The Effects of Isoflavones on Androgens and Glucocorticoids During Puberty on Male Wistar Rats

Abstract

Isoflavones are the most common phytoestrogens found in human diets. However, it is still not clear whether isoflavones have effects on the reproductive and the endocrine systems under normal dietary intake and overdose. The aim of this study was to determine how the most important isoflavones, genistein and daidzein, affect androgen and glucorticoid levels on male prepuberal rats. A hundred and seventy-five 30-day-old male Wistar rats were dosed orally by stomach tube every day for 35 days, with saline solution, low and high doses of genistein, daidzein and a mixture of both. Serum samples were analysed by an enzyme immunoassay for hormone determinations. In control group, there was a peak of testosterone (T) and dihydrotestosterone levels associated to the onset of puberty, at the third week. However, in low-dose groups, the same peak was found at the fourth week (p < 0.05), indicating a delay in the onset of puberty in these groups. Moreover, high doses groups serum androgen levels were significantly lower (p < 0.05) than the control group from the first week until fifth week. This fact was supported by a epididymal histological analysis that indicate in low doses there were several content of spermatozoa at fourth week and in high doses there were few content of spermatozoa. Besides, corticosterone levels followed the same pattern of androgens in all groups. We can conclude that oral administration of isoflavones in male rats decreased the secretion of androgens and glucocorticoids causing a delay in the onset of puberty and may cause physiological and developmental problems.

Effects of soya milk on reproductive hormones during puberty in male Wistar rats

“…In this study, testicular androgen production on low doses of isoflavones groups resulted in a significant increase of T testicular levels, and a significant increase in DHT testicular levels. These findings are related to the serum androgen levels found in these animals previously reported by our group and confirm the onset of puberty at that delayed stage compare to control group at a hormonal and histological levels, as it was also reported that rats administered with high and low doses of isoflavones presented lower content of spermatozoa than control group (Caceres et al, ). On high doses of isoflavones group, T and A4 testes homogenates levels were significantly lower than control group.…”

“…In this study, exposure to low and high doses of isoflavones resulted in an alteration on the secretion of these hormones. This could be due to a delay on the onset of puberty previously reported (Caceres et al, ). On high‐dose groups LH levels did not increase until fifth week and FSH levels were higher during all the experiment.…”

“…Exposure to chemical agents, such as phytoestrogens, during this period can cause changes in puberty and alter the reproductive function. Isoflavones have been shown to change steroid hormone levels (Patisaul & Jefferson, ; Siepmann et al, ) and delay the onset of puberty in male Wistar rats (Caceres et al, ). Therefore, in the present study, we evaluated the effects of isoflavones on the secretion of precursors of steroid hormones in serum and testes homogenates and determined whether isoflavones can alter the onset of puberty in male Wistar rats.…”

“…It is considered that, male Wistar rats begin to be pubertal around 50 days after birth, when serum T levels increased (Evuarherhe et al, ); however, exposure to endocrine disruptors in critical periods of life on male animals can have consequences on reproductive and endocrine development (Caceres et al, ). According to this study, we found that testes homogenate DHT levels in control group showed a maximum concentration at third week of experiment due to the onset of puberty on rats.…”

Influence of prolonged flaxseed ( Linum usitatissimum ) consumption over epididymis and testicle histoarchitecture of Wistar rats

“…Soybean phytoestrogens, in high and low dosages, have been reported to reduce testosterone serum concentrations (Weber et al 2001, Caceres et al 2014. Wisniewski et al (2003) stated that reduced testosterone biosynthesis can affect the reproductive physiology and behavior of phytoestrogen-fed rats.…”