Oxytocin Flashcards

1
Q

what is the structure of OT

A

small
9 aa peptides (nonapeptides) with 1 internal disulphide bridge (S-S)

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2
Q

how do AVP and OT differ

A

by 2 aa

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3
Q

what is a neurophysin

A

carrier protein for OT and AVP within vesicles

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4
Q

where is OT synthesised

A

magnocellular Neurons (SON and PVN)

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5
Q

OT release

A

packaged in neurosecretory vesicles and transported to axons
released from neurohypophysis, neural lobe, and pars nervosa (terminal that form posterior pituitary) and are released from blood

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6
Q

where do the parvocellular neurons project

A

they are small
no projection to the PP
only project to the CNS (amygdala, BS,hippocampus)

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7
Q

3 peripheral actions of OT

A

milk ejection reflex
uterine contraction during parturition
inhibit CRH in males

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8
Q

steps in the milk ejection reflex

A

myoepithelial cells express OT R
milk is inside the alveoli lumen
MC contract
milk is squeezed out of lactiferous duct

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9
Q

signalling for milk ejection reflex

A

sensory neurons in nipple
info travels from: SC to mesencephalon/diencephalon to hypothalamus
increased firing of OT in SON/PVN
synchronised burst discharged

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10
Q

what does synchronised burst discharge lead to

A

increased intramammary pressure (rapid contraction)
plasma OT levels spike
rapid contraction - mammary gland reflex

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11
Q

steps in uterine contraction during parturition

A

OT R on myometrial cells in uterus
Oestrogen stimulates OT R production on myometrial cells
uterine distention (stretching) releases OT
plasma OT levels increase during the final stages of labour

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12
Q

role of syntocin

A

synthetic OT
administered to deliver baby/placenta
(not essential as OT antagonists/KO still deliver)

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13
Q

OT endocrine action in males

A

no physiological role
released during ejaculation may enhance sperm transport?
inhibits CRH secretion (releases ACTH-releases cortical the stress hormone)

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14
Q

central role of OT (paracrine/autocrine)

A

OT stored and released from dendrites of magnocellular cells
upregulated by lactation

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15
Q

central roles of OT (neuromodulator actions)

A

stereotypical maternal behaviour
pair bonding (m&f)
social behaviour (trust/morality/empathy)

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16
Q

maternal behaviours which release OT

A

parturition
suckling
sexual activity

17
Q

Kendrick (2002)

A

icv injection of OT ant reduces pup licking in rats
OT requires estrogen – induce maternal behaviour in virgin rats
(sheep) vaginal/cervical stimulation (VCS) induces maternal behaviour and bonding
AVP - no effect on maternal behaviour

18
Q

what do plasma OT levels correlate to in humans

A

parental affection and bonding

maternal affection
paternal parenting behaviour

19
Q

voles

A

praire voles - monogamous (pair bonding /biparental care) OT induces bonding without mating
meadow voles - polygamous & solitary

20
Q

Gobrogge & Wang (2015)

A

praire voles spent increased time with partner
meadow voles spent increased time alone

21
Q

CRISPR KO of OT R in praire voles

A

pair bonding still occurs and parental behaviours
OT R not essential for social attachment in praire voles

22
Q

pair bonding in humans

A

OT release causes pair bonding
sex (orgasm/ejaculation)
plasma OT is a surrogate for central release

associated with the limbic system (VMN/amygdala)

23
Q

what does intranasal OT cause

A

altered perception of social qualities
increased trust and generosity
increases perception of attractiveness and trustworthiness

24
Q

disorders due to central OT dysfunction

A

ASD
OCD
PTSD

25
Q

ASD

A

valproic acid induces ASD symptoms
reduced ultrasonic vocalisation, repetitive stereotypical behaviours
decrease in CSF OT