Vigabatrin Inhibits Seizures and mTOR Pathway Activation in a Mouse Model of Tuberous Sclerosis Complex.

Vigabatrin Inhibits Seizures and mTOR Pathway Activation in a Mouse Model of Tuberous Sclerosis Complex.

PLoS One. 2013; 8(2): e57445
Zhang B, McDaniel SS, Rensing NR, Wong M

Epilepsy is a common neurological disorder and cause of significant morbidity and mortality. Although antiseizure medication is the first-line treatment for epilepsy, currently available medications are ineffective in a significant percentage of patients and have not clearly been demonstrated to have disease-specific effects for epilepsy. While seizures are usually intractable to medication in tuberous sclerosis complex (TSC), a common genetic cause of epilepsy, vigabatrin appears to have unique efficacy for epilepsy in TSC. While vigabatrin increases gamma-aminobutyric acid (GABA) levels, the precise mechanism of action of vigabatrin in TSC is not known. In this study, we investigated the effects of vigabatrin on epilepsy in a knock-out mouse model of TSC and tested the novel hypothesis that vigabatrin inhibits the mammalian target of rapamycin (mTOR) pathway, a key signaling pathway that is dysregulated in TSC. We found that vigabatrin caused a modest increase in brain GABA levels and inhibited seizures in the mouse model of TSC. Furthermore, vigabatrin partially inhibited mTOR pathway activity and glial proliferation in the knock-out mice in vivo, as well as reduced mTOR pathway activation in cultured astrocytes from both knock-out and control mice. This study identifies a potential novel mechanism of action of an antiseizure medication involving the mTOR pathway, which may account for the unique efficacy of this drug for a genetic epilepsy. HubMed – drug


Klotho Sensitizes Human Lung Cancer Cell Line to Cisplatin via PI3k/Akt Pathway.

PLoS One. 2013; 8(2): e57391
Wang Y, Chen L, Huang G, He D, He J, Xu W, Zou C, Zong F, Li Y, Chen B, Wu S, Zhao W, Wu J

Klotho was first identified in 1997 and has been considered as an anti-aging gene. Emerging evidence demonstrates that klotho has a close relationship with cancers, including lung cancer, breast cancer, etc, by inhibiting the proliferation and promoting apoptosis of cancer cells. Cisplatin has been the most widely used drug in the first-line chemotherapy. However, the increase in cisplatin-resistant cancer cells has become a major obstacle in clinical management of cancers. In our study, we for the first time demonstrated that klotho could attenuate the resistance of lung cancer to cisplatin based chemotherapy and the apoptosis of the resistant cells with klotho overexpression was markedly increased. However, klotho knockdown cells showed enhanced resistance to chemotherapy. Further analysis showed that inhibition of PI3K/Akt pathway with specific inhibitor (LY294002) attenuated the promotive effects on cancer growth following interfering with klotho shRNA. Moreover, we demonstrated that klotho modulated the resistance to cisplatin in a xenograft nude mice model. These observations suggested that klotho could improve the resistance of lung cancer cells to chemotherapy and may serve as a potential target for the gene therapy of lung cancers resistant to cisplatin based chemotherapy. HubMed – drug


Olanzapine treatment of adolescent rats causes enduring specific memory impairments and alters cortical development and function.

PLoS One. 2013; 8(2): e57308
Milstein JA, Elnabawi A, Vinish M, Swanson T, Enos JK, Bailey AM, Kolb B, Frost DO

Antipsychotic drugs are increasingly used in children and adolescents to treat a variety of psychiatric disorders. However, little is known about the long-term effects of early life antipsychotic drug treatment. Most antipsychotic drugs are potent antagonists or partial agonists of dopamine D2 receptors; atypical antipsychotic drugs also antagonize type 2A serotonin receptors. Dopamine and serotonin regulate many neurodevelopmental processes. Thus, early life antipsychotic drug treatment can, potentially, perturb these processes, causing long-term behavioral- and neurobiological impairments. Here, we treated adolescent, male rats with olanzapine on post-natal days 28-49. As adults, they exhibited impaired working memory, but normal spatial memory, as compared to vehicle-treated control rats. They also showed a deficit in extinction of fear conditioning. Measures of motor activity and skill, habituation to an open field, and affect were normal. In the orbital- and medial prefrontal cortices, parietal cortex, nucleus accumbens core and dentate gyrus, adolescent olanzapine treatment altered the developmental dynamics and mature values of dendritic spine density in a region-specific manner. Measures of motor activity and skill, habituation to an open field, and affect were normal. In the orbital- and medial prefrontal cortices, D1 binding was reduced and binding of GABA(A) receptors with open Cl(-) channels was increased. In medial prefrontal cortex, D2 binding was also increased. The persistence of these changes underscores the importance of improved understanding of the enduring sequelae of pediatric APD treatment as a basis for weighing the benefits and risks of adolescent antipsychotic drug therapy, especially prophylactic treatment in high risk, asymptomatic patients. The long-term changes in neurotransmitter receptor binding and neural circuitry induced by adolescent APD treatment may also cause enduring changes in behavioral- and neurobiological responses to other therapeutic- or illicit psychotropic drugs. HubMed – drug



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