PKR is activated in Alzheimer’s disease and in experimental models

Abstracts: Pharmacological Treatments / 1 (Suppl 1) (2005) P-176

PRECLINICAL BASIS FOR THE EFFICACY OF MEMANTINE IN ALZHEIMER’S DISEASE

Pradeep K. Banerjee1, Debomoy K. Lahiri2, Heikki Tanila3, Jose Javier Miguel-Hidalgo4, Khalid Iqbal5; 1Forest Research Institute, Jersey City, NJ, USA; 2Indiana University School of Medicine, Indianapolis, IN, USA; 3University of Kuopio, Kuopio, Finland; 4 University of Mississippi Medical Center, Jackson, MS, USA; 5New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA Background: Memantine is a low-moderate affinity, uncompetitive NMDA receptor antagonist and the first drug in this class approved for the treatment of moderate to severe Alzheimer’s disease (AD). The mechanisms by which memantine exerts its beneficial effects in AD are still under investigation, but appear to include normalization of glutamatergic neurotransmission and effects on ␤-amyloid (A␤)- and tau-mediated neurotoxicity. Objective(s): To review the preclinical evidence for the mechanisms which indicate potential multifaceted effects of memantine in AD. Methods: In rat hippocampal slices, therapeutic concentrations of memantine (⬃ 1 ␮M) counteracted NMDA-induced deficits in long-term potentiation, an in vitro measure of learning and memory. In vivo experiments showed that at therapeutic doses memantine reversed NMDA- or quinolinic acid-induced learning impairment and neurotoxicity. Subchronic dosing of memantine producing a steady-state plasma level of 2.34 ␮M prevented A␤1-40-induced apoptotic cell death in the rat hippocampus. In human neuroblastoma cells (SK-N-SH) and primary fetal rat cortical neurons, memantine (1-4 ␮M) decreased levels of secreted amyloid precursor protein (sAPP) derivatives and A␤1-40 /A␤1-42 peptides. In APP/PS1 transgenic mice exhibiting A␤ plaques and impaired learning, memantine (30 mg/kg/day p.o. for 2-3 weeks) improved performance in the water-maze learning task. Finally, in organotypic cultures of rat hippocampal slices, memantine reversed abnormal hyperphosphorylation and accumulation of tau. Conclusions: The above data provide a mechanistic basis for the clinical experience with memantine. As demonstrated by double-blind, placebo-controlled trials, memantine improves symptoms associated with mild, moderate, and severe stages of AD. P-177

THE EFFECTIVENESS OF GETO EXTRACT IN THE TREATMENT OF MILD COGNITIVE IMPAIRMENT IN COMMUNITY ELDERLY

Jinzhou Tian1, Aihua Zhu1, Jing Shi1, Chang Sheng Lu2, Jian Zhong3, Yu Gao4, Yongyan Wang5; 1Dongzhimen Hospital, Beijing University of Chinese Medicine,, Beijing, China; 2Shanghai Baokun Medicament Technology Co., Ltd, Shanghai, China; 3Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China; 4Beijing Chaoyang Hospital, Beijing, China; 5China Academy of Traditional Chinese Medicine, Beijing, China Background: Mild cognitive impairment (MCI) is at risk of dementia development (Tian et al., J Neurol Neurosurg Psychiatry 2003; 74: 433⬃438). However, no study on the effect of Chinese herbal extract on MCI has been performed. Objective: The aim of this study was to evaluate the effectiveness of GETO extract from ginseng, epimedium herb, thinleaf milkwort root, and other two herbs in the treatment of MCI in the community elderly. Methods: All of 70 subjects with MCI aged ⱖ65 years screened according to MCI diagnostic criteria published were randomly assigned into a GETO group (n⫽30) given 4 GETO capsules (1.8mg ginseng saponins per one) with 2 simulation tablets or a Piracetam group (n⫽30) given 2 tablets of Piracetam with 4 simulation tablets, or a Placebo control (n⫽15) given 6 placebos (4 tablets and 2 capsule), 3 times a day for 3 months. Subjects were assessed with a battery composed of MMSE and 5 memory measures (episodic memory assessing immediate and delayed story recall (AMIPB), 3 words recall (MMSE), verbal learning, and verbal recognition (HVLT), at baseline, endpoint, and follow-up point (1 year following endpoint). Results: There were a significant higher (p⬍0.05) mean MMSE score (28.3⫾1.7) at endpoint than that (27.5⫾1.7) at baseline

