Abstract:
ob<x>jective To investigate the role and significance of cannabinoid receptor 1(CB1R) in hypothalamic paraventricular nucleus (PVN) in acute acetic acid visceral pain model, and to provide theoretical basis for clinical rational drug use. Methods 40 male C57 mice were randomly divided into 5 groups (n = 8). Firstly, the drug was micro injected into PVN, and then the mouse model of acute acetic acid visceral pain was established. The changes of writhing reaction times and peak period of writhing reaction induced by acetic acid were observed. The ex<x>pression level of c-Fos in PVN was detected by immunofluorescence staining. Results ①The number of writhing reactions in acetic acid model group was significantly higher than that in normal control group, indicating that the acute acetic acid visceral pain model was successfully established. ②Compared with PVN micro injection of normal saline, micro injection of CB1R agonist WIN55212-2 into PVN could significantly reduce the number of writhing reaction in acetic acid model group within 60 minutes, and reach the peak time in 15~30 minutes, and significantly reduce the ex<x>pression of c-Fos in PVN. ③After micro injection of CB1R antagonist AM-251 into PVN, there was no significant difference in the number of writhing reaction and the ex<x>pression of c- Fos in PVN in acetic acid model group within 60 minutes, but the writhing reaction reached the peak in 0~15 minutes. Conclusion Microinjection of CB1R agonist WIN55212-2 into PVN can reduce acute acetic acid visceral pain in mice by inhibiting ne uronal activity in PVN