Human/Animal Repro Exam 1

Berthold endocrine experiment

removed testes from chick to see what it would do, led to underdeveloped male rooster; when testes removed and then replaced, fully developed male rooster

Berthold endocrine experiment impact

organ (testes) secrete chemical (testerosterone) which makes changes

four types of experiments in endocrinology- is the molecule sufficiet for an effect

give the hormone and determine its effects; tells us whats possible, may not be physiological

four types of experiments in endocrinology- is the molecule necessary for an effect

block the hormone and determine if physiological response is blocked without the molecule; tells you when you disrupt something changes

four types of experiments in endocrinology- is the molecule made or secreted in response to stimuli

measure the concentration of the molecules in blood or tissue

four types of experiments in endocrinology- what does the molecule look like

what is the sequence or structure of the molecule, where is it made

hormone

chemical messenger that is secreted by cells, travels though blood, and acts on other cells

exocrine secretions

digestive enzynes; excreted outside the body; go through duct

pheromones

secreted outside of the body, don’t get into blood

paracrine signaling molecules

acts on cells nearby the ones that secrete it

autocrine signalling molecules

acts on the same cell that secretes it

intracrine signalling molecule

act within the cell that produces it; doesnt go thru blood

three major classes of hormones

proteins, steroids, modified amino acids

protein subclass

proteins, peptides, glycoproteins

protein hormones hydrophilic or lipophilic

hydrophilic

protein hormone structure/precursor

DNA → RNA → protein

steroid hormones subclass

n/a

steroid hormone hydrophilic or lipophilic

lipophilic

steroid hormone strucutre/precursor

enzymatically modified cholesterol

steroid hormone examples

estrogen, progesterone, testosterone

modified amino acid hormone subclass

n/a

modified amino acid hormones hydrophilic or lipophilic

both- hydrophilic and lipophilic

modified amino acids strucutre/precursor

enzymatically modified amino acids

modified amino acid hormone examples

thyroid hormone

hormone like

prostaglandinsp

prostaglandins

lipid derived signaling molecules; sometimes get into blood, sometimes don’t; act locally

g-protein coupled receptors

7 transmembrane domain receptors; extracellular; second messenger system

receptor tyrosine kinsases

phosphorylation/activation of effector proteins; extracellular

intracellular receptors

nuclear receptors, ligand induced transcription factors (make new proteins)

additive effects

summation of the response of each hormone

synergistic effect

effects of 2 or more hormones are greater than predicited by adding the effect of each hormone

permissive factors

one hormone must be present to have full effect of another hormone

antagonistic effects

2 hormones have opposing effects

ligand

molecule that binds a receptor

receptor

a molecule that responds specificially to neurotransmitters, hormones, antigens, light, pressure or other substances, binding is competitive and saturable

agonist

molecule that activates a receptor

antagonist

molecule that binds to a receptor and does nothing

protein hormone synthesis

translation (RNA), initial processing, prohormone passes thru golgi, packaged, released, into circulation

preprohormone

signal sequence directs amino acid chain to ER; necessary for secreted proteins

prohormone

many peptide/protein hormones are synthesized with extra amino acids are cut out; can be multiple hormones from one gene

major steroid hormone classes

estrogens, androgens, progestins, glucocorticoids, mineralocorticoids

where are steroidogenic cells located

ovary, testes, placenta, fat, brain

steroid hormone precursor

cholesterol

where does majority of cholesterol come from

diet

what is the other way we get cholesterol

de novo synthesis (cells make it)

steroidogenic acute regulatory protein (StAR) function

transports cholesterol from outer to inner mitochondrial membrane

what is the rate limiting step for steroidogenesis

steroidogenic acute regulatory protein

increased amount of LH, FSH, ACTH leads to

increased steroidogenic acute regulatory protein activity

what is P450scc

enzyme that absorbs light at 450nm; cholesterol side chain cleavage

where is P450scc found

inner mitochondrial membrane

what enzyme starts delta-4

3-beta-hydroxysteroid dehydrogenase (3β-HSD)

what does 3β-HSD make

progesterone

what enzyme starts the delta-5 pathway

17α-hydroxylase

what does CYP17A1 produce

17α-hydroxypregnenolone → DHEA

name the key enzymes involved with testosterone production

StAR, P450scc, 3β-HSD, 17α-hydroxylase, 17/20 lyase, 17β-HSD

what does LH upregulate

StAR, P450scc, P450 17a

how is DHT made

testosterone to DHT via 5α-reductase

can DHT become estradiol

no

estradiol cell types

theca cells (1st) and granulosa cells (2nd)

what do theca cells produce

androgens (testosterone, androstendione)

what does LH stimulate

StAR, P450scc, P450 17a

what do granulosa cells produce

estradiol

what does FSH increase

aromatase and 17β-HSD

what does aromatase convert

testosterone to estradiol

what does 17β-HSD convert

androstenedione to testosterone

major steroid families

mineralocorticorids, glucocorticoids, androgens, estrogens

mineralocorticoids key hormone

aldosterone

glucocorticoids key hormone

cortisol

androgens key hormone

DHEA, testosterone, DHT

estrogens key hormones

estradiol, estrone, estriol

steroid hormone release

can diffuse through plasma membrane, cannot be stored in cells

is steroid hormone release regulated

no only steroid hormone synthesis is regulated

low LH and low FSH

low estrodiol and low androgens

high LH and low FSH

high androgens, low or normal estrodiol

steroid hormone mode of action

through the blood bound to carrier proteins

sex hormone binding globulin

albumin

where can steroids bind

membrane receptors and intracellular receptors

when steroid hormones bind to membrane receptors it lead to

rapid effects

what happens when the hormone bind to the intracellular receptor in the nucleus

dimerizes and increases transcription

what happens when the hormone binds the the intracellular receptor in the cytoplasm

dimerizes, translocates to the nucleus and increases transcription

hormone response time when binding intracellularly

slow (hours to days)

precursor for prostaglandins

arachidonic acid

prostoglandins signalling method

GPCRs

anterior pituitary gland

epithelial cells, connected to hypothalamus via portal blood system

posterior pituitary gland

neural cells, axons that project from the hypothalamus

posterior pituitary gland secretes

oxytocin

HPG axis

hypothalamic pituitary gonadal axis

where are kisspeptin and GNRH located

hypothalamus

kisspeptin

two populations, regulate GnRH neuron activity

gonadotropic releasing hormone (GnRH)

stimulates pituitary release of LH and FSH

where are lutenizing hormone and follicle stimulating hormone kept

anterior pituitary gland

luteinizing hormone (LH)

acts on gonads to promote steroidgenesis

follicle stimulating hormone (FSH)

supports gametogenesis and follicular/spermatogenic development

where is estradiol, progesterone, and testosterone kept

gonads

estradiol

key sex steroid regulating feedback to hypothalamus/pituitary

progesterone

supports reproductive cycles and negative feedback

testosterone

drive male secondary sex characteristics and spermatogenesis

spermatogenesis

production of sex steroids

gametogenesis

formation of eggs or sperm

negative feedback

self regulating to maintain hormone concentrations at a given set point