VEGFR-dependent signaling contributes to postnatal brown adipose tissue development in Syrian hamsters.

In most mammals, brown adipose tissue (BAT) forms before or soon after birth, whereas Syrian hamsters are born without BAT, which develops postnatally through the proliferation and differentiation of brown adipocyte progenitors. Since sympathetic innervation and vascularization are critical for BAT function, we examined their roles in postnatal BAT formation using interscapular adipose tissue from postnatal day (P) 6-14 hamsters. Putative progenitor-like cells were sparsely distributed at P6 and became progressively more abundant throughout the tissue with postnatal age. Sympathetic innervation emerged after P8, whereas blood vessels were detectable from P6 and increased with age during BAT development. Inhibition of vascular endothelial growth factor receptor (VEGFR) signaling by SU5416 significantly reduced cell proliferation and UCP1 expression. These findings suggest that VEGFR-dependent signaling contributes to postnatal BAT development in Syrian hamsters.