Hepatic glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase levels in Japanese quail following the ingestion of p,p -DDT and related compounds

Can we use stable isotopes for ecotoxicological studies? Effect of DDT on isotopic fractionation in Perca fluviatilis

Nitrogen and carbon stable isotope analyses are frequently used to assess contaminant biomagnification in animals in the wild. Previous studies, mainly on plant but also on animal tissues, have shown that chemical stress can lead to shifts in delta(15)N. In order to assess if an exposure to DDT at realistic concentration disrupted stable isotope signature in animals, delta(15)N and delta(13)C were studied in several tissues (liver, muscle, gill) of Perca fluviatilis fed with the same commercial diet uncontaminated or contaminated with DDT. We observed no DDT effect on the delta(15)N and delta(13)C of fish tissues. Our results show that stable isotopes can remain useful for field ecotoxicological studies despite food-chain contamination. However, correlations between the delta(13)C or delta(15)N values measured in the different organs were only found in DDT treated fish, suggesting some disruption of major biochemical compound metabolism in tissues.

The effects of 1,1-di(p-chlorophenyl)-2-chloroethylene (DDMU) on hepatic morphology of Japanese quail

The effects of dietary administration of 1,1-di(p-chlorophenyl)-2-chloroethylene (DDMU) to Japanese quail at a concentration of 100 ppm were investigated for periods of up to 32 days. Hepatic morphology was studied by light microscopy. Histologic changes observed included cytoplasmic and nuclear degeneration in the hepatocytes followed by severe lipid accumulation and hepatocellular hypertrophy. There was a progressive increase in cytoplasmic vacuoles containing lipid up to Day 24 followed by a decrease by Day 32 when the numbers of vacuoles remained greater than those in untreated quail livers. The vacuoles showed a distribution which followed the functional acinar units of the liver. Increased numbers and hypertrophy were observed in Kupffer cells and fibrocytes. There was an occasional necrotic hepatocyte observed but this lesion was not a prominent feature. Hepatocellular hyperplasia occurred as the lipid accumulation decreased. The histologic findings are compared with the biphasic response previously described.

The effects of 1,1-di(p-chlorophenyl)-2-chloroethylene on plasma enzymes and blood constituents in the Japanese quail

Glutamate oxaloacetate transminase (GOT), glutamate dehydrogenase (GDH), sorbitol dehydrogenase (SDH), pseudo-cholinesterase (ChE) and various blood constituents were measured in the plasma of Japanese quail fed 1,1-di(p-chlorophenyl)-2-chloroethylene (DDMU) at low levels for periods ranging from 2 to 32 days. Previous work has shown that DDMU is a potent inducer of hepatic microsomal enzymes causing marked structural changes in the liver. A rapid increase in plasma GOT was observed within 4 days accompanied by an increase in relative liver weight. Plasma GDH and SDH increased to a maximum between 16 and 24 dyas which seems to be associated with hepatic cell proliferation. Plasma ChE showed a steady increase over the time course of DDMU administration. The level of plasma lipid was reduced after 4 days whereas the hepatic lipid content was substantially increased suggesting that the fatty liver condition may be caused by decreased release of triglyceride from the liver. Plasma glucose was reduced at 8 days but there was no evidence of a hyperglycaemic state. The changes noted after 2 days of DDMU diet were confirmed by measurements on birds 18 h after oral dosing the DDMU. The study demonstrates the value of plasma enzyme measurements for the early detection of toxic effects and indicates that DDMU administration leads to extrahepatic effects in addition to those previously described in the liver.

Pesticide-induced changes in hepatic microsomal enzyme systems: further studies on the effects of 1,1,-di(p-chlorophenyl)-2-chloroethylene (DDMU) in the Japanese quail

Changes in the liver resulting from the low level dietary administration of 1,1-di(p-chlorophenyl)-2-chloroethylene (DDMU),p,p'-DDT, o,p'-DDT, p,p'-DDD and p,p'-DDE to Japanese Quail have been monitored. DDMU was exceptional in causing substantial increases in relative liver wt. and hepatic glucose-6-phosphatase after feeding at 100 ppm for 28 days. The time course of liver enzyme induction by DDMU has also been studied in Japanese Quail after periods of dietary administration ranging from 1--28 days with particular reference to changes in hepatic cytochrome P-450 and relative liver wt. Structural changes in the liver have been followed by reference to protein and lipid components. The hepatic response to DDMU appears to be biphasic. Initially there are substantial increases in hepatic cytochrome P-450 and relative liver wt., but the latter is largely due to accumulation of triglycerides. After approximately 20 days the level of hepatic cytochrome P-450 remain at a high 'plateau' level. This secondary phase of liver induction probably involves cell proliferation. It is concluded that DDMU causes major changes in the avian liver and either directly or through a metabolite causes pronounced microsomal enzyme induction.

Effect of polychlorinated biphenyls (Aroclor 1254) on liver gluconeogenic enzyme activities in embryonic and growing chickens

Fertile Nick Chick eggs were injected with 0.05, 0.1, 0.5 and 5 p.p.m. of PCB (Aroclor 1254) on day zero and were incubated until the 14th day of incubation. Nick Chick cockerels, one day old, were fed different levels of PCB in their diet for two weeks. The levels of PCB used were 0.1, 1, 5, 100 and 200 p.p.m. Key gluconeogenic enzyme activities were measured in the liver of both experimental groups. In the liver of chick embryos and growing chickens the decrease of the activity of all key gluconeogenic enzymes, with the exception of G6P-ase in embyronic liver, and FDP-ase in that of growing chickens, was estimated. The inhibited gluconeogenesis may account for the embryonic death in eggs contaminated with PCB's.