A nomogram for predicting cerebral white matter lesions in elderly men.

Objective: This study aimed to develop a nomogram tool to predict cerebral white matter lesions (WMLs) in elderly men. Methods: Based on a retrospective cohort from January 2017 to December 2019, a multivariate logistic analysis was performed to construct a nomogram for predicting WMLs. The nomogram was further validated using a follow-up cohort between January 2020 and December 2022. The calibration curve, receiver operating characteristics (ROC) curves, and the decision curves analysis (DCA) were used to evaluate discrimination and calibration of this nomogram. Result: A total of 436 male patients were enrolled in this study, and all 436 patients were used as the training cohort and 163 follow-up patients as the validation cohort. A multivariate logistic analysis showed that age, cystatin C, uric acid, total cholesterol, platelet, and the use of antiplatelet drugs were independently associated with WMLs. Based on these variables, a nomogram was developed. The nomogram displayed excellent predictive power with the area under the ROC curve of 0.951 [95% confidence interval (CI), 0.929-0.972] in the training cohort and 0.915 (95% CI, 0.864-0.966) in the validation cohort. The calibration of the nomogram was also good, as indicated by the Hosmer-Lemeshow test with p-value of 0.594 in the training cohort and 0.178 in the validation cohort. The DCA showed that the nomogram holds good clinical application value. Conclusion: We have developed and validated a novel nomogram tool for identifying elderly men at high risk of WMLs, which exhibits excellent predictive power, discrimination, and calibration.

PI3Kδ inhibition alleviates the brain injury during cerebral ischemia reperfusion via suppressing pericyte contraction in a TNF-α dependent manner.

The pericytes (PCs) surrounding capillaries are vital regulators of capillary constriction. Persistent PC contraction results in the increased capillary constriction, therefore leading to the impaired cerebral blood flow (CBF) recovery after reperfusion and worsening the clinical outcomes in stroke patients. However, the potential determinants of PC functions during ischemia/reperfusion are poorly understood. Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit Delta (PIK3CD/PI3Kδ) is a crucial factor involved with neuronflammation during ischemic stroke. PI3Kδ has shown the expression in PCs, while its effect on PC functions has not been explored yet. In this study, a rodent ischemia/reperfusion model was established in C57BL/6 mice via transient middle cerebral artery occlusion and reperfusion (MCAO/R). The PI3Kδ expression in ischemic penumbra was remarkably upregulated following MCAO/R induction. PI3Kδ inhibitor CAL-101 improved the CBF recovery, ischemic brain injury, and suppressed capillary constriction in MCAO/R mice. Besides, the production of tumor necrosis factor alpha (TNF-α), an inducer for tissue injury, and the expression of transient receptor potential vanilloid type 2 (TRPV2), a channel protein permitting calcium (Ca2+) uptake, were significantly reduced in ischemic penumbra after CAL-101 treatment. In vitro, oxygen-glucose deprivation and reoxygenation (OGD/R) enhanced the expression of PI3Kδ and TRPV2 in primary mouse PCs. CAL-101 suppressed the TNF-α-induced TRPV2 expression in OGD/R-treated PCs, thus inhibiting the Ca2+ uptake and PC contraction. Collectively, this study suggests that PI3Kδ is a critical regulator of PC function during ischemic stroke.

Efficacy of remote ischemic conditioning does not differ between men and women: A secondary analysis of the RICAMIS study.

