Hepatic triglyceride (TG) (top) and cholesterol (bottom) in wild-type (controls) and peroxisome proliferator-activated receptor–α (PPAR-α) knockout (KO) mice. Study groups received the PN–ω-6 regimen, either alone (PN–ω6) or supplemented with oral pioglitazone (PN–ω-6 + Pio) (*P < .05, **P < .01, compared with controls). PN-O, oral, fat-free parenteral nutrition (PN) solution only; PN–ω-6, PN-O plus intraperitoneal (IP) ω-6 fatty acid (FA)–predominant supplements; PN–ω-3, PN-O plus IP ω-3 FA.