[Experimental studies with Phytosoya].

Abstract

In order to nvestigate the vascular and osseus effects of an isoflavone rich commercially available product (Phytosoya), Arkochim, two types of experiments have been carried out. A. Fifty rats of the Wistar strain and 250 gr/weight were ovariectomized and fed a low calcium diet over 8 weeks. From these animal, two groups of 10 rats each received Phytosoya at 62,5 and 321,5 mg/Kg/day. Another group (n = 10) was treated with 150 microg estradiol valerianate weekly, 10 more animals did not received any treatment and a final group of 10 was fed a standard rat chow. At the end of 8 weeks of treatment animals were decapitated, the right tibia were submitted to densiometry and the uterus was dissected and weighted, Hypocalcic diet induced a marked reduction in bone mineral density as compared to controls. Estrogen treatment totally prevented bone mineral loss whereas Phytosoya was able to partially prevent this reduction. However, estrogen treatment reduced tibia lenght significantly whereas no effect was exerted by Phytosoya on this parameter. B. Thirty-eight New Zealand rabbits were ovariectomized and fed a standard rabbit chow (n = 6) or another diet rich in cholesterol and saturated fats (n = 32) (CHO). The CHO fed animals were divided into 5 different groups: a) Treated with estradiol valerianate (200 microg/week/,n = 7); b) Treated with Phytosoya 31,5 (n = 6), 62,5 (n = 7) and 315,5 mg/kg (n = 6) or c) not treated (n = 6). After 10 weeks animals were sacrificed to study their aortas. All CHO fed rabbits showed very high cholesterol levels (2100 +/- 93 mg/100 ml) as compared with standard chow fed (64 +/- 19 mg/100 ml), and treatments were not able to significantly modify these values. Maximal vasodilatation to acetilcholine of the rabbits fed the standard chow, was 86% of phenilephrine precontraction whereas hupercholesterolemic animals showed only a 28% vasodilatation. Estrogen treatment restaured dilatation to 82%, together with a uterine increase also vasodilatation to 61% in the two highest dosages and to 50% at the lowest dose without affecting uterine weight. Pertreatment with L-NAME induced a vasoconstrictory response to acetilcholine that was maximal in the hypercholesterolemic rabbits (20 +/- 4,5%) as compared to standard chow (,6%). Estrogen treatment reduced constriction to 13 +/- 2% and phytosoya to 15 +/- 6%. Thirty tree percent of animals fed a standard diet showed ateroesclerotic plaque whereas it was a present in 100% of the cholesterol rich diet. Estrogens reduced the number to 16% and Phytosoya to 71% of the animals.