ABSTRACT
Objective: To investigate the effects of muscarinic cholinergic receptor 3 (M3R) antagonist 4-diphenylacetoxy-N -methylpiperidine methiodide (4-DAMP) on the growth of small cell lung cancer and angiogenesis in nude mice. Methods: The mRNA and protein expressions of M3R in human small cell lung cancer SBC3 cells were detected by RT-PCR and Western blotting, respectively. The subcutaneous transplantation tumor model of SBC3 cells in nude mice was established. The model mice were randomly divided intofour groups, then intraperitoneally injected with 0.9% sodium chloride solution (as the control group) and different doses of 4-DAMP (0.5, 1 and 2 mg/kg), respectively (once a day, for 15 days). The size of xenograft tumor was measured every 2 days. After the nude mice were sacrificed, the tumor mass was measured, and the tumor inhibitory rate was calculated. The expressions of M3R and vascular endothelial growth factor (VEGF) in the tumor tissues were detected by real-time fluorescent quantitative PCR and Western blotting, respectively. The microvessel density (MVD) and VEGF expression were detected by immunohistochemistry. Results: Human small cell lung cancer SBC3 cells expressed M3R mRNA and protein. After the subcutaneous transplantation tumor model of SBC3 cells in nude mice was successfully established and treated with different doses (0.5-2 mg/kg) of 4-DAMP, the sizes of xenograft tumors were significantly decreased as compared with the control group (all P < 0.05), and the weights of tumor tissues were significantly reduced (all P < 0.01). The tumor growth inhibitory rates in 0.5, 1 and 2 mg/kg 4-DAMP-treated groups were 15.82%, 33.54% and 55.06%, respectively. Furthermore, the relative expression levels of M3R and VEGF as well as MVD in the tumor tissues of 0.5, 1 and 2 mg/kg 4-DAMP-treated groups were significantly down-regulated as compared with the control group (all P < 0.05). Conclusion: M3R antagonist 4-DAMP can inhibit the growth and angiogenesis of human small cell lung cancer in nude mice.
ABSTRACT
Aim To observe the protective effects of choline and pilocarpine,the M3 receptor agonists,on the arrhythmias of Wistar rats induced by barium chloride.Methods Barium chloride was used to induce the experimental arrhythmias of Wistar rats.Choline,pilocarpine,and 4-diphenylacetoxy-N-methylpiperidine-methiodide (4-DAMP),the selective antagonist of M3 receptor,were used to explore the effects of M3 receptor on the arrhythmias induced by barium chloride.The occurence and the severity of arrhythmias were observed.Results Choline 10 mg?kg-1 and pilocarpine 0.2 mg?kg-1 inhibited the occurence of arrhythmias,shortened the duration of arrhythmias (P
ABSTRACT
BACKGROUND: Peripheral nerve injury may produce a syndrome consisting of spontaneous pain, allodynia and hyperpathia. In previous study, we examined the antiallodynic action produced by intrathecal (i.t.) cholinesterase inhibitors (ChEi) in a neuropathic pain rat model and the reversal of antiallodynic state by i.t. atropine, muscarinic antagonist, but not by nicotinic antagonist mecamylamine. The purpose of this study was to determine the selective antagonistic action of four subtypes of muscarinic receptor on antiallodynic state by i.t. ChEi in a rat model of neuropathic pain. METHODS: Sprague Dawley rats were prepared with tight ligation of left L5/L6 spinal nerves with 6-0 black silk and chronic lumbar intrathecal catheters. After obtaining the baseline hindpaw withdrawal scores, edrophonium (100 microgram) or neostigmine (10 microgram) was administered intrathecally. Tactile allodynia was measured using von Frey filaments and allodynic threshold was calculated by the up-down method. Allodynic changes were tested at 15, 30, 45, 60, 90, 120 and 180 minutes. To examine the reversal of antiallodynia and to compare the antagonizing action of antiallodynic state produced by i.t. administration of ChEi, non-selective muscarinic receptor antagonists atropine (10 microgram), M1 antagonist pirenzepine (3 microgram), M2 antagonist methoctramine (3 microgram), M3 antagonist 4-DAMP (3 microgram) and M4 antagonist tropicamide (3 microgram) were injected intrathecally respectively 5 minutes prior to the injection of edrophonium or neostigmine. RESULTS: Antiallodynia produced by i.t. edrophonium was reversed by pretreatment with i.t. methoctramine, 4-DAMP, tropicamide and pirenzepine (P<0.05). On the contrary, antiallodynic state made by i.t. neostigmine was not antagonized by methoctramine, 4-DAMP and tropicamide. M1 antagonist pirenzepine had a moderate, statistically significant (P<0.05) effect on reversal of increased allodynic threshold while atropine showed a complete antagonism. CONCLUSION: These experiments suggest that antialllodynic action of cholinesterase inhibitors is likely due to mediation of spinal muscarinic system and M1 receptor subtype is more likely involved in this mechanism.