammatory cytokine levels in the sera of the MIA rats were below detectable limits of the ELISA protocol we used. We thereby carried out serum assays of Ig light chains and pro-inflammatory cytokines of commercially available schizophrenia patient sera for research. Although the number of samples was limited, we found augmentation of free Ig light chains but not pro-inflammatory cytokines in sporadic schizophrenia patient sera. Our findings suggest that Ig light chain assay of the schizophrenia/autism patient sera would be worthy to be validated in larger scale.

The avian cerebellum is organized into multiple longitudinal stripes defined by expression profiles of aldolase C (zebrin II) in Purkinje cells. The relationship between the aldolase C striped pattern and the olivocerebellar projection pattern is crucial in understanding cerebellar functional compartmentalization. We identified all aldolase C stripes across all lobules with the serial section alignment analysis method and then looked at this relationship by anterograde and retrograde labeling of olivocerebellar axons in the chick cerebellum. Aldolase C stripes were generally consistent and continuous from lobule I through VII and to the medial part of lobules VIII-IXb. The dorsal and ventral lamellas (DL, VL) of the inferior olive projected to the stripes in these areas with a simple mediolateral topographic relation. A few aldolase C stripes appeared at the lateral edge of lobules VI-VIII. Several more stripes were added in the lateral parts of lobules IXa-IXb and IXc-X. The medial column (MC) of the inferior olive projected to the stripes in lobules VIII-X, including the added lateral stripes, with a complex topographic relation. Sharp boundaries between aldolase C-positive and -negative stripes often accompanied a gap in the Purkinje cell layer and bordered topographically distinct groups of axons. Although the compartmental organization of the chick cerebellum is comparable to that of the mammalian cerebellum, several significant differences in the organization suggest partly separate evolutionary lineages of the mammalian and avian cerebella. We propose that rostral lobules may be evolved by rostral extension of medial stripes from caudal lobules in the avian cerebellum.

It has been suggested that maternal immune activation increases the risk of psychiatric disorders such as schizophrenia in offspring. There are many reports about hippocampal structural pathology in schizophrenia. Antipsychotic drug administration in adolescence prevented postpubertal hippocampal structural pathology in the maternal immune activation animal model. These findings suggest the possibility that maternal immune activation induces hippocampal dysfunction in juvenile offspring. To test this hypothesis, we investigated hippocampal function in juvenile offspring of maternal immune activation model rat. A synthetic double-stranded RNA polyriboinosinic-polyribocytidilic acid (Poly I:C; 4 mg/kg/day, I.P.) was injected to pregnant rats on gestation days 15 and 17, in order to cause immune activation by stimulating Toll-like receptor 3. Hippocampal synaptic function and morphology in their juvenile offspring (postnatal days 28-31) were compared to those in vehicle-injected control offspring. Field responses were recorded in the hippocampal CA1 region by stimulating commissural/Schaffer collaterals. Pre-synaptic fiber volley amplitudes (mV) and field excitatory post-synaptic potential slopes (mV/ms) were significantly lower in treated offspring. In addition, short-term synaptic plasticity, namely, the paired-pulse facilitation ratio, was significantly higher and long-term synaptic plasticity (long-term potentiation) was significantly impaired in treated offspring. Furthermore, major pre-synaptic protein (synaptophysin) expressions were decreased, but not major post-synaptic proteins (GluR1, GluR2/3, and NR1), in hippocampal CA1 of treated offspring, whereas neuronal loss was not detected in the hippocampal CA1-CA3 regions. These results indicate that maternal immune activation leads to synaptic dysfunction without neuronal loss in the hippocampus of juvenile offspring, and this may be one of the early stages of schizophrenia pathologies.

