title: Age-related changes in glucose metabolizing enzymes in spleen, thymus, and pulmonary lavage cells from F344 rats.
abstract: Healthy male Fischer 344 rats were sampled at 6, 12, 18, and 24 months of age. There was no gross pathological evidence or deviations in body weight, hematology, or clinical chemistry that were indicative of disease. Mixed populations of thymus, spleen, and pulmonary cells were obtained for enzymatic analyses. Key enzymes from the hexose monophosphate shunt, glycolysis and the tricarboxylic acid cycle were evaluated to determine if there were tissue-specific or pathway-specific changes that occurred during aging. The enzyme responses among the tissues were not consistent during the aging process. Generally the activities of the glucose metabolizing enzymes in thymus and pulmonary lavage cells decreased with age whereas they increased in the spleen cells. Between 18 and 24 months enzymes representative of all three glucose metabolic pathways decreased in pulmonary lavage cells, whereas the decreases in thymic cells were mainly restricted to glycolytic enzymes. By contrast there were two- to ten-fold increases during aging in all of the splenic enzymes measured except malate dehydrogenase. The alterations in tissue enzyme activities probably reflected the changing cellular populations during aging, and in the thymic and pulmonary lavage cellular environment resulted in a loss of energy production by glucose oxidation, compared to the vigorous activity maintained in spleen.
mesh_terms: D000375:Aging; D000818:Animals; D002952:Citric Acid Cycle; D004798:Enzymes / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006019:Glycolysis; D008168:Lung / Q000378:metabolism; D008297:Male; D010427:Pentose Phosphate Pathway; D051381:Rats; D011916:Rats, Inbred F344; D013154:Spleen / Q000378:metabolism; D013950:Thymus Gland / Q000378:metabolism
chemical_list: D004798:Enzymes; D005947:Glucose