[Effects of glucocorticoids on cardiovascular response after microinjection of noradrenaline/neuropeptide Y into nucleus tractus solitarius and the underlying mechanism in rats]

Abstract

The present study was designed to observe the effect of glucocorticoids in the NTS on cardiovascular regulation, and to explore the effect of glucocorticoids on cardiovascular responses to microinjection of NA/NPY into the NTS. A large dosage of Dex was found to evoke a decrease of blood pressure and heart rate, and an increase of serum NO concentration. A small dosage of Dex rapidly attenuated or even abolished the cardiovascular responses to NA/NPY microinjected into NTS, and this effect continued for a longer period. It indicates that the effect of Dex on cardiovascular responses to NA/NPY is mediated through both the genomic and non-genomic pathways. As regards the non-genomic mechanism, it was found that the rapid inhibitory effect had nothing to do with the intracellular glucocorticoid receptors, but was mediated through the stimulation of GABAA receptor to decrease the depressor reflex, or decreasing the sensitivity of alpha 2-adrenergic receptor and inhibiting NO formation, or directly affecting the potassium and calcium channel in the membrane and altering the response of cardiovascular neurons in the NTS to NA/NPY.