What are the key glands in the fish endocrine system?
pineal, thyroid, hypothalamus and pituitary
What are the four classifications of hormones?
single amino acids, peptides/proteins/glycoproteins, steroids and eicosanoids
What are hormones MOA?
Bind to receptors on the genome that triggers responses, often to many different organs and glands
What is an example of a hormone “axis” in fish and describe what it does
the hypothalamus, pituitary, gonad and liver-controls estrogen and testosterone production
What is DDEs MOA?
Androgen receptor agonist, weak estrogen receptor agonist and prostaglandin synthesis inhibitor
What are the results on organisms from DDE exposure then?
eggshell thinning due to decreased calcium transport and feminization of males, all leading to decreased population
What are all the ways a chemical can disrupt hormones?
synthesis, secretion, transport, binding, action or elimination
Why are EDCs so concerning?
they can have effects at low concentrations
What are 6 ways ED can manifest?
ovarian and testicular cancers, altered sex ratios, behavioral alterations, impaired reproduction, delayed development, and declined population
What are some potential targets of hormone synthesis for EDCs?
precursors, enzymes, and regulation of transcription and translation
How are hormones transported?
plasma binding proteins or free transport (peptide hormones)
How can EDCs disrupt transportation?
can bind the transporters
What are the effects of EDCs disrupting hormone metabolism?
altered plasma levels of hormones
What are examples of hormone nuclear receptors?
17b-estradiol, testosterone, thyroid, aryl hydrocarbon
Why is the estrogen receptor considered promiscuous?
It can bind lots of compounds even if they are chemically unrelated to estrogen
What happened when a lake was dosed with EE2?
male minnows had vitellogenin expression, oocytes in testicular tissues, intersex and reproductive failure
What happens when frogs are exposed to estrogen compounds?
all the population will become males, the phenotypic sex is female but the genotypic is still male so it yields 100% males
When is the most sensitive time for an organism to be exposed to EDCs?
early life stages
