Effect of melatonin on salt gland and kidney function of gulls, Larus glaucescens

Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada. <>
General and Comparative Endocrinology (Impact Factor: 2.47). 06/2007; 151(3):300-7. DOI: 10.1016/j.ygcen.2007.01.017
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This study examined effects of exogenous melatonin on osmoregulatory hormones and water and sodium secretion by salt glands and excretion via the kidneys of Glaucous-winged gulls (Larus glaucescens). Six saline acclimated gulls were injected with inulin and paraminohippuric acid and then infused with 500 mM NaCl to stimulate salt gland secretion. Each bird was given infusions of NaCl alone and NaCl plus melatonin. Experiments were made one week apart in a randomized order. A large blood sample (to measure osmoregulatory hormones) was taken before infusion, at secretion, and at the end of infusion. A small blood sample was taken at the midpoint of each of six 10 min sequential collections of salt gland secretion and urine. Melatonin tended to increase plasma sodium concentration, did decrease plasma osmolality, but did not affect potassium concentration. Melatonin did not affect salt gland secretion rate or concentration nor renal plasma flow or glomerular filtration. Melatonin increased urine flow rate, tended to increase urine sodium concentration, and did decrease urine potassium concentration. Combined renal and extrarenal sodium excretion was greater during MT treatment. During NaCl infusion, angiotensin II increased, aldosterone decreased, and arginine vasotocin remained unchanged. Melatonin did not affect these responses. These data suggest an osmoregulatory role for melatonin in birds with salt glands.

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Available from: Darin C Bennett,
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    • "Building on this foundation, recent studies of tetrapods' salt glands have taken the form of comparisons among closely related marine and freshwater species (Bennett and Hughes 2003; Babonis and Evans 2011), the role of water-regulatory proteins in modulating the secretory output of the glands (Muller et al. 2006; Babonis and Evans 2011), variation in the composition of the secretion (Butler 2002), the modulation of secretion by various endocrine and neurological agents (Reina et al. 2002; Krohn and Hildebrandt 2004; Franklin et al. 2005; Hughes et al. 2006; Butler 2007; Cramp et al. 2007; Hughes et al. 2007; Cramp et al. 2010), phenotypic plasticity of the form and function of salt glands under various environmental conditions (Cramp et al. 2008; Babonis et al. 2009; Gutierrez et al. 2011), the combined osmoregulatory function of salt glands and other organs (Hughes 2003; Laverty and Skadhauge 2008; Babonis et al. 2011), and several recent reports of bacterial infections of salt glands (Klopfleisch et al. 2005; Brito-Echeverria et al. 2009; Suepaul et al. 2010; Oros et al. 2011). Interestingly, although the basic physiology of these glands has been quite well characterized, there have been relatively few hypotheses about the convergent evolution of this specialized tissue across taxa (but see Peaker and Linzell 1975). "
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