alitretinoin and Neurodegenerative-Diseases

Anomalous neuritogenesis is a hallmark of neurodegenerative disorders, including retinal degenerations, epilepsy, and Alzheimer's disease. The neuritogenesis processes result in a partial reinnervation, new circuitry, and functional changes within the deafferented retina and brain regions. Using the light-induced retinal degeneration (LIRD) mouse model, which provides a unique platform for exploring the mechanisms underlying neuritogenesis, we found that retinoid X receptors (RXRs) control neuritogenesis. LIRD rapidly triggered retinal neuron neuritogenesis and up-regulated several key elements of retinoic acid (RA) signaling, including retinoid X receptors (RXRs). Exogenous RA initiated neuritogenesis in normal adult retinas and primary retinal cultures and exacerbated it in LIRD retinas. However, LIRD-induced neuritogenesis was partly attenuated in retinol dehydrogenase knockout (Rdh12(-/-)) mice and by aldehyde dehydrogenase inhibitors. We further found that LIRD rapidly increased the expression of glutamate receptor 2 and β Ca(2+)/calmodulin-dependent protein kinase II (βCaMKII). Pulldown assays demonstrated interaction between βCaMKII and RXRs, suggesting that CaMKII pathway regulates the activities of RXRs. RXR antagonists completely prevented and RXR agonists were more effective than RA in inducing neuritogenesis. Thus, RXRs are in the final common path and may be therapeutic targets to attenuate retinal remodeling and facilitate global intervention methods in blinding diseases and other neurodegenerative disorders.

Topics: Alcohol Oxidoreductases; Alitretinoin; Animals; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Disease Models, Animal; Mice; Mice, Inbred BALB C; Mice, Mutant Strains; Neurodegenerative Diseases; Primary Cell Culture; Receptors, AMPA; Receptors, Retinoic Acid; Retinal Cone Photoreceptor Cells; Retinal Degeneration; Retinal Rod Photoreceptor Cells; Retinoic Acid Receptor alpha; Retinoic Acid Receptor gamma; Signal Transduction; Tretinoin; Vision, Ocular

In most neurodegenerative disorders, including multiple sclerosis, Parkinson disease, and Alzheimer disease, a massive neuronal cell death occurs as a consequence of an uncontrolled inflammatory response, where activated astrocytes and microglia and their cytotoxic agents play a crucial pathological role. Current treatments for these diseases are not effective. In the present study we investigate the effect of thiadiazolidinone derivatives, which have been recently suggested to play a role in neurodegenerative disorders. We have found that thiadiazolidinones are potent neuroprotector compounds. Thiadiazolidinones inhibited inflammatory activation of cultured brain astrocytes and microglia by diminishing lipopolysaccharide-induced interleukin 6, tumor necrosis factor alpha, inducible nitric-oxide synthase, and inducible cyclooxygenase type 2 expression. In addition, thiadiazolidinones inhibited tumor necrosis factor-alpha and nitric oxide production and, concomitantly, protected cortical neurons from cell death induced by the cell-free supernatant from activated microglia. The neuroprotective effects of thiadiazolidinones are completely inhibited by the peroxisome proliferator-activated receptor gamma antagonist GW9662. In contrast the glycogen synthase kinase 3beta inhibitor LiCl did not show any effect. These findings suggest that thiadiazolidinones potently attenuate lipopolysaccharide-induced neuroinflammation and reduces neuronal death by a mechanism dependent of peroxisome proliferator-activated receptor gamma activation.

Topics: Alitretinoin; Anilides; Animals; Anti-Inflammatory Agents; Apoptosis; Astrocytes; Brain; Cell Death; Cell Line; Cell-Free System; Cells, Cultured; Cyclooxygenase 2; Dose-Response Relationship, Drug; Enzyme Inhibitors; Glutamic Acid; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Hippocampus; Immunohistochemistry; In Vitro Techniques; Inflammation; Interleukin-6; Lipopolysaccharides; Lithium Chloride; Mice; Microscopy, Confocal; Microscopy, Fluorescence; Models, Chemical; Neurodegenerative Diseases; Neuroglia; Neurons; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitrites; PPAR gamma; Prostaglandin-Endoperoxide Synthases; Rats; Staurosporine; Thiazolidinediones; Time Factors; Transfection; Tretinoin; Tumor Necrosis Factor-alpha