comparative study of inhibition of brain and plasma cholinesterase and hepatic and plasma aliesterases in young and adult rats following exposures to three organophosphorothionate insecticides

Young rats are more sensitive than adults to a variety of Organophosphorothionate insecticides [OPS], compounds which act in vivo by inhibition of Cholinesterase and aliesterases. Little is known, however, regarding age-related differences in biochemical responses to these toxicants. The time course of Cholinesterase and aliesterases inhibit and recovery in different tissues were compared in young [14 days of age] and adult [90-100 days of -age] rats after treatment with high sublethal intraperitoneal dosages of parathion, methyl parathion or chlorpyrifos. Young rats were more sensitive than adult in all cases [high sublethal doses for parathion, methyl parathion and chlorpyrifos; young = 0.5, 5 and 10 mg/kg, i.p.; adult = 4, 12 and 60 mg/kg, i.p... respectively]. In general, the maximal inhibition of brain regions and plasma Cholinesterase activity was not immediate with parathion and chlorpyrifos, in young and adult rats, reflecting the time required for bioactivation of the phosphorothionates as well as the effectiveness of the aliesterases to inactive much of the hepatically generated oxons. In contrast, brain regions and plasma Cholinesterase activities were rapidly inhibited following administration of methyl parathion in both age groups reflecting the low sensitivity of the aliesterases to methyl paraoxon. In general, maximal plasma and brain regions Cholinesterase inhibition was similar [greater than 80 percent] in both age groups but Cholinesterase activity recovered faster in young rats. Aliesterases were inhibited to a greater extent than acetyl cholinesterase at each sampling time with parathion and chlorpyrifos in young and adult rats where the reverse was true with methyl parathion .The very prolonged inhibition of esterase activities following chlorpyrifos treatment probably results from its substantially greater lipophilicity compared to the other compouritls, which would allow it to be stored and released for gradual bioactivation The data reported indicate that young rats are more sensitive to sublethal dosages from these compounds and that high sublethal doses exposure produce extensive plasma and different brain regions cholinesterase and plasma and liver aliesterases inhibition in both age groups. Significant inhibitor- related and age-related differences in the duration of cholinesterase and aliesterases inhibition can ensue, however, following such Organophosphorothionate insecticides exposures. Additionally, under defined experimental conditions plasma cholinesterase inhibition may be a useful quantitative index for the degree of brain cholinesterase inhibition following organophosphorous exposures

Seasonal variation in lipid metabolism in serum and tissues of the snake malpolon monspessulanus and the lizard uromastix aegyptius

Studies were carried out to examine the changes in total lipids, triglycerides, cholesterol and phospholipids metabolism in serum and different tissues during the different phases of the hibernating cycle in two of the hibernating reptiles, Malpolon monspessulanus and Uromastix aegyptius. The present results revealed the occurrence of marked and significant declines in the total lipid content of serum and tissues [liver, brain and skeletal muscle] of both Malpolon monspessulanus and Uromastix aegyptius hibernation. The data indicated active utilization of lipids during winter to supply the hibernating animals with the required energy to maintain physiological process, especially after the depletion of glycogen stores. Significant declines were recorded in the triglyceride content of serum and tissues in U. aegyptius and M. monspessulanus during hibernation. The decreases recorded in the triglyceride content reflect the hydrolysis of triglycerides to fatty acids and glycerol which may provide precursor molecules that are used for gluconeogenesis. The levels of cholesterol and phospholipids in the blood and tissues [liver, brain and skeletal muscle] of both M. monspessulanus and U. aegyptius showed significant increases during hibernation. The hypercholesterolemia recorded during hibernation may be related either to a diminution in the rate of cholesterol secretion into the bile or to a fall in the cholesterol excretion. Also, the decreased rate of catabolism and turnover may account for the increase recorded in cholesterol level during hibernation

Effect of acute administration of amphetamine sulphate on some hormones, metabolites and enzymes in serum of rat

An acute dose of amphetamine sulfate [50 mg/kg] was administered intraperitoneally to rats. The results obtained indicated that blood glucose level showed a highly significant decrease in acutely treated animals. Marked and significant increases were recorded in serum insulin and thyroxine [T4], while nonsignificant increase was recorded in triiodothyronine [T3] in rats treated with acute amphetamine. The cholesterol and triglyceride levels exhibited significant decrease in serum of rats after acute administration. Total lipids and phospholipids did not change significantly. A marked increase in serum protein concentration was recorded. On the other hand, the serum total free amino acids level showed a significant decline which might suggest that the protein biosynthesis was stimulated in rats following amphetamine treatment. The serum GOT and GPT activities exhibited highly significant increases and nonsignificant increase was recorded in alkaline phosphatase activity after acute administration of amphetamine. Elevation of serum GOT and GPT levels reflects hepatocellular damage in response to drug administration. It is proposed that the acute effect of amphetamine is related to the marked hypermetabolic state, which is produced by high doses