Osteoarthritis (OA) is a common disease among elders and athletes. Mitogen-activated protein kinases (MAPKs) are molecules of stress sensitivity which play a significant role in the occurrence and development of OA. MAPKs are closely related with chondrocyte apoptosis and cartilage degradation. This paper reviewed the related studies between OA and MAPKs.

Objective:To investigate effect of reperfusion injury following different ischemic duration on skeletal muscle in rats.Methods:A model of ischemia/reperfusion injury (IRI) was established by unilateral clamping femoral artery and additional application of tourniquet in skeletal muscle of hind limbs in 35 male Wsitar rats. According to different ischemia time, the animals were assigned to 2-hour ischemia and 24-hour reperfusion (I2R24 group), 2.5-hour ischemia and 24-hour reperfusion (I2.5R24 group), 3-hour ischemia and 24-hour reperfusion (I3R24 group), 4-hour ischemia and 24-hour reperfusion (I4R24 group) and sham group, with 7 rats per group. At the end of reperfusion, gastrocnemious tissues and plasma samples were collected and analyzed. The ratio of wet ∶ dry weight (W/D) was used to measure muscle edema. The assay of 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) was conducted to evaluate muscle viability. HE staining was executed to observe histopathological changes. Immunofluorescence staining was performed to assess the levels of C1q, C3b/c, tissue factor (TF), fibrinogen (FN), bradykinin receptor 1 (BR1), BR2, vascular cell adhesion molecule-1 (VCAM-1), E-selectin, fibrinogen-like protein-2 (FGL-2) and myeloperoxidase (MPO) in muscle tissues. ELISA method was used to determine the concentrations of interferonγ (IFN-γ), interleukin7 (IL-7), IL-18, macrophage inflammatory1α (MIP-1α) and monocyte chemotactic protein 1 (MCP-1) in plasma.Results:With prolongation of ischemia time and subsequent reperfusion, tissue edema became severe gradually. The ratio of W/D was 5.3±0.2, 6.1±0.3, 6.9±0.2, 7.6±0.3 in I2R24, I2.5R24, I3R24 and I4R24 groups, higher than that in sham group (4.5±0.1) (all P<0.01). Muscle viability got decreased gradually. Muscle viability was (62.4±3.5)%, (45.3±3.3)%, (35.4±3.4)%, (27.1±5.9)% in I2R24, I2.5R24, I3R24 and I4R24 groups, lower than that in sham group［(93.8±7.2)%］(all P<0.01). Histopathological changes became aggravated gradually. The most severe group was I4R24 group, with the most severe myocyte injury, interstitial edema and extensive inflammatory infiltration, followed by I3R24, I2.5R24 and I2R24 groups in order. There was normal structure integrity and neatly arranged myocyte in sham group. Meanwhile, levels of C1q, C3b, FN, BR1, VCAM-1, E-selectin and FGL-2 got increased gradually. The highest levels for these factors were seen in I4R24 group, followed by I3R24 group, I2.5R24 group, I2R24 group and sham group in order. The rough ratio of the number of positive MPO cells/total cell number under high lens (×200) were increased gradually, with the highest level in I4R24 group, followed by I3R24 group, I2.5R24 group, I2R24 group and sham group in order. However, expression of TF and BR2 were not altered significantly among the groups. Plasma levels of INF-γ, IL-7, IL-18, MIP-1α and MCP-1 elevated gradually with prolongation of ischemia time (all P<0.01). The sequence was the sham group, I2R24 group, I2.5R24 group, I3R24 group and I4R24 groups for levels of these factors from low to high (all P<0.01). Conclusion:Reperfusion after prolongation of ischemia duration can increase the activation of complement, coagulation, kinin and endothelial cells as well as the release of inflammatory factors, and thus aggravate the degree of skeletal muscle tissue injury.

