| Abstract: | The purpose of the work was to establish the eventual "metabolic toxicity" of pesticide-contaminated diets in the Rat. The liver metabolic response to various stimuli was compared in dithiocarbamate-fed animals and in non-contaminated ones. 112 weanling male Wistar CF rats were fed, during 15 days, with a demi-synthetic control diet. They were then divided into 4 lots:--the control group C, which went on to receive the same diet,--the nabame group N, the diet of which was supplemented with 275 ppm of the dithiocarbamate;--the thirame groupe R, receiving the control diet + 600 ppm thirame;--the zineb groupe Z, given the control diet + 3 600 ppm Zineb. The animals were fed with these diets during 14 days, their dithiocarbamate intake thus averaging 1/20 th of the per os LD 50/rat/day. At the end of this 2-week period, each of the 4 groups was divided into 4 sub-groups, all the animals were fasted overnight, then sacrified:--after no other treatment (sub-groups T);--30 minutes after an i.p. injection of 2.6 g/kg glucose (G);--after having been forced to walk in a restraint wheel for 50 minutes/hr during the 18 hrs of the night fast (sub-groups W);--after a 90 minutes exposure in a cold room (F). The weights of the animals, of their liver, heart, kidneys, adrenals and epididymal pads were recorded. In their liver, the following compounds were determined: water, proteins, total lipids, triglycerides, long-chain acyl-CoA, non-esterified fatty acids, total cholesterol, glycogen, glucose, alpha-glycerophosphate. The thirame rats had a lower food intake than the others and the smallest body weight, but their relative liver and kidneys weights were the highest. The nabame animals did not differ from the control ones but the zineb rats had the lightest epididymal fat pads. The primary effects of the dithiocarbamate diets on liver metabolism were apparently not the same in the 3 groups compared to the control ones: nabame and thirame increased glycogen, thirame increased the lipid compounds: long-chain actyl-CoA and triglycerides, where as zineb feeding resulted in an increase of glucose concentration and in a decrease of triglycerides and total lipids. Muscular exercise, or cold exposure, had the following effects compared to those they had in the control group: a greater glucose utilization in the nabame and thirame rats, a smaller glycogen and glucose utilization, associated with an increase of alpha-glycerophosphate, in the zineb animals. These results were considered altogether with those obtained in a previous paper by the same authors, which concerned liver ketone bodies and adenine nucleotides changes after the same experimental conditions, and it was concluded that the 3 dithiocarbamates actually had a common effect on rat metabolism: they all impaired glucose utilization by the liver. Also, fat mobilization from peripheral depots was shown to occur in the 3 experimental groups, resulting in liver fatty acid oxidation in the nabame and zineb rats, and in liver steatosis for the thirame ones... |
