Effects of genistein on neuronal discharges in paraventricular nucleus of rat hypothalamic slices / 中国药理学与毒理学杂志

ABSTRACT

AIM To study the central role of genistein (GST) in regulating cardiovascular function of nervous center by examining the effects of GST on the electrical activity of rat paraventricular nucleus neurons in slice preparation and to elucidate the mechanism involved. METHODS Using extracellular single-unit discharge recording technique to examine discharges of neurons in paraventricular nucleus of hypothalamic slices at the resting potential level. RESULTS ①In response to the application of GST 10, 50 and 100 μmol·L-1, respectively, in the perfusate for 2 min, the spontaneous discharge rates (SDR) of neurons in 25/26 hypothalamic slices were significantly decreased in a concentration-dependent manner. ②Pretreatment with L-glutamate 0.2 mmol·L-1 led to a marked increase in the SDR of slices in an epileptiform pattern. GST 50 μmol·L-1 significantly attenuated the increased SDR in all 7 slices. ③In 8/8 slices, the G protein-coupled inwardly rectifying K+ channels (GIRKs) antagonist, tetraethylammonium 1 mmol·L-1 completely blocked the inhibitory effect of GST 50 μmol·L-1. ④Pretreatment with nitric oxide synthase inhibitor Nω-nitro-L-arginine methyl ester 50 μmol·L-1 increased SDR in all 7 slices, but did not affect the inhibitory effect of GST 50 μmol·L-1. CONCLUSION GST can inhibit the electrical activity of paraventricular neurons, and play a protective role on the central neurons. The inhibitory effect of GST may be related to the activation of GIRKs which induce K+ outward current and then engender the cell membrane hyperpolarization, but be not due to the NO release.