| Jf Steroid Biochem Mol Biol 89-90: 339-341,2004 |
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| Modulation of the response to estradiol-17 of rat vascular tissues
by a non calcemic vitamin D analog |
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| Dalia Somjen, Sara Katzburg, Merav Baz, Naftali Stern and Gary H.
Posner |
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| Tel-Aviv Sourasky Medical Center, Institute of Endocrinology, Metabolism
and Hypertension, 6 Weizman St., Tel-Aviv 64239, Israel |
|
Estradiol-17 (E2) increases creatine kinase (CK) specific activity
in aorta (Ao) and left ventricle of the heart (Lv) from rat females.
In the present study, we analyzed the effects of pretreatment with
the non calcemic analog of vitamin D, JK 1624 F2-2 (JKF) on the response
to E2 (either 0.5 or 5 g/rat) of Ao and Lv from prepubertal female
rats. JKF did not affect CK in either organ. However, pretreatment
with JKF (0.1 ng/g body weight for 1 or 2 weeks) increased the CK response
to E2 (0.5 g/rat) by 50±10% in Ao and by 150±12% in Lv. The CK response
to 5 g/rat of E2 in intact female rats, was increased by 118±15% and
99±11% in the Ao and by 89±6% and 112±13% in the Lv, in animals treated
daily with JKF for 1 or 2 weeks, respectively, before administration
of E2. JKF also increased the response to 500 g/rat raloxifene (Ral)
by 47±8% in Ao and by 56±12% in Lv. Preliminary experiments showed
that JKF treatment induced a ~50% increase in estradiol receptor ER
in both organs. The results indicate that the vitamin D analog JKF
upregulates the response and sensitivity of vascular tissues to E2,
in association with increased expression of their ER. These results
should prompt examination of the possibility that the effects estrogen
therapy in postmenopausal women can be augmented by vitamin D or its
analogs.
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