Morphological bases for intestinal paracellular absorption in bats and rodents

Author(s)

Brun, Antonio ^{[1, 2]} ; Fernandez Marinone, Guido ^[3] ; Price, Edwin R. ^[4] ; Nell, Lucas A. ^[5] ; Simoes, Beatriz M. V. ^[6] ; Castellar, Alexandre ^[6] ; Gontero-Fourcade, Manuel ^{[3, 1]} ; Cruz-Neto, Ariovaldo P. ^[6] ; Karasov, William H. ^[2] ; Caviedes-Vidal, Enrique ^{[3, 1]}

Affiliation

^[1] Consejo Nacl Invest Cient & Tecn, Inst Multidisciplinario Invest Biol San Luis, San Luis - Argentina

^[2] Univ Wisconsin, Dept Forest & Wildlife Ecol, 1630 Linden Dr, Madison, WI 53706 - USA

^[3] Univ Nacl San Luis, Fac Quim Bioquim & Farm, Dept Bioquim & Ciencias Biol, San Luis - Argentina

^[4] Univ North Texas, Dept Biol Sci, Denton, TX - USA

^[5] Univ Wisconsin, Dept Integrat Biol, Madison, WI - USA

^[6] Univ Estadual Paulista Julio de Mesquita Filho Ri, Dept Zool, Inst Biociencias, Sao Paulo - Brazil

• Document type: Journal article
• Source: Journal of Morphology; v. 280, n. 9 JULY 2019.
• Web of Science Citations: 1

Abstract

Flying mammals present unique intestinal adaptations, such as lower intestinal surface area than nonflying mammals, and they compensate for this with higher paracellular absorption of glucose. There is no consensus about the mechanistic bases for this physiological phenomenon. The surface area of the small intestine is a key determinant of the absorptive capacity by both the transcellular and the paracellular pathways; thus, information about intestinal surface area and micro-anatomical structure can help explain differences among species in absorptive capacity. In order to elucidate a possible mechanism for the high paracellular nutrient absorption in bats, we performed a comparative analysis of intestinal villi architecture and enterocyte size and number in microchiropterans and rodents. We collected data from intestines of six bat species and five rodent species using hematoxylin and eosin staining and histological measurements. For the analysis we added measurements from published studies employing similar methodology, making in total a comparison of nine species each of rodents and bats. Bats presented shorter intestines than rodents. After correction for body size differences, bats had similar to 41% less nominal surface area (NSA) than rodents. Villous enhancement of surface area (SEF) was similar to 64% greater in bats than in rodents, mainly because of longer villi and a greater density of villi in bat intestines. Both taxa exhibited similar enterocyte diameter. Bats exceeded rodents by similar to 103% in enterocyte density per cm(2) NSA, but they do not significantly differ in total number of enterocytes per whole animal. In addition, there is a correlation between SEF and clearance per cm(2) NSA of L-arabinose, a nonactively transported paracellular probe. We infer that an increased enterocyte density per cm(2) NSA corresponds to increased density of tight junctions per cm(2) NSA, which provides a partial mechanistic explanation for understanding the high paracellular absorption observed in bats compared to nonflying mammals. (AU)

• FAPESP's process: 12/04610-5 - Comparative analysis of the gastrointestnal traits and routes of nutrient absorption in bats and rodents: evidence for convergent adapation with birds?
• Grantee: Ariovaldo Pereira da Cruz-Neto
• Support Opportunities: Regular Research Grants