BACKGROUND AND PURPOSE: The present study aimed to determine sex difference in clinical outcomes after Remote Ischemic Conditioning for Acute Moderate Ischemic Stroke (RICAMIS). METHODS: In this secondary analysis of the RICAMIS study, eligible patients aged 18 years or older with acute moderate ischemic stroke who received remote ischemic conditioning (RIC) within 48 h of stroke onset were divided into two groups: men and women. The primary endpoint was an excellent functional outcome, defined as a modified Rankin Scale score of 0-1 at 90 days. Binary logistic regression analyses and generalized linear models were used. RESULTS: Of 1707 eligible patients, 34% (579) were women. Women had a higher burden of hypertension and diabetes, and less alcohol and smoking consumption than men. The mean systolic blood pressure and blood glucose level at randomization were higher in women than in men. Compared with the control group, RIC was associated with an increased rate of primary endpoint in men (unadjusted odds ratio [OR] = 1.277; 95% confidence interval [CI] 0.933-1.644; p = 0.057) and women (unadjusted OR = 1.454; 95% CI 1.040-2.032; p = 0.028). Furthermore, a higher absolute risk difference in primary endpoint between control and RIC groups was found in women (9.2%) than in men (5.7%), but there was no significant interaction effect between sex and intervention on primary outcome (p interaction = 0.545). CONCLUSION: Compared with men, women may have a higher probability of excellent functional outcomes at 90 days in the RIC group than in the control group; however, no interaction effect between sex and intervention was found.

Predicting symptomatic intracranial hemorrhage in anterior circulation stroke patients with contrast enhancement after thrombectomy: the CAGA score.

BACKGROUND: The aim of the study was to establish a reliable scoring tool to identify the probability of symptomatic intracranial hemorrhage (sICH) in anterior circulation stroke patients with contrast enhancement (CE) on brain non-contrast CT (NCCT) after endovascular thrombectomy (EVT). METHODS: We retrospectively reviewed consecutive patients with acute ischemic stroke (AIS) who had CE on NCCT immediately after EVT for anterior circulation large vessel occlusion (LVO). We used the Alberta stroke program early CT score (ASPECTS) scoring system to estimate the extent and location of CE. Multivariable logistic regression was performed to derive an sICH predictive score. The discrimination and calibration of this score were assessed using the area under the receiver operator characteristic curve, calibration curve, and decision curve analysis. RESULTS: In this study, 194 of 322 (60.25%) anterior circulation AIS-LVO patients had CE on NCCT. After excluding 85 patients, 109 patients were enrolled in the final analysis. In multivariate regression analysis, age ≥70 years (adjusted OR (aOR) 9.23, 95% CI 2.43 to 34.97, P＜0.05), atrial fibrillation (AF) (aOR 4.17, 95% CI 1.33 to 13.12, P＜0.05), serum glucose ≥11.1 mmol/L (aOR 9.39, 95% CI 2.74 to 32.14, P＜0.05), CE-ASPECTS ＜5 (aOR 3.95, 95% CI 1.30 to 12.04 P＜0.05), and CE at the internal capsule (aOR 3.45, 95% CI 1.03 to 11.59, P＜0.05) and M1 region (aOR 3.65, 95% CI 1.13 to 11.80, P＜0.05) were associated with sICH. These variables were incorporated as the CE-age-glucose-AF (CAGA) score. The CAGA score demonstrated good discrimination and calibration in this cohort, as well as the fivefold cross validation. CONCLUSION: The CAGA score reliably predicted sICH in patients with CE on NCCT after EVT treatment.

Changes in blood gas values and electrolytes in the occluded artery predict outcomes after endovascular treatment in ischemic stroke.

BACKGROUND AND PURPOSE: Endovascular treatment (EVT) is the best treatment for acute ischemic stroke with large vessel occlusion (LVO) and makes it possible to analyze the blood contents from the occluded vascular compartments. In this study, we attempted to evaluate regional changes in blood gas values and electrolytes in the occluded vessels, aiming to determine whether these changes can predict outcomes in LVO patients receiving EVT. MATERIALS AND METHODS: We prospectively observed 45 consecutive ischemic stroke patients with LVO of the anterior circulation who underwent EVT. We collected the arterial blood proximal to the occlusion site before and after EVT, and the blood within the core of the occluded vascular compartment (distal to the thrombus) and evaluated the labs for blood gas values and electrolytes. Femoral samples were obtained under physiological flow conditions to represent systemic arterial blood. RESULTS: Compared with the femoral arterial blood samples, significant decreases in K+, Ca2+, HCO3-, BE, HCT, tHbc, and TCO2 levels were observed in the proximal luminal blood before EVT. Decreases in K+ and Ca2+ levels were also observed in the proximal luminal blood after EVT. Proximal/femoral ratio of pH and Na+ was associated with short-term clinical outcomes at 72 hours after EVT. A higher proximal/femoral Na+ ratio was associated with successful recanalization. Further analysis after propensity score matching showed significant changes in blood gas and electrolyte among different arterial locations in ICA and MCA LVO participants. Linear regression analyses indicated that the proximal/femoral ratio of pH, Na+, pCO2, HCO3, and TCO2 before EVT were associated with decrease in NIHSS score at 72 hours in ICA-LVO group. CONCLUSIONS: Obvious changes in several parameters of arterial blood gas and electrolyte from the ischemic vasculature occur during hyperacute stroke. Proximal/femoral pH and Na+ ratio before EVT may be associated with short-term clinical outcome, which deserve to be further investigated.

