TABLE 3

Effect of leptin on the food intake

Preinjection (kcal/d)Postinjection (kcal/d)Decrease (%)
3-Day control
 Vehicle72.4 ± 7.869.2 ± 6.64 ± 2
 Leptin71.4 ± 5.950.5 ± 3.4*29 ± 3*
3-Day ad libitum
 Vehicle109.2 ± 4.5103.9 ± 3.85 ± 1
 Leptin107.3 ± 9.6105.3 ± 4.32 ± 1
 High leptin98.1 ± 8.787.1 ± 6.711 ± 5
  • Data are means ± SE. The effect of a single subcutaneous injection of leptin or vehicle was tested in rats fed either a high-fat diet or normal chow for 3 days. The subcutaneous injection of leptin 2 mg/kg body wt decreased food intake by ∼30% in chow-fed rats (3-day control). However, injection of the same dose in rats overfed for 3 days (3-day ad libitum) failed to alter food intake compared with subcutaneous vehicle injection. To further characterize the feeding response in this model, leptin was also injected at a 2.5-fold higher dose (high leptin, 5 mg/kg body wt) in 3-day overfed rats. Leptin modestly decreased food intake by ∼11%.

  • *

    * P < 0.01 vs. vehicle.