Serum calcitonin, calcium and thyroxine in young and old Zucker fatty rats (fa/fa).
We determined the serum levels of calcitonin (CT), calcium (Ca), and thyroxine (Ti) in lean (?/+) and fatty (fa/fa) male Zucker rats 10 weeks and 10-12 months of age. The most dramatic finding was a high level of serum CT (3.24 +/- 1.18 ng/ml) in young fatties whereas sera from young leans were all below the limit of assay detection (less than 0.120 ng/ml, p less than 0.01). Young fat rats also had elevated levels of both Ca (11.2 +/- 0.2 vs. 9.7 +/- 0.2 mg/dl, p less than 0.001) and Ti (6.7 +/- 0.48 vs. 4.72 +/- 0.28 micrograms/dl, p less than 0.01). In older animals the mean serum level of CT increased further in the fatties and became readily measurable in leans (5.67 +/- 1.94 vs. 1.49 +/- 0.55, p less than 0.01). Thyroid C-cells, identified immunohistochemically, were abundant in both leans and fatties at this age but were substantially more numerous in the fat rats (p less than 0.001). Calcium levels increased somewhat in the older leans, but still remained higher in the fat rats (p less than 0.05). Thyroxine values were essentially the same for old animals of both genotypes (5.07 +/- 0.61 vs. 5.54 +/- 0.88). Age effects were not significant for any measure in the fat animals, but in the leans there were significant age-related increases in CT (p less than 0.02) and serum Ca (p less than 0.05).
D000367:Age Factors; D000818:Animals; D001835:Body Weight; D002116:Calcitonin / Q000097:blood*; D002118:Calcium / Q000097:blood*; D008297:Male; D051381:Rats; D011922:Rats, Mutant Strains / Q000097:blood*; D011924:Rats, Zucker / Q000097:blood* / Q000235:genetics; D013961:Thyroid Gland / Q000166:cytology; D013974:Thyroxine / Q000097:blood*
D002116:Calcitonin; D013974:Thyroxine; D002118:Calcium