Estrogen stimulates PTHrP but not PTH/PTHrP receptor gene expression in the kidney of ovariectomized rat
✍ Scribed by Magali Cros; Caroline Silve; Anne-Marie Graulet; Caroline Morieux; Pablo Ureña; Marie-Christine de Vernejoul; Zhor Bouizar
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 146 KB
- Volume
- 70
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
The aim of the present study was to test the hypothesis that the decreased renal tubular reabsorption of calcium observed in estrogen deficiency is associated with a local regulation of either PTHrP or PTH/PTHrP receptor genes in the kidney. Rats were randomly sham-operated (S) or ovariectomized receiving either vehicule (OVX) or 4 µg E2/kg/day (OVXϩE4) or 40 µg E2/kg/d (OVXϩE40) during 14 days using alzet minipumps. Plasma PTH and calcium levels were lower in untreated OVX animals than in all other groups (P Ͻ 0.01). Plasma PTH was higher in OVXϩE40 than in OVXϩE4 (P Ͻ 0.05). PTHrP mRNA expression in the kidney was unaffected by ovariectomy but was increased in OVXϩE40 (0.984 Ϯ 0.452 for PTHrP/GAPDH mRNAs expression vs. 0.213 Ϯ 0.078 in sham, P Ͻ 0.01). PTH/PTHrP receptor mRNA expression and the cAMP response of renal membranes to PTH were unaffected by ovariectomy and estrogen substitution. In conclusion, renal PTHrP and PTH/PTHrP receptor mRNAs are not modified by ovariectomy. However, 17-estradiol increases renal expression of PTHrP mRNA without evident changes in its receptor expression and function. This may help to explain the pharmacological action of estrogen in the kidney, especially how it prevents the renal leak of calcium in postmenopausal women.