title: Ex vivo bupivacaine treatment results in increased adipogenesis of skeletal muscle cells in the rat.
abstract: Intramuscular adipose tissue (IMAT) is observed in some skeletal muscle pathologies. IMAT is implicated not only in the disorders of muscle contraction, but also of metabolism and insulin sensitivity due to its nature as a secretary organ. Several studies indicate the presence of cells with adipogenic potential in skeletal muscle. However, the mechanism of fate specification that triggers these cells to enter an adipogenic program in vivo remains to be solved. In the present study, we examined whether activation of the adipogenic program of muscle-resident cells precedes their proliferation upon muscle injury. For this purpose, muscle injury was induced by injecting bupivacaine (BPVC) to excised skeletal muscle ex vivo. Cells isolated from ex vivo BPVC-treated muscle exhibited higher adipogenic potential than those from saline-treated muscle. Pre-plating exposure of skeletal muscle cells to basic fibroblast growth factor (bFGF) mimicked the effect of ex vivo BPVC-treatment, suggesting that bFGF released from extracellular matrix in response to muscle injury activates their adipogenic program. Interestingly, the number of myotubes were significantly reduced in the culture from BPVC-treated muscle, suggesting that adipocytes negatively regulate myogenesis.
authors.affiliation: Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, Japan.
authors.forename: Keitaro
authors.initials: K
authors.lastname: Yamanouchi
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Nakamura
authors.forename: Yuki
authors.initials: Y
authors.lastname: Takegahara
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Nakano
authors.forename: Masugi
authors.initials: M
authors.lastname: Nishihara
mesh_terms: D050156:Adipogenesis / Q000187:drug effects*; D000818:Animals; D002045:Bupivacaine / Q000494:pharmacology*; D007150:Immunohistochemistry; D008297:Male; D018482:Muscle, Skeletal / Q000293:injuries / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D002045:Bupivacaine
keywords: adipogenesis; basic fibroblast growth factor; bupivacaine; intramuscular adipose tissue; muscle injury