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 microanatomical 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~41% less nominal surface area (NSA) than rodents. Villous enhancement of surface area (SEF) was~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~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. K E Y W O R D Sbats, enterocytes, nutrient absorption, rodents, small intestine surface area
Heatwaves and warm spells at global level, product of climate change, causes alterations on homeostasis in animals (heat stress), so they must respond to these changes in order to survive. The response involves several physiological changes, such as releasing of glucocorticoids and catecholamines, to restore homeostasis. Due the lack of knowledge on this subject in wild birds, the objective of the present work was study the effect of heat stress on body condition and digestive system in house sparrows (Passer domesticus), as well as a possible role of capsaicin as a dietary additive in mitigating heat stress. In this work, we measure heterophils/lymphocytes ratio (as proxy of stress), body mass, hematocrit, uric acid and digestive enzymes (intestinal and pancreatic) under stress conditions at 32 degrees Celsius and under normal conditions at 22 degrees Celsius. In addition, we evaluate the effect of capsaicin in both situations (heat stress at 32 degrees Celsius and normal condition 22 degrees Celsius). We found an increase of H/L ratio and uric acid in plasma under heat stress, and decrease of H/L ratio with capsaicin on animals exposed to heat stress. Although a loss of intestinal mass was observed in animals exposed at 32 degrees Celsius, digestive enzyme activity does not change under heat stress or under capsaicin administration. Improving knowledge in this field is relevant at the level of animal nutrition and veterinary medicine, reducing the stress of wild birds in captivity and improving dietary mixes for future global warming scenarios.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.