Oxytocin Flashcards
where are oxytocin neurons found
mainly in magnocellular neurons of PVN and SON. also in parvocellular PVN neurons
where is OT released? what type of cells reach that region?
posterior pituitary.
only magnocellular OT neurons reach post pituitary
in what structure is OT stored?
large dense core vesicles LDCVs
what are OT’s emotional functions?
analgesia, anxiolysis, positive mood
what are OT’s neuroendocrine functions?
anorexiant, attenuates HPA axis response to stress
how is OT increase during labour? what does it do?
OT increases uterine contractions during labour through increase in OT receptor expression
how does kisspeptin affect OT during late pregnancy?
kisspeptin increases OT release through increase of kisspeptin expression in periventricular neurons projecting to PNZ of SON
how does OT stimulate lactation?
it stimulates myoepithelial cells of the mammary gland to eject milk in the mammary ducts.
how is OT released when triggered by a baby cry?
in bursts
what is a difference in OT vs AVP release during parturition?
increases in both expression and release of OT are specific and timed.
what rats get an OT response triggered by kisspeptin? how?
late-pregnant rats only. maybe due to apparition of new excitatory kisspeptin projections.
what type of functional changes in magnocellular OT neurons happen during parturition and suckling?
OT and AVP coordinated metabolism and coordinated electrical activity
how many OT neurons fire simultaneously during parturition and suckling?
4 500
what types of plastic changes in OT neurons are observed during parturition and lactation? where?
glial retraction, increased somatic appositions, increased contact among dendrites (dendritic bundling)
in SON
what kind of synapses are usually found at somatic vs dendritic zones?
GABAergic or DA synapses at somatic region.
Noradrenergic in dendritic zone
electronic coupling of new synapses in SON OT neurons involves what?
dendritic priming
what is dendritic priming?
when an intracellular calcium release triggers peptide release from dendrites. it is enhance by K+ and TG
in what neurons do somatic apposition and dendritic priming take place?
magnocellular SON neurons
what increases OT later and longer than neuroendocrine secretion in blood?
priming of SON OT neurons by osmotic stimulation
where is plasma OT coming from?
from axonal release at posterior pituitary which goes into circulation
where is SON OT coming from?
from dendritic release
can parvo and magnocellular communicate?
yes parvocellular can synapse on magnocelullar OT neurons
what other than depolarization can also trigger axonal and somatodendritic OT release?
MC4Rs or TM proteins like CD38
what can OT bind to after somatodendritic release? to do what?
bind to autoreceptors and prime OT neurons for firing
what’s different between OT and AVP dendritic release?
unlike OT, dendritic AVP inhibits activity of AVP neurons in the SON
what other cells in the NTS are activated during parturition and increase OT activation?
noradrenergic cells
what triggers NTS noradrenergic cells activation?
uterine contractions (in the lab, OT neurons)
what do OT infusions cause?
uterine contraction,
intermittent NA release,
c-Fos expression in OT neurons in the SON through alpha-1 adrenergic receptors,
activation of NA neurons in the NTS
is NA the only factor modulating OT neurons?
no! progesterone also does?
what does suckling induces?
large OT bursts of activity in SON and PVN
how do OT and VP cells respond to osmolality?
gradually (no bursts) increase their firing activity with elevated concentration of particles in plasma
what state is associated with high osmolality?
dehydration
OT synergizes with VP to promote what? where?
OT in the blood synergizes with VP on the kidney to promote natriuresis (salt excretion)
where do OT neurons get their osmotic input from?
directly from ECM osmotic pressure or from SFO and OVLT neurons that have osmoreceptors
osmotic input from SFO and OVLT osmoreceptors are excitatory or inhibitory?
both
where do SFO and OVLT neurons project to?
OT neurons in PVN and SON
how does stress affect OT secretion?
- increases OT in blood due to magnocellular OT neurons in SON and PVN releasing in post pituitary
- increases somatodendritic OT release in PVN
why does stress increase OT secretion?
inhibit CRH neurons activation to reduce the HPA axis activity
what stress hormone increases central and peripheral OT release? how did we test this?
CORT;
by removing adrenal glands
what hypothalamic OT neurons are the most important for food intake control?
parvocellular neurons projecting from the PVN to the NTS
through what other hormone does OT control hunger?
leptin
what does blood OT do in obese people?
reduce fat accumulation in adipocytes
what satiety signal can OT potentiate?
CCK
in what situation does OT not decrease apetite?
during pregnancy and lactation
leptin triggers Arc to produce what substances?
POMC and CART
POMC and CART activate what?
PVN parvocellular OT neurons
how are dominant mice affected by OT antagonist?
increased sugar consumption in social or lonely environment
what OT neurons participate in analgesia?
parvocellular OT PVN neurons projecting to SON and SC
what is OT’s effect on parenting?
induces parenting behavior
how is OT increased around/after parturition?
increased CSF levels and increased OT receptors expression in the brain
what is the difference between male prairie voles and montane voles?
male prairie voles have higher OT receptor expression in the brain and are monogamous
where does the bond between partners in adulthood originate from?
from the mother-infant bond relying on overlapping brain areas and neurotransmitter systems (oxytocin, vasopressin, dopamine)
what nt does OT interact with to link a partner with reward system?
dopmaine
what happens to paternally deprived pups?
they mature slower than biparentally raised ones
what is mediated by OT signalling in the anterior cingulate cortex?
males consoling behavior after females are exposed to stress?
what “couples” have coordinated OT responses?
parents and child
romantic partners (also cortisol)
what other 2 behaviors involve OT release?
interactions between friends
acts of empathy
in what context might OT induce defensive behavior?
during “unsafe” social cues
how does OT affect people with autism?
promotes social information retention
reduces repetitive behaviors
complete:
____ neurons tighlty control _____ neurons activity to regulate _______ OT release
parvocellular OT
magnocellular OT
peripheral
which OT neurons act as first responders to somatosensory input?
parvocellular
parvocellular OT neurons (but not magno) are innervated by what brain region involved in social touch?
insular cortex