Association of serum biomarkers with early neurologic improvement after intravenous thrombolysis in ischemic stroke.

BACKGROUND: Early neurologic improvement (ENI) after intravenous thrombolysis is associated with favorable outcome, but associated serum biomarkers were not fully determined. We aimed to investigate the issue based on a prospective cohort. METHODS: In INTRECIS study, five centers were designed to consecutively collect blood sample from enrolled patients. The patients with ENI and without ENI were matched by propensity score matching with a ratio of 1:1. Preset 49 biomarkers were measured through microarray analysis. Enrichment of gene ontology and pathway, and protein-protein interaction network were analyzed in the identified biomarkers. RESULTS: Of 358 patients, 19 patients with ENI were assigned to ENI group, while 19 matched patients without ENI were assigned to Non ENI group. A total of nine biomarkers were found different between two groups, in which serum levels of chemokine (C-C motif) ligand (CCL)-23, chemokine (C-X-C motif) ligand (CXCL)-12, insulin-like growth factor binding protein (IGFBP)-6, interleukin (IL)-5, lymphatic vessel endothelial hyaluronan receptor (LYVE)-1, plasminogen activator inhibitor (PAI)-1, platelet-derived growth factor (PDGF)-AA, suppression of tumorigenicity (ST)-2, and tumor necrosis factor (TNF)-α were higher in the ENI group, compared with those in the Non ENI group. CONCLUSIONS: We found that serum levels of CCL-23, CXCL-12, IGFBP-6, IL-5, LYVE-1, PAI-1, PDGF-AA, ST-2, and TNF-α at admission were associated with post-thrombolytic ENI in stroke. The role of biomarkers warrants further investigation. TRIAL REGISTRATION: Clinical Trial Registration: https://www.clinicaltrials.gov; identifier: NCT02854592.

Net Water Uptake Calculated in Standardized and Blindly Outlined Regions of the Middle Cerebral Artery Territory Predicts the Development of Malignant Edema in Patients With Acute Large Hemispheric Infarction.

Background and purpose: Previous studies have demonstrated that Net Water Uptake (NWU) is associated with the development of malignant edema (ME). The current study aimed to investigate whether NWU calculated in standardized and blindly outlined regions of the middle cerebral artery can predict the development of ME. Methods: We retrospectively included 119 patients suffering from large hemispheric infarction within onset of 24 h. The region of the middle cerebral artery territory was blindly outlined in a standard manner to calculate NWU. Patients were divided into two groups according to the occurrence of ME, which is defined as space-occupying infarct requiring decompressive craniotomy or death due to cerebral hernia in 7 days from onset. The clinical characteristics were analyzed, and the receiver operating characteristic curve (ROC curve) was used to assess the predictive ability of NWU and other factors for ME. Results: Multivariable analysis showed that NWU was an independent predictor of ME (OR 1.168, 95% CI 1.041-1.310). According to the ROC curve, NWU≥8.127% identified ME with good predictive power (AUC 0.734, sensitivity 0.656, specificity 0.862). Conclusions: NWU calculated in standardized and blindly outlined regions of the middle cerebral artery territory is also a good predictor for the development of ME in patients with large hemispheric infarction.

Salvianolic Acids for Injection alleviates cerebral ischemia/reperfusion injury by switching M1/M2 phenotypes and inhibiting NLRP3 inflammasome/pyroptosis axis in microglia in vivo and in vitro.

