Jinhao Sun

Developmental changes and regional localization of Dspp, Mepe, Mimecan and Versican in postnatal developing mouse teeth

It has been implicated noncollagenous proteins act as important regulators during odontogenesis. To test the hypothesis that the roles of Dspp, Mepe, Versican and Mimecan in the regulation of odontogenesis may be complementary, comparative investigations on the localization of four proteins were performed by immunohistochemical staining using mouse first molar at different developmental stages as a model. In postnatal 1- day-old mice, all the proteins, excluding Mepe, showed co-expression in young odontoblasts. At postnatal 3, strong immunoreactions for all proteins were detected in odontoblasts. Interestingly, Mepe was present within both cytoplasm and nucleus in odontoblasts. In mice older than 5xa0days, the expression of Dspp, Mimecan and Versican accumulated in subodontoblastic layer of the coronal pulp at high levels while the co-expression of Mepe and Mimecan significantly existed in predentin. The temporal-spatial specific pattern and unique co-localization of Dspp, Mepe, Mimecan and Versican suggest they play complementary roles during odontogenesis.

Dopaminergic differentiation of grafted GFP transgenic neuroepithelial stem cells in the brain of a rat model of Parkinson's disease

Neuroepithelial stem cells (NEPs) possess multipotent potential for self-renewal and neuronal differentiation. Using green fluorescent protein (GFP) positive NEPs, we explored, firstly, the survival and differentiation of grafted NEPs in the host rat and, secondly, whether or not transplantation of NEPs is a feasible therapeutic option for treating Parkinsons disease. NEPs were harvested from the neural tube of enhanced GFP transgenic embryos. In culture, GFP(+) NEPs generated abundant neurospheres and differentiated into both neurons and glia. When stereotaxically transplanted into the 6-hydroxydopamine (6-OHDA)-lesioned striatum of rats, NEPs survived and tyrosine hydroxylase (TH)-positive cells were detected in the graft. Furthermore, these grafted GFP(+) NEPs significantly ameliorated Parkinsonian behavioral symptoms compared with controls which were treated only with normal saline. Our results suggest that transplanted NEPs accomplish dopaminergic differentiation may be used for treating Parkinsons disease.

Melatonin treatment during the incubation of sensitization attenuates methamphetamine-induced locomotor sensitization and MeCP2 expression

Behavior sensitization is a long-lasting enhancement of locomotor activity after exposure to psychostimulants. Incubation of sensitization is a phenomenon of remarkable augmentation of locomotor response after withdrawal and reflects certain aspects of compulsive drug craving. However, the mechanisms underlying these phenomena remain elusive. Here we pay special attention to the incubation of sensitization and suppose that the intervention of this procedure will finally decrease the expression of sensitization. Melatonin is an endogenous hormone secreted mainly by the pineal gland. It is effective in treating sleep disorder, which turns out to be one of the major withdrawal symptoms of methamphetamine (MA) addiction. Furthermore, melatonin can also protect neuronal cells against MA-induced neurotoxicity. In the present experiment, we treated mice with low dose (10mg/kg) of melatonin for 14 consecutive days during the incubation of sensitization. We found that melatonin significantly attenuated the expression of sensitization. In contrast, the vehicle treated mice showed prominent enhancement of locomotor activity after incubation. MeCP2 expression was also elevated in the vehicle treated mice and melatonin attenuated its expression. Surprisingly, correlation analysis suggested significant correlation between MeCP2 expression in the nucleus accumbens (NAc) and locomotion in both saline control and vehicle treated mice, but not in melatonin treated ones. MA also induced MeCP2 over-expression in PC12 cells. However, melatonin failed to reduce MeCP2 expression in vitro. Our results suggest that melatonin treatment during the incubation of sensitization attenuates MA-induced expression of sensitization and decreases MeCP2 expression in vivo.

Striatal extracts promote the dopaminergic differentiation of GFP-bone mesenchymal stem cells

Bone mesenchymal stem cells (BMSCs) are an attractive donor graft source because of the potential of self-renewal and multi-direction differentiation. However, it is a great challenge to induce BMSCs to specifically differentiate to dopamine (DA) neurons for the treatment of Parkinsons disease. Because the striatum is the target tissue for the projection of DA neurons in the midbrain, we investigated whether its extracts could promote the dopaminergic differentiation of BMSCs. BMSCs were isolated from green fluorescent protein (GFP) transgenic mice. Flow cytometry was used to identify the expression of CD29 and CD11b in cultured BMSCs; and immunochemical staining was employed to determine the differentiation of BMSCs. Our results showed that striatal extracts could induce differentiation of BMSCs into both neurons and glia, especially the DA neurons. When transplanted to the rat striatum, GFP-BMSCs could differentiate into tyrosine hydroxylase positive neurons and demonstrate potential migration in the brain. Taking together, our results suggest that striatal extracts can specifically promote the dopaminergic differentiation of GFP-BMSCs, thereby providing a feasible strategy for the treatment of Parkinsons disease.