The cerebellar cortex is organized by transverse foliation and longitudinal compartmentalization. Although the latter, which is recognized through the molecular expression in subsets of Purkinje cells (PCs), is closely related to topographic axonal projection and represents functional divisions, the details have not been fully clarified in mammals other than rodents. Therefore, we examined folial and compartmental organization of the marmoset cerebellum, which resembles the macaque cerebellum, and compared it with that of the rodent cerebellum by aldolase C immunostaining, three-dimensional reconstruction of the PC layer, and labeling of olivocerebellar and corticonuclear projections. Longitudinal stripes of different aldolase C expression intensities separated the entire cerebellar cortex into multiple compartments. Lobule VIIAb-d was equivalent to rodent lobule VIc in that it contained a transverse gap in the cortical layers and served as the rostrocaudal boundary for compartments and axonal branching. Olivocortical and corticonuclear projection patterns in major compartments indicated that the compartmental organization in the marmoset cerebellum was generally equivalent to that in the rodent cerebellum, although two compartments were missing in the pars intermedia and several compartments that have not been seen in rodents were recognized in the flocculus, nodulus, and the most lateral hemisphere. Reconstruction showed that the paraflocculus and flocculus were formed by a single longitudinal sheet, the axis of which was parallel to the aldolase C compartments, PC dendrites, and olivocerebellar climbing fiber distribution. The results indicate that molecular compartmentalization in the marmoset cerebellum reflected both the common fundamental organization of the mammalian cerebellum and species-dependent differentiation.

Activation of N-methyl-d-aspartic acid (NMDA) glutamate receptors (NMDARs) is required for long-term potentiation (LTP) of excitatory synaptic transmission at hippocampal CA1 synapses, the proposed cellular mechanisms of learning and memory. We demonstrate here that a brief bath co-application of a low concentration of NMDA, an agonist of NMDARs, and the selective antagonist of NR2B-containing NMDARs, (alpha R, beta S)-alpha-(4-hydroxyphenyl)-beta-methyl-4-(phenylmethyl)-1-piperidinepropanol (Ro25-6981), to hippocampal slices from young adult rats produced a slowly developing LTP persisting at least for 6 h following a transient depression of synaptic transmission in CA1 synapses. The LTP was likely to occur at postsynaptic site and was initiated by activation of NMDARs, and its development was mediated by cAMP-dependent protein kinase (PKA) activation and protein synthesis. This chemically induced LTP and the tetanus-induced late phase of LTP (L-LTP) were mutually occluding, suggesting a common expression mechanism. Thus, we have demonstrated that a brief bath co-application of NMDA with Ro25-6981 to a slice offers an alternative to electrical stimulation as a stimulation method to induce L-LTP. The chemically induced LTP did not require the low-frequency test stimulation typically used to monitor the strength of synapses during and after drug application. Thus, the LTP may occur at a large fraction of synapses in the slice and not to be confined to a small fraction of the synapses where electrical stimulation can reach and induce LTP. Therefore, this chemically induced LTP may be useful for assessing the biochemical and morphological correlates and the molecular aspects of the expression mechanism for L-LTP that has been proven to correlate to hippocampal long-term memory.

To produce an animal model of a dopa-responsive motor disorder with depletion of dopamine (DA) release in the striatum by dysfunction of the transmitter release machinery of the nigrostriatal DA system, we performed an intra-nigral injection of an HVJ–liposome gene transfer vector containing antisense oligodeoxynucleotides (ODNs) against synaptotagmin I (SytI), a key regulator of Ca2+-dependent exocytosis and endocytosis in adult rats. A unilateral intra-nigral injection of HVJ–liposome vectors containing antisense ODNs against SytI (syt-AS) caused a moderate disruption of methamphetamine-induced release of DA in the treated side of the striatum, while the syt-AS treatment did not affect physiological release of DA in the treated striatum. A bilateral intra-nigral injection of HVJ–liposome vectors containing syt-AS induced an impairment of the striatal DA-mediated acquisition of skilled behavior in a rotarod task without any deficits in general motor functions, such as spontaneous locomotor activity, motor adjusting steps, equilibrium function, or muscle strength. These findings suggest that an intra-nigral treatment with HVJ–liposome vectors containing syt-AS may cause a long-lasting nigral knockdown of SytI which, in turn, leads to a moderate dysfunction of the DA release machinery in the terminals of the nigrostriatal DA system and a subsequent mild depletion of DA release in the striatum.

