Figure 5.

Ghrelin and leptin fail to modulate cytoplasmic-free Ca²⁺ levels in arcuate NPY neurons from Tg2576 mice. A, Ghrelin increases cytoplasmic-free Ca²⁺ levels in arcuate NPY neurons from WT but not Tg2576 mice. Cytoplasmic-free Ca²⁺ was measured using fura-2 AM in arcuate NPY neurons isolated by enzymatic digestion from WT or Tg2576 mice. After obtaining baseline levels, cells were perfused with ghrelin (100 nm). n = 34 WT and n = 7 Tg2576 cells from ≥ 3 mice per group. Statistical analysis: two-tailed paired Student's t test (WT: t = 2.664, df = 34, p = 0.0117; Tg2576: t = 1.020, df = 7, p = 0.3471). B, Leptin decreases cytoplasmic-free Ca²⁺ levels in arcuate NPY neurons from WT but not Tg2576 mice. Cytoplasmic-free Ca²⁺ was measured using fura-2 AM in arcuate NPY neurons isolated by enzymatic digestion from WT or Tg2576 mice. After obtaining baseline levels, cells were perfused with leptin (100 nm). n = 25 WT and n = 20 Tg2576 cells from ≥ 3 mice per group. Statistical analysis: two-tailed paired Student's t test (WT: t = 3.032, df = 24, p = 0.0057; Tg2576: t = 2.030, df = 19, p = 0.0566). C, I–V relationships for L-type Ca²⁺ currents in arcuate NPY neurons from WT brain slices after application of leptin (100 nm). Compared with vehicle treatment, leptin significantly decreased the peak L-type Ca²⁺ current at 0 mV. Data are represented as L-type Ca²⁺ current density (pA/pF). n = 7 cells per group. Statistical analysis at 0 mV: two-tailed paired Student's t test (t = 3.601, df = 6, p = 0.0114). D, I–V relationships for L-type Ca²⁺ currents in arcuate NPY neurons from Tg2576 brain slices after application of leptin (100 nm). Compared with vehicle treatment, there is no significant difference in L-type Ca²⁺ currents. Data are represented as L-type Ca²⁺ current density (pA/pF). n = 4 cells per group. Statistical analysis at −20 mV: two-tailed paired Student's t test (t = 1.379, df = 3, p = 0.2617). Data are mean ± SEM. *p < 0.05. **p < 0.01.