Chronic High Dose Intraperitoneal Bisphenol A (BPA) Induces Substantial Histological and Gene Expression Alterations in Rat Penile Tissue Without Impairing Erectile Function

Department of Surgery, Division of Urology, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
Journal of Sexual Medicine (Impact Factor: 3.15). 10/2013; 10(12). DOI: 10.1111/jsm.12336
Source: PubMed


Bisphenol A (BPA), released from plastics and dental sealants, is a suspected endocrine disruptor and reproductive toxicant. In occupationally exposed workers, BPA has been associated with erectile dysfunction (ED).
To determine whether long-term exposure to high doses of BPA in the rat affects serum levels of testosterone (T) and estradiol (E2), and induces corporal histopathology and resultant ED.
Young rats were injected intraperitoneal (IP) injection daily with BPA at 25 mg/kg/day or vehicle (n = 8/group). Erectile function was measured at 3 months by cavernosometry and electrical field stimulation (EFS). BPA was assayed in serum, urine, and penile tissue, and serum T and E2 were determined. Quantitative Masson trichrome, terminal deoxynucleotidyl transferase dUTP nick end labeling, Oil Red O, immunohistochemistry for calponin, α-smooth muscle actin, and Oct 4 were applied to penile tissue sections. Protein markers were assessed by Western blots and 2-D minigels, and RNA by DNA microarrays.
Erectile function, histological, and biochemical markers in corporal tissue.
In the BPA-treated rats, total and free BPA levels were increased in the serum, urine, and penile tissue while serum T and E2 levels were reduced. In addition, the corpora cavernosa demonstrated a reduction in smooth muscle (SM) content, SM/collagen ratio, together with an increase in myofibroblasts, fat deposits, and apoptosis, but no significant change in collagen content or stem cells (nuclear/perinuclear Oct 4). In the penile shaft, BPA induced a downregulation of Nanog (stem cells), neuronal nitric oxide synthase (nitrergic terminals), and vascular endothelial growth factor (angiogenesis), with genes related to SM tone and cytoskeleton upregulated 5- to 50-fold, accompanied by changes in the multiple protein profile. However, both cavernosometry and EFS were unaltered by BPA.
While rats treated chronically with a high IP dose of BPA developed hypogonadism and a corporal histo- and molecular-pathology usually associated with ED, no changes were detected in erectile function as measured by EFS and cavernosometry. Further studies using alternate routes of BPA administration with various doses and length of exposure are needed to expand these findings. Kovanecz I, Gelfand R, Masouminia M, Gharib S, Segura D, Vernet D, Rajfer J, Li DK, Liao CY, Kannan K, and Gonzalez-Cadavid NF. Chronic high dose intraperitoneal bisphenol A (BPA) induces substantial histological and gene expression alterations in rat penile tissue without impairing erectile function. J Sex Med **;**:**-**.

