Changes of c-fos, malondialdehyde and lactate in brain tissue after global cerebral ischemia under different brain temperatures

MiR-100-5p-rich small extracellular vesicles from activated neuron to aggravate microglial activation and neuronal activity after stroke

Ischemic stroke is a common cause of mortality and severe disability in human and currently lacks effective treatment. Neuronal activation and neuroinflammation are the major two causes of neuronal damage. However, little is known about the connection of these two phenomena. This study uses middle cerebral artery occlusion mouse model and chemogenetic techniques to study the underlying mechanisms of neuronal excitotoxicity and severe neuroinflammation after ischemic stroke. Chemogenetic inhibition of neuronal activity in ipsilesional M1 alleviates infarct area and neuroinflammation, and improves motor recovery in ischemia mice. This study identifies that ischemic challenge triggers neuron to produce unique small extracellular vesicles (EVs) to aberrantly activate adjacent neurons which enlarge the neuron damage range. Importantly, these EVs also drive microglia activation to exacerbate neuroinflammation. Mechanistically, EVs from ischemia-evoked neuronal activity induce neuronal apoptosis and innate immune responses by transferring higher miR-100-5p to adjacent neuron and microglia. MiR-100-5p can bind to and activate TLR7 through U18U19G20-motif, thereby activating NF-κB pathway. Furthermore, knock-down of miR-100-5p expression improves poststroke outcomes in mice. Taken together, this study suggests that the combination of inhibiting aberrant neuronal activity and the secretion of specific EVs-miRNAs may serve as novel methods for stroke treatment.

Role of pERK1/2-NFκB signaling in the neuroprotective effect of thalidomide against cerebral ischemia reperfusion injury in rats

In the present investigation, we tested the hypothesis that suppression of the phospho-extracellular signal regulated kinase (pERK1/2)-nuclear factor kappa (NFκ)-B signaling, subsequent to tumor necrosis factor-α (TNF-α) inhibition, underlies thalidomide (TLM) mediated neuroprotection. Male Wistar rats (250-280 g) were divided into five groups: (1) sham; (2) negative control receiving TLM (5μg/1μl/site) and 3 groups of ischemia-reperfusion (IR) injury rats pretreated with: (3) vehicle (DMSO 100%); (4) TLM (5μg/1μl/site) or (5) PD98059 (0.16μg/1μl/site). IR rats were subjected to occlusion of both common carotid arteries for 45 min followed by reperfusion for 24 h. Drugs and/or vehicles were administered by unilateral intrahippocampal injection after removal of the carotid occlusion and at the beginning of the reperfusion period. IR rats exhibited significant infarct size, histopathological damage, memory impairment, motor incoordination and hyperactivity. Unilateral intra-hippocampal TLM ameliorated these behavioral deficits along with the following ex vivo hippocampal effects: (i) abrogation of the IR-evoked elevations in hippocampal TNF-α, pERK1/2, NFκB, BDNF, iNOS contents and (ii) partial restoration of the reduced anti-inflammatory cytokine IL-10 and p-nNOS S852. These neurochemical effects, which were replicated by the pERK1/2 inhibitor PD98059, likely underlie the reductions in c-Fos and caspase-3 levels as well as the anti-apoptotic effect of TLM in the IR model. These results suggest a crucial anti-inflammatory role for pERK1/2 inhibition in the salutary neuronal and behavioral effects of TLM in a model of brain IR injury.

The Ying and Yang of Adenosine A1 and A2A Receptors on ERK1/2 Activation in a Rat Model of Global Cerebral Ischemia Reperfusion Injury

Adenosine impacts cerebral ischemia reperfusion (IR) through the inhibitory A₁ and the excitatory A₂ receptors. The present study aimed at investigating the contrasting role of pERK1/2 in mediating adenosine A₁R (protective) versus A_2AR (deleterious) effects in IR. Male Wistar rats subjected to bilateral carotid occlusion (45 min) followed by reperfusion (24 h) exhibited increased pERK1/2 activity, downstream from DAG pathway, along with increases in hippocampal glutamate, c-Fos, NF-κB, TNF-α, iNOS, TBARS, cytochrome c, caspase-3, BDNF, Nrf2, and IL-10 contents. Further, hippocampal microglial reactivity, glial TNF-α, and BDNF expression were observed. Although unilateral intrahippocampal injection of either the A₁R agonist CHA or the A_2AR agonist CGS21680 increased pERK1/2, only CHA mitigated histopathological and behavioral deficits along with reducing glutamate, microglial activation, c-Fos, TNF-α, iNOS, TBARS, cytochrome c and caspase-3 and elevating Nrf2 and IL-10 levels in IR rats. These results yield insight into the double-faceted nature of pERK1/2 in mediating protective and deleterious effects of A₁R and A_2AR signaling, respectively, against IR injury.

Serum C-reactive protein, fibrinogen and D-dimer in patients with progressive cerebral infarction

OBJECTIVE

Progressive cerebral infarctions increase mortality and functional disability through mechanisms which have yet to be completely understood. The goal of this study was to explore the dynamic changes of serum C-reactive protein (CRP), fibrinogen (FIB) and D-dimer (D-D) in order to better characterize progressive cerebral infarction.

METHODS

The amount of serum CRP, FIB and D-D was measured in 82 patients with progressive cerebral infarction by taking samples from the internal carotid artery (progressive group), and in 186 patients with non-progressive cerebral infarction (non-progressive group) by using an automatic biochemical analyzer during the next day (day 1), day 3, day 7, and day 14 after being admitted to hospital. Carotid vascular ultrasound and neurological deficit score (National Institutes of Health Stroke Scale, NIHSS) were also recorded.

