Melatonin excretion in photoperiodic mammalian and bird species: chinchilla and Japanese quail

DOMINCHIN MF; BIANCONI SANTIAGO; PONZIO MF; TURINA AV; LABUCKAS DIANA; BUSSO JM

Berlín

Conferencia; 5th International Society of Wildlife Endocrinology; 2015

Photoperiodis a powerful synchronizer of seasonal changes in physiology and behavior. Melatonin(Mel) is considered a zeitgeber for seasonal photoperiodic changes and plays arole in energy expenditure and body mass regulation. Our studies explore thepossible influence of Mel in stress and reproductive responses to environmentalcues, in photoperiodic species such 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 basicinformation about melatonin excretion, determining its main route and timecourse of excretion, determining its main route and time course of excretion. LabeledMel (125I-Mel; 5µCi/male) and unlabeled Mel (25µg / 100g b.w.) were intraperitoneallyinjected to separately housed males (n=3 in each group). Excretes werecollected from each individual before (-24h) and after 125I-Melinjection (every 2 h during the first day and every 12 h until 96 h werereached). Samples were stored at −20 ºC until processing. After 125I-Meladministration in chinchilla, a radioactive peak appeared in the first urinesamples (range: 2-6 h post-excretion) and rapidly decreased; in feces, maximumradioactivity exhibited a median of 8 h post-administration (range: 6-34 h). Mostof the radioactive metabolites were recovered 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 was similar in males of both photoperiodicspecies. Chinchilla employed mainly urine as a route to excrete melatonin. Quailexhibited two radioactive peaks in excreta, presumably representing urine andfeces excretion. Future research is necessary to characterize excretedmetabolites of endogenous melatonin in order to develop and/or choose the appropriateimmunoassay.