text: 4-chloro-6-[(2,3-xylidine)-pirimidinylthio] acetic acid (<< WY-14,643 >>), a specific ligand of the PPAR-alpha subtype, causes the most dramatic increase in [[ UCP-3 ]] mRNA, whereas troglitazone, a specific activator of PPAR-gamma, also significantly increases UCP-3 mRNA abundance in skeletal muscle of lactating mice.