Peroxisome proliferator-activated receptor (PPAR) α is a transcription factor that regulates genes involved in fatty acid catabolism. Here we provide evidence that PPARα is constitutively expressed in nuclei of hippocampal neurons and surprisingly controls calcium influx and the expression of various plasticity-related genes via direct transcriptional regulation of CREB. Accordingly, Ppara-null, but not Pparb-null, mice are deficient in CREB and memory-associated genes, and have decreased spatial learning and memory. While shRNA knockdown of PPARα in the hippocampus suppressed CREB and NR2A rendering wild type animals markedly poor in consolidating spatial memory, introduction of PPARα to the hippocampus of Ppara-null mice increased hippocampal CREB and NR2A and improved spatial learning and memory. These results together with detailed analyses of CREB, NR2A and spatial learning and memory in bone marrow chimeric animals lacking PPARα in the CNS describe a novel mechanism for transcriptional control of Creb and associated plasticity genes by PPARα.

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Huntington's disease (HD) is a neurological disorder caused by a genetic mutation in the IT15 gene. Progressive cell death in the striatum and cortex, and accompanying declines in cognitive, motor, and psychiatric functions, are characteristic of the disease. Animal models of HD have provided insight into disease pathology and the outcomes of therapeutic strategies. Earlier studies of HD most often used toxin-induced models to study mitochondrial impairment and excitotoxicity-induced cell death, which are both mechanisms of degeneration seen in the HD brain. These models, based on 3-nitropropionic acid and quinolinic acid, respectively, are still often used in HD studies. The discovery in 1993 of the huntingtin mutation led to the creation of newer models that incorporate a similar genetic defect. These models, which include transgenic and knock-in rodents, are more representative of the HD progression and pathology. An even more recent model that uses a viral vector to encode the gene mutation in specific areas of the brain may be useful in nonhuman primates, as it is difficult to produce genetic models in these species. This article examines the aforementioned models and describes their use in HD research, including aspects of the creation, delivery, pathology, and tested therapies for each model.

Huntington's disease (HD) is a fatal, genetic, neurological disorder resulting from a trinucleotide repeat expansion in the gene that encodes for the protein huntingtin. These excessive repeats confer a toxic gain of function on huntingtin, which leads to the degeneration of striatal and cortical neurons and a devastating motor, cognitive, and psychological disorder. Trophic factor administration has emerged as a compelling potential therapy for a variety of neurodegenerative disorders, including HD. We previously demonstrated that viral delivery of glial cell line-derived neurotrophic factor (GDNF) provides structural and functional neuroprotection in a rat neurotoxin model of HD. In this report we demonstrate that viral delivery of GDNF into the striatum of presymptomatic mice ameliorates behavioral deficits on the accelerating rotorod and hind limb clasping tests in transgenic HD mice. Behavioral neuroprotection was associated with anatomical preservation of the number and size of striatal neurons from cell death and cell atrophy. Additionally, GDNF-treated mice had a lower percentage of neurons containing mutant huntingtin-stained inclusion bodies, a hallmark of HD pathology. These data further support the concept that viral vector delivery of GDNF may be a viable treatment for patients suffering from HD.gene therapy ͉ neurodegeneration ͉ neuroprotection ͉ polyglutamine ͉ adenoassociated virus H untington's disease (HD) is an autosomal dominant neurodegenerative disorder resulting from an expanded trinucleotide (CAG: cytosine, adenine, and guanine) repeat at the IT15 locus on chromosome 4 (1) within the huntingtin gene. The abnormal DNA is translated into mutant huntingtin with an expanded glutamine stretch at the N terminus of the protein. The excessive number of glutamine repeats is responsible for the misfolding of huntingtin and the subsequent formation of neuronal inclusions, degeneration of striatal and cortical neurons, and a triad of symptoms including severe motor, cognitive, and psychological disturbances that are ultimately fatal.To date, HD remains incurable. Several therapies have yielded positive results in animal models, including those that alleviate potential glutamate-induced excitotoxicity such as riluzole and remacemide (2-4); those that increase the production of energy in the form of ATP in the cell, including creatine and coenzyme Q 10 (5-9); those that inhibit caspase activation and apoptosis, such as minocycline (10, 11); and those that aim at replacing degenerating cells by means of fetal tissue transplantation (12-18). However, when tested clinically, none has made a major impact in the symptomatic treatment of HD, nor have any demonstrated the ability to alter the natural history of the disease by preventing cell death.Genetic testing can identify mutated gene carriers destined to suffer from HD. Unlike other neurodegenerative disorders, identification of the genetic marker provides the unique opportunity to intercede therapeutically before the onset of symptoms that result from n...

Parkinson’s disease (PD) is a progressive, neurodegenerative disorder for which there is currently no effective neuroprotective therapy. Patients are typically treated with a combination of drug therapies and/or receive deep brain stimulation to combat behavioral symptoms. The ideal candidate therapy would be the one which prevents neurodegeneration in the brain, thereby halting the progression of debilitating disease symptoms. Neurotrophic factors have been in the forefront of PD research, and clinical trials have been initiated using members of the GDNF family of ligands (GFLs). GFLs have been shown to be trophic to ventral mesencephalic cells, thereby making them good candidates for PD research. This paper examines the use of GDNF and neurturin, two members of the GFL, in both animal models of PD and clinical trials.