Akt Inhibitor Perifosine Prevents Epileptogenesis in a Rat Model of Temporal Lobe Epilepsy / 神经科学通报·英文版

Accumulating data have revealed that abnormal activity of the mTOR (mammalian target of rapamycin) pathway plays an important role in epileptogenesis triggered by various factors. We previously reported that pretreatment with perifosine, an inhibitor of Akt (also called protein kinase B), abolishes the rapamycin-induced paradoxical increase of S6 phosphorylation in a rat model induced by kainic acid (KA). Since Akt is an upstream target in the mTOR signaling pathway, we set out to determine whether perifosine has a preventive effect on epileptogenesis. Here, we explored the effect of perifosine on the model of temporal epilepsy induced by KA in rats and found that pretreatment with perifosine had no effect on the severity or duration of the KA-induced status epilepticus. However, perifosine almost completely inhibited the activation of p-Akt and p-S6 both acutely and chronically following the KA-induced status epilepticus. Perifosine pretreatment suppressed the KA-induced neuronal death and mossy fiber sprouting. The frequency of spontaneous seizures was markedly decreased in rats pretreated with perifosine. Accordingly, rats pretreated with perifosine showed mild impairment in cognitive functions. Collectively, this study provides novel evidence in a KA seizure model that perifosine may be a potential drug for use in anti-epileptogenic therapy.

Rapamycin treatment starting at 24 h after cerebral ischemia/reperfusion exhibits protective effect on brain injury in rats / 浙江大学学报·医学版

OBJECTIVE@#To investigate whether rapamycin treatment starting at 24 h after cerebral ischemia/reperfusion(I/R) has protective effect on brain injury in rats.@*METHODS@#The rat I/R model was established by middle cerebral artery occlusion according to Longa's method. A total of 104 Sprague Dawley rats were randomly divided into sham group, model group, and rapamycin-treated groups (6 h or 24 h after modeling). Neurological function was assessed with neurological severity score (NSS). Triphenyl tetrazolium chloride (TTC) staining and Fluoro-Jade B (FJB) staining were used to examine the infarct volume and neuronal apoptosis, respectively. The expression of p-S6 protein in mTOR signaling pathway was detected by Western blot analysis.@*RESULTS@#Compared with sham group, NSS of the model group was significantly increased and TTC staining indicated obvious infarct area (all 0.05).@*CONCLUSIONS@#Rapamycin treatment starting at 24 h after I/R exhibits protective effect on brain injury in rats.

Efficacy of brain-targeted rapamycin for treatment of epilepsy in rats / 浙江大学学报·医学版

OBJECTIVE@#To investigate the efficacy of brain-targeted rapamycin (T-Rap) in treatment of epilepsy in rats.@*METHODS@#Rapamycin nanoparticles targeting brain were prepared. The epilepsy model was induced by injection of pilocarpine in rats. The rats with pilocarpine-induced epilepsy were treated with rapamycin (Rap group) or brain-targeted rapamycin (T-Rap group). Seizure activity was observed by electroencephalography; the effect on mTOR signaling pathway was detected by Western blot; neuronal death and moss fiber sprouting were analyzed by Fluoro-Jade B (FJB) and Timm's staining, respectively.@*RESULTS@#Electroencephalography showed that both preparation of rapamycin significantly reduced the frequency of spontaneous seizures in rats, and the effect of T-Rap was stronger than that of conventional rapamycin (<0.05). Western blot showed that the phosphorylation levels of S6K and S6 in T-Rap group were lower than those in Rap group (all <0.05), indicating that T-Rap had a stronger inhibitory effect on mTOR signaling pathway. FJB staining showed that T-Rap significantly decreased neuronal death, but there was no significant difference as compared with Rap group. Timm's staining showed that both preparations of rapamycin significantly reduced the germination of mossy fibers, while the effect of T-Rap was more pronounced than Rap group (<0.05). The inhibition of body weight gain of T-Rap group was less than that of Rap group (<0.05).@*CONCLUSIONS@#T-Rap has a better therapeutic effect on epilepsy than conventional rapamycin with a less adverse effects in rats.

Effects of ginsenosides Rb1 on learning and memory and expression of somatostatin in sleep deprivation rats / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To determine the effects of ginsenosides Rb1(GSRb1) on learning and memory and expression of somatostatin (SS) in the hippocampus and the frontal cortex in rat model of sleep deprivation (SD).</p><p><b>METHODS</b>Rats were randomized into groups of SD 2 d, SD 4 d, SD 6 d, and SD 0 d, while each group was sub-divided into GSRb1 group and normal saline (NS) sub-groups. Rats were intraperitoneal administered with 30 mg/(kg*d) of GSRb1 or NS for 7 d, then the learning and memory abilities were examined by measuring average swimming speed and mean escape latency using Morris maze.Expression of somatostatin was detected with immunohistochemical method and image analysis in the hippocampus and the frontal cortex.</p><p><b>RESULTS</b>Compared with SD 0 d rats, SD rats exhibited significant decrease in the average swimming speed and increase in the escape latency (P <0.01). The expression of somatostatin in the hippocampus was decreased significantly in SD 2 d, SD 4 d and SD 6 d rats (P<0.05). However, decrease was only observed in SD 4 d and SD 6 d rats in the frontal cortex (P <0.05). Parallel comparison between NS control and GSRb1 treated rats demonstrated that rats treated with GSRb1 in each subgroup exhibited faster swimming speed and shorter escape latency (P <0.05). Meanwhile, the expression of somatostatin was increased in SD 2 d, SD 4 d and SD 6 d rats in the hippocampus and in SD 4 d and SD 6 d rats in the frontal cortex (P <0.05), respectively.</p><p><b>CONCLUSION</b>GSRb1 enhances the expression of somatostatin in sleep deprivation rats and subsequently may improve learning and memory abilities of rats.</p>