Oxytocin

Question 1

what is the structure of OT

Answer 1

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

Question 2

how do AVP and OT differ

Answer 2

by 2 aa

Question 3

what is a neurophysin

Answer 3

carrier protein for OT and AVP within vesicles

Question 4

where is OT synthesised

Answer 4

magnocellular Neurons (SON and PVN)

Question 5

OT release

Answer 5

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

Question 6

where do the parvocellular neurons project

Answer 6

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

Question 7

3 peripheral actions of OT

Answer 7

milk ejection reflex
uterine contraction during parturition
inhibit CRH in males

Question 8

steps in the milk ejection reflex

Answer 8

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

Question 9

signalling for milk ejection reflex

Answer 9

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

Question 10

what does synchronised burst discharge lead to

Answer 10

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

Question 11

steps in uterine contraction during parturition

Answer 11

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

Question 12

role of syntocin

Answer 12

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

Question 13

OT endocrine action in males

Answer 13

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

Question 14

central role of OT (paracrine/autocrine)

Answer 14

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

Question 15

central roles of OT (neuromodulator actions)

Answer 15

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

Question 16

maternal behaviours which release OT

Answer 16

parturition
suckling
sexual activity

Question 17

Kendrick (2002)

Answer 17

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

Question 18

what do plasma OT levels correlate to in humans

Answer 18

parental affection and bonding

maternal affection
paternal parenting behaviour

Question 19

voles

Answer 19

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

Question 20

Gobrogge & Wang (2015)

Answer 20

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

Question 21

CRISPR KO of OT R in praire voles

Answer 21

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

Question 22

pair bonding in humans

Answer 22

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

associated with the limbic system (VMN/amygdala)

Question 23

what does intranasal OT cause

Answer 23

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

Question 24

disorders due to central OT dysfunction

Answer 24

ASD
OCD
PTSD

Question 25

ASD

Answer 25

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