Objective:To analyze the effect of Croton leaf on ERK1/2 pathway in hippocampal of rats with cerebral ischemia-reperfusion.Methods:A total of 216 SD male rats were divided into sham operation group, model group, nimodipine group, low-dose, medium-dose and high-dose groups of croton leaf according to random nubmer table method, with 36 rats in each group. The MACO model of rats was prepared by the method of wire embolization. The high, medium and low dose groups were intragastrated with the water decoction 0.06 g/ml, 0.12 g/ml and 0.18 g/ml of Croton leaf; nimodipine group was intragastrated with nimodipine suspension 1.08 g/L; sham operation group and model group were intragastrated with equal volume of normal saline. Garcia JH score was used to conduct neurological function score, and HE staining was used to observe the morphology of hippocampal neurons after 7 days of continuous administration. Apoptosis of hippocampal CA3/DG region was detected by TUNEL assay. Western Blot was used to detect the expression of ERK1/2 and p-ERK1/2 proteins.Results:Compared with the model group at simultaneous point, the neurological function scores of low-dose, medium-dose and high-dose groups of Croton leaf increased ( P<0.01), the number of apoptotic cells decreased ( P<0.01), the expression of p-ERK1/2 / ERK1/2 [1 d: (0.22±0.03, 0.34±0.02, 0.46±0.01 vs. 0.19±0.02); 3 d: (0.38±0.02, 0.50±0.02, 0.68±0.02 vs. 0.27±0.02); 7 d: (0.29±0.03, 0.43±0.02, 0.59±0.02 vs. 0.21±0.03)] in hippocampus of the low-dose, medium-dose and high-dose groups of Croton leaf significantly increased ( P<0.01). Conclusion:Croton leaf could regulate the expression of ERK1/2 pathway protein upward, effectively improve the neural function and resist the apoptosis of hippocampal CA3/DG area of rats with cerebral ischemia-reperfusion injury.

Exercise is benefic for osteoporosis, without clear molecular biology mechanism. The osteoprotegerin/receptor activator of nuclear factor-κB ligand/receptor activator of nuclear factor-κB (OPG/RANKL/RANK) signal pathway contributes to osteoporosis, which can be mediated by mechanical force. Research progress on osteoporosis and the stress sensitive signal pathway OPG/RANKL/RANK were reviewed in this paper.

BACKGROUND:Croton cream can activate ERK pathways and have anti-apoptotic effects on neuronal cells.It is not clear whether it synergistically exerts anti-apoptotic effects by inhibiting the activation of JNK and p38 pathways. OBJECTIVE:To explore the effects and mechanisms of croton cream on neuronal damage and apoptosis in the ischemic cortex of rats with cerebral ischemia-reperfusion injury. METHODS:(1)Ninety Sprague-Dawley rats were randomly divided into sham operation group,model group,croton cream low-dose group,croton cream medium-dose group,croton cream high-dose group and nimodipine group,with 15 rats in each group.Except for the sham operation group,animal models of middle cerebral artery occlusion were prepared in rats by the thread method.Rats in the three croton cream groups were given 20,40,and 60 mg/kg croton cream,respectively.Rats in the sham operation and model groups were given the same amount of normal saline,once a day,for 7 consecutive days.The optimal concentration of croton cream,namely the high dose of croton cream,was selected based on neurological deficit score,TTC staining,brain tissue water content,hematoxylin-eosin staining and Nissl staining.(2)Another 120 Sprague-Dawley rats were randomly divided into sham operation group,model group,croton cream group,JNK inhibitor group,croton cream+JNK inhibitor group,p38 MAPK inhibitor group,croton cream+p38 MAPK inhibitor group,and nimodipine group,with 15 rats in each group.Animal models of middle cerebral artery occlusion were prepared using the thread method in all the groups except in the sham operation group.Thirty minutes before modeling,10 μL of SP600125(JNK inhibitor)and 10 μL of SB203580(p38 MAPK inhibitor)were injected into the lateral ventricle of the rats,respectively.Rats in croton cream groups were intragastrically given 60 mg/kg croton cream.Seven days later,the JNK/p38 MAPK signaling pathway,apoptosis-related proteins and cell apoptosis were detected by western blot,TUNEL staining and flow cytometry,respectively. RESULTS AND CONCLUSION:(1)Compared with the sham operation group,neurological deficit score,cerebral water content,cerebral infarction volume and apoptosis rate were significantly increased in the model group(P<0.05),where nerve cells showed scattered distribution.Compared with the model group,neurological deficit score,water content of brain tissue and cerebral infarction volume were significantly decreased in the croton cream medium-dose group,high-dose group and nimodipine group(P<0.05),and the pathological morphology of nerve cells was significantly improved.(2)Compared with the JNK inhibitor group,p-JNK/JNK,p-p38/p38 and Bax expressions in rat brain tissue and the apoptotic rate were significantly decreased in the croton cream+inhibitor groups(P<0.05),while the expression of and Bcl-2 was significantly increased(P<0.05).To conclude,croton cream may inhibit the activation of JNK/p38 MAPK signaling pathway and reduce neuronal apoptosis to achieve neuroprotective effects in rats with cerebral ischemia-reperfusion injury.