Dopamine-deficient (DD) mice cannot synthesize dopamine (DA) in dopaminergic neurons due to selective inactivation of the tyrosine hydroxylase gene in those neurons. These mice become hypoactive and hypophagic and die of starvation by 4 weeks of age. We used gene therapy to ascertain where DA replacement in the brain restores feeding and other behaviors in DD mice. Restoration of DA production within the caudate putamen restores feeding on regular chow and nest-building behavior, whereas restoration of DA production in the nucleus accumbens restores exploratory behavior. Replacement of DA to either region restores preference for sucrose or a palatable diet without fully rescuing coordination or initiation of movement. These data suggest that a fundamental difference exists between feeding for sustenance and the ability to prefer rewarding substances.
Brachial plexus nerve sheath tumors are challenging mass lesions that should be evaluated and surgically resected by an experienced team of physicians to optimize clinical outcome.
Commercial PCB mixtures have been shown to induce liver tumors in female rats and this effect has been attributed to the effects of PCBs on estrogen metabolism. Catechol metabolites of PCBs are potent inhibitors of COMT activity and are likely to contribute significantly to reduced clearance of genotoxic catechol metabolites of estrogen. The effect of PCB metabolites on COMT expression in cultured cells was investigated to explore potential mechanisms by which PCB exposure alters catechol estrogen clearance. We hypothesize that estrogenic PCB metabolites may contribute to reduction of COMT expression via interaction with the estrogen receptor. To test this hypothesis, human MCF-7 cells were exposed to PCB analogues and the expression of COMT determined. Western blot analysis demonstrated that COMT protein levels were statistically significantly reduced by both the phenolic and the catechol compounds, an effect which was abolished by the anti-estrogen, ICI182780. The above suggests that COMT levels may be reduced by estrogenic PCB metabolites, via interactions between PCB metabolites and the ER. It supports the hypothesis that both phenolic and catechol metabolites of PCBs may contribute to PCB-mediated carcinogenesis through reduction of COMT levels and activities and subsequent reduction in clearance of endogenous and xenobiotic catechols.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.