2-4-hexadienal and Body-Weight

Since a number of food and food products contain 2,4-hexadienal (HX), an unsaturated aldehyde, human exposure to HX is likely. Long term HX feeding to rodents induces forestomach cancers. Aldehyde dehydrogenases (ALDH) are key enzymes in the stomach for the metabolism of aldehydes. We examined the effect of short term feeding of HX on ALDH activity using HX as the substrate (HXDH) in different tissues of the GI tract. Feeding HX at a dose of 200 mg/kg body weight/day to post-suckling rats for 5 days elevated HXDH activity in the forestomach and esophagus but not in the glandular stomach, liver, small intestine or kidney. The induction of HXDH by HX was evident at 12.5 mg/kg dose and showed a dose-dependence up to 200 mg/kg. Increase in HXDH was time dependent but detectable after the first feeding (1 day). A similar dose (200 mg/kg) of acetylaldehyde or ethanol had no effect on HXDH activity. The increase in HXDH level in the forestomach and esophagus was transient. HXDH activity returned to normal 4 days after withdrawal of HX. Zymograms of gastric HXDH isozyme patterns in control and HX-fed counterparts were similar but showed selective increase in two particular forms in the forestomach. It is possible that these isoforms metabolize HX differently resulting in an accumulation of potential carcinogenic metabolites within the forestomach.

Topics: Aldehyde Dehydrogenase; Aldehydes; Alkadienes; Animals; Animals, Newborn; Body Weight; Dose-Response Relationship, Drug; Esophagus; Kinetics; L-Lactate Dehydrogenase; Lipid Peroxidation; Organ Size; Rats; Rats, Sprague-Dawley; Stomach

2,4-Hexadienal (2,4-Hx) was studied for its toxicity and carcinogenicity because of its alpha, beta-unsaturated aldehyde structure and potential link between exposure to lipid peroxidation products in the diet and human malignancies. Male and female F344N rats and B6C3F1 mice received 2,4-Hx in corn oil by gavage for 16 days, 14 weeks, or 2 years. In the 16-day studies 2,4-Hx induced forestomach necrosis and ulceration at 240 mg/kg and forestomach epithelial hyperplasia at 80 mg/kg in rats and mice. In the 14-week studies the chemical induced forestomach hyperplasia and nasal olfactory atrophy or necrosis at 120 mg/kg in rats and mice. In the 2-year studies 2,4-Hx induced squamous cell papilloma and carcinoma of the forestomach in male and female rats at 45 and 90 mg/kg and in male and female mice at 120 mg/kg. Two male mice in the 120 mg/kg group had uncommon squamous cell carcinoma of the oral cavity (tongue). Mechanistic studies indicated that the forestomach carcinogenesis in rats and mice may be due to depletion of glutathione as a result of oxidative stress induced by 2,4-Hx.

Topics: Administration, Oral; Aldehydes; Alkadienes; Animals; Body Weight; Carcinogenicity Tests; Carcinogens; Female; Food Additives; Glutathione; Hyperplasia; Liver; Male; Mice; Mice, Inbred Strains; Neoplasms, Squamous Cell; Organ Size; Oxidative Stress; Papilloma; Rats; Rats, Inbred F344; Stomach; Stomach Neoplasms

2,4-Hexadienal, a colorless to yellow liquid with a pungent "green" or citrus odor, is used as a food additive for flavor enhancement, as a fragrance agent, as a starting material or intermediate in synthetic reactions in the chemical and pharmaceutical industries, as a fumigant, and as a corrosion inhibitor for steel. 2,4-Hexadienal was nominated for study by the National Cancer Institute because of the potential for carcinogenicity based on its alpha,beta-unsaturated aldehyde structure and the potential link between exposure to lipid peroxidation products in the diet and human malignancies. The commercial product is a mixture containing chiefly trans,trans-2,4-hexadienal in equilibrium with cis,trans-2,4-hexadienal. Male and female F344/N rats and B6C3F1 mice received 2,4-hexadienal (89% trans,trans; 11% cis,trans) in corn oil by gavage for 16 days, 14 weeks, or 2 years. Tissues and plasma from dosed rats were examined for malondialdehyde and glutathione concentrations, and DNA adducts were characterized in liver and forestomach samples from dosed rats and mice. Genetic toxicology studies were conducted in Salmonella typhimurium, rat and mouse bone marrow cells, and mouse peripheral blood erythrocytes. 16-DAY STUDY IN RATS: Groups of five male and five female rats were administered 0, 3, 9, 27, 80, or 240 mg 2,4-hexadienal/kg body weight in corn oil by gavage, 5 days per week, for 16 days. Three male and three female 240 mg/kg rats died before the end of the study. Mean body weight gains of 240 mg/kg rats were significantly less than those of the vehicle controls. Clinical findings included diarrhea, ataxia, lethargy, and nasal/eye discharge in males, and lethargy, paleness, and abnormal breathing in females in the 240 mg/kg groups. Liver weights of 240 mg/kg females were significantly greater than those of the vehicle controls. Gross and microscopic lesions indicative of forestomach necrosis and ulceration were present in most 240 mg/kg rats, and forestomach epithelial hyperplasia was microscopically evident in most 80 mg/kg rats. 16-DAY STUDY IN MICE: Groups of five male and five female mice were administered 2,4-hexadienal in corn oil by gavage at doses of 0, 3, 9, 27, 80, or 240 mg/kg, 5 days per week, for 16 days. Chemical-related deaths occurred in one male and one female in the 240 mg/kg groups. Female mice in the 240 mg/kg group lost weight during the study. Gross and microscopic lesions indicative of forestomach necrosis and ulceration were pre. 2,4-Hexadienal was mutagenic in S. typhimurium strain TA100 with and without induced hamster or rat liver enzymes; no mutagenic activity was detected with strains TA1535 or TA98, with or without S9. Results of bone marrow tests in male rats and male mice given intraperitoneal injections of 2,4-hexadienal showed a small increase in the induction of micronucleated erythrocytes. However, neither test was repeated, and the test results were judged to be inconclusive. Results of peripheral blood micronucleus tests in male and female mice treated with 2,4-hexadienal by gavage for 14 weeks were negative.. Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenic activity* of 2,4-hexadienal in male and female F344/N rats and male and female B6C3F1 mice based on increased incidences of squamous cell neoplasms of the forestomach. The occurrence of squamous cell carcinoma of the oral cavity (tongue) in male B6C3F1 mice may have been related to the administration of 2,4-hexadienal. Hyperplasia of the forestomach in male and female rats and mice was associated with administration of 2,4-hexadienal. Synonyms: Hexa-2,4-dienal; 2,4-hexadienal; 2,4-hexadien-1-al; 2,4-Hx; 1,3-pentadiene-1-carboxaldehyde; 2-propylene acrolein; sorbaldehyde; sorbic aldehyde

Topics: Aldehydes; Alkadienes; Animals; Body Weight; Carcinogens; DNA Adducts; Estrous Cycle; Intubation, Gastrointestinal; Mice; Mice, Inbred Strains; Mutagens; Organ Size; Oxidative Stress; Rats; Rats, Inbred F344; Reproduction