Spontaneous ovarian adenocarcinoma in the domestic turkey breeder hen (Meleagris gallopavo): effects of photoperiod and melatonin.
OBJECTIVE
The effect of photoperiod or melatonin treatments on ovarian adenocarcinoma in turkey breeder hens (Meleagris gallopavo) was investigated to evaluate the usefulness of this animal as a model for studying ovarian cancer.


METHODS
In Experiment 1, photoperiod effects were tested by exposing turkeys with ovarian tumors to 8 wks of short days (8:16LD) followed by a 12 wk period of long days (16:8LD). In Experiment 2, exogenous melatonin was administered to turkeys during long day-induced development of ovarian tumors. In both experiments, the stage of tumor growth was scored weekly on a scale of 0 to 4.


RESULTS
It was clear that exposure to short days produced complete regression of tumors, with a mean time to score 0 of 4.4 wks. Following re-exposure to a long photoperiod, all of the same birds showed re-growth of the ovarian tumor with a mean time to first palpable detection of 5.4 wks. When melatonin was administered daily during the long photoperiod (Experiment 2), there was a significant delay in the re-growth of tumors.


CONCLUSIONS
It was clear from this study that the growth of solid ovarian tumors in the turkey breeder hen was promoted by long photoperiods and ceased, to the point of remission, on short photoperiods. Thus, ovarian adenocarcinoma in turkeys can be completely manipulated by photoperiod. In addition, treatment with melatonin attenuates tumor growth in the turkey hen. The results suggest that the domestic turkey hen is a useful in vivo model for studying spontaneous ovarian adenocarcinoma.
Moore
Christopher B
CB
Department of Poultry Science, North Carolina State University, Raleigh, North Carolina 27695-7608, USA. tom_siopes@ncsu.edu
Siopes
Thomas D
TD
D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D008027:Light; D008550:Melatonin / Q000502:physiology*; D010051:Ovarian Neoplasms / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D017440:Photoperiod; D011201:Poultry Diseases / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D014422:Turkeys / Q000378:metabolism* / Q000502:physiology
D008550:Melatonin