Changes in plasma gonadotrophins, 17β-oestradiol, progesterone, prolactin, thyroxine and triiodothyronine concentrations in female Japanese quail (Coturnix coturnix japonica) of a heavy body weight line during photo-induced ovarian growth and regression

Abstract

1. Simultaneous changes of the width of the cloacal opening and plasma luteinising hormone (LH), follicle stimulating hormone (FSH), 17β-oestradiol, progesterone, prolactin, thyroxine (T₄) and triiodothyronine (T₃) during photo-induced ovarian growth and regression were measured in commercially bred Japanese quail from a heavy body weight line.

2. Somatically mature female Japanese quail were transferred from short days (light:dark 8L:16D) at 10°C to long days (16L:8D) at 20°C, and sexually mature female Japanese quail were transferred from long to short days. All variables were measured at transfer and every five days thereafter (except for a measurement at 12 instead of 10 d) for 35 d.

3. Transfer from short to long days caused significant increases in LH, FSH, 17β-oestradiol, ovary weights and oviduct weights after five days, and in the cloacal opening after 12 d. T₃ decreased after five days, whereas no significant changes were observed in T₄ concentrations. Progesterone and prolactin both decreased after 25 long days.

4. The transfer of quail from long to short days caused significant decreases in LH, FSH, 17β-oestradiol, progesterone, prolactin, ovary and oviduct weights after 12 d and an increase in T₃. There was no significant change in T₄ concentrations. The cloacal opening decreased after 25 short days.

5. These results are the first to show simultaneous changes in gonadotrophins, sex steroids, thyroid hormones and prolactin during photo-induced gonadal growth and regression in female Japanese quail.

Acknowledgements

The authors express gratitude to members of the Conservation Endocrinology Research Group for practical assistance. The work was funded by the Kakapo Recovery Programme of the New Zealand Department of Conservation and the Institute of Veterinary, Animal and Biomedical Sciences Post-graduate Research Fund. SJH was a recipient of a Tuapapa Putaiao Fellowship, Foundation for Research, Science and Technology. This research was conducted under an approval from the Massey University Animal Ethics Committee.