Bisphenol A

Bisphenol A

Synonyma

• BPA
• 2,2-bis(4-hydroxyphenyl)propane
• CAS Registry No. 80-05-7

• Composed of
• Two phenol rings
• Connected by a methyl bridge
• Two methyl functional groups attached to the bridge [87]

Chemické vlastnosti

• Made by combining acetone and phenol [87]

Historie

• 1930s
• Initially investigated for its potentially therapeutic estrogenic properties
• Diethylstilbestrol (DES) was found to be more potent [91]
• 1950s
• Commercial value was reassessed
• As a fundamental component in the manufacturing of some plastics
• Key monomer in the production of the most common form of clear and shatter-proof polycarbonate plastic [91]

Epidemiologie zamoření [68]

• One of the highest volume chemicals in worldwide production
• Estimated at 10-billion pounds per year in 2011 [68]
• All human fetuses that have been examined
• Have measurable blood levels of BPA [64]
• Mean or median levels found in humans
• Higher than levels in fetal and neonatal mice in response to maternal doses
• Increase postnatal growth [64]

• Lipophilic compound [68]
• Detectable at nanomolar levels [68]
• In food [68]
• Tap water [68]
• In rivers, lakes and sea [68]
• In human blood samples and urine worldwide [68]
• In the placenta [68]
• In amniotic fluid of pregnant women [68]
• In human milk [68]

• Acute toxicity to aquatic organisms
• In the range of 1–10 g/ml for freshwater and marine species (Alexander et al., 1988) [87]

Výskyt BPA

• Key monomer in the production of the polycarbonate (74%) and epoxy resins (20%) [91]
• Primarily to make polycarbonate plastic
• Epoxy resins
• Phenol resins
• Polycarbonates
• Polyacrylates
• Polyesters
• Lacquer coatings on food cans (Staples et al., 1998) [87]
• Canned goods [57]
• BPA epoxy resin films to prevent corrosion [92]

• Compound used ubiquitously in the plastic manufacturing industry [57]
• In products containing polycarbonate plastics [68]

• Plastic food and beverage containers
• Including baby bottles
• water bottles
• Lining for metal cans [68]
• Dental sealants (Maserejian et al. 2014) [57]
• Wide use of BPA in water bottles [57]
• Electronics, sports safety equipment
• Adhesives
• Cash register receipts (thermal printing paper ) [92]
• Medical devices
• Dialysis patients appear to have higher rates of exposure [92]
• Eyeglass lenses
• water supply pipes
• Adjunct in the production of
• Brominated flame retardants
• Brake fluid
• BPA derivatives
• bisphenol A-glycidyl methacrylate
• bisphenol A-dimethacrylate
• Incorporated into the dental fillings and sealants

• Main exposure to BPA occurs through the diet
• Contaminated food and drinking water (Kang et al. 2006)

• Main factors influencing the migration of BPA from can surfaces are:
• Heating times
• Temperatures
• In the manufacturing process !!! [87]

• High levels of BPA were identified from
• Leachates of waste landfill
• (Yamada et al., 1999; Behnisch et al., 2001; Yamamoto et al., 2001; Filho et al., 2003) [87]
• Leaching of BPA from plastic wastes into water was also reported
• Highest levels (9.8 and 139 ug/g) were identified from polyvinylchloride products
• Use BPA as a stabilizer (Yamamoto and ara,1999)

• At room temperature, leaching of BPA occurred into the contained fluid
• Increased 55-fold if boiling water was added !!! [92]
• Exposure levels increased also with repeated use of a container !!! [92]

• All canned foods are autoclaved after canning
• The fact that bisphenol A is leached into water during autoclaving in these experiments suggests that any product packed in similar cans will contain bisphenol A
• It is also likely that substantially more bisphenol A will leach into fatty products [93]

4 Maternal exposure to Bisphenol A

• Synthetic estrogen and ubiquitous industrial contaminant
• Inducing DNA hypomethylation at Avy and another metastable epiallele, CabpIAP (Dolinoy et al., 2007) [1]

Chození kolem horké kaše

• Regulatory agencies in the USA and Europe have focused on a very narrow set of BPA studies that followed regulatory guidelines and used “good laboratory practices (GLP)” protocols.
• This name does not imply “good science”
• GLP was instituted as a result of fraud in record keeping by commercial chemical testing laboratories [68]
• Lack of use of GLP protocols
• Greatly increase the cost of the research
• An inappropriate basis for rejecting studies for inclusion in assessing the health hazards of BPA [68]
• Selektivní výběr propagačních studií chemického průmyslu k obhajobě "neškodnosti" Bisfenolu A
• “For the third time since 2007, and as a result of a comprehensive review of more than 800 recent studies, EFSA has again confirmed that bisphenol A (BPA) is safe for use in products that come in contact with food,” said Steven G. Hentges, Ph.D., of the American Chemistry Council.
• 2012 U.S. Food and Drug Administration banned BPA in baby bottles and sippy cups. Its use is more broadly banned elsewhere in the world. [89]

