Leptin transiently antagonizes ghrelin and long-lastingly orexin in regulation of Ca2+ signaling in neuropeptide Y neurons of the arcuate nucleus

Figure 3 Prior treatment with leptin suppressed [Ca²⁺]_i responses to subsequent administration of orexin, but not ghrelin, in NPY neurons. A, C: Repeated administrations of ghrelin or orexin-A at 10^-10 mol/L increased [Ca²⁺]_i twice in single ARC neurons; B, D: Prior administration of leptin failed to inhibit the effect of ghrelin added subsequently (B), but inhibited the effect of orexin-A (D); E: The number of neurons in which [Ca²⁺]_i responses to the second ghrelin or orexin addition were suppressed by prior administration of leptin or HKRB (Control) is expressed by percentage. The numbers above the bars indicate the number of neurons whose second responses were inhibited over that exhibited first responses to ghrelin or orexin-A.