title: Contrasting apoptotic responses of conjugated linoleic acid in the liver of obese Zucker rats fed palm oil or ovine fat.
abstract: We hypothesized that reducing weight properties of conjugated linoleic acid (CLA) are due to adipocyte apoptosis and that CLA differentially modulates the apoptotic responses in hepatic lipotoxicity from rats fed saturated fat diets. Obese Zucker rats were fed atherogenic diets (2%w/w of cholesterol) formulated with high (15%w/w) saturated fat, from vegetable or animal origin, supplemented or not with 1% of a mixture (1:1) of cis-9, trans-11 and trans-10, cis-12 CLA isomers for 14 weeks. CLA induced no changes on retroperitoneal fat depot weight, which was in line with similar levels of apoptosis. Interestingly, CLA had a contrasting effect on cell death in the liver according to the dietary fat. CLA increased hepatocyte apoptosis, associated with upregulation of Fas protein in rats fed palm oil, compared to rats receiving palm oil alone. However, rats fed ovine fat alone displayed the highest levels of hepatic cell death, which were decreased in rats fed ovine fat plus CLA. This reducing effect of CLA was related to positively restoring endoplasmic reticulum (ER) ATF-6α, BiP and CHOP protein levels and increasing phosphorylated c-Jun NH(2)-terminal kinase (JNK) and c-Jun, thus suggesting an adaptive response of cell survival. These findings reinforce the role of CLA as regulator of apoptosis in the liver. Moreover, the dietary fat composition is a key factor in activation of apoptosis.
authors: CIISA, Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Pólo Universitário do Alto da Ajuda, Lisboa, Portugal. ampalopes@fmv.utl.pt
authors: Paula A
authors: PA
authors: Lopes
authors: Susana V
authors: SV
authors: Martins
authors: Ricardo S J
authors: RS
authors: Viana
authors: Rita M
authors: RM
authors: Ramalho
authors: Cristina M
authors: CM
authors: Alfaia
authors: Mário S
authors: MS
authors: Pinho
authors: Eliana
authors: E
authors: Jerónimo
authors: Rui J B
authors: RJ
authors: Bessa
authors: Matilde F
authors: MF
authors: Castro
authors: Cecília M P
authors: CM
authors: Rodrigues
authors: José A M
authors: JA
authors: Prates