• An extensive review conducted in 2007 concluded that
• BPA levels in human blood and/or urine are within the range shown to be dangerous in animals
• Are therefore likely to be biologically active in humans [92]
• Blood and urine testing may underestimate the full extent of exposure and bioaccumulation [92]
• Conversely, an industry-sponsored literature review from 2008 declared that
• Daily human consumption was far below dangerous levels and is therefore of minimal concern [92]

• In 2010 the Minister of Health for the Canadian Government declared the results of a four-year study indicating
• "Our science indicated that Bisphenol A may be harmful to both human health and the environment”
• The Canadian government became the first to prohibit the sale of BPA-containing polycarbonate baby bottles [92]
• France, Denmark and several American states have since implemented similar regulations [92]

Metabolismus bisfenolu A mikroorganismy v prostředí

• Metabolites of BPA can enhance estrogenicity or toxicity [87]
• Many bacteria capable of biodegrading BPA have beeb identified from soils (Sasaki et al., 2005), river waters [87]
• Bacteria capable of biodegrading BPA are distributed in river waters [87]
• Half-lives for BPA biodegradation averaged below 5 days [87]

Bakterie

Gram-negative aerobic bacterium (strain MV1)

• Minor pathway
• Bisphenol A is first oxidized to a triol [86]
• Major pathway
• Intermediates 4-hydroxybenzoate and 4-hydroxyacetophenone
• Converted to carbon dioxide and biomass (Spivack et al., 1994) [86]

Sphingobium xenophagium Bayram and Sphingomonas sp. strain TTNP3

• Can metabolize bisphenol A
• Ipso-substitution mechanism
• Ring hydroxylation at the site of the substituent
• Product can be cleaved to form hydroquinone and a proposed 2-(4-hydroxyphenyl)-isopropyl cation
• To 4-(2-hydroxypropan-2-yl)phenol
• Dehydrogenation to form 4-isopropenylphenol
• Reduced to 4-isopropylphenol
• Other possible routes
• Formation of a 2-(4-hydroxyphenyl)-isopropyl anion (Gabriel et al., 2007, Kolvenbach et al., 2007) [86]

Sphingobium fuliginis TIK-1

• Can metabolize and grow on 4-isopropylphenol [86]

S. fuliginis

• Proposed to hydroxylate 4-ispropylphenol to 4-isopropylcatechol
• Metabolized by a meta-cleavage pathway
• 3-Methyl-2-butanone was the major degradation product observed (Toyama et al., 2010) [86]

Efektivita biodegradace

• Only two strains showed high BPA biodegradability (about 90%)
• Pseudomonas sp.
• Pseudomonas putida strain [87]
• Streptomyces sp. strain isolated from river water
• Has high BPA biodegradability (>90% for 10 days) [87]

• Influenced by temperature and bacterial counts [87]
• BPA in the anaerobic slurry was not biodegraded even after 3 months of incubation
• Anaerobic bacteria have no or little BPA biodegradability
• BPA in anaerobic environment such as anaerobic marine sediment can persist for an extended period of time [87]

Houby

• More effective for BPA biodegradation
• Fusar iumsporotrichioides NFRI-1012
• Fusariummoniliforme 2-2,
• Aspergillus terreus MT-13
• Emericella nidulans MT-98 [87]

• Mainly by
• Lignin-degrading enzymes
• Manganese peroxidase (MnP)
• Laccase
• Produced by white rot basidiomycetes fungi [87]

Plankton

• Chlorella fusca var. vacuolata
• Could biodegrade BPA and removed its estrogenic activity
• C. fusca
• Removal of BPA was
• 85% under light conditions for 120 h
• 22% under dark [87]

• BPA was accumulated in the zooplankton cells through the phytoplankton cells [87]

Rostliny

• Plants can rapidly absorb BPA from water
• Through their roots
• Metabolize it to several glycosidic compounds [87]
• Glycosylation of BPA main route in plants
• Loss the estrogenicity
• Distribution of BPA and its metabolites in plant may be variable according to plant species

Ptáci a ryby

Farmakokinetika BPA (savci a lidi)

• P.o. absorbed BPA
• Subject to greater first pass metabolism in the liver versus parental apl. [68]
• Serum unconjugated BPA in adult rodents
• Maximum value reached after a bolus administration
• Average exposure over the 24 hr after administration does not differ based on route of administration
• Between 12 – 24 hr after administration [68]
• Average internal concentration of BPA over the 24 hr after administration via oral or sc route is actually not very different
• Dramatically contradicts assumptions made by the European Food Safety Agency [68]
• In newborn rodents
• Route of administration is even less of a factor than the relatively small effect it has in adults
• Adult prostate disease as a result of neonatal exposure
• To the same low 10 µg/kg/day dose of BPA oral or sc administration [68]
• Pharmacokinetics of BPA does not differ between mice, rhesus monkeys and humans [68]

