Effects of dried fish on antioxidant levels in rat liver.

Short-term feeding studies were carried out to investigate the effect of ingestion of salted dried fish on alterations in tissue lipid peroxidation and modulation of the activities of detoxification enzymes in liver in order to study the induction of oxidative stress. Rats were fed diets with either 5, 10 and 20% dried mackerel for 4 weeks and levels of antioxidants in liver were estimated. The results showed that the fish intake at 10 and 20% dietary level reduced glutathione with a reciprocal increase in thiobarbituric acid reactive substances and a concomitant decrease in antioxidant vitamins A and C contents in liver. A significant decline in the activities of hepatic glutathione peroxidase and glutathione reductase were also observed at these levels of fish consumption. Kidney gamma-glutamyl transpeptidase activity on the other hand was increased abnormally at 20% fish intake. The results suggested that the dried fish consumption at higher concentrations (at 10 and 20%) for a short period caused lowering of the activities of antioxidative enzymes thereby inducing oxidative stress in rat liver.

Effect of increased level of CO2 exposure in a closed environment on calcium and phosphorus balance in rats.

In rats, exposed to increased ambient CO2 level (1.5%) for 30 days a 40% reduction in food intake during first 10 days was observed which subsequently improved. Similarly the body weight also declined initially, which showed progressive gain thereafter, almost reaching that of ad libitum fed control by 30th day. The lowered Ca intake consequent to reduced food consumption was followed by diminution in renal and faecal excretion of Ca. The lowered renal Ca excretion was probably unrelated to reduced Ca intake, since the pair-fed-control, not exposed to raised CO2 level, did not show any such alteration. The net result was a drastic reduction in Ca balance despite the diminution in its excretion. Though the intake and renal excretion of P were reduced in the CO2 exposed group due to a reduction in food intake, the P balance showed a cyclic pattern as in the pair-fed controls. The serum Ca after 30 days' exposure remained unchanged while the serum inorganic P showed a variation. The data indicated that hypercapnia produced hypophagia which affected growth of rats. The reduced renal excretion of Ca may not pose a risk on calcification of soft tissues, since its retention was also reduced on exposure to raised concentration of CO2.