The responses of RU486 to the effects of corticosterone sulfate on cardiovascular neurons in the rostral ventrolateral medulla of rats / 中国药理学通报

ABSTRACT

AIM　To study the roles of non-genomi c mechanism of glucocorticoid in the integration of sympathetic nervous system. METHODS　The spontaneous discharge of the identified cardiovascula r neurons in the rostral ventrolateral medulla (RVLM) were extracellularly recor ded in urethane-anaesthetized rats. The effects of microiontophoresis of cortic ostersone sulfate (CORT) on the discharge of the cardiovascular neurons in the RVLM were observed. The responses of RU 486 (a blocker for cytosolic glucocortic oids) to the effects of CORT on the cardiovascular neurons were investigated. RESULTS　Totally 33 cardiovascular neurons in the RVLM were recorded , the firing rate of 25 (76%) cardiovascular neurons increased by microiontophor esis of CORT. The effects of CORT were also positively correlated with the curre nt. In 8 (24%) cardiovascular neurons, microiontophoresis of CORT had no effect on their spontaneous discharge. In 12 of 33 cardiovascular neurons, which discha rge increased by CORT, microiontophoresis of RU 486 had no responses to the base line discharge of these cardiovascular neurons (P>0.05), but completely (3 neurons) or partially (9 neurons) blocked the excitatory effect induced by CORT. CONCLUSION　CORT had rapid excitatory effects on the cardiovascul ar neurons in the RVLM. RU 486 had no responses to the baseline activity of the cardiovascular neurons, and but completely or partially blocked the effect of CO RT on the cardiovascular neurons.