Savci

• Free BPA is excreted in feces at the range of 56–82%
• Its metabolites are in urine at the range of 13–28%
• Metabolicke drahy degradace BPA savců

Glucuronidation

• Liver microsomes [87]
• Mediated by UGT2B1 n isoform of UGT
• Slightly less in pregnancy than in nonpregnancy
• Because multidrug resistance-associated protein II
• UGT decrease in pregnancy [87]
• UGT levels in the human fetal liver are lower / none compared to the adult liver [87]

Sulfation

• Sulfotransferases in the liver
• Humans:
• Simple phenol (P)-phenol sulfotransferase (SULT1A1)
• Thermostable phenol sulfotransferase (ST1A3)

[87]

Potkani

• After glucuronidation or sulfation in the rat liver
• Metabolites of BPA are excreted mainly into the bile [87]
• The venous excretion of metabilites increases three-fold in pregnancy [87]
• Mainly BPA glucuronide, in the liver [88]
• After 2-3 days, excretion of BPA and its metabolites, mainly in the feces, is mostly complete [88]
• A very small fraction, less than 1%, is retained in the tissues [88]
• Microsomal cytochrome P450 enzymes in rat liver
• Inhibitor of the cytochrome P450 system, SKF 525-A, inhibited the metabolism of BPA
• Metabolize BPA into bisphenol-o-quinone via
• 5-hydroxy BPA
• A bisphe-nol semiquinone [87]
• BPA can inhibit human hepatic cytochromeP450s
• Metabolites of BPA produced by microsomal cytochrome P450s
• Enhanced toxic activity
• DNA adduct formation with BPA metabolites (Atkinson and Roy, 1995a,b) [87]
• Bisphenol-o-quinone, could bind DNA in vitro and in vivo
• Estrogenni aktivita zesilena
• 4-methyl-2,4-bis(p-hydroxyphenyl)pent-1-ene (MBP)

Humans

• Three males and three females, and four males [85]
• Administered d(16)-bisphenol A (5 mg)
• Blood and urine samples were taken in intervals (up to 96 h)
• D(16)-Bisphenol A glucuronide
• Was the only metabolite of d(16)-bisphenol A detected in urine and blood samples [85]
• Concentrations of free d(16)-bisphenol A
• Were below the limit of detection both in urine (6 nM) and blood samples (10 nM) [85]
• D(16)-Bisphenol A glucuronide
• Cleared from human blood and excreted with urine
• With terminal half-lives of less than 6 h [85]
• Applied doses
• Completely recovered in urine as d(16)-bisphenol A glucuronide [85]
• Maximum blood levels of d(16)-bisphenol A glucuronide
• Approximately 800 nM
• 80 min after p.o. administration of d(16)-bisphenol A (5 mg) [85]

• Enterohepatic circulation of bisphenol A glucuronide
• In rats results in a slow rate of excretion
• By humans - bisphenol A is rapidly conjugated and excreted due to the absence of enterohepatic circulation [85]
• Efficient glucuronidation of bisphenol A and the rapid excretion of the formed glucuronide [85]

• In humans, 100% of BPA-G was cleared via urinary elimination
• Whereas in rodents there was extensive excretion via the bile
• In humans and other primates p.o. BPA
• Free BPA in blood was typically below detection limits
• Or represented a very small fraction of the total circulating metabolites
• The predominant form of circulating BPA was BPA-G [91]
• Cave - novorozenci
• Undeveloped constitutive expression of uridine glucuronosyltransferase (UGT) [91]

• Absorpce rychlejsi u lidi a primatu nez u potkanu
• Longer time to eliminate BPA from serum in primates than in rats [87]
• Human liver microsomes can’t glucuronidate BPA as extensively as the rat liver microsomes
• The very complete conversion to the BPA glucuronide means that
• Effects in rodents due to the parent compound (BPA) are unlikely to be found in humans [88]
• Glucuronide metabolite, which is formed rapidly and almost exclusively in humans
• Does not bind to the estrogen receptor
• Suggests that BPA is even less likely to be an endocrine modulator than was concluded on the basis of the results of the rodent-metabolism studies [88]
• BPA-glucuronide and the minor urinary metabolite BPA-sulphate do not interfere with hormonal regulation of reproduction [90]
• Dubbed MBP
• 2004, Shin'ichi Yoshihara, PhD, and colleagues at Hiroshima International University
• Produced when BPA was metabolized
• MBP has a 100-fold to 1,000-fold stronger bond to the estrogen receptor than BPA [89]
• MBP’s longer structure allows both ends of the chemical to interact with the estrogen receptor in a way similar to estradiol.
• MBP is one (of perhaps several BPA metabolites) that causes disruption of estrogen signaling in humans and other animals [89]

