This study was to evaluate the effect of androgen deficiency on thyroid immunoreactive C-cells and bone structure and function in a male orchidectomized middle-aged rat model. Fifteen-month-old male Wistar rats were divided into orchidectomized (Orx) and the sham-operated control (Sham) group. In the Orx group significant decreases (P < 0.05) were found in the volume of C cells (by 14%), their relative volume density (by 13%) and serum calcitonin concentration (by 54%) compared to the controls. Analyses of trabecular microarchitecture of the proximal tibia metaphysis showed that Orx induced marked decreases of cancellous bone area, trabecular thickness and trabecular number (by 52, 20 and 19% respectively; P < 0.05), whereas trabecular separation was increased by 27% (P < 0.05). In Orx rats, serum osteocalcin concentration was increased by 119% (P < 0.05), while serum calcium and phosphorus were 6 and 14% (P < 0.05) lower, respectively, compared to the levels in the Sham. In addition, urine calcium content was considerably higher (by 129%; P < 0.05) in Orx animals. These findings indicate that the androgen deficiency caused by Orx in middle-aged rats modulated the structure of C cells and diminished secretion of calcitonin. Histomorphometrical and biochemical analyses demonstrated a decrease of cancellous bone mass and increased bone turnover.

The effects of short-term genistein exposure on ovarian folliculogenesis in immature rats were examined stereologically. To determine whether genistein acts as an estrogen agonist or antagonist, the results were compared with the effects of 17α-ethynylestradiol. Immature female rats received 50 mg/kg/bw of genistein in dimethyl sulfoxide subcutaneously daily for three consecutive days from 18 to 20 days. The second group was injected with 1 μg/kg/bw of 17α-ethynylestradiol in olive oil in the same schedule. Each group had a corresponding control. Genistein increased ovary and ovarian stroma volumes by 18.50% (P < 0.05) and 53.40% (P < 0.05), respectively, and changed the parenchyma to stroma ratio in favor of stroma. Genistein induced decreases in the number of primordial (by 17.23%; P < 0.05), primary (16.62%; P < 0.05), and secondary follicles (12.29%: P < 0.05), whereas the number of atretic secondary follicles increased (5.10-fold; P < 0.05). The number of healthy large follicles was raised by 27.3% (P < 0.05), accompanied by 35.64% more atretic large follicles (P < 0.05). Similarly to genistein, estradiol changed the parenchyma to stroma ratio in favor of stroma, and reduced the number of primordial follicles, but the number of primary follicles was elevated. There were more healthy and atretic small and large follicles. In conclusion, genistein acted as an estrogen antagonist and had an inhibitory effect on the initial phase of folliculogenesis. In the other phases, genistein acted as an estrogen agonist, stimulating transition from the preantral to antral stage of folliculogenesis, and altering the ratio of follicular parenchyma and ovarian stroma in favor of stroma.

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 We examined whether isoflavones increase hepatic thyroid hormone concentrations and affect cholesterol metabolism in middle-aged rats  Serum T3 was not affected while hepatic T3 was almost doubled, which supports increased local T3 availability.  Obtained results are compatible with displacement of TH from TTR, major transport protein in rodent blood and human CSF.  Hepatic increase of T3 correlated with up-regulated expression of the Cyp7a1 gene and elevated 7α-hydroxycholesterol  IF also lowered 24-hydroxycholesterol and desmosterol in liver and serum, while the total cholesterol levels remained unchanged.

These results suggest that genistein has a significant effect on hypothalamic region, involved in the regulation of somatotropic system function, and could contribute to the understanding of genistein as substance that alter the hormonal balance.