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Title: Relationship of the wasting syndrome to lethality in rats treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Authors: Christian, B J; Inhorn, S L; Peterson, R E

Published In Toxicol Appl Pharmacol, (1986 Feb)

Abstract: Young adult male Sprague-Dawley rats treated with a LD95 dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exhibited a progressive reduction in feed intake and body weight until death occurred 15 to 32 days post-treatment. The time course and magnitude of weight loss and lethality of pair-fed control rats were essentially identical to that of TCDD-treated rats with each pair-fed control animal dying within 3 days of its TCDD-treated partner. Body composition analysis of the dead animals revealed that the total amounts of protein, fat, water, and ash in the carcasses of TCDD-treated and pair-fed control rats were each reduced to a similar extent. The temporal pattern of daily feed intake in TCDD-treated and pair-fed control rats (3 meals/day) or (1 meal/day) did not influence the results. Studies conducted at LD25-62 doses of TCDD in male Sprague-Dawley rats of different ages--weanling (90 g), young adult (275 g), and mature (450 g)--showed that the severity of the wasting syndrome in all age groups was greatest for animals that died. Also, young adult rats treated with a LD25 dose of TCDD that died displayed the same degree of hypophagia and weight loss prior to death as rats administered a LD95 dose. Histopathology of the liver and gastrointestinal tract was compared in TCDD-treated (LD95 dose) and pair-fed control rats killed 1 day before they otherwise would have died. Hepatocytes of TCDD-treated rats were enlarged relative to those of pair-fed control rats and contained nuclei that varied in size and number. Pair-fed control rats exhibited atrophy of the liver cords due to a decrease in the cytoplasmic volume of their hepatocytes. The stomach and small intestine of TCDD-treated rats were histologically similar to those of ad libitum-fed controls. In contrast, the glandular mucosa of the stomach of pair-fed control rats was ulcerated and the intestinal mucosa was atrophied. Stomach ulcers were the source of clotted blood found throughout the gastrointestinal tract of pair-fed control rats but not that of TCDD-treated animals. These findings demonstrate that hypophagia-induced weight loss is one of perhaps several responses that contribute to the death of TCDD-treated rats. That other responses are also involved is suggested by differences between pair-fed control and TCDD-treated rats in the weight and histopathology of certain organs. In addition, gastrointestinal blood loss contributes to the death of pair-fed control rats but not TCDD-treated animals.

PubMed ID: 3945951 Exiting the NIEHS site

MeSH Terms: Aging; Animals; Body Weight/drug effects*; Dioxins/toxicity*; Feeding Behavior/physiology; Gastric Mucosa/pathology; Intestinal Mucosa/pathology; Intestine, Small/pathology; Liver/pathology; Male; Organ Size/drug effects; Polychlorinated Dibenzodioxins/toxicity*; Rats; Rats, Inbred Strains

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