Treadmill running on neuropathic pain: via modulation of neuroinflammation.

Neuropathic pain is a type of chronic pain caused by an injury or somatosensory nervous system disease. Drugs and exercise could effectively relieve neuropathic pain, but no treatment can completely stop neuropathic pain. The integration of exercise into neuropathic pain management has attracted considerable interest in recent years, and treadmill training is the most used among exercise therapies. Neuropathic pain can be effectively treated if its mechanism is clarified. In recent years, the association between neuroinflammation and neuropathic pain has been explored. Neuroinflammation can trigger proinflammatory cytokines, activate microglia, inhibit descending pain modulatory systems, and promote the overexpression of brain-derived neurotrophic factor, which lead to the generation of neuropathic pain and hypersensitivity. Treadmill exercise can alleviate neuropathic pain mainly by regulating neuroinflammation, including inhibiting the activity of pro-inflammatory factors and over activation of microglia in the dorsal horn, regulating the expression of mu opioid receptor expression in the rostral ventromedial medulla and levels of γ-aminobutyric acid to activate the descending pain modulatory system and the overexpression of brain-derived neurotrophic factor. This article reviews and summarizes research on the effect of treadmill exercise on neuropathic pain and its role in the regulation of neuroinflammation to explore its benefits for neuropathic pain treatment.

Potential contribution of hypoxia-inducible factor-1α, aquaporin-4, and matrix metalloproteinase-9 to blood-brain barrier disruption and brain edema after experimental subarachnoid hemorrhage.

The current research aimed to investigate the role of hypoxia-inducible factor-1α (HIF-1α), aquaporin-4 (AQP-4), and matrix metalloproteinase-9 (MMP-9) in blood-brain barrier (BBB) dysfunction and cerebral edema formation in a rat subarachnoid hemorrhage (SAH) model. The SAH model was induced by injection of 0.3 ml fresh arterial, non-heparinized blood into the prechiasmatic cistern in 20 s. Anti-AQP-4 antibody, minocycline (an inhibitor of MMP-9), or 2-methoxyestradiol (an inhibitor of HIF-1α), was administered intravenously at 2 and 24 h after SAH. Brain samples were extracted at 48 h after SAH and examined for protein expressions, BBB impairment, and brain edema. Following SAH, remarkable edema and BBB extravasations were observed. Compared with the control group, the SAH animals have significantly upregulated expressions of HIF-1α, AQP-4, and MMP-9, in addition to decreased amounts of laminin and tight junction proteins. Brain edema was repressed after inhibition of AQP-4, MMP-9, or HIF-1α. Although BBB permeability was also ameliorated after inhibition of either HIF-1α or MMP-9, it was not modulated after inhibition of AQP-4. Inhibition of MMP-9 reversed the loss of laminin. Finally, inhibition of HIF-1α significantly suppressed the level of AQP-4 and MMP-9, which could induce the expression of laminin and tight junction proteins. Our results suggest that HIF-1α plays a role in brain edema formation and BBB disruption via a molecular signaling pathway involving AQP-4 and MMP-9. Pharmacological intervention of this pathway in patients with SAH may provide a novel therapeutic strategy for early brain injury.

Potential contribution of matrix metalloproteinase-9 (mmp-9) to cerebral vasospasm after experimental subarachnoid hemorrhage in rats.

This study investigated the possible involvement of matrix metalloproteinase 9 (MMP-9) in cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH) in rats. The CVS model was established by injection of fresh autologous nonheparinized arterial blood into the cisterna magna. Experiment 1 aimed to investigate the timecourse of the MMP-9 expression in the basilar artery after SAH. In Experiment 2, we chose the maximum time point of vasospasm (Day 3) and assessed the effect of SB-3CT (a selective MMP- 9 inhibitor) on the regulation of cerebral vasospasm. The cross-sectional area of basilar artery was measured by H&E staining and the MMP-9 expression was assessed by immunohistochemistry analysis. The elevated expression of MMP-9 was detected in the basilar artery after SAH and peaked on day 3. After intracisternal administration of SB-3CT, the vasospasm was markedly attenuated after blood injection on day 3. Our results suggest that MMP-9 is increasingly expressed in a parallel time course to the development of cerebral vasospasm in this rat experimental model of SAH and that the administration of the specific MMP-9 inhibitor could prevent or reduce cerebral vasospasm caused by SAH.

