Inhibitory effect of activation of cardiac TRPV1 receptors on cardiovascular activity in rats / 吉林大学学报(医学版)

ABSTRACT

Objective: To investigate the cardiovascular reflex induced by the activation of cardiac transient receptor potential vanillic acid receptor 1(TRPV1), the central location of reflex and its peripheral neurotransmitters of the rats, and to elucidate the central and peripheral neural mechanisms of cardiovascular reflex mediated by TRPV1 receptor. Methods: A total of 60 healthy male SD rats were randomly divided into control group, ido-RTX group, atropine group, immunofluorescence group and nerve tract tracking group; there were 12 rats in each group. Pericardial intubation was performed in the rats in various groups after anesthesia. The changes of heart rates and blood pressures of the rats in control group, ido-RTX group and atropine group were observed by arterial intubation. The tissue samples were collected 1 h after intropericardial injection of capsaicin in imunofluorescence group, and the co-expression of c-Fos positive neurons induced by capsaicin and cholinesterase positive neurons in the medulla oblongata was observed by immunofluorescence technigue. Intraopericardial injected carbonyl cyanine fluorescent dye (Dil) was used as retrograde tracer in nerve tract group, and the distribution of Dil positive cells in the medulla oblongata was observed by fluorescence microscope 1 week later. Results: The blood pressure and heart rate of the rats in control group were decreased significantly after intrapericardial injection of capsaicin of the rats in control group (P0. 05); after intrapericardial injection of capsaicin, the number of c-Fos positive neurons in nucleus tractus solitarii, dorsal motor nucleus of vagus and nucleus ambiguous of medulla oblongata was increased significantly (P<0. 05); most of these neurons were cholinesterase positive neurons; after intrapericardial injection of Dil, a large number of red fluorescent labeled neurons and nerve endings appeared in the nucleus tractus solitarii, dorsal motor nucleus of vagus and nucleus ambiguous. Conclusion: Intrapericardial injection of capsaicin can selectively activate the TRPV1 receptors in the heart, increase the excitability of cholinergic neurons in the cardiovascular center of the medulla oblongata, increase the peripheral release of acetylcholine, and produce an inhibitory effect on the cardiovascular activity by activating the M receptor.