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J Comp Physiol B

Title:		Detoxification and elimination of nicotine by nectar-feeding birds
Author(s):		Lerch-Henning S; Du Rand EE; Nicolson SW;
Address:		"Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa. Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa. ezette.durand@up.ac.za. Department of Biochemistry, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa. ezette.durand@up.ac.za"
Journal Title:		J Comp Physiol B
Year:		2017
Volume:		20170201
Issue:		4
Page Number:		591 - 602
DOI:		10.1007/s00360-016-1055-4
ISSN/ISBN:		1432-136X (Electronic) 0174-1578 (Linking)
Abstract:		"Many dilute nectars consumed by bird pollinators contain secondary metabolites, potentially toxic chemicals produced by plants as defences against herbivores. Consequently, nectar-feeding birds are challenged not only by frequent water excess, but also by the toxin content of their diet. High water turnover, however, could be advantageous to nectar consumers by enabling them to excrete secondary metabolites or their transformation products more easily. We investigated how the alkaloid nicotine, naturally present in nectar of Nicotiana species, influences osmoregulation in white-bellied sunbirds Cinnyris talatala and Cape white-eyes Zosterops virens. We also examined the metabolic fate of nicotine in these two species to shed more light on the post-ingestive mechanisms that allow nectar-feeding birds to tolerate nectar nicotine. A high concentration of nicotine (50 microM) decreased cloacal fluid output and increased its osmolality in both species, due to reduced food intake that led to dehydration. White-eyes excreted a higher proportion of the ingested nicotine-containing diet than sunbirds. However, sugar concentration did not affect nicotine detoxification and elimination. Both species metabolised nicotine, excreting very little unchanged nicotine. Cape white-eyes mainly metabolised nicotine through the cotinine metabolic pathway, with norcotinine being the most abundant metabolite in the excreta, while white-bellied sunbirds excreted mainly nornicotine. Both species also utilized phase II conjugation reactions to detoxify nicotine, with Cape white-eyes depending more on the mercapturic acid pathway to detoxify nicotine than white-bellied sunbirds. We found that sunbirds and white-eyes, despite having a similar nicotine tolerance, responded differently and used different nicotine-derived metabolites to excrete nicotine"
Keywords:		"Animal Nutritional Physiological Phenomena Animals Cotinine/metabolism Dehydration/chemically induced Eating/drug effects Inactivation, Metabolic/*physiology Nicotine/analogs & derivatives/metabolism/*pharmacokinetics Osmoregulation/drug effects Passerifo;"
Notes:		"MedlineLerch-Henning, S Du Rand, E E Nicolson, S W eng Germany 2017/02/06 J Comp Physiol B. 2017 May; 187(4):591-602. doi: 10.1007/s00360-016-1055-4. Epub 2017 Feb 1"