[Hippocampus is involved in 17ß-estradiol exacerbating experimental occlusal inter- ference-induced chronic masseter hyperalgesia in ovariectomized rats].

OBJECTIVE: To investigate the influence of chronic masseter hyperalgesia induced by 17ß-estradiol (E2) and experimental occlusal interference (EOI) on underlying mechanism in hippocampus of ovariectomized (OVX) rats. METHODS: In the study, 32 OVX rats were randomly divided into 4 groups (8 rats/group): The control group was OVX group, and 0 µg/d E2 (vehicle) injection was started 7 d after OVX without EOI; in the experimental group (1) OVX + E2 group, 80 µg/d E2 injection was started 7 d after OVX without EOI; in the experimental group (2) OVX + EOI group, vehicle injection was started 7 d after OVX and EOI was applied 17 d after OVX; in the experimental group (3) OVX + E2 + EOI group, 80 µg/d E2 injection was started 7 d after OVX and EOI was applied 17 d after OVX. Bilateral masseter muscle mechanical withdrawal thresholds were measured before OVX, 7 days after OVX (before E2 injection), 17 days after OVX (10 days after E2 injection and before EOI) and 24 days after OVX (7 days after EOI). Immunofluorescence staining was used to reveal phospho-extracellular signal regulated kinase 1/2 (p-ERK1/2)-positive neurons in CA3 of hippocampus. The protein expression of p-ERK1/2 in hippocampus was detected using Western Blot. RESULTS: Compared with the control group [left side: (135.3±8.5) g, right side: (135.4±10.8) g], bilateral masseter muscle mechanical withdrawal thresholds of OVX+E2 group [left side: (113.3±5.6) g, right side: (112.5 ± 5.6) g] and OVX+EOI group [left side: (93.3±5.4) g, right side: 90.8±5.5) g] were decreased (P < 0.01). Bilateral masseter muscle mechanical withdrawal thresholds were significantly lower in OVX+E2+EOI group [left side: (81.2±6.2) g, right side: 79.8±7.7) g] than in the control, OVX+E2 and OVX+EOI groups (P < 0.05). The proportion of p-ERK1/2 positive neurons in the CA3 region of the hippocampus was increased in the control, OVX+E2, OVX+EOI and OVX+E2+EOI groups in turn, and the difference between the groups was statistically significant (P < 0.05). p-ERK1/2 protein expression was increased in the control, OVX+E2 and OVX+EOI groups in turn, but the difference was not statistically significant (P>0.05). p-ERK1/2 expression was significantly higher in OVX+E2+EOI group than in the other three groups (P < 0.05). CONCLUSION: High concentration of E2 could exacerbated EOI-induced chronic masseter hyperalgesia in ovariectomized rats, and its central mechanism may be related to the upregulation of the phosphorylation of ERK1/2 in hippocampus.

[Adenosine triphosphate induced odontoblastic differentiation of human dental pulp cells in vitro and in vivo].

Objective: To choose a suitable efficient concentration of adenosine triphosphate (ATP) which can induce human dental pulp cells (HDPC) differentiate into odontoblast successfully, and explore the role of this concentration of ATP in dentin regeneration in vivo. Methods: HDPC were treated with different concentrations (0, 10, 400, 600, 800 µmol/L) of ATP. Then cell counting kit-8 (CCK-8), quantitative real-time PCR, and Western blotting were used to detect the cell proliferation and the expressions of odontoblastic differentiation related markers, dentin matrix protein 1 (DMP1) and dentin sialophosphoprotein (DSPP). Alizarin red S staining experiment was used to analyze the effect of ATP on the mineralization ability of HDPC. By the above experiments, the suitable effective concentration of ATP was chosen to pretreat the HDPC for 7 days, then cells were seeded on gelfoam, inserted into the root canal fragment, and subsequently transplanted into the subcutaneous space on the back of immunodeficient mice, after three months, the samples were stained with HE for histological analysis. Results: The CCK-8 results in 5 d showed that 10 µmol/L ATP obviously promoted the proliferation of HDPC, while the 600 and 800 µmol/L ATP apparently inhibited the HDPC proliferation, however, the proliferation in 800 µmol/L ATP group was lower than that of 600 µmol/L ATP group (P<0.05). qPCR and Western blotting results showed that the 600 and 800 µmol/L ATP significantly up-regulated the DMP1 and DSPP expressions (P<0.05), furthermore, there was no significant difference in the two groups, but no changes were found in other groups (P>0.05). After 21 days of culturing, there were obvious mineralization nodules in 600 and 800 µmol/L ATP groups, but no mineralization nodules in other groups. Quantitative analysis of the staining results showed the A value in 0, 10, 400, 600, and 800 µmol/L ATP groups were respectively 1.05±0.15, 1.11±0.23, 1.15±0.17, 3.65±0.30, and 3.40±0.43, and the A value in 600 and 800 µmol/L ATP groups were higher than those of other groups; however, there was no difference in 600 and 800 µmol/L ATP groups. The histological analysis showed that 600 µmol/L ATP could induce the HDPC differentiate into dentin-like structure in the root canal fragment. Conclusions: Therefore, the suitable effective concentration of ATP is 600 µmol/L, which could induce HDPC differentiate into odontoblast-like cells, and form the dentin-like structure in vivo.