Sohlh1 suppresses glioblastoma cell proliferation, migration, and invasion by inhibition of Wnt/β-catenin signaling

Glioblastoma (GBM) is the most aggressive and highly invasive type of astrocytic tumors. Despite advances in diagnosis and therapy, the prognosis and survival time remain poor. Identifying key mediators of tumor cell proliferation, migration, and invasion is crucial to the development of new and more effective therapies. In this paper, we report the novel role of Spermatogenesis‐ and oogenesis‐ specific basic helix‐loop‐helix transcription factor1 (Sohlh1) in the inhibition of Wnt/β‐catenin signaling and aggressive behaviors in GBM cells. Immunohistochemistry was performed to examine the expression of Sohlh1 and related proteins in astrocytomas. Human glioblastoma U87 and U251 cellswere transfected with appropriate plasmids and/or siRNAs to evaluate their functions on cell proliferation, migration, and invasion. Western blot and TOPflash luciferase assay were used to determine the involvement of Wnt/β‐catenin signaling pathway in Sohlh1‐mediated cellular activities in glioblastomas. We observed that Sohlh1 was downregulated in astrocytomas. The reduction in Sohlh1 expression was inversely correlated with the degree of malignancy in astrocytomas. In GBM cell lines, cellular proliferation, migration, and invasion were significantly enhanced after Sohlh1 knockdown, but significantly inhibited after Sohlh1 overexpression. These functional effects of Sohlh1 were achieved by upregulating GSK3β and inhibiting Wnt/β‐catenin signaling. Our findings provide novel mechanistic insights of Sohlh1 in malignant progression of astrocytomas, suggesting that the level of Sohlh1 expression may be a predictor of astrocytoma behavior and further, Sohlh1 may serve as a potential therapeutic target for GBM.

Resveratrol Protects PC12 Cell against 6-OHDA Damage via CXCR4 Signaling Pathway

Resveratrol, herbal nonflavonoid polyphenolic compound naturally derived from grapes, has long been acknowledged to possess extensive biological and pharmacological properties including antioxidant and anti-inflammatory ones and may exert a neuroprotective effect on neuronal damage in neurodegenerative diseases. However, the underlying molecular mechanisms remain undefined. In the present study, we intended to investigate the neuroprotective effects of resveratrol against 6-OHDA-induced neurotoxicity of PC12 cells and further explore the possible mechanisms involved. For this purpose, PC12 cells were exposed to 6-OHDA in the presence of resveratrol (0, 12.5, 25, and 50u2009μM). The results showed that resveratrol increased cell viability, alleviated the MMP reduction, and reduced the number of apoptotic cells as measured by MTT assay, JC-1 staining, and Hoechst/PI double staining (all p < 0.01). Immunofluorescent staining and Western blotting revealed that resveratrol averts 6-OHDA induced CXCR4 upregulation (p < 0.01). Our results demonstrated that resveratrol could effectively protect PC12 cells from 6-OHDA-induced oxidative stress and apoptosis via CXCR4 signaling pathway.

Postnatal Administration of Dizocilpine Inhibits Neuronal Excitability in PFC and Induces Social Deficits Detected by MiceProfiler

Schizophrenia is a devastating mental disease with social deficit as its core component of negative symptoms, which could be induced in rodents by dizocilpine (MK-801), a noncompetitive NMDA receptor antagonist. NMDA receptors are highly expressed during the postnatal period. However, less attention has been paid to the effects of postnatal MK-801 administration on social interaction. In this study, we evaluated the effects of postnatal administration of MK-801 on social interaction and explored the possible mechanisms. Postnatal day-7 mice were intraperitoneally injected with MK-801 twice daily for 5xa0days, and their social interaction repertoire was monitored by a computerized video in the 10th week. The contact event, relative position event, stop-state, and dynamic event were analyzed with MiceProfiler automatic idTracker system. The results showed that MK-801 reduced the number of the contact events, relative position events, and stop-states, while increased the number and duration of dynamic events. These changes implied that MK-801-injected mice had indifference and lower motivation in social interaction and could be a useful model for studies on the social deficit of schizophrenia. The prefrontal cortex is the key region for social interaction behaviors. Slice patch clamp was performed to analyze the cellular excitability of prefrontal cortical neurons after postnatal treatment with MK-801 in mice. The results demonstrated that MK-801 injection reduced the frequency and amplitude of action potentials, but increased the frequency of miniature inhibitory postsynaptic currents. These data illustrated that the excitability of neurons in the prefrontal cortex was inhibited. Finally, immunoblotting data demonstrated that MK-801 significantly decreased the levels of sirtuin 1 (SIRT1) and phosphorylated protein kinase B (p-PKB) in the prefrontal cortex (both Pxa0<xa00.05). Taken together, our results indicated that administration of MK-801 to postnatal mice induces social interaction deficits possibly due to inhibiting the neuronal excitability and decreasing the levels of SIRT1 and p-PKB in the prefrontal cortex.

