ABSTRACT
The effects of Co(II) and Mn (II) supplements at abundant as well as, deficient doses on in vitro synthesis of serum lipoproteins in rats maintained on normal and atherogenic diets were studied. While an adequate oral supplement of Co(II) or iv administration of Mn (II) at very low doses to the experimental rats fed on salt-free stock ration diet produces hyperlipidemic changes in increasing C/P ratio in serum and also the serum LP content. On the other hand, the animals on atherogenic diet supplemented with deficient Co(II) or excess Mn(II) results in a lowering of hyperlipidemia and hyperlipoproteinemia, with concomitant decrease in C/P ratio. Dietary lipids (eg. cholesterol, butter-fat etc.) vis-a-vis Mn (II) deficiency or Co(II) in excess reflect a homeostatic control mechanism for keeping the excess lipid in a state of solution as lipoprotein complexes. Deficient Co(II) or excess Mn (II) in turn, results in a decrease in protein synthesis and a relatively impaired rate of secretion of protein from liver to serum. Moreover, Mn (II) deficiency increases, while its abundance, significantly restricts 14C- labelled amino acid incorporation into alpha 2-lipoprotein molecules. Neither cobalt depletion, nor its adequate oral substitution help improvise the hepatic synthesis of alpha 2-apolipoproteins in experimental animals. This situation remains unaltered even by overloading the diets with saturated fats or by other atherogenic agents, instead of vegetable oils preferably rich in mono or dienoic fatty acids.