ETHNOPHARMACOLOGICAL RELEVANCE: After cerebral ischemia/reperfusion injury, pro-inflammatory M1 and anti-inflammatory M2 phenotypes of microglia are involved in neuroinflammation, in which activation of NLRP3 inflammasome and subsequent pyroptosis play essential roles. Salvianolic Acids for Injection (SAFI) is Chinese medicine injection which composed of multiple phenolic acids extracted from Radix Salviae Miltiorrhizae, and has been reported to generate neuroprotective effects after cerebral ischemic insult in clinical and animal studies. AIM OF THE STUDY: The present study was designed to investigate whether SAFI exerts neuroprotective effects by switching microglial phenotype and inhibiting NLRP3 inflammasome/pyroptosis axis in microglia. MATERIALS AND METHODS: The middle cerebral artery occlusion/reperfusion (MCAO/R) model in rats and oxygen-glucose deprivation/reoxygenation (OGD/R) model in co-cultured primary neurons and primary microglia were utilized. The neuroprotective effect of SAFI was evaluated through measuring neurological deficit scores, neuropathological changes, inflammatory factors, cell phenotype markers, and related proteins of NLRP3 inflammasome/pyroptosis axis. RESULTS: The results showed that SAFI treatment was able to: (1) produce a significant increase in neurological deficit scores and decrease in infarct volumes, and alleviate histological injury and neuronal apoptosis in cerebral cortex in MCAO/R model; (2) increase neuronal viability and reduce neuronal apoptosis in the OGD model; (3) reshape microglial polarization patterns from M1-like phenotype to M2-like phenotype; (4) inhibit the activation of the NLRP3 inflammasome and the expression of proteins related to NLRP3 inflammasome/pyroptosis axis in vivo and in vitro. CONCLUSION: These findings indicate that SAFI exert neuroprotective effect, probably via reducing neuronal apoptosis, switching microglial phenotype from M1 towards M2, and inhibiting NLRP3 inflammasome/pyroptosis axis in microglia.

A novel rat model of cerebral artery occlusion complicated with prior venous stagnation.

BACKGROUND: To establish a novel rat model of middle cerebral artery occlusion (MCAO) complicated with prior venous stagnation, and to investigate the role of cerebral venous drainage in neural injury after acute cerebral infarction. NEW METHOD: Eighteen SD rats were randomly divided into two groups: control group and jugular vein ligation group. The left jugular vein ligation was performed to produce the jugular venous stagnation. In the control group, the jugular vein was exposed but not ligated. Cerebral blood flow (CBF) was measured through laser speckle imaging before and after the surgery. At 1 week after the surgery, CBF was again measured and then a left MCAO was performed in both groups. At 24 h after MCAO, neurological deficit scoring was performed and the infarct volume was measured by 2,3,5-triphenyltetrazolium chloride staining. RESULTS: Compared with the control group, a significant decrease in the CBF level was observed immediately after the ligation. A moderate recovery in CBF level was observed at 1 week after the ligation. The neurological deficit scores were significantly higher in the ligation group than in the control group at 24 h after the MCAO. Additionally, the volume of cerebral infarction increased significantly in the ligation group compared with that in the control group at the 24 h after MCAO. COMPARISON WITH EXISTING METHOD(S) AND CONCLUSIONS: The novel rat model of cerebral artery occlusion complicated with long-term unilateral venous stagnation indicates cerebral venous drainage impairment may aggravate behavioral impairment and increase infarct volume after cerebral infarction.

Time dependent neuroprotection of dexamethasone in experimental focal cerebral ischemia: The involvement of NF-κB pathways.

