In vivo exposure to bisphenol F induces oxidative testicular toxicity: role of Erβ and p53/Bcl-2 signaling pathway

Abstract

Introduction: Bisphenol F (BPF), an alternative to bisphenol A has been implicated as a gonadotoxic substance. BPF has been shown to induce hormonal imbalance and testicular oxidative damage. However, the mechanism associated with BPF-induced testicular toxicity has not been fully explored. This study was designed to explore the role of tumor protein (p53)/ B-cell lymphoma 2 (BCl-2) signaling and oestrogen receptor beta (Erβ) in BPF-induced testicular toxicity.

Methods: Male Wistar rats were randomized into control (Cntrl), BPF-treated (10, 30, and 50 mg/kg for low dose (BPF-L), medium dose (BPF-M), and high dose (BPF-H) respectively), and BPF-treated recovery (Cntrl-R, BPF-L-R, BPF-M-R, and BPF-H-R). The administration was via gavage and lasted for 28 days and the animals in the recovery groups were allowed 28-days exposure free period for recovery from BPF exposure.

Results: BPF resulted in the distortion of the testicular histoarchitecture, which was accompanied by a significant rise in testicular gamma-lutamyl transferase and lactate dehydrogenase activities but a decline in sorbitol dehydrogenase activities. Also, BPF caused a significant reduction in plasma gonadotropin-releasing hormone, luteinising hormone, follicle-stimulating hormone, and testosterone, which was associated with the downregulation of testicular 3beta-hydroxysteroid dehydrogenase and 17beta-hydroxysteroid dehydrogenase activities. Furthermore, BPF induced testicular inflammation, redox imbalance, and apoptosis, accompanied by distortion in p53/BCl-2 signaling and overexpression of Erβ. Again, the observed toxic effects of BPF were dose-dependent and not completely reversed by BPF cessation.

Discussion: Bisphenol F induced gonadotoxicity by distorting p53/BCl2 signaling and the expression of Erβ. These observed alterations were not completely reversed after the cessation of BPF exposure.

Keywords: apoptosis; bisphenol f; endocrine disruptors; hypothalamic-pituitary-gonadal axis; inflammation; oxidative stress.

Figure 1

(A) Cntrl: the histoarchitecture appears normal. The seminiferous tubules appear normal in shape with germ cells at varying degree of maturation (arrow head). The Sertoli cells appear normal (red arrow). The lumen of the seminiferous tubules shows normal sperm cells (L). The interstitial space appears normal with normal Leydig cell mass (black arrow). BPF-L and BPF-M: The testicular histoarchitecture shows some distortions. The seminiferous tubules show germ cells at varying degree of maturation (arrow head) with some degenerated cell lines (*). The Sertoli cells appear normal (red arrow). The lumen of some seminiferous tubules shows scanty sperm cells (black circle). The interstitial space appears normal with normal Leydig cell mass (black arrow). BPF-H: The testicular histoarchitecture shows some distortions. The seminiferous tubules show germ cells at varying degree of maturation (arrow head) with some degenerated cell lines (*). The Sertoli cells appear scanty (red arrow). The lumen of most seminiferous tubules shows scanty sperm cells (black circle). The interstitial space appears normal with normal Leydig cell mass. Black span: diameter of the seminiferous tubules; red span: epithelial height; green span: diameter of the seminiferous lumen. Cntrl, control; BPF-L, bisphenol F low dose; BPF-M, bisphenol F medium dose; BPF-H, bisphenol F high dose; Cntrl-R, control recovery; BPF-L-R, bisphenol F low dose recovery; BPF-M-R, bisphenol F medium dose recovery; BPF-H-R, bisphenol F high dose recovery. (B) Cntrl-R: The histoarchitecture appears normal. The seminiferous tubules appear normal in shape with germ cells at varying degree of maturation (arrow head). The Sertoli cells appear normal (red arrow). The lumen of the seminiferous tubules shows normal sperm cells (L). The interstitial space appears normal with normal Leydig cell mass (black arrow). BPF-L-R and BPF-M-R: The testicular histoarchitecture shows some distortions. The seminiferous tubules show germ cells at varying degree of maturation (arrow head) with some degenerated cell lines (*). The Sertoli cells appear scanty (red arrow). The lumen of most seminiferous tubules appears widened with scanty sperm cells (black circle). The interstitial space appears widened with mild congestion (red circle). The Leydig cell mass appears normal (black arrow). BPF-H-R: The testicular histoarchitecture shows gross distortions. The seminiferous tubules show grossly altered spermatogenesis with coagulative necrosis in the germ cells (arrow head). The Sertoli cells are markedly scanty (red arrow). The lumen of almost all the seminiferous tubules appears widened with very scanty or no sperm cells (black circle). The interstitial space appears widened with mild congestion (red circle). The Leydig cell mass is reduced (black arrow). Black span: diameter of the seminiferous tubules; red span: epithelial height; green span: diameter of the seminiferous lumen. Cntrl, control; BPF-L, bisphenol F low dose; BPF-M, bisphenol F medium dose; BPF-H, bisphenol F high dose; Cntrl-R, control recovery; BPF-L-R, bisphenol F low dose recovery; BPF-M-R, bisphenol F medium dose recovery; BPF-H-R, bisphenol F high dose recovery.

