Expression of leptin and leptin receptor (LepR) in cerebral cortex of young (10–12 week) and old (48–52 week) wild-type (WT) and 5XFAD (Tg) mice. Leptin was detected in neurons and endothelial cells in (a) young-WT, (b) young-Tg and (c) old-WT mice. Leptin was detected in neurons and glia in (d) old-Tg mice. LepR expression was also detected in neurons and endothelial cells of (e) young-WT, (f) young-Tg and (g) old-WT mice. Moreover, LepR was observed to be expressed by neurons as well glia in (h) old-Tg mice. Block arrows—neurons; pointed arrows—endothelial cells; *—glia. Scale bar for large figures, 100 μm; smaller figures in bottom left, 20 μm.