Diurnal Variation of Plasmatic Melatonin, Corticosterone and Variation of General Activity in Pigeons under Light-Dark Cycle and Constant Light

ZANI DE SOUZA ; ROSA E SILVA AA; CALDAS MCS; VALENTINUZZI VS; FERRARI, E.A.M

BIOLOGICAL RHYTHM RESEARCH

Swets & Zeilinger

Lugar: Leiden; Año: 2001 vol. 32 p. 243 - 254

0929-1016

This work analyzed the diurnal variation of general activity and plasmatic levels of melatonin and corticosterone in pigeons submitted to a light-dark (LD) cycle or to constant light (LL). In both conditions pigeons were observed in 5-min sessions at times 03:00, 06:00, 09:00, 12:00, 15:00, 18:00, 21:00 and 24:00 during two sucessive days. Behavior was video taped in the homecages for posterior categorization and quantification. Blood samples were obtained at the same time of behavioral observation. Radioimmunoassays were used to evaluate pasmatic levels of melatonin and corticosterone. In the LD condition the results showed day-night variation of general activity and a robust diurnal rhythm of plamatic melatonin. Both of these variations as well as the oscillatory secretion of corticosterone disappeared under constant the constant light condition. The possible correlations between rhymicity in melatonin and corticosterone secretion and general activity are discussed.