Season-related post-embryonic changes in the diurnal rhythm of AA-NAT activity in the chicken pineal gland
2006
Nowak, K. | Majewski, P.,Uniwersytet Warszawski, Warszawa (Poland). Zaklad Fizjologii Zwierzat | Waloch, M.,Panstwowy Zaklad Higieny, Warszawa (Poland) | Skwarlo-Sonta, K.,Uniwersytet Warszawski, Warszawa (Poland). Zaklad Fizjologii Zwierzat
The aim of the present study was to examine early post-embryonic changes in the rhythm of AA-NAT activity in chickens hatched in summer and winter. Experiments were performed on Hi-Line cockerels kept from the time of hatching in the artificial photoperiod L:D 12:12. Pineal glands were collected from 2-, 9-, and 16-day-old chicks killed at light or at 1, 5 or 8 h of darkness. Regardless of season and age, AA-NAT activity was elevated during darkness, however, in winter it was lowest in the youngest birds and increased with age. Surprisingly, in all chicks hatched in the summer, the magnitude of the nocturnal peak of AA-NAT activity was similar to that found in adult birds reared under the natural photoperiod. This suggests the existence of a photoperiodic memory in the chicken pineal gland, the molecular mechanisms of which are currently being investigated
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