Effect of stress and dexamethasone treatment on circadian rhythms of melatonin and corticosterone in ring dove (Streptopelia risoria).

The possible relationship between the circadian rhythm of blood levels of melatonin and corticosterone in ring dove (Streptopelia risoria) subjected to both immobilization stress and immobilization stress plus dexamethasone treatment were studied. The results show changes in the circadian rhythm of melatonin, with increased daytime levels in situations of stress accompanied by increased corticosterone levels. The highest blood melatonin levels over the 24 h of the study were obtained when the animals were treated with dexamethasone and then subjected to stress.