INSTITUTO DE INVESTIGACIONES EN CIENCIAS DE LA SALUD
Unidad Ejecutora - UE
Melatonin administration modifies the circadian motor activity under constant light depending on the lighting conditions during suckling
CARPENTIERI AR; OLIVA C; DIEZ-NOGUERA A; CAMBRAS T
TAYLOR & FRANCIS INC
Año: 2015 vol. 23 p. 1 - 1
Early lighting conditions have been described to produce long-term effects on circadian behavior, which may also influence the response to agents acting on the circadian system. It has been suggested that melatonin may act on the circadian pacemaker and as a scavenger of reactive oxygen and nitrogen species. Here, we studied the oxidative and behavioral changes caused by prolonged exposure to constant light in groups of rats that differed in melatonin administration and in lighting conditions during suckling. The rats were exposed to either a light-dark cycle (LD) or constant light (LL). At 40 days old, rats were treated for two weeks with a subcutaneous injection of melatonin (10 mg /kg body weight) or a vehicle at activity onset. Blood samples were taken before and after treatment, to determine catalase activity and nitrite level. As expected, LL-reared rats showed a more stable motor activity circadian rhythm than LD rats. Melatonin treatment produced more reactivity in LD- than in LL rats, and was also able to alter the phase of the rhythm in LD rats. There were no significant differences in nitrite levels or catalase activity between the groups, although both variables increased with time. Finally, we also tested depressive signs by means of sucrose consumption, and anhedonia was found in LD males treated with melatonin. The results suggest that the lighting conditions in early infancy are important for the long-term functionality of the circadian system, including rhythm manifestation, responses to melatonin and mood alterations.