[Research progress on factors influencing early liver dysfunction after liver transplantation].

Liver transplantation is the most effective treatment for end-stage liver disease, and early graft dysfunction often occurs after surgery. Early liver dysfunction after liver transplantation has become one of the complications after liver transplantation, which seriously affects the graft and patient survival. Therefore, reducing its occurrence can be an important means to improve the prognosis of recipients after liver transplantation. This paper discusses the research progress on the definition, influencing factors, and prognosis and prediction model in order to provide better prevention and effective reference for improving the success rate and prognosis of early liver dysfunction in recipients after liver transplantation.

[Changes of productions of energy metabolism in masseter of rats induced by occlusal interference].

OBJECTIVE: To investigate the effect of occlusal interference on the energy metabolism of masticatory muscle by studying the changes of adenosine triphosphate (ATP), adenosine diphosphate (ADP), inosine monophosphate (IMP), phosphocreatine, creatine, lactate and pH level in masseter muscles of rats after occlusal interference. METHODS: Fifty male Sprague-Dawley rats were randomly assigned into experimental group (n=40) and control group (n=10). In experimental group, 0.4 mm thick metal crown was cemented to the upper right first molar of the rat, and maintained for 3, 7, 10, 14 d separately (n=10 for each time point). No occlusal interference was applied for control group. Bilateral masseter muscles of all the rats were acquired under general anesthesia. The samples of 5 rats in each group were fully homogenized with 0.4 mol/L perchlorate (10 mL/g). The homogenates were centrifuged, filtered and analyzed for ATP, ADP, IMP, phosphocreatine, creatine and lactate content by high performance liquid chromatography. The other samples in each group were mixed with homogenates containing 5 mmol/L sodium iodoacetate (10 mL/g), then homogenized and measured for pH value by pH meter in thermostatic water bathunder 37 degrees centigrade. RESULTS: Compared with control group, ATP content in bilateral masseter of the rats increased 3 d after occlusal interference [right side:(5.36±0.13) µmol/g,left side:(5.77±0.25) µmol/g] (P<0.05), and back to normal on 7, 10 and 14 d. There was an increase in IMP [right side:(0.21±0.03) µmol/g,left side:(0.19±0.03) µmol/g]and creatine content [right side:(24.76±2.94) µmol/g,left side:(27.75±2.23) µmol/g]in bilateral masseter of the rats 7 d after occlusal interference (P<0.05) and no difference was detected on 3, 10, and 14. Phosphocreatine content in bilateral masseter started to decline 7 d after occlusal interference and maintained the low level on 10 and 14 d [right side:(10.70±0.71) µmol/g, (11.57±0.52) µmol/g, (10.74±1.39) µmol/g, left side:(10.05±0.57) µmol/g, (10.75±1.12)µmol/g, (10.61±1.15) µmol/g](P<0.05). No change of ADP, lactate or pH level in bilateral muscles of the rats after occlusal interference was observed (P>0.05). CONCLUSION: Occlusal interference influences the content of energy metabolites in masticatory muscle of rats, which may be related to the pathological process of masticatory muscles induced by occlusal interference, such as muscle pain, dysfunction and altered fiber architecture.

Ghrelin and truncated ghrelin variant plasmid vectors administration into skeletal muscle augments long-term growth in rats.

Ghrelin is an acylated peptide recently identified as an endogenous ligand for the growth hormone (GH) secretagogues (GHSs) receptor (GHS-R) and is involved in a novel system for regulating GH release. To study the biological activities of ghrelin using plasmid vector administration, we constructed myogenic expression vectors containing the full length cDNA of swine ghrelin-28 (pGEM-wt-sGhln) and truncated variant (pGEM-tmt-sGhln) consisting of the first seven residues of ghrelin (including Ser3 substituted with Trp3) with addition of a basic amino acid, Lys (K) at the C-terminus. After intramuscular injection of pGEM-wt-sGhln and pGEM-tmt-sGhln, RT-PCR analysis demonstrated that the ectopic expressions of ghrelin and its variant were observed 30 days post-injection. The level of GH increased in rat serum, and was significantly higher than that of the control group 20 days post-injection with pGEM-tmt-sGhln (P < 0.05). Administration of 150 microg of pGEM-wt-sGhln and pGEM-tmt-sGhln enhanced growth in rats over 30 days and great stimulatory responses were observed at day 10 and 20 post-injection respectively, whose body weight gains were on average 15% (P < 0.05) and 21% P < 0.033 significantly heavier than controls. These results suggested that skeletal muscle might have the potential to perform post-translational acylation for ghrelin, and short ghrelin variant might have the biological effects as wild type ghrelin.