Figure 2.

Effect of leptin on epithelial proliferation and localization of leptin-receptor subtypes in the skin. (a and d) Hematoxylin/eosin-stained frozen sections from 10-day wounds isolated from the same C57BL/6J-ob/ob individual that had been treated topically with 1 μg leptin/20 μL PBS twice a day on the left-side wounds (a) or PBS only on the right-side wounds (d), respectively. Arrows indicate the leading edge of the migrating epithelium. (b and e) Frozen sections from 5-day wounds isolated from leptin-treated (intraperitoneally) (b) or PBS-injected (e) C57BL/6J-ob/ob mice were incubated with a monospecific, polyclonal Ab directed against murine Ki67. (c) Frozen section from a 13-day wound isolated from a leptin-treated (intraperitoneally) mouse. The section was incubated with a monospecific polyclonal Ab against the ObRb-receptor subtype. (f) Frozen section from a 7-day wound isolated from a PBS-treated (intraperitoneally) mouse. The section was incubated with a monospecific polyclonal Ab against the ObRb-receptor subtype. Note that the epithelium did not extend into the granulation tissue (compare to b, epithelium of leptin-treated mouse, 5 days). (g) Frozen section from a 13-day wound isolated from a wild-type mouse (BALB/c). The section was incubated with a monospecific polyclonal Ab recognizing the ObRb- and ObRa-receptor subtypes. Sections were stained with the avidin-biotin-peroxidase complex system using 3-amino-9-ethylcarbazole as a chromogenic substrate (b, c, e, f, g). Nuclei were counterstained with hematoxylin. Strongly immunopositive signals within the sections are indicated with arrows. e, epithelium; g, granulation tissue; he, hyperproliferative epithelium; s, scab.