Effect of ghrelin on the firing of the GnRH neurons from the brain slice of the female (metestrus and proestrus) and male mice.

<p><b>a</b> and <b>b</b>) Ghrelin (40 nM N=4 and 4 µM N=14) decreased the firing rate in the metestrus with no change in the shape of the individual spikes (insets). Time course of the instantaneous frequency is figured under the firing recordings. <b>c</b>) In proestrus, firing rate showed no change (N=11). <b>d</b>) Ghrelin administration in the male mouse resulted in a decrease in the firing rate (N=15). <b>e</b>) Bar graph shows the significant changes in the firing rate in the metestrous female (40nM-4 µM but not at 4 nM) and male, whereas ghrelin exerted no effect in the proestrous female mice. <b>f</b>) Dose-response curve of effect of ghrelin on the firing in metestrous mice (0%=full effect, 100%=no effect). Met=metestrus; Pro=proestrus. Arrow shows onset of ghrelin administration whereas double arrow marks wash-out. *=p<0.05.