Prevention and Intervention Studies with Telmisartan, Ramipril and Their Combination in Different Rat Stroke Models

The effects of AT1 receptor blocker, telmisartan, and the ACE inhibitor, ramipril, were tested head-to head and in combination on stroke prevention in hypertensive rats and on potential neuroprotection in acute cerebral ischemia in normotensive rats. Normotensive Wistar rats were treated s.c. 5 days prior to middle cerebral artery occlusion (MCAO) for 90 min with reperfusion. Groups (n = 10 each): (1) sham, (2) vehicle (V; 0,9% NaCl), (3) T (0,5 mg/kg once daily), (4) R (0,01 mg/kg twice daily), (5) R (0,1 mg/kg twice daily) or (6) T (0,5 mg/kg once daily) plus R (0,01 mg/kg twice daily). Twenty-four and 48 h after MCAO, neurological outcome (NO) was determined. Forty-eight h after MCAO, infarct volume by MRI, neuronal survival, inflammation factors and neurotrophin receptor (TrkB) were analysed.Stroke incidence was reduced, survival was prolonged and neurological outcome was improved in all treated SHR-SP with no differences between treated groups. In the acute intervention study, T and T+R, but not R alone, improved NO, reduced infarct volume, inflammation (TNFα), and induced TrkB receptor and neuronal survival in comparison to V.T, R or T+R had similar beneficial effects on stroke incidence and NO in hypertensive rats, confirming BP reduction as determinant factor in stroke prevention. In contrast, T and T+R provided superior neuroprotection in comparison to R alone in normotensive rats with induced cerebral ischemia

Candesartan but not ramipril pretreatment improves outcome after stroke and stimulates neurotrophin BNDF/TrkB system in rats

Parallele Umschlagtitel franz.-ital

Comparison between single and combined treatment with candesartan and pioglitazone following transient focal ischemia in rat brain

Angiotensin AT1 receptor blockers (ARBs) and thiazolidinediones (TZDs) have become well established drugs for the treatment of major risk factors of stroke. Since several studies provided evidence that ARBs and TZDs also have additional anti-inflammatory effects, we hypothesized that a combined treatment with the ARB, candesartan, and the TZD, pioglitazone, ameliorates ischemia-induced brain injury and inflammation by synergistic anti-inflammatory actions. Normotensive Wistar rats were pre-treated for 5 days with vehicle (0.9% NaCl), 0.2 mg/kg/day candesartan (s.c.), and/or 2 and/or 20 mg/kg/day pioglitazone (p.o.), respectively and underwent 90 min of middle cerebral artery occlusion (MCAO) with successive reperfusion. Neurological deficits and infarct size were determined 24 h and 48 h after MCAO, respectively, followed by tissue sampling. Animals treated with candesartan, pioglitazone, and the combination of candesartan and pioglitazone had reduced neurological deficits 24 h and 48 h after MCAO, respectively (P < 0.05–0.01). Infarct size was reduced by treatment of candesartan, pioglitazone, and their respective combination (each P < 0.05) 48 h after stroke compared to vehicle. Treatment with candesartan, pioglitazone, and their combination resulted in significantly reduced mRNA expression of the inflammatory markers CXCL1 and TNFα in vivo (P < 0.01). The combination of candesartan plus pioglitazone is equally effective compared to their single applications concerning neuroprotection and attenuation of inflammation after MCAO. Therefore, we conclude that a direct synergistic neuroprotective action of parallel ARB and TZD treatment is unlikely

Enhanced susceptibility to erythrocyte "apoptosis" following phosphate depletion.

Among the sequelae of phosphate depletion is anaemia, due in part to a decreased life span of mature erythrocytes. Recent studies have disclosed that cellular stress leads to an increase of cytosolic Ca(2+) activity in erythrocytes thereby triggering cell shrinkage and breakdown of phosphatidylserine asymmetry of the cell membrane, both typical features of apoptosis. In the present experiments, phosphatidylserine exposure and cell size were measured by fluorescence-activated cell sorting (FACS) analysis of annexin binding and forward scatter, respectively. Erythrocytes from intact mice were compared with erythrocytes from mice exposed to a low-phosphate diet for 4 days. Annexin binding of freshly drawn erythrocytes was slightly but significantly enhanced by the low-phosphate diet. Furthermore, intracellular phosphate and ATP concentrations were significantly decreased in those erythrocytes whereas intracellular Ca(2+) activity was unaltered. Osmotic shock (exposure to 700 mOsm by addition of sucrose for 12 h), removal of Cl(-) (replaced by gluconate for 15 h) or removal of glucose (12 h) decreased cell volume and increased the number of annexin-binding erythrocytes. Interestingly, these effects were significantly larger in erythrocytes from phosphate-depleted animals. The experiments reveal a novel mechanism triggered by phosphate depletion that presumably contributes to the enhanced vulnerability and accelerated sequestration of erythrocytes and, thus, to anaemia

The beta-lactam antibiotic, ceftriaxone, dramatically improves survival, increases glutamate uptake and induces neurotrophins in stroke

OBJECTIVE: Ceftriaxone has been reported to reduce neuronal damage in amyotrophic lateral sclerosis and in an in-vitro model of neuronal ischaemia through increased expression and activity of the glutamate transporter, GLT1. We tested the effects of ceftriaxone on mortality, neurological outcome, and infarct size in experimental stroke in rats and looked for underlying mechanisms. METHODS: Male normotensive Wistar rats received ceftriaxone (200 mg/kg intraperitoneal) as a single injection 90 min after middle cerebral artery occlusion (90 min with reperfusion). Forty-eight hours after middle cerebral artery occlusion, infarct size (MRI) and neurological deficits were estimated. GLT1 expression was determined by real time RT-PCR, immunoblotting and promoter reporter assay, astrocyte GLT1 activity by measuring glutamate uptake. Bacterial load in various organs was measured by real time RT-PCR, neurotrophins and IL-6 by immunoblotting. RESULTS: Ceftriaxone dramatically reduced early (24-h) mortality from 34.5% (vehicle treatment, n = 29) to 0% (P < 0.01, n = 19). In a subgroup, followed up for 4 weeks, mortality persisted at 0%. Ceftriaxone strongly tended to reduce infarct size, it significantly improved neuronal survival within the penumbra, reduced neurological deficits (P < 0.001) and led to an upregulation of neurotrophins (P < 0.01) in the peri-infarct zone. Ceftriaxone did not increase GLT1 expression, but increased GLT1 activity (P < 0.05). CONCLUSION: Ceftriaxone causes a significant reduction in acute stroke mortality in a poststroke treatment regimen in animal studies. Improved neurological performance and survival may be due to neuroprotection by activation of GLT1 and a stimulation of neurotrophins resulting in an increased number of surviving neurons in the penumbra