Regulation of Retinoid Homeostasis

atRA regulates retinoid homeostasis. It induces LRAT transcription ~ 100-fold and induces CRBP(I) transcription. These may be housekeeping functions that maintain retinol esterification and handling during vitamin A sufficiency. On the other hand, induction of CYP26A1 by atRA can be viewed both as a general mechanism of clearance and as a site-specific mechanism to maintain an environment during specific stages of development.

Several xenobiotics, including ethanol and poly-chlorinated biphenyls, reduce RE stores, possibly through enhancing atRA catabolism by inducing CYP. In addition, clofibrate, a ligand of PPARa (peroxisome proliferator activated receptor), causes a remarkably rapid depletion of liver retinoids and decreases TTR mRNA fourfold. In contrast, PPAR7, expressed in liver stellate cells among others, induces transcription of carotene 15,15'-monooxygenase. PPAR7 also induces expression of CRBP(I), CRBP(II), LRAT, and RARft. These actions of PPARa and -7 with retinoids reflect their effects on lipid metabolism: PPARa enhances fatty acid cata-bolism, whereas PPAR7 enhances adipogenesis and fatty acid storage.

Breaking Bulimia

Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

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