23 Reads
  • Source
    • "In the rabbit, a high dose of BPA given intraperitoneally for 2 weeks reduced the in vitro relaxation of corpora cavernosa strips and induced lipofibrotic infiltration of the corpora smooth muscle, but other histopathological markers or erectile function in vivo were not measured (13). In our previous study (14) in young male rats (1.5 months old) exposed for 3 months to intraperitoneal administration of BPA at relatively high levels (25 mg/kg/day), but only 1/3 of those in the aforementioned rabbit study and ½ of the Lowest Observed Adverse Effect Level (LOAEL) for BPA (15), we found a) a corporal histopathology normally associated with ED, b) hypogonadism, and c) parallel changes in global gene expression that would be consistent with ED, Although this exposure in the rats led to urinary excretion of BPA that was 7-fold higher than that in the occupationally exposed workers who were found to have ED, no frank ED by EFS or corporal veno-occlusive dysfunction (CVOD) could be detected in our animals. This posed the question as to whether oral administration of BPA for longer periods, which is more representative of human exposure, and with different BPA kinetics and metabolism than by the intraperitoneal route may eventually exacerbate the underlying corporal pathology when applied to older rats that are more prone to ED. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Bisphenol A (BPA), a suspected reproductive biohazard and endocrine disruptor, released from plastics is associated with ED in occupationally exposed workers. However, in rats, despite the induction of hypogonadism, apoptosis of the penile corporal smooth muscle (SM), fat infiltration into the cavernosal tissue and changes in global gene expression with the intraperitoneal administration of high dose BPA, ED was not observed. We investigated whether BPA administered orally rather than intraperitoneally to rats for longer periods and lower doses will lead to ED. Main outcome measures are ED, histological, and biochemical markers in rat penile tissues. In all, 2.5-month-old rats were given drinking water daily without and with BPA at 1 and 0.1 mg kg(-1) per day. Two months later, erectile function was determined by cavernosometry and electrical field stimulation (EFS) and serum levels of testosterone (T), estradiol (E2) and BPA were measured. Penile tissue sections were assayed by Masson (SM/collagen), Oil Red O (fat), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) (apoptosis), immunohistochemistry for Oct4 (stem cells), and α-SM actin/calponin (SM and myofibroblasts), applying quantitative image analysis. Other markers were assayed by western blotting. DNA microarrays/microRNA (miR) assays defined transcription profiles. Orally administered BPA did not affect body weight, but (1) decreased serum T and E2; (2) reduced the EFS response and increased the drop rate; (3) increased within the corporal tissue the presence of fat, myofibroblasts and apoptosis; (4) lowered the contents of SM and stem cells, but not nerve terminals; and (5) caused alterations in the transcriptional profiles for both mRNA and miRs within the penile shaft. Long-term exposure of rats to oral BPA caused a moderate corporal veno-occlusive dysfunction (CVOD), possibly due to alterations within the corporal tissue that pose gene transcriptional changes related to inflammation, fibrosis and epithelial/mesenchymal transition (EMT).International Journal of Impotence Research advance online publication, 5 December 2013; doi:10.1038/ijir.2013.37.
    Full-text · Article · Dec 2013 · International journal of impotence research
  • [Show abstract] [Hide abstract]
    ABSTRACT: IntroductionThe success of medical therapies for Peyronie's disease (PD) has not been optimal, possibly because many of them went directly to clinical application without sufficient preclinical scientific research. Previous studies revealed cellular and molecular pathways involved in the formation of the PD plaque and in particular the role of the myofibroblast.AimsThe current work aimed to determine under normal and fibrotic conditions what differentiates PD cells from tunica albuginea (TA) and corpora cavernosa (CC) cells by defining their global transcriptional signatures and testing in vivo whether PD cells can generate a PD-like plaque.Methods Human TA, PD, and CC cells were grown with transforming growth factor beta 1 (TGFβ1; TA+, PD+, CC+) or without it (TA−, PD−, CC−) and assayed by (i) immunofluorescence, Western blot and RT-PCR for myofibroblast, smooth muscle cell and stem cell markers; (ii) collagen content; and (iii) DNA microarray analysis. The ability of PD+ cells to induce a PD-like plaque in an immuno-suppressed rat model was assessed by Masson trichrome and Picrosirius Red stainings.Main Outcomes MeasuresFibroproliferative features of PD cells and identification of related key genes as novel targets to reduce plaque size.ResultsUpon TGFβ1stimulation, collagen levels were increased by myofibroblasts in the PD+ but not in the CC+ cells. The transcriptional signature of the PD− cells identified fibroproliferative, myogenic (myofibroblasts), inflammatory, and collagen turnover genes that differentiate them from TA− or CC− cells and respond to TGFβ1 with a PD+ fibrotic phenotype, by upregulation of IGF-1, ACTG2, MYF5, ACTC1, PSTN, COL III, MMP3, and others. The PD+ cells injected into the TA of the rat induce a PD-like plaque.Conclusions This suggests a novel combination therapy to eliminate a PD plaque by targeting the identified genes to (i) improve collagenase action by stimulating endogenous metalloproteinases specific to key collagen types and (ii) counteract fibromatosis by inhibiting myofibroblast generation, proliferation, and/or apoptosis. Gelfand RA, Vernet D, Kovanecz I, Rajfer J, and Gonzalez-Cadavid NF. The transcriptional signatures of cells from the human Peyronie's disease plaque and the ability of these cells to generate a plaque in a rat model suggest potential therapeutic targets. J Sex Med **;**:**–**.
    No preview · Article · Feb 2015 · Journal of Sexual Medicine