Effekt von Equol, Puerarin, Daidzein und Quercetin auf die Knochenparameter der ovarektomierten Ratte

Effect of equol, puerarin, daidzein and quercetin on bone in ovariectomized rats

by Susanne Moysich
Doctoral thesis
Date of Examination:2013-03-04
Date of issue:2013-03-01
Advisor:Prof. Dr. Wolfgang Wuttke
Referee:PD Dr. Stephan Sehmisch
Referee:Prof. Dr. Dr. Karl Günter Wiese
Persistent Address: http://dx.doi.org/10.53846/goediss-3759

 

 

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Abstract

English

Phytoestrogen-rich food is known to reduce the postmenopausal bone loss. The ovariectomized rat is an established model to study the postmenopausal osteoporosis. We investigated the estrogenic effects of daidzein, equol, puerarin and quercetin in comparison to 17beta-estradiol on trabecular and cortical bone in ovariectomized (OVX) rats. 127 female ovx Sprague Dawley rats were seperated in twelve groups and fed soy-free or supplemental food with E2, daidzein, equol, puerarin or quercetin, respectively in two different doses for three months. In the beginning and in the end of the study proximal tibia, lumbar spine bone mineral density (BMD) and body weight were measured. The BMD was determined by using peripheral quantitative computed tomography. In addition in the end of the study we investigated the influence of the phytoestrogens on osteocalcin and beta-crosslaps in the blood plasma of the animals. The results of the investigated phytoestrogens are summarized in the following list. The isoflavons daidzein, equol and puerarin shows an estrogenic effect on the trabecular bone loss and increased its BMD but showed no significant effect on the cortical bone. This could be because of the known fact that these isoflavons interact with ERbeta that is mostly represented in trabecular bone. The highest bone sparing effect was induced by the highest dose of daidzein and equol. quercetin has lesser effect on trabecular bone loss of the OVX rats. This eventually can be reevaluated through another study with different doses. There are surprising effects from the measures of the plasma values osteocalcin and beta-CrossLaps. The concentration of osteocalcin was not influenced by the isoflavons (daidzein, equol, puerarin), but quercetin n had a concentration of significance. It seem to stimulate the osteoblastogenesis. The level of beta-CrossLaps was mildly inhibited by daidzein and equol. We suppose a estrogenic effect by limiting the high level bone turnover. At the other hand puerarin and quercetin stimulated the level of beta-CrossLaps and seemed to activate the osteoclastogenesis. We have no explanation for this result. Obviously the results for the BMD contradict the indirect effects of the serum parameter on the BMD. These effects could not be understood in the scope of this work.
Keywords: phytoestrogens; isoflavone; rat bone; osteoporosis; estrogen; bone mineral density
 
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