Capacity for absorption of water-soluble secondary metabolites greater in birds than in rodents

• Autores: Karasov, William; Caviedes Vidal, Enrique Juan Raul; Bakken, Bradley Hartman; Izhaki, Ido; Samuni Blank, Michal; Arad, Zeev
• Año de publicación: 2012
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: INTESTINAL ABSORPTION; PLANT SECONDARY METABOLITES; PARACELLULAR PATHWAY; MAMMALS & BIRDS
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Plant secondary metabolites (SMs) are pervasive in animal foods and potentially influence feeding behavior, interspecies interactions, and the distribution and abundance of animals. Some of the major classes of naturally occurring SMs in plants include many water-soluble compounds in the molecular size range that could cross the intestinal epithelium via the paracellular space by diffusion or solvent drag. There are differences among species in paracellular permeability. Using Middle Eastern rodent and avian consumers of fruits containing SMs, we tested the hypothesis that avian species would have significantly higher paracellular permeability than rodent species. Permeability in intact animals was assessed using standard pharmacological methodology to measure absorption of two radiolabeled, inert, neutral water-soluble probes that do not interact with intestinal nutrient transporters, L-arabinose (M r = 150.1 Da) and lactulose (M r = 342.3 Da). We also measured absorption of labeled 3-O-methyl-D-glucose (3OMD-glucose; M r = 194.2 Da), which is a nonmetabolized analogue of D-glucose that is passively absorbed through the paracellular space but also transported across the enterocyte membranes. Most glucose was absorbed by all species, but arabinose fractional absorption (f) was nearly three times higher in birds (1.03±0.17, n = 15 in two species) compared to rodents (0.37±0.06, n = 10 in two species) (P<0.001). Surprisingly, the apparent rates of absorption in birds of arabinose exceeded those of 3OMD-glucose. Our findings are in agreement with previous work showing that the paracellular pathway is more prominent in birds relative to nonflying mammals, and suggests that birds may be challenged by greater absorption of water-soluble, dietary SMs. The increased expression of the paracellular pathway in birds hints at a tradeoff: the free energy birds gain by absorbing water-soluble nutrients passively may be offset by the metabolic demands placed on them to eliminate concomitantly absorbed SMs.
Fil: Karasov, William. University of Wisconsin; Estados Unidos
Fil: Caviedes Vidal, Enrique Juan Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina
Fil: Bakken, Bradley Hartman. University of Wisconsin; Estados Unidos
Fil: Izhaki, Ido. University Of Haifa; Israel
Fil: Samuni Blank, Michal. University Of Haifa; Israel
Fil: Arad, Zeev. University Of Haifa; Israel