• P.o. unconjugated BPA
• Biologically active form of BPA
• Historically been thought to be:
• Rapidly conjugated in the liver
• Then excreted through bile or urine, with a half life of cca 5.3 h
• Rapid excretion has been the basis of reassuring safety evaluations and declarations given by some public health authorities worldwide [92]
• Particularly in the lungs, livers and kidneys in rats, and the placenta of animals and humans
• ß-glucuronidase enzyme is present at detectable concentration
• Deconjugate BPA and release its active form again
• In pregnancy fetal exposure in utero [92]
• May also result in bioaccumulation of some portion of BPA after exposure
• Most plasma BPA (about 95%) is bound to serum proteins
• At low concentrations BPA has lipophilic affinity:
• Fat: blood coefficient of 3.3
• In fat, the accumulation of BPA was cca 3 x higher than in other tissues [92]

• In normal circumstances the daily volume of urine is much higher than sweat
• Urine remains an important mode of elimination of BPA from the human body [92]

Vlivy na organismus [53]

• Environmentally BPA doses
• Induce changes in gene expression [53]
• Affect their activity [53]
• Large number of genes are modulated by BPA
• Induce negative health effects (Singh & Li 2012) [53]
• Endocrine disruption [92]
• Epigenetic modification [92]
• Cytokine release [92]
• Oxidative stress [92]

PA exposure has been linked to: [57]

• Risk of miscarriages [57]
• obesity [57]
• Cancer (Rochester 2013) [57]
• Breast and prostate
• Exposure of breast epithelial cells to BPA was found to alter gene expression of 170 genes [92]
• Increase their vulnerability to other carcinogens [92]
• Silencing of lysosomal-associated membrane protein 3
• Occurs in ER?-positive breast cancer [92]
• Irregular cycles [92]
• Multiple ovarian cysts [92]
• Reduction in primordial follicles [92]
• Placental dysfunction [92]
• Increased incidence of miscarriage and neonatal mortality [92]
• Precocious puberty [92]
• Erectile dysfunction [92]
• Decreased libido [92]
• Ejaculation difficulties [92]
• Interference with the production and signaling of sex hormones [92]
• Led to neurological impairment [92]
• Synapse formation during development is regulated by estrogen and androgens [92]
• Levels deemed safe by the US Environment Protection Agency [92]
• Completely abolish the response of synapses to estrogen in the prefrontal cortex and hippocampus [92]
• Metabolic syndrome
• obesity
• Non-insulin-dependent diabetes mellitus
• Allergies and asthma
• ADHD, autism, cognitive decline, memory impairment
• Depression, and anxiety

• Accumulate in fat
• With 50% of breast adipose tissue from women containing BPA (Fernandez et al. 2007) [57]

• Workers producing this compound and its products (eg, epoxy resins) have been exposed to time-weighted average air levels to about 10 mg/m3 over decades
• High exposures to BPA are
• Irritating to the eye and respiratory tract
• May cause skin lesions [88]
• Photosensitization of the skin [88]
• No studies reporting systemic effects were identified
• No epidemiologic studies of workers who have been exposed occupationally were found [88]

Děti

• Human neonates
• Glucuronidation (2-5 fold lower in premature neonates)
• Glomerular filtration (1.7 fold lower)
• Within one and seven months after birth
• Considered sufficient capacity in the neonate to conjugate BPA at doses below 1 mg/kg bw [90]
• That exposures at the TDI of 0.05mg/kg bw are 20 fold lower than this [90]

Hormonální dirupce

• Endocrine disruptor
• Activation of estrogen receptors alfa and ß (ERß) (Wozniak et al. 2005, Welshons et al. 2006, Le et al. 2008, Kim et al. 2012, Li et al. 2012, Chen Zee et al. 2013) [57]
• Competing with endogenous hormones [53]
• Estrogen-like properties [53]
• Low environmentally doses - can act as an estrogen antagonist [53]
• Non-classical ER pathways (Li et al. 2012, Boucher et al. 2014) [53]
• Increases in weight and size of the prostate gland in male offspring of treated mice
• Decreases in sperm efficiency in young mice [88]

• Disrupting effects on the: [53]
• Classical nuclear receptors estrogen receptors alpha and beta (ER alfa and ER beta) [53]
• Non-classical membrane estrogen receptor (ncmER) [53]
• Estrogen-related receptor gamma (ERR gamma) [53]
• G protein-coupled receptor 30 (GPR30) [53]
• Aryl hydrocarbon receptor (AhR) (Hugo et al. 2008, Alonso-Magdalena et al. 2012) [53]

Animal models, BPA has been shown to disrupt:

