ABSTRACT
BACKGROUND: Transient receptor potential vanilloid 1 (TRPV1) is a non-selective cation channel implicated in pain sensation in response to heat, protons, and capsaicin (CAPS). It is well established that TRPV1 is involved in mechanical allodynia. This study investigates the effect of Ononis spinosa (Fabaceae) in CAPS-induced mechanical allodynia and its mechanism of action. METHODS: Mechanical allodynia was induced by the intraplantar (ipl) injection of 40 µg CAPS into the left hind paw of male Wistar rats. Animals received an ipl injection of 100 µg O. spinosa methanolic leaf extract or 2.5% diclofenac sodium 20 minutes before CAPS injection. Paw withdrawal threshold (PWT) was measured using von Frey filament 30, 90, and 150 minutes after CAPS injection. A molecular docking tool, AutoDock 4.2, was used to study the binding energies and intermolecular interactions between O. spinosa constituents and TRPV1 receptor. RESULTS: The ipsilateral ipl injection of O. spinosa before CAPS injection increased PWT in rats at all time points. O. spinosa decreased mechanical allodynia by 5.35-fold compared to a 3.59-fold decrease produced by diclofenac sodium. The ipsilateral pretreatment with TRPV1 antagonist (300 µg 4-[3-Chloro-2-pyridinyl]- N-[4-[1,1-dimethylethyl] phenyl]-1-piperazinecarboxamide [BCTC]) as well as the ß2-adrenoreceptor antagonist (150 µg butoxamine) attenuated the action of O. spinosa. Depending on molecular docking results, the activity of the extract could be attributed to the bindings of campesterol, stigmasterol, and ononin compounds to TRPV1. CONCLUSIONS: O. spinosa alleviated CAPS-induced mechanical allodynia through 2 mechanisms: the direct modulation of TRPV1 and the involvement of ß2 adrenoreceptor signaling.
ABSTRACT
BACKGROUND: Dyslipidaemias are common in patients with diabetes mellitus. A high prevalence of type 2 diabetes in hyperlipidaemic patients also exists. The aim of this study was to find a treatment that lowers both blood glucose and lipid levels simultaneously. METHODS: The hypolipidaemic effect of (R)-(-)-carvone was investigated in a tyloxapol-induced hyperlipidaemia mice model. Furthermore, its effect on insulin secretion and proliferation of 1.1E7 human pancreatic ß-cells was studied. In addition, using molecular docking, the binding affinity of (R)-(-)-carvone against 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase was estimated. RESULTS: (R)-(-)-carvone (100 mg/kg) decreased plasma triglyceride, total cholesterol, low-density lipoprotein cholesterol (LDL-C) levels and atherogenic index by 90.6%, 49.3%, 56.6% and 70.3%, respectively, but it had no effect on high-density lipoprotein cholesterol (HDL-C). Furthermore, it increased hepatic triglyceride level and catalase activity by 79.6% and 59.6%, respectively. In-vitro, 500 µM (R)-(-)-carvone increased insulin secretion by 454.4% and proliferation of 1.1E7 cells with no cytotoxic effects up to a concentration of 100 µM. Molecular docking simulation demonstrated a good binding affinity with -5.03 Kcal/mol of (R)-(-)-carvone to HMG-CoA reductase. CONCLUSION: The hypolipidaemic effect of (R)-(-)-carvone is comparable to that of fenofibrate. (R)-(-)-carvone has the advantage over fenofibrate of not producing hypoglycaemia in animals. Furthermore, (R)-(-)-carvone increased proliferation and insulin secretion of human pancreatic ß-cells.
