Neuroreport
-
Our assumption that blood pressure (BP) in supratentorial hypertensive intracerebral hemorrhage patients does not differ significantly according to the hemispheric laterality has never been verified before. This study was carried out to explore the possibility of hemispheric BP differences and whether this might influence the outcomes. A review of the charts/radiographic images of 281 patients with putaminal/thalamic hemorrhages diagnosed within 6 h of symptom onset was performed. ⋯ Multivariate regression analysis showed that patients with SBPs of at least 220 mmHg were 2.9 times more likely to harbor left-sided hemorrhages. There were no significant intergroup differences in responsiveness to a continuous intravenous nicardipine infusion or 30-day mortality rates. Although the differences in BPs are unlikely to have influenced outcomes, future trials involving supratentorial hypertensive intracerebral hemorrhages may benefit from considering hemispheric differences in BP and other demographic variables.
-
Recent studies on cerebrospinal fluid (CSF) homeostasis emphasize the importance of water flux through the pericapillary (Virchow-Robin) space for both CSF production and reabsorption (Oreskovic and Klarica hypothesis), and challenge the classic CSF circulation theory, which proposes that CSF is primarily produced by the choroid plexus and reabsorbed by the arachnoid villi. Active suppression of aquaporin-1 (AQP-1) expression within brain capillaries and preservation of AQP-1 within the choroid plexus together with pericapillary water regulation by AQP-4 provide a unique opportunity for testing this recent hypothesis. We investigated water flux into three representative regions of the brain, namely, the cortex, basal ganglia, and third ventricle using a newly developed water molecular MRI technique based on JJ vicinal coupling between O and adjacent protons and water molecule proton exchanges (JJVCPE imaging) in AQP-1 and AQP-4 knockout mice in vivo. The results clearly indicate that water influx into the CSF is regulated by AQP-4, and not by AQP-1, strongly supporting the Oreskovic and Klarica hypothesis.
-
Transient global ischemia induces selective hippocampal pyramidal neuronal death. Under conditions of severe ischemic hypoxia, hypoxia-inducible factor-1α (HIF-1α) induces apoptosis. Exendin-4 (Ex-4), the glucagon-like peptide-1 receptor (GLP-1R) agonist, provides neuroprotection against brain damage after cerebral ischemia. ⋯ These in-vivo results were confirmed in vitro in SH-SY5Y cells and primary cortical neurons treated with 100 nM of Ex-4 under hypoxic conditions (0.1%>O2). We found that Ex-4 decreased the HIF-1α expression in the SH-SY5Y cell line and primary cortical neurons under hypoxic conditions, and this effect was reversed by cotreatment with exendin (9-39), a GLP-1R antagonist. These results suggest that HIF-1α may be involved in the neuroprotective effect of Ex-4 in the hypoxia-damaged brain.
-
Intrastriatal transplantation of dopamine (DA) neurons can restore DA levels in the striatum and improve parkinsonian deficits in experimental studies. However, the mechanisms underlying these effects are poorly understood. Corticostriatal synaptic plasticity represents an important cellular mechanism for information storage and behavioural learning in the brain. ⋯ In turn, malfunctioning synaptic plasticity is associated with motor deficits that resemble features of PD. It is yet unknown whether or not transplanted dopaminergic neurons can restore these striatal deficits in PD. Could this be the mechanism underlying the therapeutic effects of transplants? Recent studies have begun to shed light on this matter using different approaches.
-
Randomized Controlled Trial
Motor cortex-induced plasticity by noninvasive brain stimulation: a comparison between transcranial direct current stimulation and transcranial magnetic stimulation.
The aim of this study was to test and compare the effects of a within-subject design of repetitive transcranial magnetic stimulation (rTMS) [coupled with sham transcranial direct current stimulation (tDCS)] and tDCS (coupled with sham rTMS) on the motor cortex excitability and also compare the results against sham tDCS/sham rTMS. We conducted a double-blinded, randomized, sham-controlled, cross-over trial. Eleven right-handed, healthy individuals (five women, mean age: 39.8 years, SD 13.4) received the three interventions (cross-over design) in a randomized order: (a) high-frequency (HF) rTMS (+sham tDCS), (b) anodal tDCS (+sham rTMS), and (c) sham stimulation (sham rTMS+sham tDCS). ⋯ In conclusion, here, we showed that although both techniques induced similar motor gains, they induce opposing results in cortical excitability. HF rTMS is associated with an increase in corticospinal excitability, whereas 20 min of tDCS induces the opposite effect. We discuss potential implications of these results to future clinical experiments using rTMS or tDCS for motor function enhancement.