• Thyroid hormones [53]
• Estrogens [53]
• Testosterone [53]
• Corticosteroids [53]
• Growth hormone [53]
• Leptin [53]

• Alter adipogenesis [53]
• Beta-cell and endocrine pancreas function [53]
• Inflammation [53]
• insulin sensitivity [53]

• Found to be oestrogenic in the MCF-7 human breast cancer cell culture in 1993 (Krishnan et al., 1993)
• Concentrations as low as 2-5 ppb (2-5 µg/l)

• Can also act as an antiandrogen
• Blocking the action of dihydrotestosterone in a yeast screen containing a human androgen receptor (Sohoni and Sumpter, 1998)
• Cca as potent as flutamide, a well known anti-androgen

• Liquor containing bisphenol-A obtained from tinned vegetables
• Found to be oestrogenic to human breast cancer cells
• Identical effects to oestradiol on rat uterus and vagina

• Exposure of developing male mice
• Enlarge their prostate glands

• Female mice exposed in the womb to low doses of bisphenol a (2.4 micro-g per kg per day to the mother)
• Significantly reduced delay between vaginal opening and first vaginal oestrus (Howdeshell et al., 1999)

Estrogens

• Shared homology with estrogen [57]
• Upregulation of downstream targets [57]
• Peroxisome proliferator-activated receptor gamma (PPARG) [57]
• Lipoprotein lipase (LPL) genes on rodents (Melzer et al. 2011) [57]

• Regulate cellular metabolism by programming gene expression in adipocytes
• Implicated in metabolic disorder restoration
• In adipose tissue
• ERß is less expressed than ER alfa (Hugo et al. 2008) [57]
• Overexpression of ERR alfa
• High binding affinity of BPA for ERR alfa (Takayanagi et al. 2006, Okada et al. 2008)
• ERR alfa
• A constitutive activator of transcription
• Able to modulate the estrogen-signaling pathway not by binding directly to E2
• By controlling the transcription of essential genes that regulate metabolic processes (Liu et al. 2007, Giguere 2008) [53]
• Expression also increased after E2 treatment
• Lack of estrogens
• Increases fat mass
• Impairs glucose tolerance
• Lead to insulin resistance (Vom Saal et al. 2012) [53]

Low doses of BPA

• Modulated the abundance of the ER alfa transcript
• No changes in ERß mRNA levels were found [57]

• BPA may exert its action through non-classical estrogen receptors
• Independent effects (Hugo et al. 2008, Tohme et al. 2014)
• High BPA accumulation in adipose tissue
• Increasing the abundance of ERR alfa transcripts [57]

• BPA activity varies depending on
• Specific estrogen receptor expression
• Distribution of those receptors within tissues [57]

• BPA elicit
• Rapid responses by binding GPR30
• Activating alternative non-genomic estrogen signaling pathways (Thomas & Dong 2006)
• GPR30 knockout mice displayed
• Impaired glucose tolerance
• Reduced body growth
• Increased body weight (Martensson et al. 2009, Ford et al. 2011) [57]

• Increased plasma concentrations of estrogens [68]
• Associated with a reduction in food intake
• Red. body weight in adults [68]
• Loss of ovarian estrogen secretion related to menopause in women
• Results in weight gain
• During critical periods in development, estrogenic chemicals
• Can have unexpected effects
• Differentiation of adipocytes [68]
• Postnatal growth [68]
• “programming” of obesity related to exposure to environmental estrogens during critical periods in organogenesis
• Adult mice - estradiol-17 beta - via estrogen receptor alfa
• Inhibitory effect on adipocyte number and lipogenesis [68]
• Ovariectomy or genetic mutation in the gene controlling the enzyme aromatase (CYP19)
• Impaired glucose tolerance
• insulin resistance
• Increased fat mass [68]
• Central effects on food consumption and energy expenditure
• Overall inhibitory effects on adipose deposition in adults [68]
• Estrogens and other hormones
• Can cause permanent changes - “organizational” effects
• By programming gene expression when cells are differentiating - “critical periods ” [68]

• Mechanisms that determine:
• Which genes in a cell can be transcribed
• The level at which transcription occurs [68]
• Jsou ovlivňovány i:
• Epigenetic modifications of DNA
• Associated histone proteins [68]

• Estrogenic EDCs can:
• Program gene activity via epigenetic changes during critical periods in development
• With long-term consequences [68]

• Methylation sensitive promoter
• Genistein (increased methylation)
• bisphenol A (decreased methylation)
• Predicted an adult phenotype of yellow coat color, diabetes, tumors and obesity [68]
• Coat color
• obesity in mice [68]

• “fetal estrogenization syndrome” [68]