RESULTS

Carotid stenosis ratio was significantly higher in the progressive group than in the non-progressive group (P < 0.01) on admission. In the progressive group, CRP increased significantly on day 3, followed by a decline on day 7 and day 14, but was significantly higher than those in the non-progressive group (P < 0.01). The levels of FIB and D-D increased in the progressive group more than those in the non-progressive group on day 3, day 7, and day 14 (P < 0.01). The progressive group patients' NIHSS score gradually increased after admission, which was opposite to the non-progressive group patients whom followed a downward trend. The difference between these two groups was significant (P < 0.01).

CONCLUSION

Observing changes of CRP, FIB and D-D may contribute to early identification and timely treatment of progressing ischemic strokes.

Role of adenosine A2A receptor in cerebral ischemia reperfusion injury: Signaling to phosphorylated extracellular signal-regulated protein kinase (pERK1/2)

Following brain ischemia reperfusion (IR), the dramatic increase in adenosine activates A2AR to induce further neuronal damage. Noteworthy, A2A antagonists have proven efficacious in halting IR injury, however, the detailed downstream signaling remains elusive. To this end, the present study aimed to investigate the possible involvement of phospho-extracellular signal-regulated kinase (pERK1/2) pathway in mediating protection afforded by the central A2A blockade. Male Wistar rats (250-270 g) subjected to bilateral carotid occlusion for 45 min followed by a 24-h reperfusion period showed increased infarct size corroborating histopathological damage, memory impairment and motor incoordination as well as increased locomotor activity. Those events were mitigated by the unilateral intrahippocampal administration of the selective A2A antagonist SCH58261 via a decrease in pERK1/2 downstream from diacyl glycerol (DAG) signaling. Consequent to pERK1/2 inhibition, reduced hippocampal microglial activation, glial tumor necrosis factor-alpha (TNF-α) and brain-derived neurotropic factor (BDNF) expression, glutamate (Glu), inducible nitric oxide synthase (iNOS) and thiobarbituric acid reactive substances (TBARS) were evident in animals receiving SCH58261. Additionally, the anti-inflammatory cytokine interleukin-10 (IL-10) increased following nuclear factor (erythroid-derived 2)-like 2 (Nrf-2). Taken all together, these events suppressed apoptotic pathways via a reduction in cytochrome c (Cyt. c) as well as caspase-3 supporting a crucial role for pERK1/2 inhibition in consequent reduction of inflammatory and excitotoxic cascades as well as correction of the redox imbalance.

Psychological distress, social support and medication adherence in patients with ischemic stroke in the mainland of China

Stroke research and rehabilitation have traditionally focused on the physical and functional impact of a stroke. Less attention has been given to the psychosocial factors associated with this chronic condition. By the few studies that have specifically focused on psychosocial factors in the context of stroke, poststroke depression is demonstrated to significantly influence stroke outcomes. Associations of stroke with psychological symptoms other than depression have rarely been evaluated. This study was aimed to investigate the changes of psychological stress, social support and medication adherence in patients with ischemic stroke in the mainland of China. In this study, 90 patients with hemiplegia one year after first-ever middle cerebral artery infarction (stroke group) in the Zhongnan Hospital of Wuhan University from June 2008 to June 2011 were recruited for interview. Ninety age- and sex-matched normal volunteers (control group) were also examined at the same period. The psychological distress was assessed by the Symptom Checklist 90 (SCL-90), the social support by the Social Support Rating Scale (SSRS), and medication adherence by Morisky's self-reported inventory, respectively. Group differences were analyzed using unpaired-t test and chi-squared test. The results showed that total mean scores of the SCL-90 in the stroke group were higher than those in the control group (P<0.01). Except two dimensions, paranoid ideation and psychoticism, mean scores of the rest dimensions (including somatization, obsession-compulsion, interpersonal sensitivity, depression, anxiety, hostility, and phobic anxiety) of SCL-90 were significantly higher in the stroke group than those in the control group (P<0.05, or P<0.01). The objective support, subjective support, support availability and total social support scores in the stroke group were significantly higher than those in the control group (P<0.05, or P<0.01). Those in the "SCL-90 total scores >150 group" were significantly higher than in the "SCL-90 total scores <100 group" and the "SCL-90 total scores between 100 to 150 group" (P<0.05, or P<0.01). Those in the "SCL-90 total scores between 100 to 150 group" were significantly higher than in the "SCL-90 total scores <100 group" (P<0.05). In 90 patients with ischemic stroke, 26 (28.89%) patients obtained high medication adherence, 47 (52.22%) patients medium medication adherence, and 17 (18.89%) patients low medication adherence, respectively. Among these stroke patients, there were 17 (50.00%) patients with high medication adherence in the "SCL-90 total scores >150 group", 28 (75.67%) patients with medium medication adherence in the "SCL-90 total scores between 100 to 150 group", and 12 (61.16%) patients with low medication adherence in the "SCL-90 total scores <100 group", respectively. There was significant difference in the medication adherence rate among the different SCL-90 scores groups in these stroke patients (P<0.05 or P<0.01). It was led to conclude that ischemic stroke patients one year after hemiplegia have psychological distress, low level of social support and poor medication adherence in the mainland of China. Therefore, it is necessary to mobilize the government, medical institutions and various social support groups to offer psychological interventions to relieve the stress of patients with ischemic stroke, and improve their medication adherence.