Endocrinology
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Peroxisome proliferator-activated receptors (PPARs) are transcription factors involved in the regulation of numerous metabolic processes. The PPARalpha isotype is abundant in liver and activated by fasting. However, it is not very clear what other nutritional conditions activate PPARalpha. ⋯ Remarkably, in PPARalpha null mice on HFD, PPARgamma mRNA was 20-fold elevated compared with wild-type mice fed a LFD, reaching expression levels of PPARalpha in normal mice. Adenoviral overexpression of PPARgamma in liver indicated that PPARgamma can up-regulate genes involved in lipo/adipogenesis but also characteristic PPARalpha targets involved in fatty acid oxidation. It is concluded that 1) PPARalpha and PPARalpha-signaling are activated in liver by chronic high-fat feeding; and 2) PPARgamma may compensate for PPARalpha in PPARalpha null mice on HFD.