Obezitogenní

• Increase fat cell numbers or sizes [53]
• Increases expression of FABP4 and CD36 [53]
• Involved in lipid metabolism [53]
• BPA exposure during adipocyte differentiation
• Affects gene expression
• Modulates adipose tissue functions:
• PPAR
• C/EBP
• LPL
• GLUT4
• CYP19 [57]
• GPAT
• DGAT
• Leptin (OB) (Vom Saal et al. 2012, Boucher et al. 2014, Ohlstein et al. 2014) [57]

• Increases lipoprotein lipase gene expression
• Tím i enzymatic activity
• Leads to triacylglycerol accumulation (Masuno et al. 2002) [57]

• Increase glucose transporter GLUT4 levels
• Alter glucose uptake (Masuno et al. 2002, Sakurai et al. 2004)

• Up-regulation of leptin mRNA levels (Angle et al. 2013) [57]
• Jako důkaz většího obsahu tuku v tukové tkáni

FABP4

• Produced in adipocytes
• Fatty acid uptake and metabolism
• Important contributor to metabolic dysfunction in obesity-induced chronic inflammation and dyslipidemia (Hardaway & Podgorski 2013)
• Elevated FABP4 plasma levels
• Associated with metabolic syndrome (Xu et al. 2007)
• Obesogenic role for BPA
• BPA Up-regulation of FABP4 and CD36
• Significant increase in intracellular lipid droplets and in triglyceride concentration
• BPA affects adipocyte lipid storage which leads to cellular hypertrophy
• Results in a resistin secretion increase
• Decrease in adiponectin production in vitro
• (C Menale, A Grandone, C Nicolucci, G Cirillo, S Crispi, A Di Sessa, S Rossi, D G Mita, L Perrone, E M Del Giudice, N Diano, unpublished observations)
• Might impair glucose metabolism
• Confirmed by preliminary experiments performed in a mouse model (C Menale, personal communication)
• Might increase the oxidative stress of hypertrophic adipocytes
• Might contribute to the inflammation and dysregulation of free fatty acid efflux (Zha & Zhou 2012)

PC1/3

• Cleaves pro-insulin to produce active insulin
• Mutations of or deficiencies in PC1/3
• Cause early obesity (Creemers et al. 2012, Turpeinen et al. 2013)
• Deficiency of PCSK1
• Leads to serious multi-hormonal disorder marked by early-onset obesity (Jackson et al. 1997) [57]

BPA mediates adipogenesis through an ER-dependent pathway gen expression

• 1. signif. elevace exprese adipogennních genů již 7. den po oš. BPA: [53]
• Mid-stage adipogenesis [53]
• C/EBP [53]
• Late adipogenic genes [53]
• IGF1 [53]
• LPL [53]
• The greatest induction !!! [53]
• Master transcriptional regulator of adipogenesis [53]
• PPAR [53]
• Upon treatment with the ER antagonist ICI 182 780
• The effect of BPA on adipogenic differentiation was blocked [53]

• Prenatal exposure to BPA in rodents
• Increased white adipose depots
• Increased expression of C/EBP?, PPAR?, and LPL [57]

• Induction of DLK and IGF1 mRNA transcripts
• DLK expression has been linked to adipogenesis
• Target of PPAR transcriptional activity (Couture & Blouin 2011) [57]
• IGF1 has been associated with obesity, insulin resistance, and adipogenesis (De Pergola & Silvestris 2013, Xie & Wang 2013) [57]

• In mouse 3T3-L1 cells BPA increased
• Lipoprotein lipase (LPL) activity
• Triacylglycerol accumulation
• Presence of larger lipid droplets in the differentiated cells [68]
• Insulin and BPA interacted synergistically to further accelerate these processes
• BPA also stimulated an
• Increase in the glucose transporter GLUT4
• Glucose uptake into 3T3-F442A adipocytes [68]

• Up-regulation of GLUT4
• Increased basal and insulin-induced glucose uptake into adipocytes

Koncentrace BPA

• BPA has a maximal effect at a concentration of 1 µM [57]
• Significant increase in adipogenesis in ASCs treated for 14 days at levels as low as 100 pM was observed
• Average BPA serum levels
• Between 1 and 20 nM [57]
• With BPA showing activity in cellular assays as low at 1 pM to 1 nM
• Robust response to BPA at 21 days
• Substantial increase in transcriptional activity at day 7 was observed
• Increased adipogenesis at 14 days in response to lower concentrations of BPA was noted [57]
• Even low-level exposure to BPA can expedite differentiation of ASCs into a mature adipocytes [57]

• Maximal effect at a concentration of 1 µM [68]
• Observed cell death at a concentration of 10 µM [68]

Prozánětlivý

• Increases the expression of pro-inflammatory cytokines [53]

CCL20

• Gen pro cytokine
• Hldina v krvi directly correlated with BMI (Hashimoto et al. 2006, Duffaut et al. 2009, Villaret et al. 2010) [53]
• Elevated serum CCL13 and CCL20 concentrations [53]
• In overweight subjects during chronic inflammation [53]
• IL18 and IL1B [53]
• Regulators of inflammatory responses

