Ghrelin Stimulation of Growth Hormone-Releasing Hormone Neurons Is Direct in the Arcuate Nucleus
Figure 1
Ghrelin enhanced the activity of GHRH neurons.
A, time course of an experiment where the superfusion of a sagittal brain slice with 10 nM ghrelin increased, in a reversible manner, the rate of spontaneous action potentials of a GHRH neuron (individual traces shown on the top). B, summary of the effects of ghrelin (10 nM) on the cumulative distributions of action potential frequencies in GHRH neurons from adult males; C, mean effects of 0.3 to 10 nM ghrelin on the rate of spontaneous action potentials in GHRH neurons: the action potential frequencies observed at the half maximal values of the cumulated histograms were collected in each experiment in the absence and presence of ghrelin (see Methods for details). D, the proportion of stimulatory effects induced by ghrelin increased in a dose-dependent manner in GHRH neurons. E, summary of the effects of ghrelin (10 nM) on the distributions of action potential frequencies in GHRH neurons from adult females. In B & E, the symbols and lines are the means and sem. Statistical differences (p<0.05, paired student-t test) between curves are framed by the grey areas. In D, the bars and lines are the means and sem of the numbers of experiments indicated. ***, statistical difference from control values (p<0.001, paired student-t test).