HISTOLOGICAL AND BIOCHEMICAL STUDIES ON THE EFFECT OF NICKEL IN BIOLOGICAL SYSTEMS

Abstract

The present study is in two parts. Part I deals with biochemical, histopathological and structural changes induced by intramuscular administration of cumulative doses of NiS0..7H_0 in rat liver and kidney. Part II reports the biochemical effects of NiS0..7H20 on peanut seedlings with special reference to some key enzymes involved in mobilizing the stored food from the cotyledons to different anatomical parts of the plant during germination and early growth and development period and also some plasma membrane bound enzymes which may act as bioindicators for the stress conditions. Part I: Intramuscular administration of cumulative dose of NiSO.. 7Ho0 4 2 (0.5 - 2mg/100g body weight) in rats for a period of 15 days produced a dose dependent loss in body weight. The nickel contents of liver and kidney increased from 15ppm to 166ppm in liver and from 16ppm to 2G8ppm in kidney in rats which were given NiS0..7H„0 doses (2mg/100g body weight) indicating bioaccumu1 at ion of nickel in these tissues. Protein and carbohydrate contents of both liver and kidney were also significantly decreased, but in contrast the concentration of total lipids in these organs was markedly increased. In fact, a 3-4-fold increase in neutral and phospholipids was observed in both rat liver and kidney as a result of nickel treatment. A detailed study of the changes induced by nickel in the composition of various components of neutral and glycerophosphatidy1 lipids in rat liver and kidney by GC and HPLC showed that the increase in neutral lipids was largely due to increase in the level of triacy1glycerol and esterified cholesterol while in the case of g lycerophosphatidy1 lipids, it was mainly due to phosphatidyl choline. These results indicated a selective action of nickel, apparently by enhancing the rate of synthesis of triacylglycerol, esterified cholesterol and glycerophosphatidy1 choline in liver and kidney cells. Nickel has also altered the percentage composition of various components of lipids of the subcellular membrane fractions. The relative proportion of phosphatidyl choline th« m«-i phosnholin^ • ,. cnoune, the major component of Bhl ' " membr—• — significantly increased in all subcellular fractions with maximum increase in .1. I followed bv i-„i„j increase in plasma membrane owed by Golg, apparatus. mitochondrial membranes and the endoplasmic reticulum. The proportion of phosphatidyl .th , • the second most abundant .,ycerophosphat idy^ ,J£ "fL Z ""^ *"" -: r-:r:r;hrept nur ~~ ^