Hyperthermia induces upregulation of Connexin43 in the golden hamster neural tube

BACKGROUNDnDuring early embryonic development, maternal exposure to hyperthermia induces neural tube defects (NTDs). Connexins are essential for the formation of gap junctions and Connexin43 (Cx43) is crucially involved in neural tube development. This study was designed to explore the potential role of Cx43 in NTDs induced by hyperthermia.nnnMETHODSnUsing PCR, the Cx43 cDNA was screened from the cDNA library of the neural tube from golden hamsters treated with hyperthermia. By Northern blot, the expression of Cx43 in heat-treated and control groups of the golden hamsters at day 8.5 after mating was detected. Finally, by in situ hybridization and RT-PCR, the expression of Cx43 was examined in the neural tube at different time points after heat treatment.nnnRESULTSnCx43 was stably expressed in heat-treated and control groups of the golden hamsters, whereas the expression was evidently higher in the heat-treated group. Cx43 expression in the neural tube at different time points after heat treatment was significantly higher than in control groups (p < 0.01). Hyperthermia did not induce any mutations in Cx43 cDNA.nnnCONCLUSIONSnOur data provide the first evidence that hyperthermia induces upregulation of Cx43 in the golden hamster neural tube. NTDs caused by hyperthermia may be intimately related with the overexpression of Cx43.

Resveratrol Suppresses Rotenone-induced Neurotoxicity Through Activation of SIRT1/Akt1 Signaling Pathway: RESVERATROL ATTENUATES NEUROTOXICITY THROUGH SIRT1/AKT1

Rotenone is a common pesticide and has been reported as one of the risk factors for Parkinson disease. Rotenone can cause neuronal death or apoptosis through inducing oxidative injury and inhibiting mitochondrial function. As a natural polyphenolic compound, resveratrol possesses the antioxidant capacity and neuroprotective effect. However, the mechanism underlying the neuroprotective effect of resveratrol against rotenone‐induced neurotoxicity remains elusive. Here, we treated PC12 cells with rotenone to induce neurotoxicity, and the neurotoxic cells were subjected to resveratrol treatment. The CCK8 and LDH activity assays demonstrated that resveratrol could suppress neurotoxicity induced by rotenone (Pu2009<u20090.01). The DCFH‐DA assay indicated that resveratrol reduced the production of reactive oxygen species (ROS). JC‐1 and Hoechst 33342/PI staining revealed that resveratrol attenuated mitochondrial dysfunction and cell apoptosis. Moreover, resveratrol reversed rotenone‐induced decrease in SIRT1 expression and Akt1 phosphorylation (Pu2009<u20090.05). Furthermore, when the SIRT1 and Akt1 activity was inhibited by niacinamide and LY294002, respectively, the neuroprotective effect of resveratrol was remarkably attenuated, which implied that SIRT1 and Akt1 could mediate this process and may be potential molecular targets for intervening rotenone‐induced neurotoxicity. In summary, our study demonstrated that resveratrol reduced rotenone‐induced oxidative damage, which was partly mediated through activation of the SIRT1/Akt1 signaling pathway. Our study launched a promising avenue for the potential application of resveratrol as a neuroprotective therapeutic agent in Parkinson disease. Anat Rec, 301:1115–1125, 2018.

Paliperidone increases spontaneous and evoked firing of mesocortical dopaminergic neurons by activating a hyperpolarization-activated inward current.

Mesocortical dopaminergic (DA) subtype neurons specifically project to the prefrontal cortex, which is closely related with schizophrenia. Mesocortical DA neurons have unique physiological characteristics that are different from those of mesostriatal and mesolimbic DA neurons. Paliperidone, an atypical antipsychotic, is currently used to treat schizophrenia and has better therapeutic effects than typical antipsychotics. However, the underlying physiological mechanism remains unclear. To explore the effects of paliperidone on mesocortical DA neuron activity, here, we retrogradely labeled these cells with fluorescent microsphere retrobeads, and the electrophysiological changes were recorded in whole-cell recordings in rat midbrain slices with or without paliperidone. The data showed that paliperidone (20μmol/L) increased the spontaneous firing rates of labeled mesocortical neurons (P<0.05). Moreover, paliperidone also increased the frequency of evoked action potentials by current injection stimulation (P<0.05), whereas the accompanying amplitude decreased. Furthermore, to explore the mechanisms of paliperidones effect, Ih currents were detected, and the results showed that hyperpolarizing voltage pulses evoked instantaneous Ih inward currents and paliperidone increased the maximum Ih current. In addition, paliperidone decreased the spontaneous inhibitory postsynaptic currents. Thus, paliperidone increased the spontaneous and evoked firing of mesocortical neurons, possibly by activating the Ih inward current and reducing the inhibitory synaptic transmission, which provides an underlying mechanism of paliperidones application in schizophrenia.