Limits...
Effects of dietary phytoestrogens on plasma testosterone and triiodothyronine (T3) levels in male goat kids.

Gunnarsson D, Selstam G, Ridderstråle Y, Holm L, Ekstedt E, Madej A - Acta Vet. Scand. (2009)

Bottom Line: A slightly higher concentration of free T3 was detected in the phytoestrogen group at the same time point, but it was not until October 8 and 15 (week 9 and 10) that a significant difference was found between the groups.Phytoestrogen-fed animals also had lower plasma and testicular testosterone concentrations, but these differences were not statistically significant.It is possible that feedback signalling underlies the tendency towards decreased steroid production at the end of the experiment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Molecular Biology, Umeå University, S-901 87 Umeå, Sweden. david.gunnarsson@molbiol.umu.se

ABSTRACT

Background: Exposure to xenoestrogens in humans and animals has gained increasing attention due to the effects of these compounds on reproduction. The present study was undertaken to investigate the influence of low-dose dietary phytoestrogen exposure, i.e. a mixture of genistein, daidzein, biochanin A and formononetin, on the establishment of testosterone production during puberty in male goat kids.

Methods: Goat kids at the age of 3 months received either a standard diet or a diet supplemented with phytoestrogens (3-4 mg/kg/day) for approximately 3 months. Plasma testosterone and total and free triiodothyronine (T3) concentrations were determined weekly. Testicular levels of testosterone and cAMP were measured at the end of the experiment. Repeated measurement analysis of variance using the MIXED procedure on the generated averages, according to the Statistical Analysis System program package (Release 6.12, 1996, SAS Institute Inc., Cary, NC, USA) was carried out.

Results: No significant difference in plasma testosterone concentration between the groups was detected during the first 7 weeks. However, at the age of 5 months (i.e. October 1, week 8) phytoestrogen-treated animals showed significantly higher testosterone concentrations than control animals (37.5 nmol/l vs 19.1 nmol/l). This elevation was preceded by a rise in plasma total T3 that occurred on September 17 (week 6). A slightly higher concentration of free T3 was detected in the phytoestrogen group at the same time point, but it was not until October 8 and 15 (week 9 and 10) that a significant difference was found between the groups. At the termination of the experiment, testicular cAMP levels were significantly lower in goats fed a phytoestrogen-supplemented diet. Phytoestrogen-fed animals also had lower plasma and testicular testosterone concentrations, but these differences were not statistically significant.

Conclusion: Our findings suggest that phytoestrogens can stimulate testosterone synthesis during puberty in male goats by increasing the secretion of T3; a hormone known to stimulate Leydig cell steroidogenesis. It is possible that feedback signalling underlies the tendency towards decreased steroid production at the end of the experiment.

Show MeSH

Related in: MedlinePlus

Effects of phytoestrogens on plasma total triiodothyronine (T3) concentrations in male goat kids. Goat kids at the age of 3 months received either a standard diet (controls) or a diet supplemented with phytoestrogens (3 - 4 mg/kg/day) for a period of ~3 months (August 19 to November 7). At week 6 of the experiment (i.e. September 17), phytoestrogen-exposed animals (closed circles, solid line) had significantly (* P < 0.05) higher total T3 concentrations than controls (open circles, dashed line).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2803173&req=5

Figure 2: Effects of phytoestrogens on plasma total triiodothyronine (T3) concentrations in male goat kids. Goat kids at the age of 3 months received either a standard diet (controls) or a diet supplemented with phytoestrogens (3 - 4 mg/kg/day) for a period of ~3 months (August 19 to November 7). At week 6 of the experiment (i.e. September 17), phytoestrogen-exposed animals (closed circles, solid line) had significantly (* P < 0.05) higher total T3 concentrations than controls (open circles, dashed line).

Mentions: The total T3 levels gradually decreased from around 3 nmol/l in the beginning of the experiment to around 1.8 nmol/l three weeks later in both groups (Fig. 2). At week 6 of the experiment (i.e. September 17) total T3 levels were significantly higher in the phytoestrogen group than in the control group (2.3 ± 0.3 vs. 1.2 ± 0.2 nmol/l). The free T3 levels at weeks 9 and 10 (i.e. October 8 and 15) were significantly higher in treated animals than in controls (5.1 ± 0.6 vs. 2.5 ± 0.6 pmol/l and 8.8 ± 0.6 vs. 6.0 ± 0.6 pmol/l, respectively) (Fig. 3).


