Effect of bisphenol F, an analog of bisphenol A, on the reproductive functions of male rats

Abstract

Objective: Bisphenol A (BPA) is a monomer primarily used in the production of polycarbonate plastic and epoxy resins. Bisphenol F (BPF) is apparently the main BPA replacement that is used increasingly. BPF has been detected in canned food, thermal paper receipts, and soft drinks. In the present experiment, we did both in vitro and in vivo studies to evaluate the effect of low and high-dose BPF exposures on testosterone concentration, oxidative stress, and antioxidants activity in reproductive tissues of male rats.

Methods: Adult (80-90 days old) male Sprague Dawley rats (n = 36) obtained from the rodent colony of Animal Sciences Department of Quaid-i-Azam University. The direct effects of BPF on the antioxidant enzymes and testosterone secretion were measured in vitro and in vivo studies. In an in vivo experiment, adult male Sprague Dawley rats (n = 42) were exposed to different concentrations of bisphenol F (1, 5, 25, and 50 mg/kg/d) for 28 days. Various biochemical parameters were analyzed including the level of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), reactive oxygen species (ROS), and lipid peroxidation (LPO). Moreover, sperm motility, daily sperm production (DSP), comet assay, and histological analysis were performed.

Results: In vitro study showed that BPF exposure significantly (p < 0.05) induced oxidative stress biomarkers, i.e., ROS and LPO, while it did not change antioxidant enzyme and testicular testosterone concentration. Whereas, an in vivo study revealed that BPF induced dose-dependent effect and high-dose (100 mg/kg) exposure of BPF significantly reduced tissue protein (p < 0.05) content, CAT (p < 0.001), SOD (p < 0.05), and POD (p < 0.05) levels while significantly (p < 0.05) augmented ROS and lipid peroxidation. Furthermore, BPF reduces testosterone, LH, and FSH secretion in a dose-dependent manner. Significant (p < 0.001) reduction in plasma and intra-testicular testosterone, LH, and FSH was noticed at 100 mg/kg BFP dose. High-dose exposure reduces spermatogenesis.

Conclusion: BPF showed an antagonistic effect on male reproductive hormones and induce alterations in testicular morphology. Increased oxidative stress and decreased testicular antioxidant status might be the underlying mechanism of BFP-induced testicular toxicity.

Keywords: Antioxidant enzymes; Bisphenol F; Male reproductive system; Oxidative stress; Reproductive toxicity.

Fig. 1

Photomicrographs of rats testicular tissues of control and treated animals with different concentrations of BPF. The control (a) reveals normal germ cells: spermatogonia (SP), spermatocytes (SPC), spermatids (SPT), spermatozoa (SPZ). b–f Treated groups with BPF (1, 5, 25, 50, and100 mg/kg/day) showing changes in the testicular tissues seminiferous tubules with epithelium (Line without arrowhead), showing change in the testicular parenchyma, absence of sperm in lumen, seminiferous tubules with germ cells, Leydig cells (LeyC), absence of sperm in lumen of tubules and spermatids. Presenting ST, seminiferous tubules; SP, spermatogonia; SPC, spermatocytes; SPT, spermatids; SPZ, spermatozoa; IT, interstitial tissue; LeyC, Leydig cell (White arrow). H&E (× 40)

Fig. 2

Photomicrograph of caput epididymis tissue showing a control; with compact arrangement of caput tubules with sperm-filled lumen b BPF (1 mg/kg/day)-exposed group, presenting normal caput tubules like in the control. c BPF (5 mg/kg/day) exposed group showing seminiferous tubules with less number of sperm in the lumen (arrow). d BPF (25 mg/kg/day)-exposed group presenting caput tubules with empty lumen (arrow). Similarly, e BPF (50 mg/kg/day)-exposed group showing less number of sperms in the lumen. f BPF (100 mg/kg/day)-exposed group showing less number of sperms and empty lumen (arrow). Presenting SP, spermatozoa; ST, seminiferous tubules; E, epithelium. H&E (× 40)

Fig. 3

Photomicrograph of cauda epididymis tissue showing a control; with compact arrangement of cauda tubules with sperm-filled lumen. b BPF (1 mg/kg/day)-exposed group, presenting normal caput tubules like in the control. c BPF (5 mg/kg/day)-exposed group, presenting cauda tubules with sperm-filled lumen. d BPF (25 mg/kg/day-exposed group presenting cauda tubules with less sperm in the lumen. Similarly, e BPF (50 mg/kg/day)-exposed group presenting cauda tubules with fewer sperm in the lumen. Likewise, f BPF (100 mg/kg/day)-exposed group presenting cauda tubules with empty spaces and fewer number of sperm in the lumen. Presenting SP, spermatozoa, ST, seminiferous tubules; E, epithelium. H&E (× 40)