FIG. 7.

Steady-state levels of total STAT3 and phosphorylated STAT3 are increased in LepRb-Socs3-OE mice. A: The 6-week-old control and LepRb-Socs3-OE mice were injected with either saline or leptin (3 mg/kg), and perfused 45 min later. Double immunofluorescence analysis was carried out to examine pSTAT3 in different areas of hypothalamus and in POMC neurons. ARC, arcuate nucleus; VMH, ventromedial hypothalamus; DMH, dorsomedial hypothalamus; PH, posterior hypothalamic area. Representatives of leptin-injected mice are shown to illustrate different regions of the hypothalamus. B: Quantification of pSTAT3-positive cells in different areas of the hypothalamus and in POMC neurons. n = 3–5 sections per mouse from 3–4 mice per group between bregma −1.94 and −2.30. C: LepRb-Socs3-OE and control mice were fasted overnight and injected with leptin (3 mg/kg). Mice were killed 1 h later; hypothalamic protein extract was prepared. Western blot analysis was performed with equal amount of total protein input, and pSTAT3 was examined. The same blots were stripped and blotted with an antibody to detect total STAT3 protein levels. Sal, saline; Lep, leptin. D: Free-fed LepRb-Socs3-OE and control mice were killed, and hypothalamic protein extracts were prepared. Western blot analysis was performed to examine total STAT3 expression levels. The same blot was stripped and subsequently blotted with GAPDH. *P < 0.05, between controls and mutants as determined by Student t test.