Effects of dietary phytoestrogens on plasma testosterone and triiodothyronine (T3) levels in male goat kids.

Gunnarsson D, Selstam G, Ridderstråle Y, Holm L, Ekstedt E, Madej A - Acta Vet. Scand. (2009)

Effects of phytoestrogens on plasma total triiodothyronine (T3) concentrations in male goat kids. Goat kids at the age of 3 months received either a standard diet (controls) or a diet supplemented with phytoestrogens (3 - 4 mg/kg/day) for a period of ~3 months (August 19 to November 7). At week 6 of the experiment (i.e. September 17), phytoestrogen-exposed animals (closed circles, solid line) had significantly (* P < 0.05) higher total T3 concentrations than controls (open circles, dashed line).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2803173&req=5

Figure 2: Effects of phytoestrogens on plasma total triiodothyronine (T3) concentrations in male goat kids. Goat kids at the age of 3 months received either a standard diet (controls) or a diet supplemented with phytoestrogens (3 - 4 mg/kg/day) for a period of ~3 months (August 19 to November 7). At week 6 of the experiment (i.e. September 17), phytoestrogen-exposed animals (closed circles, solid line) had significantly (* P < 0.05) higher total T3 concentrations than controls (open circles, dashed line).
Mentions: The total T3 levels gradually decreased from around 3 nmol/l in the beginning of the experiment to around 1.8 nmol/l three weeks later in both groups (Fig. 2). At week 6 of the experiment (i.e. September 17) total T3 levels were significantly higher in the phytoestrogen group than in the control group (2.3 ± 0.3 vs. 1.2 ± 0.2 nmol/l). The free T3 levels at weeks 9 and 10 (i.e. October 8 and 15) were significantly higher in treated animals than in controls (5.1 ± 0.6 vs. 2.5 ± 0.6 pmol/l and 8.8 ± 0.6 vs. 6.0 ± 0.6 pmol/l, respectively) (Fig. 3).

Bottom Line: A slightly higher concentration of free T3 was detected in the phytoestrogen group at the same time point, but it was not until October 8 and 15 (week 9 and 10) that a significant difference was found between the groups.Phytoestrogen-fed animals also had lower plasma and testicular testosterone concentrations, but these differences were not statistically significant.It is possible that feedback signalling underlies the tendency towards decreased steroid production at the end of the experiment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Molecular Biology, Umeå University, S-901 87 Umeå, Sweden. david.gunnarsson@molbiol.umu.se

ABSTRACT

Background: Exposure to xenoestrogens in humans and animals has gained increasing attention due to the effects of these compounds on reproduction. The present study was undertaken to investigate the influence of low-dose dietary phytoestrogen exposure, i.e. a mixture of genistein, daidzein, biochanin A and formononetin, on the establishment of testosterone production during puberty in male goat kids.

Methods: Goat kids at the age of 3 months received either a standard diet or a diet supplemented with phytoestrogens (3-4 mg/kg/day) for approximately 3 months. Plasma testosterone and total and free triiodothyronine (T3) concentrations were determined weekly. Testicular levels of testosterone and cAMP were measured at the end of the experiment. Repeated measurement analysis of variance using the MIXED procedure on the generated averages, according to the Statistical Analysis System program package (Release 6.12, 1996, SAS Institute Inc., Cary, NC, USA) was carried out.

Results: No significant difference in plasma testosterone concentration between the groups was detected during the first 7 weeks. However, at the age of 5 months (i.e. October 1, week 8) phytoestrogen-treated animals showed significantly higher testosterone concentrations than control animals (37.5 nmol/l vs 19.1 nmol/l). This elevation was preceded by a rise in plasma total T3 that occurred on September 17 (week 6). A slightly higher concentration of free T3 was detected in the phytoestrogen group at the same time point, but it was not until October 8 and 15 (week 9 and 10) that a significant difference was found between the groups. At the termination of the experiment, testicular cAMP levels were significantly lower in goats fed a phytoestrogen-supplemented diet. Phytoestrogen-fed animals also had lower plasma and testicular testosterone concentrations, but these differences were not statistically significant.

Conclusion: Our findings suggest that phytoestrogens can stimulate testosterone synthesis during puberty in male goats by increasing the secretion of T3; a hormone known to stimulate Leydig cell steroidogenesis. It is possible that feedback signalling underlies the tendency towards decreased steroid production at the end of the experiment.

Show MeSH
Related in: MedlinePlus