We propose that the neuroprotective effect of glucocorticoid in ischemic damage may be time dependent. The present study was designed to test the proposal and its possible mechanismin cerebral ischemia/reperfusion (I/R) injury model. Reperfusion injury was induced after 120 min of middle cerebral artery occlusion (MCAO) in male Sprague-Dawley rats. Atdifferenttimepoints after MCAO, rats were treated with high dose dexamethasone (10 mg/kg), and neurological deficit and infarct sizes were measured 2 h, 24 h after MCAO. The expression of NF-κB target genes, including inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß), were determined by western blot analysis and ELISA. Dexamethasone delivered 30 min (but not 60 min, 120 min) after MCAO markedly decreased the infarct size, improved neurological deficits in I/R injury model. Dexamethasone delivered 30 min (but not 60 min) after MCAO significantly inhibited NF-κB p65 expression and phosphorylation, compared with I/R group. The expression of iNOS, COX-2, TNF-α and IL-1ß, were also suppressed by dexamethasone delivered 30 min (but not 60 min) after MCAO. The results imply that neuroprotective action of dexamethasone in focal ischemic stroke model may be time dependent and attributed to inhibiting inflammation-related NF-κB p65 pathways.

Intra-arterial human urinary kallidinogenase alleviates brain injury in rats with permanent middle cerebral artery occlusion through PI3K/AKT/FoxO1 signaling pathway.

An urgent need exists to develop intra-arterial treatment for acute ischemic stroke in animal study. This study aimed to explore the beneficial effects of intra-arterial administration of human urinary kallidinogenase (HUK) on brain injury after permanent middle cerebral artery occlusion (pMCAO) in a rat model, and the potential underlying molecular mechanisms. Brain injury induced by pMCAO was evaluated through measuring neurological deficit scores, neuropathological changes, and inflammatory factors. Neurological deficits were observed 24 h after pMCAO and were alleviated by intra-arterial HUK treatment obviously. Inhibition of PI3K by LY294002 blocked the beneficial effect of HUK on neurological functions. In contrast to the pMCAO group, the intra-arterial HUK treatment group showed relatively more regularly arranged neurons and fewer pyknosis. Neurodegeneration, necrosis, infarct area and markers for brain injury were all ameliorated by intra-arterial HUK treatment. Moreover, a lower expression of inflammatory factors including interleukin (IL)-1ß, IL-6, and tumor necrosis factor (TNF)-α, and a higher expression of IL-10 were observed in the intra-arterial HUK treatment group than that in the pMCAO group. Additionally, when comparing with pMCAO group, a lower level of caspase-3, bax, and apoptotic rate, and a higher level of bcl-2, p-PI3K, p-AKT and p-FoxO1were observed in the pMCAO + HUK group. These results suggest that intra-arterial administration of HUK is a promising therapeutic strategy against pMCAO induced brain injury, and PI3K/AKT/FoxO1 signaling pathway may be involved in this process.

Identification of cytokines for early prediction of malignant middle cerebral artery infarction.

PURPOSE: We aimed to profile cytokines in patients with malignant middle cerebral artery infarction (MMI) and non-acute cerebral infarction (NACI), and identify potential cytokines for early prediction of MMI. MATERIALS AND METHODS: A total of 16 subjects were recruited, including 8 patients with MMI and 8 patients with NACI. Cytokine profiles and levels in serums were analyzed by Quantibody® Human Cytokine Antibody Array700. The two-tailed Student t-test and Fisher's Exact Test were respectively conducted for continuous variables and categorical variables to evaluate their differences between patients with MMI and those with NACI. Binary logistic regression was further conducted to verify the association of differentially expressed cytokines with MMI. RESULTS: The concentrations of 320 unique inflammatory cytokines in serums were measured. Ten cytokines were discovered to be differentially expressed between patients with MMI and patients with NACI, including transforming growth factor beta-1 (TGFB1), matrix metallopeptidase 10 (MMP10), neural cell adhesion molecule 1 (NCAM1), interleukin-27 (IL27), epidermal growth factor (EGF), insulin-like growth factor-binding protein 6 (IGFBP6), platelet-derived growth factor subunit A (PDGFA), C-C motif chemokine 2 (C-C CCL2), neutrophil gelatinase-associated lipocalin (Lipocalin 2) and lymphatic vessel endothelial hyaluronic acid receptor 1 (LYVE1). Among these cytokines, the concentrations of NCAM1, IGFBP6, Lipocalin2 and LYVE1 were significantly higher while the concentrations of the other six cytokines were significantly lower in patients with MMI compared with those in patients with NACI. Multivariate logistic regression analysis verified the association of these 10 cytokines with MMI except for IL-27 (p = 0.5422). CONCLUSIONS: Nine cytokines, including NCAM1, IGFBP6, Lipocalin2, LYVE1, TGFB1, MMP10, EGF, PDGFA and CCL2, might act as potential markers for early prediction of MMI and involve in the progression from NACI to MMI. Further studies with a better control group are still needed.

