Effects of soy isoflavones on the hypothalamic-pituitary system in rats: a morphofunctional study

Izoflavoni soje, genistein i daidzein, se sve više koriste u preventivi i alternativnoj terapiji različitih patoloških stanja. Uticaj izoflavona soje na neuroendokrini sistem bio je, a i danas je, predmet istraživanja različitih studija. Veliki broj literaturnih podataka govori o uticaju izoflavona soje na reproduktivni sistem, s obzirom na njihovu estogensku i anti-estrogensku aktivnost. Ipak, podaci o njihovom uticaju na somatotropni i adrenokortikotropni sistem oskudni su, a neophodni, imajuću u vidu značaj ovih sistema za normalan razvoj i funkcionisanje organizma. Takoñe, mnogobrojne in vitro studije obezbeñuju samo limitirane informacije o potencijalnim efektima in vivo. Cilj ove studije je bio da se ispita uticaj hroničnih tretmana estradioldiproprionatom, genisteinom i daidzeinom na histološke, stereološke i biohemijske parametre somatotropnog i adrenokortikotropnog sistema orhidektomisanih adultnih pacova. Na početku eksperimenta adultni pacovi Wistar soja, stari 3 meseca, su podeljeni u dve eksperimentalne grupe: lažno orhidektomisanu (Sham) i orhidektomisanu (Orx) grupu. Dve nedelje nakon sham operacije ili orhidektomije pacovi su podeljeni u sedam eksperimentalnih grupa. Prvu (Sham1) grupu su sačinjavale sham operisane životinje subkutano (s.c.) tretirane odgovarajućom zapreminom sterilnog maslinovog ulja, medijumom estradiol-diproprionata (medijum I). Drugu (Orx1) grupu su sačinjavale orhidektomisane životinje s.c. tretirane odgovarajućom zapreminom medijuma I. U trećoj (Orx1+E) grupi orhidektomisane životinje su s.c. tretirane estradioldipropionatom u medijumu I (0,6 mg/kg t.m.). Četvrta (sham operisana - Sham2) i peta (orhidektomisana - Orx2) grupa s.c. su tretirane odgovarajućom zapreminom mešavine alkohola i sterilnog maslinovog ulja, medijumom genisteina i daidzeina (u odnosu 1:2; medijum II). Šestu (Orx2+G) grupu su sačinjavale orhidektomisane životinje s.c. tretirane genisteinom u medijumu II (30 mg/kg t.m.), dok je sedma (Orx2+D) grupa orhidektomisanih pacova s.c. tretirana daidzeinom u istom medijumu (30 mg/kg t.m.). Sve grupe životinja su dobijale tretman tokom tri nedelje (hroničan tretman), a žrtvovane su 24 h nakon poslednje primljene doze. Pre početka i nakon završenog tretmana izmerene su telesne mase životinja svih eksperimentalnih grupa, dok su mase hipofiza izmerene nakon žrtvovanja. Za lokalizaciju arkuatnog (Arc) i periventrikularnog (Pe) jedra, paravenrikularnog jedra (PVN) i eminencije medijane (ME) korišćeno je histološko bojenje krezil-ljubičastom bojom. Za obeležavanje oslobañajućih hormona hipotalamusa (oslobañajućeg hormona hormona rasta–GHRH, somatostatina-SS, kortikotropnog oslobañajućeg hormona-CRH) i ćelija adenohipofize (somatotropnih–GH i adrenokortikotropnih-ACTH) korišćeno je imunohistohemijsko bojenje. Histološki i imunohistohemijski obojeni preseci hipotalamusa, kao i imunohistohemijski obojeni preseci hipofiza stereološki su analizirani, uz pomoć newCAST stereološkog softverskog paketa. Dobijene su vrednosti: volumena Arc i Pe jedra i PVN, volumenske gustine SS neurona, volumena hipofize, volumenske i numeričke gustine GH i ACTH ćelija, apsolutnog broja i volumena GH i ACTH ćelija. Koncentracija GH i ACTH u cirkulaciji odreñena je biohemijskim metodama. Dobijeni podaci su statistički obrañeni...The soy isoflavones genistein and daidzein are being used increasingly as preventive or alternative therapeutics in various pathological conditions. The effects of soy isoflavones on the neuroendocrine system were, and still are, the subject of numerous studies. Literature data predominantly focus on their effects on the gonadotrophic axis, considering the soy isoflavones established estrogenic and antiestrogenic mode of action. However, data about their potential effects on the somatotrophic and adrenocorticotrophic systems are rather scarce, but nevertheless very meaningful, considering the importance of these systems for the normal development and function of an organism. Furthermore, in vitro studies provide only limited data, that cannot be fully extrapolated to in vivo conditions. The aim of this study was to investigate the effects of chronically applied estradiol dipropionate, genistein and daidzein on the histological, stereological and biochemical parameters of somatotrophic and adrenocorticotrophic systems in orchidectomized adult rats. Initially, adult (three months old) Wistar rats were divided into two groups: sham operated (Sham) and orchidectomized (Orx). Two weeks after the surgery, the rats were subdivided into seven experimental groups. The first group (Sham1) included sham operated rats subcutaneously (s.c.) treated with an adequate volume of sterile olive oil, the medium for estradiol dipropionate (medium I). In the second group (Orx1) were orchidectomized rats s.c. treated with an adequate volume of medium I. The third group (Orx1+E) was comprised of orchidectomized rats s.c. treated with estradiol dipropionate in medium I (0.6 mg/kg b.w.). The fourth (sham operated – Sham2) and fifth (orchidectomized – Orx2) group of rats were s.c. treated with adequate volumes of absolute ethanol and sterile olive oil mixture, the medium for genistein or daidzein (mixing ratio was 1:2; medium II). In the sixth group (Orx2+G) were orchidectomized rats s.c. treated with genistein in medium II (30 mg/kg b.w.), while the seventh group (Orx2+D) included orchidectomized rats s.c. treated with daidzein in the same medium (30 mg/kg b.w.). All the groups of animals received the treatment during three weeks (chronic treatment), and were sacrificed 24 h after the last injected dose. All the animals were weighed before and after the treatment, while the pituitary weights were measured after sacrificing. For the localization of arcuate (Arc), periventricular (Pe) and paraventricular (PVN) nuclei, as well as for median eminence (ME) cresyl violet histochemical staining was used. Hypothalamic releasing hormones (growth hormone releasing hormone – GHRH, somatostatin – SS, corticotrophin releasing hormone – CRH) and pituitary cells (somatotrophic – GH and adrenocorticotrophic – ACTH) were immunohistochemically (peroxidase-antiperoxidase) labeled. Histochemically stained and immunohistochemically labeled hypothalamic sections, as well as immunohistochemically labeled pituitary sections were stereologically analysed, using newCast stereological software package. The following values were obtained: the Arc, Pe and PVN nuclei volumes, volume density of SS neurones, volumes of the pituitaries, the volume and numerical density of GH and ACTH cells, as well as the absolute numbers and volumes of GH and ACTH cells. The circulating GH and ACTH were determined biochemically. The obtained data were statistically processed..