[Diurnal rhythms of thyroid hormones in rooster chicks (Gallus domesticus). 1. Studies on the colloid epithelium portion, the radioiodine accumulation in the thyroid gland and the plasma radioiodide concentration].
Four and five week old White Leghorn cockerels were investigated concerning diurnal changes of thyroidal activity. They were kept under normal conditions, including the changes in day light (light from 5.00 am to 8.00 pm). In the thyroid maxima of the per cent amount of colloid were found at 3.00 am and at noon. The values differed significantly from the intermediate ones (2P less than 0.001) which reached only 22 per cent of the maxima. The thyroidal uptake of radioiodine had also a maximum at 3.00 am (51 percent and 78 percent resp., 90 min. or 24 hours p.i.). The 24-h uptake at 3.00 am was significant different from the corresponding uptakes between 6.00 am and 6.00 pm (53-61 percent; 2P less than 0.05). The plasma radioiodide increased at afternoon and in the evening. The 9.00 pm concentration differed significantly from the 9.00 am concentration (2P less than 0.001). Since in the afternoon most of the food is ingested the thyroid can take up a greater amount of untracered iodide and therefore the radioiodide concentration of plasma may remain high. The above observations may be explained in the following way: (1) The thyroidal iodine uptake is increased in the afternoon corresponding to the increase in colloid; however these increase is not detectable by measuring the radioiodine uptake because of dilution effects (during the night the increase in colloid coincidences with the increase in iodine uptake); (2) looking at the daily changes of colloid and radioiodine uptake the thyroid may be stimulated in the early morning and in the evening.
D000818:Animals; D002645:Chickens / Q000502:physiology*; D002940:Circadian Rhythm; D003102:Colloids; D004032:Diet; D004847:Epithelial Cells; D004848:Epithelium / Q000502:physiology; D007455:Iodine / Q000097:blood / Q000378:metabolism; D007457:Iodine Radioisotopes; D008297:Male; D013961:Thyroid Gland / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors
D003102:Colloids; D007457:Iodine Radioisotopes; D007455:Iodine
Tageszyklische Schwankungen der Schiddrüsenhormone bei Hähnchen (Gallus domesticus). I. Untersuchungen des Epithel-Kolloid-Anteils und der Radiojodspeicherung der Schiddrüse sowie des Radiojodidgehalts des Plasmas