BACKGROUND:Positron Emission Tomography (PET) measurement was applied to the brain of the common marmoset, a small primate species, treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The marmoset shows prominent Parkinson's disease (PD) signs due to dopaminergic neural degeneration. Recently, the transgenic marmoset (TG) carrying human PD genes is developing. For phenotypic evaluations of TG, non-invasive PET measurement is considered to be substantially significant. As a reference control for TG, the brain of the MPTP-marmoset as an established and valid model was scanned by PET. Behavioral analysis was also performed by recording locomotion of the MPTP-marmoset, as an objective measure of PD signs. METHODOLOGY/PRINCIPAL FINDINGS: MARMOSETS RECEIVED SEVERAL MPTP REGIMENS (SINGLE MPTP REGIMEN: 2 mg/kg, s.c., per day for 3 consecutive days) were used for PET measurement and behavioral observation. To measure immobility as a central PD sign, locomotion of marmosets in their individual living cages were recorded daily by infrared sensors. Daily locomotion counts decreased drastically after MPTP regimens and remained diminished for several months or more. PET scan of the brain, using [(11)C]PE2I as a ligand of the dopamine (DA) transporter, was performed once several months after the last MPTP regimen. The mean binding potential (BP(ND)) in the striatum (putamen and caudate) of the MPTP-marmoset group was significantly lower than that of the MPTP-free control group (n = 5 for each group). In the MPTP-marmosets, the decrease of BP(ND) in the striatum closely correlated with the decrease in locomotion counts (r = 0.98 in putamen and 0.91 in caudate). CONCLUSION/SIGNIFICANCE: The present characterization of neural degeneration using non-invasive PET imaging and of behavioral manifestation in the MPTP marmoset mimics typical PD characteristics and can be useful in evaluating the phenotype of TG marmosets being developed.

The mechanism by which a lack of thyroid hormone in the early development of the brain causes permanent mental retardation in cretins is currently unknown. On the other hand, an abnormality in dopamine-related brain function is believed to underlie some forms of mental illness. In this study, we demonstrate that although the activation of a dopaminergic D(2)-like receptor inhibited glutamatergic transmission in the hippocampal slices of normal adult rats, indicating the inhibitory action of the D(2)-like receptor on glutamatergic transmission, it markedly enhanced glutamatergic transmission both in a mutant hypothyroid rat with a missense mutation in thyroglobulin and in hypothyroid rats treated with methylmercaptoimidazole (MMI), indicating the excitatory action of the D(2)-like receptor on glutamatergic transmission. Paired pulse facilitation of field excitatory postsynaptic potentials was reduced by the activation of the D(2)-like receptors from MMI-induced hypothyroid rats, suggesting a presynaptic locus of the excitatory action of the D(2)-like receptors. In normal rats, the excitatory D(2)-like dopamine receptors were observed in the developing stages and were completely replaced by normal inhibitory responses up to adulthood. Furthermore, the continuous supplement of thyroxine from birth exerted a normalising effect on the abnormal excitatory property of D(2)-like dopamine receptors in the hippocampal slices of MMI-treated hypothyroid rats. From these results, it is suggested that thyroxine may play a crucial role in reversing the excitatory property of D(2)-like dopaminergic receptors in the immature brain to an inhibitory one in the mature brain. Moreover, we suggest that the abnormal excitatory property of D(2)-like dopaminergic receptors may develop in response to a lack of thyroxine and may contribute to some central nervous system deficits, including cognitive dysfunctions accompanied by hypothyroidism.