Diabetogenní

• Decreases the expression of PCSK1 [53]
• Involved in insulin production [53]
• Involved in the onset of metabolic dysfunction [53]
• Reduced insulin-stimulated tyrosine phosphorylation of insulin receptors
• In adult adipocytes treated with BPA [53]
• Reduction of insulin downstream signaling [53]

• Associations between serum and urinary concentrations of persistent organic pollutants and diabetes have been described
• Women with Polycystic Ovary Syndrome (PCOS)
• insulin resistance
• Low-grade chronic inflammation
• Elevated serum BPA levels [59]

BPA exposure

• Cultured adipose cells derived from human subcutaneous tissue
• 3T3-L1 adipocytes

• Impaired
• insulin sensitivity
• Glucose utilization
• Enhanced
• Release of pro-inflammatory compounds
• Even in the absence of major derangement of adipocyte differentiation [59]

• Nanomolar BPA concentrations [59]
• May induce an inflammation-like response in human adipocytes [59]
• Increases the release of IL-6 and IFN [59]
• Aktivace JNK, JAK/STAT and NF-kB pathways [59]

• Binds G protein-coupled receptor 30 (GPR30)
• Novel non-classical membrane ER
• Might induce biological effects in different cell types, including adipocytes [59]

• BPA-treated adipocytes were less sensitive to insulin in terms of glucose utilization
• Effect was already detectable upon treatment of the cells with 1 nM BPA [59]

• BPA stimulated an increase in GLUT4 and glucose uptake in adipocytic cell models
• Required doses considerably higher than those found in human tissues [59]

• Increased basal glucose utilization
• Increased levels of GLUT1 [59]
• BPA-induced insulin sensitivity
• May contribute to worsen the pro-inflammatory profile [59]

• Reduced insulin-stimulated tyrosine phosphorylation of insulin receptor
• Reduction of downstream signalling
• Can be responsible for a worsening in insulin signalling via PKB/Akt and ERK
• Reduction in insulin sensitivity in fat tissue [59]

• insulin suppresses the inflammatory process (in BPA treated adipocytes)
• Preventing hyperglycemia [59]
• Modulating key inflammatory molecules [59]
• Decrease of leptin levels observed in BPA-treated adipocytes
• May be due to reduced insulin promotion of leptin gene expression [59]

• Inhibition of JNK activity
• Almost completely restored insulin receptor signalling
• Largely rescued insulin-stimulated glucose utilization in BPA-treated adipocytes [59]
• Suggesting a primary involvement of inflammatory factors [59]

• Exposure to BPA
• Impairs insulin sensitivity
• Induces the release of inflammatory factors in adipocytes [59]
• One possible mechanism
• BPA activates JNK, via TLRs or ERs [59]
• May directly impair insulin action [59]
• Release of IL-6 and IFN
• Contribute to JNK activation in the adipocytes
• Down-regulate insulin-stimulated glucose uptake [59]

PCSK1

• Encodes pro-protein convertase subtilisin/kexin type 1 (PC1/3) [53]
• Pro-insulin-processing enzyme
• Regulates insulin biosynthesis
• BPA effectively impairs active insulin production [53]
• Its decrease is related to PCSK1 mRNA down-regulation [53]
• PCSK1 could be considered a new player that is involved in the endocrine disruption that is caused by BPA
• Key role in the deregulation of insulin biosynthesis [53]
• BPA exposure in the mouse impairs glucose tolerance by compromising insulin production and/or secretion

CD36

• Integral membrane protein that binds oxidized lipoproteins and lipids (Endemann et al. 1993) [53]
• Key role in fatty acid and glucose metabolism [53]
• Dysregulation in glucose intolerance and diabetes (Hajri et al. 2002, Rac et al. 2007) [53]
• CD36 null mice [53]
• Display enhanced insulin responsiveness [53]
• Associated with a reduction in fat deposition (Hajri et al. 2002) [53]

IL1B [53]

• Associated with insulin resistance and type 2 diabetes (Tack et al. 2012) [53]
• Its inhibition reduces hyperglycemic inflammation in obese mice (Owyang et al. 2010) [53]

• Low doses of BPA
• Stimulated rapid secretion of insulin in mouse pancreatic ß cells in primary culture
• Through a non-classical, non-genomic estrogen-response system
• Magnitude of the response was the same at equal doses of BPA and estradiol [68]

• Prolonged exposure to a low oral dose of BPA (10 µg/kg/day)
• Stimulation of insulin secretion in adult mice
• Mediated by the classical nuclear estrogen receptors [68]
• Later was followed by insulin resistance [68]

