Effects of genistein on stereological and hormonal characteristics of the pituitary somatotrophs in rats

Abstract

The hypothalamic-pituitary somatotropic system plays a pivotal role in the regulation of physiological processes and metabolism, which is modulated by gonadal steroids. Considering that genistein belongs to the phytoestrogen family and acts via similar mechanisms to estrogens, the present study was designed to demonstrate whether genistein modulates the morphofunctional characteristic of somatotrophs [growth hormone (GH) cells] in adult rats in comparison with the effects of estradiol. In the study, the orchidectomized adult rats were used as an appropriate model system for testing the effects of this hormone-like substance. Changes in the pituitary somatotrophs were evaluated histologically and stereologically, while GH level was determined biochemically. Using immunolabelling and stereological methods, we showed that orchidectomy (Orx) provoked the decrease of GH cell volume density. After estradiol treatment of Orx rats, the most prominent change concerned the pituitary relative intensity of GH fluorescence and circulating GH level, which were elevated 77 % and 4.7-fold, respectively. Clearly, in contrast to orchidectomy, estradiol treatment enhanced the GH cells activity. Genistein treatment increased pituitary weight and volume, GH cell volume density, the total number of GH cells, and GH blood concentration (1.3-fold) in comparison to the Orx group. Although identical tendencies followed estradiol and genistein administration, the changes observed after genistein treatment were milder compared to estradiol treatment.

Sex steroid application reverses changes in rat castration cells: Unbiased stereological analysis

“…The used dose of E was a high pharmacological dose previously shown to elicit a strong estrogenic effect on the somatotropic and hypothalamo-pituitaryadrenal axis in the experimental model of young castrated rats [13,14]. This dose is the same as used in the experiments of Nolan and Levy [15], who examined the trophic effects of estradiol on the mitotic activity of pituitary cells following gonadectomy, and is equivalent to about 1.3 mg per week per rat.…”

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

“…Analysis of confocal microscopy images was performed 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). Relative intensity of fluorescence (RIF) in the cytoplasm of pituitary gonadotropes or lactotropes was evaluated according to previously described procedures [25,26].…”

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

“…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.…”

“…The doses of genistein and daidzein selected for this study were chosen to mimic human exposure to elevated concentrations of isoflavones when nutritional supplements are used for therapeutic purposes (Doerge and Sheehan, 2002). They induced histomorphological changes of the pituitaryadrenal axis in middle-aged (Ajd zanović et al, 2009a(Ajd zanović et al, , 2009b(Ajd zanović et al, , 2011 and adult Orx rats (Trifunović et al, , 2014a(Trifunović et al, , 2014b. The s.c. route of administration was chosen to allow precise regulation of the dose of isoflavones, and to avoid metabolism of dietary daidzein to equol (by intestinal microflora), which has stronger estrogenic properties than either genistein or daidzein (Mitchell et al, 1998).…”