Tissue manganese concentrations and antioxidant enzyme activities in rats given total parenteral nutrition with and without supplemental manganese.
BACKGROUND
Manganese is an essential but potentially toxic mineral. Parenteral administration of manganese via total parenteral nutrition (TPN) bypasses homeostatic mechanisms (intestinal absorption and presystemic hepatic elimination). Our objective in this study was to determine the effect of supplemental manganese in TPN solutions on manganese status in a rat model.


METHODS
Male Sprague-Dawley rats underwent jugular catheterization and were given 61.0 +/- 0.4 g/d TPN solution providing 0.5 +/- 0.2 nmol manganese/g (Mn-; n = 6) or 16 +/- 3 nmol manganese/g (Mn+; n = 7) for 7 days. Reference rats (RF; n = 8) were fed a purified diet containing 1.3 mmol manganese/g.


RESULTS
Liver manganese decreased in both TPN groups, but tibia, spleen, and pancreas manganese concentrations were greater in Mn+ rats than in Mn- or RF rats. Although no treatment differences were seen in heart or liver manganese superoxide dismutase activity, heart copper-zinc superoxide dismutase activity was lower in the Mn+ rats than in Mn- or RF rats (p < .05). Glutathione peroxidase activity was depressed in livers of both Mn- and Mn+ rats relative to RF rats (p < .0001), which was not due to selenium deficiency.


CONCLUSIONS
Supplemental parenteral manganese is taken up to a greater extent by peripheral tissues than the liver. In this first report of antioxidant enzyme activities in animals maintained with TPN, we found that TPN as well as supplemental manganese can influence antioxidant enzyme activities. We conclude that it is generally unnecessary and potentially toxic to supplement TPN solutions with manganese during short-term usage.
Malecki
E A
EA
Department of Nutritional Sciences, University of Wisconsin-Madison 53706, USA.
Lo
H C
HC
Yang
H
H
Davis
C D
CD
Ney
D M
DM
Greger
J L
JL
D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000378:metabolism; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008297:Male; D008345:Manganese / Q000008:administration & dosage* / Q000378:metabolism*; D020149:Manganese Poisoning; D009206:Myocardium / Q000201:enzymology; D010179:Pancreas / Q000378:metabolism; D010289:Parenteral Nutrition, Total; D051381:Rats; D017207:Rats, Sprague-Dawley; D012643:Selenium / Q000378:metabolism; D013154:Spleen / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013977:Tibia / Q000378:metabolism
D000975:Antioxidants; D008345:Manganese; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D012643:Selenium