NR2B-Tyr phosphorylation regulates synaptic plasticity in central sensitization in a chronic migraine rat model.

BACKGROUND: Although the mechanism of chronic migraine (CM) is unclear, it might be related to central sensitization and neuronal persistent hyperexcitability. The tyrosine phosphorylation of NR2B (NR2B-pTyr) reportedly contributes to the development of central sensitization and persistent pain in the spinal cord. Central sensitization is thought to be associated with an increase in synaptic efficiency, but the mechanism through which NR2B-pTyr regulates synaptic participation in CM-related central sensitization is unknown. In this study, we aim to investigate the role of NR2B-pTyr in regulating synaptic plasticity in CM-related central sensitization. METHODS: Male Sprague-Dawley rats were subjected to seven inflammatory soup (IS) injections to model recurrent trigeminovascular or dural nociceptor activation, which is assumed to occur in patients with CM. We used the von Frey test to detect changes in mechanical withdrawal thresholds, and western blotting and immunofluorescence staining assays were performed to detect the expression of NR2B-pTyr in the trigeminal nucleus caudalis (TNC). NR2B-pTyr was blocked with the Src family kinase inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)-pyrazolo [3,4-d] pyrimidine (PP2) and the protein tyrosine kinase inhibitor genistein to detected the changes in calcitonin gene-related peptide (CGRP), substance P (SP), and the synaptic proteins postsynaptic density 95 (PSD95), synaptophysin (Syp), synaptotagmin1 (Syt-1). The synaptic ultrastructures were observed by transmission electron microscopy (TEM), and the dendritic architecture of TNC neurons was observed by Golgi-Cox staining. RESULTS: Statistical analyses revealed that repeated infusions of IS induced mechanical allodynia and significantly increased the expression of NR2B Tyr-1472 phosphorylation (pNR2B-Y1472) and NR2B Tyr-1252 phosphorylation (pNR2B-Y1252) in the TNC. Furthermore, the inhibition of NR2B-pTyr by PP2 and genistein relieved allodynia and reduced the expression of CGRP, SP, PSD95, Syp and Syt-1 and synaptic transmission. CONCLUSIONS: These data indicate that NR2B-pTyr might regulate synaptic plasticity in central sensitization in a CM rat model. The inhibition of NR2B tyrosine phosphorylation has a protective effect on threshold dysfunction and migraine attacks through the regulation of synaptic plasticity in central sensitization.

Upregulation of silent information regulator 1 alleviates mitochondrial dysfunction in the trigeminal nucleus caudalis in a rat model of chronic migraine.

Although the mechanism of chronic migraine is still unclear, more and more studies have shown that mitochondrial dysfunction plays a possible role in migraine pathophysiology. Silent information regulator 1 (SIRT1) plays a vital role in mitochondrial dysfunction in many diseases. However, there is no research on the role of SIRT1 in mitochondrial dysfunction of chronic migraine. The aim of this study was to explore the role of SIRT1 in mitochondrial dysfunction in chronic migraine. A rat model was established through repeated dural infusions of inflammatory soup for 7 days to simulate chronic migraine attacks. Cutaneous hyperalgesia caused by the repeated infusions of inflammatory soup was detected using the von Frey test. Then, we detected SIRT1 expression in the trigeminal nucleus caudalis. To explore the effect of SIRT1 on mitochondrial dysfunction in chronic migraine rats, we examined whether SRT1720, an activator of SIRT1, altered mitochondrial dysfunction in chronic migraine rats. Repeated infusions of inflammatory soup resulted in cutaneous hyperalgesia accompanied by downregulation of SIRT1. SRT1720 significantly alleviated the cutaneous hyperalgesia induced by repeated infusions of inflammatory soup. Furthermore, activation of SIRT1 markedly increased the expression of peroxisome proliferator-activated receptor gamma-coactivator 1-alpha, transcription factor A, nuclear respiratory factor 1 and nuclear respiratory factor 2 mitochondrial DNA and increased the ATP content and mitochondrial membrane potential. Our results indicate that SIRT1 may have an effect on mitochondrial dysfunction in chronic migraine rats. Activation of SIRT1 has a protective effect on mitochondrial function in chronic migraine rats.

[Most effective daily dose and use method of mannitol in patients with cerebral hemorrhage at acute stage].