Figure 2

Effect of BPF on testicular (A) 3-beta HSD (B) 17-beta HSD (C) cholesterol. ^ap < 0.05 vs. age-matched control, ^bp < 0.05 vs. low dose of BPF, ^cp < 0.05 vs. medium dose of BPF, *p < 0.05 vs. groups with corresponding doses at p < 0.05 using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test for pairwise comparison. Cntrl, control; BPF-L, bisphenol F low dose; BPF-M, bisphenol F medium dose; BPF-H, bisphenol F high dose; Cntrl-R, control recovery; BPF-L-R, bisphenol F low dose recovery; BPF-M-R, bisphenol F medium dose recovery; BPF-H-R, bisphenol F high dose recovery.

Figure 3

Effect of BPF on testicular (A) GGT (B) LDH (C) SDH (D) lactate ^ap < 0.05 vs. age-matched control, ^bp < 0.05 vs. low dose of BPF, ^cp < 0.05 vs. medium dose of BPF, *p < 0.05 vs. groups with corresponding doses at p < 0.05 using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test for pairwise comparison. Cntrl, control; BPF-L, bisphenol F low dose; BPF-M, bisphenol F medium dose; BPF-H, bisphenol F high dose; Cntrl-R, control recovery; BPF-L-R, bisphenol F low dose recovery; BPF-M-R, bisphenol F medium dose recovery; BPF-H-R, bisphenol F high dose recovery.

Figure 4

Effect of BPF on testicular (A) TnF-alpha (B) IL-6 (C) MPO (D) NO (E) nFkB. ^ap < 0.05 vs. age-matched control, ^bp < 0.05 vs. low dose of BPF, ^cp < 0.05 vs. medium dose of BPF, *p < 0.05 vs. groups with corresponding doses at p < 0.05 using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test for pairwise comparison. Cntrl, control; BPF-L, bisphenol F low dose; BPF-M, bisphenol F medium dose; BPF-H, bisphenol F high dose; Cntrl-R, control recovery; BPF-L-R, bisphenol F low dose recovery; BPF-M-R, bisphenol F medium dose recovery; BPF-H-R, bisphenol F high dose recovery.

Figure 5

Effect of BPF on testicular (A) MDA (B) GSH (C) SOD (D) catalase (E) GST (F) GPx. ^ap < 0.05 vs. age-matched control, ^bp < 0.05 vs. low dose of BPF, ^cp < 0.05 vs. medium dose of BPF, *p < 0.05 vs. groups with corresponding doses at p < 0.05 using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test for pairwise comparison. Cntrl, control; BPF-L, bisphenol F low dose; BPF-M, bisphenol F medium dose; BPF-H, bisphenol F high dose; Cntrl-R, control recovery; BPF-L-R, bisphenol F low dose recovery; BPF-M-R, bisphenol F medium dose recovery; BPF-H-R, bisphenol F high dose recovery.

Figure 6

Effect of BPF on testicular (A) XO (B) UA. ^ap < 0.05 vs. age-matched control, ^bp < 0.05 vs. low dose of BPF, ^cp < 0.05 vs. medium dose of BPF, *p < 0.05 vs. groups with corresponding doses at p < 0.05 using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test for pairwise comparison. Cntrl, control; BPF-L, bisphenol F low dose; BPF-M, bisphenol F medium dose; BPF-H, bisphenol F high dose; Cntrl-R, control recovery; BPF-L-R, bisphenol F low dose recovery; BPF-M-R, bisphenol F medium dose recovery; BPF-H-R, bisphenol F high dose recovery.

Figure 7

Effect of BPF on testicular DNA fragmentation Index (DFI). ^ap < 0.05 vs. age-matched control, ^bp < 0.05 vs. low dose of BPF, ^cp < 0.05 vs. medium dose of BPF, *p < 0.05 vs. groups with corresponding doses at p < 0.05 using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test for pairwise comparison. Cntrl, control; BPF-L, bisphenol F low dose; BPF-M, bisphenol F medium dose; BPF-H, bisphenol F high dose; Cntrl-R, control recovery; BPF-L-R, bisphenol F low dose recovery; BPF-M-R, bisphenol F medium dose recovery; BPF-H-R, bisphenol F high dose recovery.

Figure 8

Effect of BPF on testicular BCl2. ^ap < 0.05 vs. age-matched control, ^bp < 0.05 vs. low dose of BPF, ^cp < 0.05 vs. medium dose of BPF, *p < 0.05 vs. groups with corresponding doses at p < 0.05 using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test for pairwise comparison.

Figure 9

Effect of BPF on testicular p53. ^ap < 0.05 vs. age-matched control, ^bp < 0.05 vs. low dose of BPF, ^cp < 0.05 vs. medium dose of BPF, *p < 0.05 vs. groups with corresponding doses at p < 0.05 using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test for pairwise comparison. Cntrl, control; BPF-L, bisphenol F low dose; BPF-M, bisphenol F medium dose; BPF-H, bisphenol F high dose; Cntrl-R, control recovery; BPF-L-R, bisphenol F low dose recovery; BPF-M-R, bisphenol F medium dose recovery; BPF-H-R, bisphenol F high dose recovery.

Figure 10

Effect of BPF on testicular ERβ. ^ap < 0.05 vs. age-matched control, ^bp < 0.05 vs. low dose of BPF, ^cp < 0.05 vs. medium dose of BPF, *p < 0.05 vs. groups with corresponding doses at p < 0.05 using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test for pairwise comparison. Cntrl, control; BPF-L, bisphenol F low dose; BPF-M, bisphenol F medium dose; BPF-H, bisphenol F high dose; Cntrl-R, control recovery; BPF-L-R, bisphenol F low dose recovery; BPF-M-R, bisphenol F medium dose recovery; BPF-H-R, bisphenol F high dose recovery.