Figure 1. Insulin suppresses ghrelin-induced [Ca2+]i increases in ARC NPY neurons. (A) Administration of 10−10 M ghrelin increased [Ca2+]i and administration of 10−12 M insulin suppressed the ghrelin-induced [Ca2+]i increases in a single neuron isolated from ARC. This neuron was subsequently identified as an NPY containing neuron by immunocytochemistry. (B) Fourteen of 19 ghrelin-activated insulin-inhibited neurons (74%) were NPY neurons. (C) The percentage of insulin-inhibited neurons among ghrelin-activated neurons. (D) The amplitude of suppression of ghrelin-induced [Ca2+]i increases by insulin is expressed as percent suppression. n=23, 17, 34 and 27 for 10−16 M, 10−14 M, 10−12 M and 10−10 M insulin, respectively. Bars in (D) represent means ± SE. *p < 0.05.