iridoids and Diabetic-Neuropathies

Loganin is an iridoid glycoside with antioxidant, anti-inflammatory, glucose-lowering activities which may address the pathological mechanisms of painful diabetic neuropathy (PDN) related to inflammation, oxidative stress, and hyperglycemia. This study investigated the underlying mechanisms of action of loganin on PDN. The in vivo model of PDN was established by streptozotocin-nicotinamide (STZ-NA) induction in Sprague Dawley (SD) rats. Subsequently, loganin (5 mg/kg) was administered by daily intraperitoneal injection. High-glucose stimulated human SH-SY5Y cells co-incubated with loganin were used to mimic the in vitro model of PDN. Loganin improved PDN rats' associated pain behaviors (allodynia and hyperalgesia), insulin resistance index (HOMA-IR), and serum levels of superoxide dismutase (SOD), catalase and glutathione. Loganin also reduced pain-associated channel protein Ca

Topics: Animals; Antioxidants; Behavior, Animal; Blood Glucose; Body Weight; Calcitonin Gene-Related Peptide; Calcium Channels, T-Type; Cell Line, Tumor; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Fasting; Humans; Hyperglycemia; Inflammation; Inflammation Mediators; Insulin; Insulin Resistance; Iridoids; Male; Neuralgia; Neuroglia; NF-kappa B; Niacinamide; Oxidative Stress; Rats, Sprague-Dawley; Signal Transduction; Spinal Cord Dorsal Horn; Streptozocin

Chronic hyperalgesia and allodynia associated with progressive damage of peripheral neurons are the most prevalent complications of diabetes mellitus. Plants belonging to the family of Oleaceae were traditionally used in folk medicine for the management of diabetes.. The aim of this study was to investigate whether an aqueous extract from the leaves of Ligustrum vulgare (common privet) could be useful to target neuropathic pain in a rat streptozotocin (STZ) model of diabetes.. The chemical composition of the aqueous extract from privet leaf was characterized with the UHPLC-DAD-MS method and the analytical quantification of its constituents was performed with HPLC-DAD. Mechanical hyperalgesia and allodynia were evaluated with the Randall-Selitto and von Frey tests.. Our investigation revealed the presence of secoiridoids: oleacein (23.48 ± 0.87 mg/g), oleocanthal (8.44 ± 0.08 mg/g), oleuropein (1.50 ± 0.01 mg/g), as well as phenylpropanoids: echinacoside (6.46 ± 0.07 mg/g), verbascoside (4.03 ± 0.04 mg/g) and p-coumaroyl glucarates in the dried aqueous extract of privet leaves. Behavioral data indicated that chronic intraperitoneal administration of the extract (50-200 mg/kg) for 21 days resulted in a decrease in diabetes-induced hyperalgesia and allodynia. Blood glucose levels remained unaltered, while body weight and water intake decreased significantly.. The aqueous privet leaf extract could serve useful in facilitating treatment of painful diabetic neuropathy. Additionally, the study showed that the antihyperalgesic activity of Ligustrum vulgare leaf extract is not likely related to its antihyperglycemic properties.

Topics: Aldehydes; Animals; Chromatography, High Pressure Liquid; Cyclopentane Monoterpenes; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Glucosides; Glycosides; Hyperalgesia; Iridoid Glucosides; Iridoids; Ligustrum; Male; Neuralgia; Phenols; Plant Extracts; Plant Leaves; Rats; Streptozocin

Diabetes mellitus can cause dysfunction of the central nervous system called "diabetic encephalopathy." Although insulin and various oral drugs are used to treat diabetes, they do not completely prevent the development of diabetic encephalopathy, and novel strategies for the prevention and treatment are urgently needed. Catalpol, an iridoid glycoside, has properties of anti-inflammation, antioxidant and decreasing blood glucose level and thus has the possibility of treating diabetic encephalopathy. Therefore, the study was designed to investigate the effects of catalpol on diabetic encephalopathy in rats. A single dose of 65 mg/kg streptozotocin was injected intraperitoneally to induce diabetes. Intragastric infusion of catalpol was performed for 6 weeks with the doses of 10, 50 and 100 mg/kg, respectively. The Y-type maze test, biochemical measurement, Nissl staining and the terminal deoxynucleotidyl transferase-mediated UTP nick end labeling methods were used to evaluate the neuropathological changes and the effects of catalpol on diabetic rats. The results showed that streptozotocin-induced diabetes produced obvious neuron damage and cognitive dysfunction coupling with markedly increased oxidative stress in the brain. Long-term oral supplementation of catalpol improved neuronal injury and cognitive dysfunction by attenuating oxidative stress. The effects that catalpol could both increase the nerve growth factor concentration and decrease the blood glucose level were related with the function of defending against oxidative stress of catalpol. The study suggested that oral supplementation of catalpol might be a potential therapeutic strategy for the treatment and/or prevention of diabetic encephalopathy.

Topics: Administration, Oral; Animals; Behavior, Animal; Blood Glucose; Body Weight; Catalase; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Dietary Supplements; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Glucosides; Glutathione Peroxidase; In Situ Nick-End Labeling; Iridoid Glucosides; Iridoids; Lipid Peroxidation; Male; Malondialdehyde; Maze Learning; Nerve Growth Factor; Oxidative Stress; Rats; Rats, Sprague-Dawley; Superoxide Dismutase; Time Factors

The present study was conducted to determine whether iridoid total glycoside from Cornus officinalis was effective in regulating expression of transforming growth factor beta 1 (TGF-beta1) and preventing overdeposition of extracellular matrix (ECM) in a diabetes state. An experimental rat model of diabetic nephropathy (DN) was successfully induced by one intraperitoneal injection of streptozotocin at a dose of 60 mg x kg(-1) and maintained for 12 weeks. All rats had free access to standard chow and water. Four groups: normal control, diabetic control, diabetic rats with aminoguanidine treatment and diabetic rats with iridoid total glycoside treatment were used in this experiment. All treatments were administered by intragastric gavage (ig). At the end of the experiment, serum was collected for ELISA determination of TGF-beta1 protein level; renal cortex was dissected for reverse transcription polymerase chain reaction (RT-PCR) analysis of its mRNA expression; and immunohistochemistry was introduced to observe ECM deposition. A significantly higher level of protein and mRNA expression of TGF-beta1, and also overdeposition of fibronectin and laminin was found in diabetic rats. Both iridoid total glycoside and aminoguanidine were effective in decreasing serum protein level and glomerular mRNA expression of TGF-beta1, and in preventing renal overdeposition of fibronectin and laminin. This study suggests that iridoid total glycoside is a beneficial agent for prevention and therapy of DN.

Topics: Animals; Cornus; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Extracellular Matrix; Iridoids; Kidney Glomerulus; Male; Rats; Rats, Sprague-Dawley; Transforming Growth Factor beta; Transforming Growth Factor beta1