Permanent uncoupling of male-specific CYP2C11 transcription/translation by perinatal glutamate.

Perinatal exposure of rats and mice to the typically reported 4mg/g bd wt dose of monosodium glutamate (MSG) results in a complete block in GH secretion as well as obesity, growth retardation and a profound suppression of several cytochrome P450s, including CYP2C11, the predominant male-specific isoform--all irreversible effects. In contrast, we have found that a lower dose of the food additive, 2mg/g bd wt on alternate days for the first 9days of life results in a transient neonatal depletion of plasma GH, a subsequent permanent overexpression of CYP2C11 as well as subnormal (mini) GH pulse amplitudes in an otherwise normal adult masculine episodic GH profile. The overexpressed CYP2C11 was characterized by a 250% increase in mRNA, but only a 40 to 50% increase in CYP2C11 protein and its catalytic activity. Using freshly isolated hepatocytes as well as primary cultures exposed to the masculine-like episodic GH profile, we observed normal induction, activation, nuclear translocation and binding to the CYP2C11 promoter of the GH-dependent signal transducers required for CYP2C11 transcription. The disproportionately lower expression levels of CYP2C11 protein were associated with dramatically high expression levels of an aberrant, presumably nontranslated CYP2C11 mRNA, a 200% increase in CYP2C11 ubiquitination and a 70-80% decline in miRNAs associated, at normal levels, with a suppression of CYP2C expression. Whereas the GH-responsiveness of CYP2C7 and CYP2C6 as well as albumin was normal in the MSG-derived hepatocytes, the abnormal expression of CYP2C11 was permanent and irreversible.

Characterization of binding between 17ß-estradiol and estriol with humic acid via NMR and biochemical analysis.

Endocrine disruptors, such as 17ß-estradiol (E2) and estriol (E3), are ubiquitously found in the environment and their presence has gained recognition as a significant health risk. Sorption of estrogens by dissolved organic matter (DOM) influences their concentration and effects. Although there is some experimental evidence suggesting that sorption occurs through hydrophobic interactions, there is not a complete understanding of this association. Therefore, we sought to more extensively characterize binding between humic acid (HA), a major component of DOM, with E2 and E3 using nuclear magnetic resonance spectroscopy (NMR). Our results indicate that binding between these estrogens and HA occurs primarily at the aromatic ring, and takes place even at relatively low HA concentration. Specific interactions between E2 and HA were confirmed by assessing binding via ELISA assay, and the effect of binding on estrogenic activity was studied via a yeast bioassay. Together, these studies build upon previously theorized interactions, yielding a more comprehensive model of binding between estrogens and HA, as well as demonstrate the value of the confluence of biochemical assay methods with analytical NMR techniques.