Lecture 10 The biology of monogamy in man and animals Flashcards
2 functions of oxytocin & vasopressin?
peripheral hormones and central neuropeptides
montane vole
solitary and promiscuous, uniparental
low selective aggression
low social contact
prairie vole
mate for life, monogamous, biparental
high selective aggression
high social contact
partner preference test?
females either side tethered, male can move freely, or vice versa.
measure time spent
partner preference test for montane v prairie, stranger v partner
prairie spend more time with partner
montane rather spend time alone
female pathways
Mating involves vaginal-cervical reflex arc to CNS to release OXYTOCIN in females
ICV (intra ventricle) oxytocin during pre socialisation, partner preference testing without prior mating but familiar
increases partner preference only in prairie vole female.
montane dont care, spend time alone
oxytocin given to females who are expose to male with no mating?
Expose to male but do not allow mating –> no bond
Expose to male, no mating, administer oxytocin –> Bonded
allow female to mate, give OTR antagonist
no bond formed
therefore In females, oxytocin is crucial for partner bond formation
oxytocin in males?
no effect on bonding
AVP given to male prairie/montane?
icv administration of AVP leads to pair bond in male prairie voles
male prairie/montane normal choice?
pairie choose previously bonded partner, montane done care either
V1a antagonist in males?
AVP facilitates and AVP blocker prevents
paternal behaviour
avp key hormone for males
AVP/OT summary sentence
Highly related peptides have similar role in mate bonding, but dramatic sex-specific action
AVP receptor distribution in montane v prairie voles
dose of avp/ot the same, receptor vol different.
higher in prairie in VP NAc.
OT receptor distribution in montane v prairie voles
Prairie:
NAc higher
Amygdala
BST - bed nucleus stria terminalisentral pallidum
OT receptor expression in NAc correlating to maternal behaviour in prairie voles.
look at natural variation
positive linear correlation
OT/AVP antagonist at different sites?
Prairie,
NAcc/PFC OT antagonist gives preference for stranger not partner (not sure what sex)
VP V1aRA gives preference for stranger not partner
lil summary
All neurohormones act via specific receptors. After release from nerve endings, the hormone binds to receptors that initiate a series of intracellular events.
It is important to understand that where the receptors are located in the brain determines which cells are activated.
In other words
the behavioural effects of any hormone are defined not just by the amount of hormone, but also by where its receptors are located in the brain.
Prairie and Montane voles have similar levels of OT and AVP.
The difference is where the receptors are.
Therefore, infusing micromolar quantities of either hormone into montane voles will not induce a pair bond.
The receptors are in the wrong target areas of the montane vole brain for either hormone to influence social attachment.
blocking Dopamine in NAc in prairie male voles, also how it changes pre/post mating
pre-post huge increase when mated, small increase when non mated.
D2 antagonist at time of mating reduces time spent in contact partner preference test.
D2 agonist without mating, time spent increases
D1/D2 differences in prairie voles?
D1 formation of bond, D2 maintenance, look some studies up
other species V1aR expression monog v non monog
different not sure how
genetic differences between voles?
Different gene length/allelic forms in monogamous and polygynous vole species.
segment in VA1R is expanded in prairie voles, in other monogamous show same segment expanded, not in non monog.
660 bases upstream of transcription start site, 500 bases of highly repetitive sequences.
This repetitive region affects which cell types will express the receptor!
Expansion or contraction of the VA1R repeat region could therefore lead to altered expression in the reward circuits of the brain
changing V1a receptor distribution in voles using a virus transgenics
- Use a virus to deliver a transgene to a local site
V1a receptor levels are artificially increased within the VP of meadow voles using adeno-associated viral (AAV) gene transfer. infect cells of host and express whatever was placed in.
Meadow + AAV now display social behavior that is reminiscent of that of monogamous prairie voles, preferring social contact with their partner over a stranger
also engages V1aR dopamine??
changing V1a receptor distribution in voles using transgenic mice
- Transgenic mouse
Knock out original and insert a new mutated copy
until recently only mice are amenable as mammals for such procedures.
replace promotor AVP gene, WT + priairie VA1R segment , no change in oxytocin levels.
The prairie vole receptor expressed in the mouse introduces a pattern remarkably like that of the prairie vole.
AVP administration icv increases affiliative behaviour in transgenic mice but not in wild type.
OT KO mice and V1aR KO mice
Social recognition is impaired in OT KO mice and V1aR KO mice
V1a-R knock-out mice show a social memory deficit
But rescued by AAV delivery of the receptor to the lateral septum.
Gene transfer by virus to lateral septum in rats?
enahnces social recognition.
Transferred gene for vole receptor directly to rat lateral septum.
Functional Va1 receptor expressed in neurones on the lateral septum.
Long-term receptor expression achieved.
Expression of receptor associated with improved long term social recognition.
This was blocked with selective Va1 antagonist.
humans gene?
not as expanded as voles, more expanded than chimps promiscuous.
human love?
Images of love activate brain regions known to be central to OT and AVP signalling.
In humans 4 polymorphic microsatellite regions of V1a receptor have been identified, and have been link to behavioural traits
Altruistic behaviour (tested in a game) higher in long variants (Isreal et al 2008, Prog. Brain Res. 170)
Swedish study of 552 twins tested for partner bonding, and perceived marital problems (Walum et al Proc Natl,Acad.Sci 2008)
AVPR1A length and maritial happiness correlation, shorter = unhappy.
