cytochrome-c-t and Diabetic-Neuropathies

Diabetic neuropathy (DN) is the most prevalent complication of diabetes. Pharmacological treatments for DN are often limited in efficacy, so the development of new agents to alleviate DN is essential. The aim of this study was to evaluate the effects of rolipram, a selective phosphodiesterase-4 inhibitor (PDE-4I), and pentoxifylline, a general PDE inhibitor, using a rat model of DN. In this study, a diabetic rat model was established by i.p. injection of STZ (55 mg/kg). Rats were treated with rolipram (1 mg/kg), pentoxifylline (100 mg/kg), and combination of rolipram (0.5 mg/kg) and pentoxifylline (50 mg/kg), orally for 5 weeks. After treatments, sensory function was assessed by hot plate test. Then rats were anesthetized and dorsal root ganglion (DRG) neurons isolated. Cyclic adenosine monophosphate (cAMP), adenosine triphosphate (ATP, adenosine diphosphate and mitochondrial membrane potential (MMP) levels, Cytochrome c release, Bax, Bcl-2, caspase-3 proteins expression in DRG neurons were assessed by biochemical and ELISA methods, and western blot analysis. DRG neurons were histologically examined using hematoxylin and eosin (H&E) staining method. Rolipram and/or pentoxifylline significantly attenuated sensory dysfunction by modulating nociceptive threshold. Rolipram and/or pentoxifylline treatment dramatically increased the cAMP level, prevented mitochondrial dysfunction, apoptosis and degeneration of DRG neurons, which appears to be mediated by inducing ATP and MMP, improving cytochrome c release, as well as regulating the expression of Bax, Bcl-2, and caspase-3 proteins, and improving morphological abnormalities of DRG neurons. We found maximum effectiveness with rolipram and pentoxifylline combination on mentioned factors. These findings encourage the use of rolipram and pentoxifylline combination as a novel experimental evidence for further clinical investigations in the treatment of DN.

Topics: Adenosine Triphosphate; Animals; Apoptosis; bcl-2-Associated X Protein; Caspase 3; Cytochromes c; Diabetes Mellitus; Diabetic Neuropathies; Ganglia, Spinal; Mitochondria; Neurons; Pentoxifylline; Phosphodiesterase Inhibitors; Rats; Rolipram

Since Thymus caramanicus Jalas is used as a folk medicine for the treatment of rheumatism, skin disorders, bacterial infections and diabetes and it contain antioxidant agents, we decided to investigate the possible effects of Thymus caramanicus Jalas (TCJ) extract on in vitro and in vivo models of diabetic neuropathy.. The high glucose-induced cell injury in Pheochromocytoma (PC12) cells and streptozotocin-induced diabetic rats were used. Tail-flick and rotarod treadmill assessments were used to determine nociceptive threshold and motor coordination. Cell viability was determined by MTT assay test. Western blotting was performed to measurement of apoptosis markers.. The data showed that elevation of glucose consecutively increases functional cell injury and apoptosis. Furthermore, diabetic rats developed thermal hyperalgesia and motor deficit. Activated caspase 3, cytochrome c release and Bax/Bcl-2 ratio were significantly increased in high glucose-treated PC12 cells and in spinal cord of diabetic animals. TCJ extract (60 and 80 µg/ml) attenuates high glucose-induced PC12 cells damage and apoptosis. In diabetic animals, TCJ extract at daily doses of 100 and 150 mg/kg ameliorated hyperalgesia and suppressed spinal apoptosis.. The data indicate that TCJ extract has neuroprotective effects against high glucose-induced neural damage. These protective effects are mediated, at least in part, through attenuation of neural apoptosis and suggest therapeutic potential of TCJ extract in amelioration of diabetic neuropathy.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Blood Glucose; Caspase 3; Cell Survival; Cytochromes c; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Hyperglycemia; Male; Neuralgia; Pain Measurement; PC12 Cells; Phytotherapy; Plant Extracts; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Wistar; Thymus Plant

Oxidative damage has been reported to be involved in the pathogenesis of diabetic neuropathy and neurodegenerative diseases. Recent evidence suggests that the antidiabetic drug metformin prevents oxidative stress-related cellular death in non-neuronal cell lines. In this report, we point to the direct neuroprotective effect of metformin, using the etoposide-induced cell death model. The exposure of intact primary neurons to this cytotoxic insult induced permeability transition pore (PTP) opening, the dissipation of mitochondrial membrane potential (DeltaPsim), cytochrome c release, and subsequent death. More importantly, metformin, together with the PTP classical inhibitor cyclosporin A (CsA), strongly mitigated the activation of this apoptotic cascade. Furthermore, the general antioxidant N-acetyl-L: -cysteine also prevented etoposide-promoted neuronal death. In addition, metformin was shown to delay CsA-sensitive PTP opening in permeabilized neurons, as triggered by a calcium overload, probably through its mild inhibitory effect on the respiratory chain complex I. We conclude that (1) etoposide-induced neuronal death is partly attributable to PTP opening and the disruption of DeltaPsim, in association with the emergence of oxidative stress, and (2) metformin inhibits this PTP opening-driven commitment to death. We thus propose that metformin, beyond its antihyperglycemic role, can also function as a new therapeutic tool for diabetes-associated neurodegenerative disorders.

Topics: Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Cells, Cultured; Cerebral Cortex; Cyclosporine; Cytochromes c; Diabetic Neuropathies; Enzyme Inhibitors; Etoposide; Hypoglycemic Agents; Membrane Potential, Mitochondrial; Metformin; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Neurodegenerative Diseases; Neurons; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Wistar