OBJECTIVE: To explore the most effective daily dose and use method of mannitol in reducing intracranial pressure in patients with cerebral hemorrhage in acute stage. METHODS: One hundred and eighteen cerebral hemorrhage patients with elevated intracranial pressure, 74 males and 44 females, aged (58 +/- 11) (33-80), that had undergone cranial CT scanning to calculate the volume of hemorrhage, were divided into 4 groups treated with 20% mannitol 125 ml: 32 cases treated q 4 h, 35 cases treated q 6 h, 25 cases treated q 8 h, and 26 cases treated q 12 h. The everyday doses of mannitol were recorded. Intracranial pressure was monitored daily by NIP-200 noninvasive intracranial pressure apparatus. The difference between the very day and that of the last day (effect of decreasing intracranial pressure per day) was calculated. Multivariate regression analysis was conducted. RESULTS: The average saturation dosage of mannitol was 750-6000 (3504 +/- 1085) ml, the time from the hospitalization till the saturation dosage was 1-8 (4.5 +/- 1.5) d. The average intracranial pressure at admission was 330-698 (486 +/- 93) mm H2O, the average intracranial pressure when mannitol reached the saturation dosage was 160-378 (253 +/- 52) mm H2O. The effect of reduction of intracranial pressure was not associated with age (P > 0.05). The effects of reducing intracranial pressure in the 1st, 2nd, 3rd, and 4th day were associated with the volume of hematoma and mannitol doses (all P < 0.01). Best effects of reducing the intracranial pressure in the 1st, 2nd, 3rd, and 4th day could be reached when 20% mannitol 125 ml was used every 4 hours. CONCLUSIONS: Mannitol use every 4 hours per day has evident effect of reducing the intracranial pressure in the 1st, 2nd, 3rd, and 4th day, then mannitol should be used temporarily according to the intracranial pressure after the 5th day. Mannitol should not be used for more than 8 days.

Expression of ASIC3 in the Trigeminal Nucleus Caudalis Plays a Role in a Rat Model of Recurrent Migraine.

Acid-sensing ion channel 3 (ASIC3) is abundant in the trigeminal nervous system and is most sensitive to a slight pH decrease. Recent studies have indicated that ASIC3 in the peripheral trigeminal ganglia is likely involved in the pathogenesis of migraine pain. However, it is unclear whether this receptor plays a role in recurrent migraine, namely, migraine chronicity. Here, we aimed to investigate the role of ASIC3 in an animal model of recurrent migraine (RM). In this study, we established a rat model of RM through repeated administration of inflammatory soup (IS) onto the dura. Then, we tested the mechanical pain thresholds of the face and hindpaws by von Frey filaments. qRT-PCR, Western blot and immunofluorescence labelling were used to detect the expression and localization of ASIC3 in the trigeminal nucleus caudalis (TNC). The protein levels of calcitonin gene-related peptide (CGRP), its receptor component receptor activity modifying protein 1 (RAMP1) and c-Fos were analysed following treatment with the ASIC3 inhibitor APETx2 and activator 2-guanidine-4-methylquinazoline (GMQ). We found decreased pain thresholds after repeated dural inflammatory stimulation, which suggested the establishment of an RM model. Based on this model, we observed elevated expression of ASIC3 in the TNC group compared to that in the Sham group. ASIC3 was primarily expressed in neurons but not in astrocytes of the TNC. Moreover, APETx2 attenuated tactile allodynia and significantly decreased the expression of c-Fos, CGRP and RAMP1, while GMQ aggravated these effects compared to those observed in the IS + vehicle group. These findings indicate a critical role of ASIC3 channels in the pathophysiology of RM, and ASIC3 might represent a potential therapeutic target to prevent the progression of migraine.

Neuroprotective effects of tetrandrine against vascular dementia.

Tetrandrine is one of the major active ingredients in Menispermaceae Stephania tetrandra S. Moore, and has specific therapeutic effects in ischemic cerebrovascular disease. Its use in vascular dementia has not been studied fully. Here, we investigated whether tetrandrine would improve behavioral and cellular impairments in a two-vessel occlusion rat model of chronic vascular dementia. Eight weeks after model establishment, rats were injected intraperitoneally with 10 or 30 mg/kg tetrandrine every other day for 4 weeks. Behavioral assessment in the Morris water maze showed that model rats had longer escape latencies in training trials, and spent less time swimming in the target quadrant in probe trials, than sham-operated rats. However, rats that had received tetrandrine showed shorter escape latencies and longer target quadrant swimming time than untreated model rats. Hematoxylin-eosin and Nissl staining revealed less neuronal necrosis and pathological damage, and more living cells, in the hippocampus of rats treated with tetrandrine than in untreated model rats. Western blot assay showed that interleukin-1ß expression, and phosphorylation of the N-methyl-D-aspartate 2B receptor at tyrosine 1472, were lower in model rats that received tetrandrine than in those that did not. The present findings suggest that tetrandrine may be neuroprotective in chronic vascular dementia by reducing interleukin-1ß expression, N-methyl-D-aspartate receptor 2B phosphorylation at tyrosine 1472, and neuronal necrosis.

