Parasite infection and caloric restriction induce physiological and morphological plasticity

To investigate the effects of parasitism and caloric restriction on morphol ogy (body composition, organ mass) and physiology (resting metabolism, inte stinal glucose transport capacity), we gave laboratory mice intestinal para sites (Heligmosomoides polygyrus, Nematoda), 30% caloric restriction, or bo th. Calorically restricted mice had smaller body mass, enhanced glucose tra nsport capacity, and lower resting metabolism than ad libitum-fed mice. Par asitized mice maintained body mass, had diminished intestinal glucose trans port capacity, and greater resting metabolism than unparasitized mice. Para sitized, calorically restricted mice had smaller organ masses than parasiti zed, ad libitum-fed mice and did not increase their glucose uptake rate as much as unparasitized, calorically restricted mice. There was a significant interaction between caloric restriction and parasite status for morphologi cal variables but not for physiological variables. Knowing the types of phe notypic changes that occur with simultaneous parasitism and caloric restric tion will provide insight into understanding human helminthiasis in food-re stricted communities and also how wild animals cope with environments where parasitism and seasonal food restriction are common.