Endocrine Abstracts

The different response of somatotropic system to genistein and daidzein in the rat hypothalamus: Svetlana Trifunović, Branka Šošić-Jurjević, Milica Manojlović-Stojanoski, Nataša Ristić, Nataša Nestorović, Branko Filipović, Verica Milošević

University of Belgrade, Institute for Biological Research ‘Siniša Stanković’, Department of Cytology, Belgrade, Serbia The different response of somatotropic system to genistein and daidzein in the rat hypothalamus Emerging evidence suggests that consumption of nutrients rich in isoflavones may has a beneficial effect on numerous diseases in animals and humans. On the other hand, given the structural similarity with estrogens, isoflavones: genistein (G) and daidzein (D), may cause adverse health effects via endocrine-mediated mechanisms in an organism. Our prior results has demonstrated that G exposure, could significantly increase activity of somatotropic system in the hypothalamus. Exactly, genistein’s treatment increased: the arcuate (Arc) nucleus volume, the volume density of growth hormone releasing hormone (GHRH) neurons- 26% and somatostatin (SS) neurons-1.5 fold, accompanied by higher GHRH and SS staining intensity in the median eminence (ME). However, there is no evidence as to whether D exposure, has the same effect. Using histological and stereological approach we investigated the effects of D on GHRH and SS neurons in the hypothalamus, as well as their content in the ME. The Arc nucleus volume was decreased by 17% following D, in the comparison to G treatment. The same parameter wasn’t change after D exposure in comparison to the control value. Also, the periventricular (Pe) nucleus volume was decreased by 15% in the D treated group in comparison to the G group. The Pe nucleus volume wasn’t change after D exposure in comparison to the control. The volume density of GHRH and SS neurons within Arc and Pe nucleus respectively, significantly decreased following D in comparison to G treatment. There is no changes in the GHRH and SS staining intensity in ME after D treatment in comparison to the control, while differences was noticed in comparison to the G treatment. The stronger affinity of G for the estrogen receptors is a probable cause of greater changes in the level of the hypothalamus following genistein’s treatment vs. daidzein’s treatment. Also, the application’s method (subcutaneously injected genistein and daidzein) i.e. reduced conversion of D into a more potent equol by enterobacteria, might be the basis for obtained results. Therefore, the eventual changes at the level of hypothalamus should be investigated after feeding experimental animals with isoflavones rich diet.