Apobec-1 increases cyclooxygenase-2 and aggravates injury in oxygen-deprived neurogenic cells and middle cerebral artery occlusion rats.

Given that cyclooxygenase-2 (COX-2) plays a crucial role during cerebral ischemia and Apobec-1 is a critical regulator of COX-2 mRNA stabilization in gastrointestinal settings, the correlation of COX-2 and Apobec-1 was investigated in neurogenic cells and rat model of cerebral ischemia. After neurogenic SH-SY5Y, NG108-15 and PC12 cells were exposed to oxygen-glucose deprivation, cell viability, LDH leakage and Apobec-1 expression were determined. The effect of Apobec-1 overexpression on injury severity of oxygen-glucose deprivation, COX-2 expression, C-to-U editing of COX-2 mRNA were measured in vitro. Then the correlation of Apobec-1 level and injury severity was analyzed in cells with oxygen-glucose deprivation and in rats with middle cerebral artery occlusion. Apobec-1 expression was elevated along with upregulation of COX-2 and injury severity of oxygen-glucose deprivation in the three cell lines. Apobec-1 overexpression aggravated injury of oxygen-glucose deprivation in vitro and could be correlated to injury severity in vivo. Meanwhile, Apobec-1 increased COX-2 expression and COX-2 mRNA stabilization in neurogenic cells, and failed to catalyze C-to-U editing of COX-2 mRNA. Apobec-1 could upregulate COX-2 expression in neurogenic cells by stabilizing COX-2 mRNA, and might aggravate injury of oxygen-glucose deprivation in neurogenic cells as well as in rats with cerebral ischemia.

Contribution of brain-derived neurotrophic factor to mechanical hyperalgesia induced by ventral root transection in rats.

It is generally believed that the development of neuropathic pain primarily results from injuries to sensory afferent fibers. Recent studies found that injuries to the motor efferent fibers (e.g. ventral root transection) also contribute to the development of neuropathic pain. Furthermore, an increase in brain-derived neurotrophic factor (BDNF) synthesis has been found in the ventral root transection model, suggesting a possible role of BDNF in this model. To determine the role of BDNF, we observed the effects of intrathecal antibody against BDNF treatment on ventral root transection-induced mechanical hyperalgesia. Paw withdrawal thresholds to mechanical stimuli were measured before and after surgery. The results showed that ventral root transection in rats produced a significant, lasting decrease of mechanical withdrawal thresholds, presenting the development of mechanical hyperalgesia. Intrathecal antibody against BDNF treatment markedly inhibited ventral root transection-induced mechanical hyperalgesia in a dose-related manner. The findings suggest that BDNF-mediated signaling pathway within spinal cord may be involved in the development of neuropathic pain involving injuries to motor efferent fibers.

The role of capsaicin-sensitive primary afferents in experimental sciatica induced by disc herniation in rats.

