Compensatory parathyroid hypertrophy after hemiparathyroidectomy in rats feeding a low calcium diet |
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Authors: | Dr Marta Ladizesky María C Diáz Susana Zeni Horacio E Romeo Daniel P Cardinali Carlos A Mautalen |
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Institution: | (1) Laboratorio de Osteopatías Médicas, Hospital de Clínicas, Argentina;(2) Departamento de Fisiologia, Facultad de Medicina, Universidad de Buenos Aires, Argentina;(3) Depto. C, Acoyte 583 Piso 7, 1405 Buenos Aires, Argentina |
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Abstract: | Summary The functional and anatomic compensatory response of the parathyroid gland was examined in hemiparathyroidectomized (HPTx)
rats whose parathyroid hormone (PTH) secretion was stimulated by a low calcium diet. These responses were compared with those
observed in the thyroid gland of hemithyroidectomized (HTx) rats. Rats kept on a low calcium diet for 10 days were subjected
to HPTx, HTx, or sham operations. Throughout the experiment (up to 28 days after surgery), serum calcium levels of HPTx rats
were lower than the basal, with Δ values (mg/dl, mean±SEM) of −0.66±0.17 and −0.84±0.17, (P<0.05) 3 and 28 days after surgery, respectively. Serum PTH decreased significantly from 7 to 21 days after HPTx, reaching
normality at day 28 after surgery. In HTx rats, serum thyroxine (T4) levels diminished significantly 7 days after surgery,
and attained normality thereafter. The mitotic index (number of metaphases/1,000 cells) in parathyroid glands of colchicine-treated
HPTx rats increased significantly in comparison to sham-operated controls, when examined 2 or 40 days after surgery. The mitotic
index of thyroid follicular cells was significantly higher than that of their respective controls, 2 but not 40 days after
HTx. These results indicate that after HPTx, a delayed compensatory response is found when the animals are kept under a low
calcium diet. Parathyroid response is both delayed and of a minor degree compared to that found in the thyroid gland after
HTx. |
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Keywords: | Compensatory hypertrophy Parathyroid hormone Calcium metabolism Thyroid Mitotic index |
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