Melatonin excretion in photoperiodic mammalian and bird species: Chinchilla and Japanese quail.

DOMINCHIN MF; BIANCONI S; PONZIO MF; TURINA AV; LABUCKAS D; BUSSO JM

Berlin

Conferencia; V International Society of Wildlife Endocrinology (ISWE) Conference; 2015

International Society of Wildlife Endocrinology

Photoperiod is a powerful synchronizer of seasonal changes in physiology and behavior. Melatonin (Mel) is considered azeitgeber for seasonal photoperiodic changes and plays a role in energy expenditure and body mass regulation. Our studiesexplore the possible influence of Mel in stress and reproductive responses to environmental cues, in photoperiodic speciessuch as chinchilla (Chinchilla lanigera) and Japanese quail (Coturnix coturnix japonica). To develop a reliable non-invasivemethod to monitor pineal function, we designed an experiment to generate basic information about melatonin excretion,determining its main route and time course of excretion, determining its main route and time course of excretion. Labeled Mel(125I-Mel; 5μCi/male) and unlabeled Mel (25μg / 100g b.w.) were intraperitoneally injected to separately housed males (n=3 ineach group). Excretes were collected from each individual before (-24h) and after 125I-Mel injection (every 2 h during the firstday and every 12 h until 96 h were reached). Samples were stored at -20 ºC until processing. After 125I-Mel administration inchinchilla, a radioactive peak appeared in the first urine samples (range: 2-6 h post-excretion) and rapidly decreased; in feces,maximum radioactivity exhibited a median of 8 h post-administration (range: 6-34 h). Most of the radioactive metabolites wererecovered in urine (median 92.65 ± 2.64%). In quail, peak excretion occurred at 3 h (range 2- 4 h). In all birds, a secondsmaller peak was observed between 8 and 12 h; total recovery was 90.57 ± 5.57%. In conclusion, the excretion pattern wassimilar in males of both photoperiodic species. Chinchilla employed mainly urine as a route to excrete melatonin. Quailexhibited two radioactive peaks in excreta, presumably representing urine and feces excretion. Future research is necessary tocharacterize excreted metabolites of endogenous melatonin in order to develop and/or choose the appropriate immunoassay.