Effects of soy phytoestrogens on pituitary-ovarian function in middle-aged female rats

Abstract

The aim of this study was to assess the effects of genistein (G) and daidzein (D) on the histological, hormonal, and functional parameters of the pituitary-ovarian axis in middle-aged female rats, and to compare these effects with the effects of estradiol (E), commonly used in the prevention and treatment of menopausal symptoms. Middle-aged (12 month old) Wistar female rats subcutaneously received 35 mg/kg of G, or 35 mg/kg of D, or 0.625 mg/kg of E every day for 4 weeks. Each of the treated groups had a corresponding control group. An intact control group was also established. G and D did not change the intracellular protein content within gonadotropic and lactotropic cells, but vacuolization was observed in all the cell types. In contrast, E caused an inhibition of gonadotropic and stimulation of lactotropic cells. Also, ovaries of middle-aged female rats exposed to G or D have more healthy primordial and primary follicles and less atretic follicles. E treatment in the ovaries had a mostly negative effect, which is reflected by the increased number of atretic follicles in all tested classes. G and D provoked decrease in CuZnSOD and CAT activity, while E treatment increased MnSOD and decreased CuZnSOD and GSHPx activity. All the treatments increased serum estradiol and decreased testosterone levels, while D and E increased the serum progesterone level. In conclusion, soy phytoestrogens exhibited beneficial effects on pituitary-ovarian function in middle-aged female rats, as compared to estradiol.

Soy Phytoestrogens Do Not Fully Reverse Changes in Rat Pituitary Castration Cells: Unbiased Stereological Study

“…After rehydration, the sections were stained immunohistochemically. Gonadotropic cells were visualized using the peroxidase enzymatic method or immunofluorescently, as previously described (Nestorović et al, ; Medigović et al, ). In both cases rabbit anti‐rat βFSH (1:300 v/v) and rabbit anti‐rat βLH polyclonal antibodies (1:500 v/v) served as primary antibodies.…”

“…Confocal microscopy images were analyzed using the Quantify option in LAS AF Lite software (Leica Application Suite Advanced Fluorescence Lite/1.7.0 build 1240, Leica Microsystems CMS GmbH; Germany). The relative intensity of fluorescence (RIF) in the cytoplasm of pituitary FSH‐ and LH‐immunolabeled cells was evaluated according to previously described procedures (Medigović et al, ; Miler et al, ; Trifunović et al, ; Waters and Swedlow, ). Briefly, the region of interest (single gonadotropic cell) was encircled with a drawing/selection tool and included the intense spots of the immunopositive granules within the cytoplasm of pituitary FSH‐ and/or LH‐immunoreactive cells.…”

“…In our previous study, short‐term exposure of immature female rats to high doses of genistein caused stimulation of pituitary gonadotropes similarly to the effect of estradiol (Medigović et al, ). However, in middle‐aged females exposed to endogenous estrogen throughout life, chronic application of genistein or daidzein had no effect on gonadotropic cell size and intracellular hormone content (Medigović et al, ). Ovariectomy (Ovx) of adult females is a widely used experimental model for examination of effects of plant derived estrogens on gonadotropic cells, since their potency to suppress LH secretion is an indirect measure of alleviation of postmenopausal vasomotor functions.…”

The Effect of Moderate Heat on Rat Pituitary ACTH Cells: Histomorphometric, Immunofluorescent and Hormonal Study

“…The immunofl uorescent analysis, as well as the evaluation of the relative intensity of fl uorescence (RIF) was performed according to previously described data [16][17]. Briefl y, pituitary sections were preincubated in normal donkey serum (Dako, Denmark; 1:10); then, after incubation for 24h with hACTH (DAKO A/S, Glostrup, Denmark; Code No., Ref: N1531, Lot No.…”

“…Image analysis was achieved by a LAS AF Lite software (Leica Microsystems, Germany). Relative intensity of fl uorescence (RIF) in the cytoplasm of pituitary ACTH cells was evaluated according to previously described procedures [16][17].…”