Prospective, randomized, blinded, and placebo-controlled study of Cerebrolysin dose-response effects on long-term functional outcomes in a rat model of mild traumatic brain injury.

Using a prospective, randomized, blinded, placebo-controlled protocol, the authors demonstrated that Cerebrolysin at doses of 0.8-7.5 ml/kg, administered 4 hours after injury and then once daily for a total of 10 consecutive days, improves long-term functional outcomes in a rat model of mild closed head injury; a 2.5-ml/kg dose was identified as optimal. These findings suggest that Cerebrolysin has the potential to treat mild traumatic brain injury, the incidence of which is high without effective treatments.

Angiogenesis and improved cerebral blood flow in the ischemic boundary area detected by MRI after administration of sildenafil to rats with embolic stroke.

To dynamically investigate the long-term response of an ischemic lesion in rat brain to the administration of sildenafil, male Wistar rats subjected to embolic stroke were treated with sildenafil (n=11) or saline (n=10) at a dose of 10 mg/kg administered subcutaneously 24-h after stroke and daily for an additional 6 days. Magnetic resonance images were acquired and functional performance was measured in all animals at 1 day, 2 days and weekly for 6 weeks post-stroke. All rats were sacrificed 6 weeks after stroke and endothelial barrier antigen immunostaining was employed for morphological analysis and quantification of cerebral vessels. Map-ISODATA was computed from T(1), T(2) and T(1sat) maps. ISODATA derived tissue signatures characterize the degree of ischemic injury. Based on the map-ISODATA calculated at 6 weeks, the ischemic lesion for each animal was divided into two specific regions, the ischemic boundary and ischemic core. The temporal profiles of cerebral blood flow (CBF) and tissue signature were retrospectively tracked in these two regions and were compared with histological evaluation and functional outcome. After 1 week of sildenafil treatment, the ischemic lesion exhibited two significantly different regions, with higher CBF level and correspondingly, lower tissue signature value in the boundary region than in the core region. Sildenafil treatment did not significantly reduce the lesion size, but did enhance angiogenesis. Functional performance was significantly increased after sildenafil treatment compared with the control group. Administration of sildenafil to rats with embolic stroke enhances angiogenesis and selectively increases the CBF level in the ischemic boundary, and improves neurological functional recovery compared to saline-treated rats.

Detection of BBB disruption and hemorrhage by Gd-DTPA enhanced MRI after embolic stroke in rat.

Thrombolytic therapy with rtPA increases the risk of hemorrhagic transformation (HT) after cerebral ischemia. We employed contrast enhancement MRI with Gd-DTPA to detect HT in a rat model of embolic stroke treated with rtPA and a glycoprotein IIb/IIIa receptor antagonist, 7E3 F(ab')2, at 4 h after embolic stroke. Male Wistar rats were subjected to embolic stroke and treated with the combination of rtPA and 7E3 F(ab')2 (n=12) or with saline (n=10) at 4 h after onset of stroke. MRI studies were performed immediately and at 24 h after embolization using a 7-T system. Histological measurements were obtained at 48 h. With Gd-DTPA, T1WI images and permeability related MRI parameters (the blood-to-brain transfer constant, Ki, and the distribution volume of mobile protons, Vp) of 15 out of 18 animals showed hyperintensity regions in gross or microscopic HT areas at 24 h, confirmed histologically at 48 h post stroke. Contrast enhancement MRI detected six of seven (86%) animals with gross HT and nine of eleven (82%) animals with microscopic HT at 24 h after ischemia. Two of eighteen animals with HT, had MRI indices of hemorrhage at 3 h post stroke. However, compared to HT data measured histologically at 48 h in embolic stroke rats, the enhanced areas by Gd-DTPA at 24 h were larger, and the patterns (time, intensity and region) did not directly correlate to the subtypes of HT, i.e., gross or microscopic hemorrhage. Contrast enhancement MRI using Gd-DTPA provides a method to detect gross and microscopic HT after stroke in rats.

Cerebrolysin dose-dependently improves neurological outcome in rats after acute stroke: A prospective, randomized, blinded, and placebo-controlled study.

BACKGROUND: Cerebrolysin is a mixture of neuropeptides and free amino acids that is clinically used for the treatment of stroke. To further standardize treatment schemes, we assessed the dose response of Cerebrolysin on sensorimotor outcome in a rat model of ischemic stroke. METHODS: This study was a prospective, blinded, placebo-controlled, preclinical experiment. Male and female Wistar rats, subjected to embolic middle cerebral artery occlusion, were randomly treated with Cerebrolysin doses of 0.8, 2.5, 5.0, 7.5 ml/kg or placebo, 4 h after middle cerebral artery occlusion for a total of 10 consecutive days. RESULTS: The primary outcome was neurologic improvement at day 28, lesion volume, mortality, and animal weight were secondary and safety outcomes, respectively. There was a significant (p < 0.001) dose effect of Cerebrolysin on neurological outcome. Cerebrolysin at a dose of ≥ 2.5 ml/kg significantly (p < 0.001) improved neurological outcome (Mean Estimate (95% CL): 0.8 ml/kg: 6.2 (-6.0/18.4), 2.5 ml/kg: -28.9 (-41.6/-16.2), 5.0 ml/kg: -33.4 (-45.0/-21.7), 7.5 ml/kg: -36.3 (-48.2/-24.4). Higher doses (≥ 2.5 ml/kg) resulted in better recovery; however, differences between effective doses were not significant. Treatment with 5 ml/kg reduced lesion volume (p = 0.016). No treatment gender interactions were found and there were no differences in death or weight loss. CONCLUSION: Collectively, these data on Cerebrolysin efficacy demonstrate the feasibility of a preclinical study setup following a randomized, placebo-controlled, and blinded design with a clinical relevant treatment scheme. Cerebrolysin at doses of ≥ 2.5 ml/kg improved functional outcome and at a dose of 5 ml/kg reduced infarct volume.

Activation of the PI3-K/Akt pathway mediates cGMP enhanced-neurogenesis in the adult progenitor cells derived from the subventricular zone.

The intracellular mechanisms that regulate neurogenesis remain unclear. Using neurospheres isolated from the subventricular zone (SVZ) of the adult rat, we investigated the effect of cyclic guanosine monophosphate (cGMP) and its signaling pathway on the induction of neurogenesis. Neurospheres expressed phosphodiesterase 5 (PDE5) and treatment of neurospheres with Sildenafil, a specific inhibitor of PDE5, significantly increased cGMP levels and neurogenesis. In addition, incubation of neurospheres with Sildenafil significantly phosphorylated Akt, which was associated with an increase of phosphorylation of glycogen synthase kinase 3 (GSK-3), a downstream target of Akt. Coincubation of neurospheres with Sildenafil and LY 294002, a pharmacological inhibitor of PI3-K/Akt, abolished Sildenafil-induced phosphorylated Akt and GSK-3. Furthermore, LY 294002 blocked Sildenafil-increased SVZ cell proliferation. These data suggest that Sildenafil-enhanced neurogenesis likely occurs through activation of the PI3-K/Akt/GSK-3 pathway.