Acute effect of ethanol on firing patterns of Purkinje cells in the rat cerebellar slice preparation

This study examined the acute effects of ethanol (EtOH) on the firing patterns of Purkinje cells (PCs) using an intracellular recording in slice preparation of rat cerebellum. The experiments were performed in sagittal cerebellar slices (400 micrometer) of adult Sprague-Dawley rats (80-100g). Ethanol was applied by a bath superfusion with a known concentration expressed as the percentage of solution by volume (v/v) at 0.1, 0.5, 1, 2, and 4%. The result of the Chi-square test illustrated that the firing patterns were altered significantly after EtOH (p=0.007). However, the firing patterns that were altered by EtOH application were not affected by EtOH concentration (p= 0.1296). Among the 54 PCs tested, 30 PCs did not display any spontaneous firing activity and 24 PCs displayed spontaneous spike activity, either spiking in the simple manner (n=14) or cyclicly oscillating (n=10). In the presence of EtOH, 31 PCs were quiet, 22 PCs exhibited simple spiking activity and 1 PC continued to oscillate. Most PCs that displayed spontaneous activity before EtOH application progressively slowed their spike activity after EtOH superfusion. Especially, it was evident that 9 out of 10 oscillating PCs stopped their regular cyclic activity. In addition, 9 out of 14 PCs that displayed simple spike activity ceased to fire after EtOH application. Eleven out of 30 quiet PCs began to fire irregularly after EtOH application and this phenomenon usually occurred with membrane depolarization. EtOH induced spontaneous activity in 36.7% (11/30) of the quiescent PCs. In conclusion, there was differential EtOH sensitivity in the vitro slice preparation. EtOH depressed the endogenously generated spontaneous activity, especially the oscillatory firing activity. In contrast, the silent PCs were excited after EtOH application. Since this differential sensitivity persists in the presence of tetrodotoxin (TTX), it is suggested that this differential sensitivity is peculiar to the PCs.     

Effect of centrifugal force on cellular activity of osteoblastic MC3T3-E1 cells in vitro

The effects of centrifugal force on growth and differentiation of osteoblastic cells cultured in alpha-MEM containing 1% Fetal bovine serum were investigated by assays of DNA synthesis, alkaline phosphatase activity and osteocalcin-production in osteoblastic MC3T3-E1 cells. Centrifugation of the cells in low concentrations (1%) of fetal bovine serum caused a 1.9-fold increase of [3H]thymidine incorporation on day 3 from the start of centrifugation, and gradually decreased with culture up to day 9. Alkaline phosphatase activity was not affected by centrifugal force until day 5, and increased rapidly after day 7. Stimulation of DNA synthesis by centrifugation was abolished in the presence of H-7, an inhibitor of protein kinase C. These results suggest that centrifugal force stimulates the proliferation of osteoblastic cells through an autocrine secretion of some diffusable growth- promoting activity. Additional centrifugation of the cells also slightly stimulated alkaline phosphatase activity, although this did not directly influence the cell's osteocalcin-production activity.     

Radiographic and microsurgical characteristics of proximal (A1) segment aneurysms of the anterior cerebral artery

Background

Proximal A1 segment aneurysms of the anterior cerebral artery (ACA) radiologically resemble internal carotid artery bifurcation (ICBIF) aneurysms because of their anatomical proximity. However, proximal A1 aneurysms exhibit distinguishing features, relative to ICBIF aneurysms. We report our experience of managing proximal A1 aneurysms, then compare them to ICBIF aneurysms.

Methods

Among 2191 aneurysms treated between 2000 and 2016 in a single institution, we retrospectively reviewed 100 cases categorized as ICBIF or A1 aneurysms. We included aneurysms originating from the ICBIF and ACA, proximal to the anterior communicating artery (A1 segment) and divided them into two groups: proximal A1 (n?=?32) and ICBIF (n?=?50). If any portion of the aneurysm involved the ICBIF, it was classified as ICBIF. Aneurysms wholly located in the A1 segment were classified as proximal A1. Patient factors and angiographic factors were evaluated and compared.

Results

The proximal A1 group exhibited differences in aneurysm size (p?=?0.013), posterior aneurysm direction (p?=?0.001), and A1 perforators as incorporating vessels (p?=?0.001). The proximal A1 group tended to rupture more frequently when the aneurysm was smaller (p?=?0.046). One case of morbidity occurred in the proximal A1 group.

Conclusion

Compared to ICBIF aneurysms, proximal A1 aneurysms were smaller and directed posteriorly, with incorporating perforators. Because of these characteristics, it may be difficult to perform clipping with 360° view in microsurgical field. Therefore, when planning to treat proximal A1 aneurysms, different treatment strategies may be necessary, relative to those used for ICBIF aneurysms.

     

Acetylcholine precursor,citicoline (cytidine 5′‐diphosphocholine), reduces hypoglycaemia‐induced neuronal death in rats

Citicoline (cytidine 5′‐diphosphocholine) is an important precursor for the synthesis of neuronal plasma membrane phospholipids, mainly phosphatidylcholine. The administration of citicoline serves as a choline donor for the synthesis of acetylcholine. Citicoline has been shown to reduce the neuronal injury in animal models with cerebral ischaemia and in clinical trials of stroke patients. Citicoline is currently being investigated in a multicentre clinical trial. However, citicoline has not yet been examined the context of hypoglycaemia‐induced neuronal death. To clarify the therapeutic impact of citicoline in hypoglycaemia‐induced neuronal death, we used a rat model with insulin‐induced hypoglycaemia. Acute hypoglycaemia was induced by i.p. injection of regular insulin (10 U kg^‐1) after overnight fasting, after which iso‐electricity was maintained for 30 minutes. Citicoline injections (500 mg/kg, i.p.) were started immediately after glucose reperfusion. We found that post‐treatment of citicoline resulted in significantly reduced neuronal death, oxidative injury and microglial activation in the hippocampus compared to vehicle‐treated control groups at 7 days after induced hypoglycaemia. Citicoline administration after hypoglycaemia decreased immunoglobulin leakage via blood‐brain barrier disruption in the hippocampus compared to the vehicle group. Citicoline increased choline acetyltransferase expression for phosphatidylcholine synthesis after hypoglycaemia. Altogether, the present findings suggest that neuronal membrane stabilisation by citicoline administration can save neurones from the degeneration process after hypoglycaemia, as seen in several studies of ischaemia. Therefore, the results suggest that citicoline may have therapeutic potential to reduce hypoglycaemia‐induced neuronal death.