Involvement of melatonin and thyroid hormones in the control of sleep, food intake and energy metabolism in the domestic fowl.

Abstract

SUMMARY1. Growing male domestic fowl of an egg-laying strain were fed ad libitum and injected intraperitoneally with melatonin or intramuscularly with triiodothyronine (T3) to study the effects on sleep, food intake, blood glucose, e.e.g., oxygen consumption and carbon dioxide production.2. Melatonin caused a dose-related depression of food intake with sleep and aphagia lasting for 21 hr following 8 mg, drowsiness and greatly reduced intake following 4 and 2 mg and a slight reduction in food intake after 1 mg.3. T3 injection was followed by increased feeding within the range 50-200 jug. The higher dose (200 jug) completely prevented the effects of 10 mg melatonin injected simultaneously.4. Melatonin (10 mg) depressed plasma glucose levels whereas T3 (200 ,sg) elevated blood glucose.5. Either darkness or melatonin (10 mg) caused an increase in amplitude and a decrease in frequency of the e.e.g. 6. Birds fasted for 3 hr before injection showed significantly lower oxygen consumption and carbon dioxide production when given melatonin (10 mg); T3 had no effect within the 4 hr period after injection and did not modify the effects of melatonin.7. It is postulated that the rapid effects of melatonin and T3 which were observed result from direct effects of these hormones on the central nervous system.

The effect of pinealectomy on oxygen consumption and rectal temperature of adult hens

“…It can be presumed that the high level of this hormone during the dark period is related to the decline in the metabolic rate occurring at this time. This conclusion is supported by the results of Bermudez et al (1983) who showed that injections of melatonin significantly decrease oxygen consumption in young cockerels. In the present experiment, we did not measure the plasma melatonin level in hens, but the literature data indicate that pinealectomy completely destroys the circadian rhythm of plasma melatonin levels (Pelham, 1975;Cogburn et al, 1987).…”

“…This hypothesis is borne out by the results of Injidi and Fobres (1983) who found that pinealectomized cockerels fed during complete darkness, in contrast with control birds. On the other hand, melatonin injections reduce feed intake and cause sleep (Bermudez et al, 1983;Injidi and Fobres, 1983).…”

“…The pineal gland mediates the effects of light on an organism, and its hormone, melatonin, has several important physiological functions. It has been found that administering large doses of melatonin decreases feed consumption by chicks and induces sleep (Bermudez et al, 1983). Melatonin infusions also restore sleep suppressed in pigeons exposed to continuous light (Philips and Berger et al, 1992).…”

Melatonin and Peripheral Circuitries: Insights on Appetite and Metabolism in Danio Rerio

“…[6][7][8][9] Melatonin is produced rhythmically with high levels at night and low levels during the day in both diurnal and nocturnal species, 4 and its effect on food intake is often different (appetite stimulation, inhibition, or no effect) depending on the habits of each species. [10][11][12][13] In particular, our recent study on the central regulation of appetite in zebrafish demonstrated that melatonin is able to modulate not only food intake but also the most central appetite signals. 9 It has been demonstrated that melatonin, the hormonal mediator of biological rhythms, also acts at the peripheral level affecting adiposity, growth, and body weight, in both mammals and fish, although such effects are highly variable.…”

The influence of long-term melatonin administration on basic physiological and metabolic variables of young Wistar:Han rats

“…MEL effects on food intake are controversial. It was demonstrated that MEL administration decreased the food intake in rats (Ishibashi et al, 1966), in domestic fowls (Bermudez et al, 1983), in hamsters (Bartness & Wade, 1985) and in fishes (Pinillos et al, 2001); while the other authors does not found any effect of MEL on food intake in rats (Dark et al, 1980;Wolden-Hanson et al, 2000). On the contrary, other studies in rodents reported the increase of food intake as a result of exogenous MEL administration (Bubenik & Pang, 1994;Shaji & Kulkarni, 1998) or melatonin agonist (Le Gouic et al, 1996).…”