Xenoestrogens and Endocrine Disruption Flashcards
Endocrine disrupter is a foreign
substance or mixture that alters the functioning of the endocrine system and consequently causes adverse health effects on an intact organism and/or its progeny
endocrine disruptors include a wide variety of chemical classes including
pharmaceutical agents, pesticides, plastics, pollutants
endocrine disruptors can act through 4 different ways:
- nuclear hormone receptors
- nonsteroid receptors
- transcriptional co-activator
- enzymatic pathways involved in steroid biosynthesis or metabolism
Obesogens
EDs that promote weight gain
Obesogens can promote weight gain directly by acting on
fat cells to increase their number of storage of fat
Obesogens can promote weight gain indirectly by acting on
mechanisms for satiety and appetite or by altering the basal metabolic rate of storage of calories
xenoestrogen
type of xenogene that imitates estrogen
orphan receptor
a receptor that has no known ligand
endocrine system
collection of glands that secretes hormones directly into the circulatory system and are carried toward distant target organs - moves SLOWLY
BPA is the most
prominent ED known
does BPA have strong or weak activity?
weak
does BPA have agonist or antagonist effects?
both! so it’s unpredictable
response from BPA depends on 3 things
- level
- expression of receptors
- availability of co-factors
Window’s of susceptibility - the timing of the exposure is
critical component of BPA toxicity
what are the most vulnerable timing periods
prenatal and neonatal
how does BPA effect epigenetics?
it induces hypomethylation on CpG islands in the gene regulator regions of several genes in agouti mice
but it also can hypermetylate
what is the most potent AhR agonist?
TCDD
The low dose hypothesis says that EDs can have effects at low doses that are not
predicted by effects at higher doses
-they have different effects at lower doses and these cannot be predicted by the effects at higher doses
what did the EPA say about the low dose hypothesis?
that there is not enough evidence to prove it
