The Influence Of Ghrelin On The Hypothalamus Pvn Neuron Discharge Activity And Its Regulation

Objective:To explore the effect of electric stimulation of CA1area on the activity of gastric distention (GD) sensitive neurons in PVN and the role of ghrelin in this nerve pathway.Methods:The effects of ghrelin on GD sensitive neurons in PVN and the effects of electric stimulation of CA1area on the activity of these neurons were observed by recording extracellular potentials of single neurons. The effects of antagonist of ghrelin-[D-Lys-3]-GHRP-6were also observed to explore the receptor involved.Results:109GD sensitivity neurons were recorded in the PVN and according to their response to GD,71of them were classified as GD-excitatory (GD-E) neurons,38of them were called as GD-inhibitory (GD-I) neurons. Microinjection of ghrelin excited72%GD-E neurons (average change:38.9±7.3%; t=2.85, P<0.01, n=51) and inhibited60%GD-I neurons (average change:-45.2±6.3%; t=3.08, P<0.01, n=23). The effect of ghrelin could be blocked by antagonist of ghrelin-[D-Lys-3]-GHRP-6. Among41GD-E neurons excited by ghrelin and15GD-I neurons inhibited by ghrelin, electric stimulation of CA1area of hippocampus excited39GD-E neurons and33GD-I neurons and the excitatory effects were partially blocked by [D-Lys-3]-GHRP-6for44%GD-E neurons.Conclusion:The neurons of the hippocampus CA1area could regulate the activity of GD sensitive neurons in PVN and this effect is partial mediated by ghrelinergic fibers.