Secretion of calcitonin from the thyroid gland increases in aged rats.
Age-related changes in the secretion rate of immunoreactive calcitonin against antiserum for human calcitonin (iCT) from the thyroid gland were investigated in adult (4-5 months old) and aged (24-29 months old) male Wistar rats anesthetized with 1.0-1.2% halothane. The secretion rate of iCT was calculated by measuring the concentration of iCT using a radioimmunoassay method in both the thyroid venous blood plasma and the systemic arterial blood plasma, as well as measuring the thyroid blood plasma flow. The secretion rate of iCT was 0.271 +/- 0.063 ng.kg-1.min-1 in the adult and 1.248 +/- 0.147 ng.kg-1.min-1 in the aged rats, indicating a significant increase in secretion in the aged rats. The concentration of iCT in the systemic arterial blood plasma was 0.091 +/- 0.013 ng/ml in the adult and 0.480 +/- 0.026 ng/ml in the aged rats. The age-related increase in the secretion rate of iCT from the thyroid gland seems to result in an increase in iCT concentration in the systemic arterial blood plasma. Furthermore, the content of iCT in the thyroid gland was also increased in the aged rats. Therefore, it is suggested that both the synthesis and secretion of iCT in the thyroid gland are increased in aged rats.
Kurosawa
M
M
Department of Physiology, Tokyo Metropolitan Institute of Gerontology, Japan.
Sato
A
A
Shiraki
M
M
Takahashi
Y
Y
D000375:Aging / Q000502:physiology*; D000818:Animals; D002116:Calcitonin / Q000097:blood*; D002118:Calcium / Q000097:blood; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013961:Thyroid Gland / Q000378:metabolism*
D002116:Calcitonin; D002118:Calcium