Rat Neutrophil Phagocytosis Following Feed Restriction

Abstract:

Migration to zymozan and spontaneous migration of neutrophils, ingestion of small hydrophilic particles (HEMA) or large cells (Saccharomyces cerevisiae) and reduction of nitroblue tetrazolium salts (NBT) were investigated in rats with defined food restriction; animals fed ad libitum served as controls. All animals of a specific-pathogen-free grade were housed under constant temperature, humidity, light/dark regime. Stimulated migration to zymozan did not significantly change in animals with slight feed restriction, but it was reduced following both moderate and the greatest restriction. Diet restriction did not significantly influence spontaneous migration of neutrophils. Both chemotactic indices and differentials fall in the first instance but regenerate afterwards. Phagocytic activity of neutrophils diminished during the first two weeks of feed restriction, but a statistically significant decrease was observed only in the group with the greatest restriction (reduction to 20% of normal feed) in the assay using large cells. Phagocytic activity at the end of the experiment, i.e. after 4 weeks of restriction was not significantly different when compared with controls although body weight reduced markedly. The phagocytic index using small particles dropped only after 4 weeks of restriction, whereas in the assay using large cells a decline of phagocytic index was observed after two weeks in the greatest restriction and after four weeks in both restricted groups. Reduction of tetrazolium salts was significantly elevated after both moderate and severe diet restriction, this elevation persisted until the end of the study. Rules for the appropriate prediction of undesirable effects of xenobiotics on phagocytosis from preclinical to clinical studies are discussed.