Melatonin activates the Nrf2-ARE pathway when it protects against early brain injury in a subarachnoid hemorrhage model.

Melatonin has beneficial effects against early brain injury (EBI) by modulating cerebral oxidative stress after experimental subarachnoid hemorrhage (SAH); however, few investigations relate to the precise underlying molecular mechanisms. To date, the relation between melatonin and nuclear factor erythroid 2-related factor 2 and antioxidant responsive element (Nrf2-ARE) pathway has not been studied in SAH models. This study was undertaken to evaluate the influence of melatonin on Nrf2-ARE pathway in rats after SAH. Adult male SD rats were divided into four groups: (i) control group (n=18); (ii) SAH group (n=18); (iii) SAH+vehicle group (n=18); and (iv) SAH+melatonin group (n=18). The rat SAH model was induced by injection of 0.3mL fresh arterial, nonheparinized blood into the prechiasmatic cistern in 20s. In SAH+melatonin group, melatonin was administered i.p. at 150mg/kg at 2 and 24hr after the induction of SAH. Brain samples were extracted at 48hr after SAH. Treatment with melatonin markedly increased the expressions of Nrf2-ARE pathway-related agents, such as Nrf2, heme oxygenase-1, NAD(P)H:quinone oxidoreductase 1, and glutathione S-transferase α-1. Administration of melatonin following SAH significantly ameliorated EBI, including brain edema, blood-brain barrier (BBB) impairment, cortical apoptosis, and neurological deficits. In conclusion, post-SAH melatonin administration may attenuate EBI in this SAH model, possibly through activating Nrf2-ARE pathway and modulating cerebral oxidative stress by inducing antioxidant and detoxifying enzymes.

[Expression of connective tissue growth factor in renal interstitial fibrosis after ureteral obstruction and effects of rapamycin thereupon: experiment with rats].

OBJECTIVE: Is a common feature of progressive renal diseases regardless of the initiating insult To clarify the role of connective tissue growth factor (CTGF) in after (UUO) in renal interstitial fibrosis and effects of rapamycin (RAP) thereupon. METHODS: Eighteen Sprague-Dawley rats were randomly divided into 3 equal groups: unilateral ureteral obstruction (UUO) model group, undergoing ligation of the left ureter; RAP treatment group, undergoing ligation of the left ureter and intraperitoneal injection of RAP 0.04 mg.kg(-1).d(-1); and sham operation group. The right kidneys were taken out 7 and 14 days after the operation respectively to undergo renal pathological examination by Masson staining. Semi-quantitative RT-PCR was used to detect the mRNA expression of CTGF. Western blotting was performed to examine the protein expression of CTGF and fibronectin (FN). RESULTS: In comparison with the sham operation group, renal interstitial fibrosis was significant more expression in the 2 UUO groups, especially the UUO model group (P < 0.01). Seven and 14 days after the operation the levels of CTGF mRNA expression of the UUO model and RAP treatment groups (both P < 0.01), and the level of CTGF mRNA expression of the RAP treatment group was significantly lower than that of the UUO model group (P < 0.01), however, there was no significant difference in the level of CTGF mRNA expression between the 2 UUO groups 14 days after the operation. Seven and 14 days after the operation the levels of CTGF protein expression of the UUO model and RAP treatment groups were both significantly higher than that of the sham operation group (both P < 0.01), and the levels of CTGF protein expression of the RAP treatment group were significantly lower than that of the UUO model group (P < 0.05 and P < 0.01). The levels of FN expression 7 and 14 days after the operation of the 2 UUO groups were both significantly higher than that of the sham operation group (both P < 0.01). and the level of FN expression 7 days after of the RAP treatment group was significantly lower than that of the UUO model group (P < 0.01), however, there was no significant difference in the level of FN expression between the 2 UUO groups 14 days after the operation. CONCLUSION: The expression of CTGF mRNA and that of CTGF protein increase after UUO. Rapamycin play a protective role in the kidney by downregulating the CTGF expression and alleviating the renal interstitial fibrosis following UUO.