Děti

• Higher and more dangerous in infants and children
• Can lead to the onset of several diseases [53]
• Cancer [53]
• Endometriosis [53]
• Birth defects [53]
• Developmental and neuronal disorders (Rochester 2013, Delclos et al. 2014) [53]

• Associated with obesity and metabolic disorders (Rochester 2013, Lakind et al. 2014)
• Specifically in children (Trasande et al. 2012, Lee et al. 2013, Nicolucci et al. 2013) [53]

• Environmentally relevant BPA concentrations in adipocytes from children [53]
• Increase the expression and the enzymatic activity of 11ß-hydroxysteroid dehydrogenase type 1 ::53:---key enzyme in adipocyte differentiation and lipid synthesis !!!
• Stimulate preadipocyte differentiation and adipogenesis
• Can thus promote obesity in childhood [53]

• Non-linear effects during childhood [53]

• Exposure to BPA just prior to puberty
• Increase body weight [68]

Epigenetické vlivy

• Maternal exposure
• Synthetic estrogen and ubiquitous industrial contaminant
• Inducing DNA hypomethylation at Avy and another metastable epiallele, CabpIAP (Dolinoy et al., 2007) [1]
• BPA and estradiol
• Generally equally potent as activators of receptors associated with the cell membrane
• Initiate rapid signaling cascades at concentrations as low as 0.01 pM [68]

• BPA is considered to be a SERM
• Variety of unique effects relative to estradiol [68]

• Exposure during gestation and lactation to BPA
• Result in a wide range of effects
• Disruption of all organs in the male and female reproductive system
• Neuroendocrine effects [68]

• Exposure to low doses of BPA during the perinatal period of development
• Increase in body weight [68]

• Neonatal exposure to a low dose (1 µg/kg/day) of the estrogenic drug diethylstilbestrol (DES)
• Also stimulated a subsequent increase in body weight
• Increase in body fat in mice [68]

• 1 nM or 0.23 ng/ml during the first two days after in vitro fertilization
• Accelerated the rate of cell division of the fertilized oocyte [68]

• After implantation of embryos exposed in vitro for two days to 1 nM BPA into an untreated female mouse
• Accelerated postnatal growth of the offspring [68]

• Developmental exposure of rats to approximately 70-µg/kg/day BPA
• Up-regulation of a number of genes in abdominal adipocytes in adulthood
• PPAR, C/EBP and LPL
• Prenatal exposure to 0.25 µg/kg/day
• Advancement of differentiation of the adipocytes in the mammary gland in fetal female mice

• Mice exposed to a low dose of BPA (10 µg/kg/day) during fetal life
• Were heavier at birth
• At 6 months of age, males prenatally exposed to BPA displayed
• Glucose intolerance
• insulin resistance
• Altered insulin release from pancreatic cells [68]
• Pregnant mice exposed to this same dose of BPA
• Glucose intolerance relative to untreated controls [68]
• At a higher dose (100 µg/kg/day)
• Trend toward altered insulin sensitivity [68]
• 4 months after delivery, the mice treated during pregnancy with BPA
• Were heavier
• Had decreased insulin sensitivity [68]
• Glucose intolerance [68]

• Permanent effects of BPA on offspring’s metabolic systems
• Occurred at a dose 10-fold lower than the dose required to cause subsequent effects in the adult mother [68]

• Subcutaneous (sc) injection of pregnant CD-1 (ICR) mice with low doses of BPA (2 and 20 µg/kg/day) and DES (0.02, 0.2 and 2 µg/kg/day)
• Accelerated puberty (a common finding)
• Reduced body weight at puberty in the female offspring !!! [68]
• Similar prenatal BPA dose (2.4 µg/kg/day) fed to pregnant CF-1 mice
• Accelerated puberty
• Increased body weight at puberty in female offspring [68]

• Disruption of nursing behavior
• Reported in rats exposed to a low dose of BPA throughout pregnancy and lactation [68]

Bisphenol A (BPA)

• Very stable in the environment
• Steadily increasing in levels in humans
• Contributing to obesity in humans and model animals
• Interfering with estrogen and androgen signaling [1]
• Nearly ubiquitous in industrialized societies
• Plasticizer
• Make plastic harder
• Used to:
• Line cans
• milk cartons
• Other metal - paper-board containers of foods and beverages
• May leach out of plastic storage containers to contaminate
• Foods
• Beverages
• Drinking water
• BPA content is greatest in
• Clear, polycarbonate plastics previously thought to be safe
• Detectable in
• Serum of pregnant women
• Cord serum taken at birth
• 5-fold higher in amniotic fluid at 15–18 weeks gestation, compared with maternal serum
• Placenta up to 100 ng/g
• BPA appears to accumulate in the fetus [1]

Literatura:

[1] Ten Putative Contributors to the Obesity Epidemic. URL < www.ncbi.nlm.nih.gov/pmc/articles/PMC2932668/?tool=pmcentrez >.