title: Simultaneous measurement of serotonin and melatonin from the intestine of old mice: the effects of daily melatonin supplementation.
abstract: Ageing is associated with important changes in gastrointestinal function and in the levels of intestinal hormones secreted. Enterochromaffin (EC) cells containing serotonin (5-HT) and melatonin may play a major role in maintaining gut function during ageing. Our aim was to characterise the mucosal availability of 5-HT and melatonin in the ileum and colon of a mouse model of ageing. Female young mice (2-5 month; n = 6), aged mice (22-24 months; n = 6) and aged mice treated with melatonin (n = 6; 10 mg/kg/day) were examined. Electrochemical methods were used to measure 5-HT and melatonin concentrations near the mucosal surface of ileum and distal colon. Amperometry studies showed that steady state levels of 5-HT from ileum and colon were decreased in aged mice treated with melatonin when compared to aged mice, while compression-evoked 5-HT release was unchanged. Differential pulse voltammetry studies showed that young mice had concentrations of 5-HT of 4.8 +/- 0.8 mum in the ileum and 4.9 +/- 1.0 mum in the colon. Concentrations of melatonin were 5.7 +/- 1.4 mum in the ileum and 5.6 +/- 1.9 mum in the colon. Compared to young mice, the levels of 5-HT and melatonin were increased in aged mice (combined ileum and colon: 5-HT = 130% and melatonin = 126% of young mice) and decreased in melatonin-treated mice (5-HT = 94% and melatonin = 82%). In conclusion, our data show that the availability of gut 5-HT and melatonin is increased in aged mice and melatonin treatment suppresses natural gastrointestinal production of 5-HT and melatonin in the aged mouse intestine.
authors.affiliation: Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia. dr.p.bertrand@gmail.com
authors.forename: P P
authors.initials: PP
authors.lastname: Bertrand
authors.forename: R L
authors.initials: RL
authors.lastname: Bertrand
authors.forename: P J
authors.initials: PJ
authors.lastname: Camello
authors.forename: M J
authors.initials: MJ
authors.lastname: Pozo
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D003106:Colon / Q000378:metabolism; D019587:Dietary Supplements; D055664:Electrochemical Techniques / Q000379:methods; D004759:Enterochromaffin Cells / Q000378:metabolism; D005260:Female; D007082:Ileum / Q000378:metabolism; D007413:Intestinal Mucosa / Q000737:chemistry* / Q000378:metabolism; D008550:Melatonin / Q000032:analysis* / Q000378:metabolism; D051379:Mice; D010084:Oxidation-Reduction; D012701:Serotonin / Q000032:analysis* / Q000378:metabolism
chemical_list: D012701:Serotonin; D008550:Melatonin