[The influence of induced hypertension in acute phase on focal cerebral ischemia injury].

OBJECTIVE: To study the influence of induced hypertension in acute phase on the infarct volume and regional cerebral blood flow (rCBF) during focal cerebral ischemia in rats. METHODS: The adult rat's models of permanent focal cerebral ischemia were established by permanent middle artery occlusion. Thirty-six rats were divided six groups. The rCBF of cortical penumbra during focal cerebral ischemia was determined by Laser-Doppler Flowmetry. After experiment was over, the brain was TTC stained and the infarct volume was calculated by computer image analytic system. RESULTS: The rCBF was resumed by (81.8 +/- 3.1)%, (56.0 +/- 2.1) and (38.8 +/- 2.0)% in induced hypertension groups compared with the basic rCBF. The volume of infarction was (14 +/- 7) mm(3), (90 +/- 24) mm(3) separately in group induced hypertension after 2 and 3 hour ischemia. Induced hypertension during 3 hours could reduce infarct volume significantly. CONCLUSION: To improve rCBF in penumbra may be one of protective mechanism of induced hypertension on brain ischemia.

[Matrix metalloproteinase-9 expression by endothelial cells incubated with peripheral blood leukocytes from patients with cerebral infarction].

OBJECTIVE: Matrix metalloproteinase-9 (MMP-9) have been implicatedin the development of cerebral infarction. In a prospective study we investigated whether the MMP-9 expression are increased by endothelial cells incubated with peripheral blood Leukocytes from patients with acute cerebral infarctions. METHODS: Using Immuno-fluorescence technique, Human umbilical vein endothelial cells were cocultured with leucocytes for 24 hours in vitro before used for detecting the MMP-9 expression. The leucocytes were purified from peripheral blood in 6 patients with acute cerebral infarction and in 6 age- and sex-matched healthy subjects. the smears of endothelial cells were stained with MMP-9 monoclonal antibodies, and detected using the ABC ELITE kit. RESULTS: Laser-Confocus confirmed the presence of MMP-9 within endothelial cells incubated with peripheral blood Leukocytes from patients with acute cerebral infarctions. Compared with the control group, MMP-9 expressions were significantly higher in the stroke group (P < 0.001). CONCLUSION: Our study demonstrated that the leukocytes from acute cerebral infarction patients were Activated, and could stimulate vessel endothelial cells excrete MMP-9. Activated leukocytes and MMP-9 expression by endothelial cells may have an important role in acute cerebrovascular ischemia and its consequences.

Clinical characteristics and the diagnosis and treatment status of headaches in the Department of Gerontology of a university hospital in China.

Headache is a common problem among the population, many factors may impact the headache characteristics and medical consultation behaviors in different age groups. The purpose of this study was to evaluate the clinical characteristics and the diagnosis and treatment status of headaches in elderly patients hospitalized in a gerontologic department. Consecutive patients hospitalized in the Department of Gerontology eligible for this study were registered. All the patients underwent a comprehensive evaluation of their whole health status, performed by three gerontologists initially. Then headache was evaluated by two physicians experienced in headache studies. Headache diagnosis was made according to the criteria of the second edition of the International Classification of Headache Disorders. In this study, 20% of the participants reported at least one headache attack in the previous year. Sixty percent of the migraineurs and 79·7% of the tension type headache (TTH) patients reported bilateral pain. Throbbing/pulsating and tightness/pressing were the most frequently described pain quality by the migraineurs and TTH patients, respectively. The migraineurs reported the most severe pain (P < 0·001). The frequency of headache attacks was not significantly different in the three subgroups (P  =  0·053). About 76·2% of the migraineurs, 68·8% of the TTH, and 80% of the other type headache patients had consulted a physician for their headaches in the previous year. Taking acute analgesics for headache was more common in migraineurs (P < 0·001). The results showed that headache remained under-recognized and under-treated in the geriatrics department.