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in GETO group, but not significant different from Piracetam groups. Mean MMSE score was decreased (26.9⫾1.9) in GETO group, but still higher than Placebo group (26.33⫾1.03) at follow-up point. Mean HVLT score increased significantly from 19.6⫾4.9 at baseline to 87.3⫾29.8 at follow-up point in GETO group, which was significantly (p⬍0.05 and p⬍0.01 respectively) higher than Piracetam group (77.8⫾29.6) and Placebo group (74.9⫾25.3). Mean total score for 5 memory items significantly increased from 66.3⫾16.7 at baseline to 93.5⫾35.6 in GETO group at follow-up point, and was significantly (P⬍0.05 and p⬍0.01, respectively) higher than Piracetam group (87.7⫾29.8) and Placebo group (84.6⫾25.4). Conclusion: This study showed certain effectiveness of GETO capsule in the treatment of memory impairment and the delaying of memory decline in the elderly with MCI. All of these herbs have been claimed to be effective in treating forgetfulness in traditional Chinese medicine, and merit further study. P-178

REGULATION OF STEM CELLS IN THE BRAIN OF STREPTOZOTOCIN INDUCED LESIONS IN MOUSE

Niloufar Haque; CUNY, New York, NY, USA We have induced lesions in the brain of young male mouse with Streptozotocin (STZ) and studied the effect of Nardostachys jatamansi in the recovery of lesions. The study has been further followed by the administration of FGF-2 to monitor the proliferation of stem cells and its migration from subventricular zone to the cortical layers. Effort is made to quantitate and identify the neuronal population affected by this study. Histochemical studies on Stem cell prolifiration and charachterization will be be reported in the different regions of the brain. The behavioral (Morris Water Maze) and biochemical parameters (lipid peroxidation, glutathione, glutathione peroxidase, glutathione reductase, glutathione-S-transfarase, superoxide dismutase and catalase) will be discussed in the meeting. P-179

PKR IS ACTIVATED IN ALZHEIMER’S DISEASE AND IN EXPERIMENTAL MODELS

Guylene Page1, Sabrina Ingrand1, Claire Lafay-Chebassier1, Agne`s Rioux-Bilan1, Martine Latta Mahieu2, Marie-Christine Pe´rault Pochat1, Thomas Bayer3, Laurent Pradier2, Jacques Hugon1; 1University of Poitiers, Poitiers, France; 2SANOFI AVENTIS, Paris, France; 3University of Saarland, Homburg, Germany Background: Neurodegeneration is a major feature of the neuropathological lesions in Alzheimer’s disease (AD). Different activated kinases have been linked to this process such as Gsk-3␤ and cdk 5. We have shown in previous studies that the kinase PKR is present in hippocampal degenerating neurons in AD brains and that the knock out of PKR attenuates A␤ neurotoxicity in neural cell cultures. Objective(s): In the present data, we assessed the newly described APPSL/PS1 knock in mice displaying hippocampal neurodegeneration, in order to evaluate, by immunohistochemical methods, the involvement of PKR in the cell death process. Methods and Results: At 3, 6 and 10 months of age, a marked and progressive loss of hippocampal CA1 neurons was observed. Degenerating cells displayed a staining of phosphorylated PKR with an intracellular accumulation of A␤ peptides. The staining of phosphorylated PKR was also seen at the periphery of amyloid plaques in the cortex and the hippocampus. Phosphorylated tau immunoreactivity was also detected in some neurons with the AT8 antibody. Western blots also revealed an increased phosphorylated PKR expression at 3 months of age in the cortex. We then tested in vitro the pharmacological blockade of PKR in A␤ neurotoxicity. We exposed SHSY5Y human neuroblastoma cells to 40 ␮M of A␤ in the presence or absence of an anti PKR oxindolic compound or an inhibitory peptide. Caspase 3 activation and phosphorylation of PKR induced by A␤ were both reduced by these compounds. Conclusions: In summary, PKR could represent a new target for future therapeutic approaches in AD.