STUDY DESIGN: The topical capsaicin treatment of the sciatic nerve, which was proved to destroy capsaicin-sensitive primary afferent (CSPA) fibers, was performed to determine the effect on decreases in paw withdrawal mechanical threshold (PWMT) and changes in spatial expression pattern of spinal c-Fos protein induced by the direct compression of L5 nerve root with autologous disc. OBJECTIVE: To investigate the role of CSPA fibers in the development of mechanical hyperalgesia in the new sciatica model. SUMMARY OF BACKGROUND DATA: To date, CSPA fibers have been shown to be involved in development of thermal hyperalgesia in various pain models. But the controversy still exists as to whether CSPA fibers are involved in the development of mechanical hyperalgesia in different pain models. To our best knowledge, the role of CSPA in sciatica was not investigated. Therefore, the present study was designed to determine the role of CSPA fibers in the newly developed sciatica model. METHODS: All surgeries were performed in Sprague-Dawley rats. PWMT was measured at the different time points postsurgery and presurgery. The changes in spatial expression pattern of c-Fos protein in the spinal cord were also determined at 3 weeks when PWMT decreased to the peak. RESULTS: The pretreatment with capsaicin produced a complete prevention of mechanical hyperalgesia induced by disc compression. The direct compression of L5 nerve root produced an obvious expression of Fos-like immunoreactivity neurons in the dorsal horn of the spinal cord, which was significantly decreased by pretreatment with capsaicin. CONCLUSION: We conclude that CSPA fibers, which mainly terminated in superficial layers of dorsal horn, may play a key role in mechanical hyperalgesia in the new sciatica model.

Peripheral involvement of PKA and PKC in subcutaneous bee venom-induced persistent nociception, mechanical hyperalgesia, and inflammation in rats.

The roles of central protein kinases A and C (PKA and PKC) in various pain states have intensively been investigated during the past decade. The aim of the present study was to investigate the peripheral involvement of PKA and PKC in persistent nociceptive response, evoked pain behaviors, and inflammation induced by subcutaneous (s.c.) injection of bee venom (BV, 0.2mg/50 microl) in rats. The effects of intraplantar injection of H-89 (a PKA inhibitor, 5-100 microg/50 microl) and chelerythrine chloride (a PKC inhibitor, 5-100 microg/50 microl) on BV-elicited persistent nociception (nociceptive flinching reflex), mechanical hyperalgesia, and inflammation were systematically investigated. Pre-treatment with H-89 dose-dependently inhibited only BV-induced mechanical hyperalgesia, but not the persistent nociception and inflammation. In contrast, pre-treatment with chelerythrine chloride dose-dependently inhibited BV-induced sustained nociception and inflammation, but not the mechanical hyperalgesia. Topical pre-treatment of the sciatic nerve with 1% capsaicin significantly blocked the inhibitory effects of the PKC inhibitor on BV-induced inflammation, but not the persistent flinching response. These results indicate that peripheral PKA and PKC involvements in BV-induced pain behaviors differ, and capsaicin-sensitive afferents appear to participate in the pro-inflammatory role of PKC in the BV pain model. Findings from the present study also suggest that targeting specific peripheral protein kinases might prove effective in the treatment of persistent pain and inflammation.

Chronic inflammation and compression of the dorsal root contribute to sciatica induced by the intervertebral disc herniation in rats.

The pathophysiological mechanisms underlying sciatica and back pain are not well understood. In the present study, a sciatica model was developed to investigate the contributions of inflammation and compression of the dorsal root (DR). The procedure used autologous disc to apply direct pressure to the L5 DR (disc compression, DC group). For control, five additional groups were included: (1). mechanical compression of L5 DR without disc (compression, CP group); (2). epidurally placed disc without mechanical compression (disc group); (3). epidurally placed nucleus pulposus (NP) without mechanical compression (NP group); (4). epidurally placed annulus fibrosus (AF) without mechanical compression (AF group) and (5). sham group. The paw withdrawal latency to heat stimulation, paw withdrawal threshold to mechanical stimulation, body weight, and motor function were determined pre- and post-surgery. It was observed that all experimental groups with the exception of the sham group showed a progressive and prolonged mechanical hyperalgesia with the DC group having the strongest effect. Furthermore, the disc group showed a greater mechanical hyperalgesia with earlier onset in comparison with the CP group and disc, AF, and NP groups developed thermal hyperalgesia in addition to mechanical hyperalgesia following surgery. Finally, rats in all groups showed normal motor function and body weight increase. These data suggest that this model is suitable to investigate the mechanisms of sciatica and inflammation as well as mechanical compression is involved in the pathogenesis of this condition. Moreover, AF and NP may contribute similarly to the development of sciatica and back pain.