Copper deficiency in rodents alters dopamine beta-mono-oxygenase activity, mRNA and protein level.
Cu is an essential cofactor for at least twelve mammalian enzymes including dopamine beta-mono-oxygenase (DBM), which converts dopamine (DA) to noradrenaline (NA). Previous studies reported that certain Cu-deficient (Cu-) rat tissues have lower NA and higher DA than Cu-adequate (Cu+) tissues, suggesting that DBM function was impaired. However, in vitro studies suggested that DBM activity is higher in Cu- tissue. Experiments were conducted on adrenal glands (AG), medulla oblongata/pons (MO), vas deferens (VD) and heart (HT) from a single rat experiment to provide data to help clarify this puzzling contradiction. In vitro DBM activity assays showed Cu- samples had significantly higher activity than Cu+ samples in both AG and MO, but not VD. Activity data were confirmed by Western immunoblots. Quantitative real-time PCR demonstrated higher DBM mRNA in Cu- tissues but unaltered levels of several other cuproenzymes and Cu-binding proteins. Previous pharmacological data implied that high DBM was associated with low NA. HPLC analyses confirmed that NA and DA levels in Cu- MO, VD and HT were significantly lower and higher, respectively, than in Cu+ tissues. However, the NA content of AG was not statistically lower. Furthermore there was no correlation between higher DBM mRNA and lower NA in four Cu-tissues. Adequate dietary Cu is essential to support DBM function in vivo but additional studies are needed to determine the mechanism for increased DBM transcription associated with Cu deficiency.
Nelson
Kyle T
KT
Department of Biochemistry and Molecular Biology, University of Minnesota Medical School Duluth, 1035 University Drive, Duluth, MN 55812, USA.
Prohaska
Joseph R
JR
D000311:Adrenal Glands / Q000201:enzymology; D000818:Animals; D000831:Animals, Newborn; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000302:isolation & purification; D000918:Antibody Specificity; D015153:Blotting, Western / Q000379:methods; D003300:Copper / Q000172:deficiency*; D004299:Dopamine beta-Hydroxylase / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression; D008297:Male; D008526:Medulla Oblongata / Q000201:enzymology; D051379:Mice; D009638:Norepinephrine / Q000032:analysis; D011149:Pons / Q000201:enzymology; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014649:Vas Deferens / Q000201:enzymology
D000911:Antibodies, Monoclonal; D012333:RNA, Messenger; D003300:Copper; D004299:Dopamine beta-Hydroxylase; D009638:Norepinephrine