Lecture 10 The biology of monogamy in man and animals

Question 1

2 functions of oxytocin & vasopressin?

Answer 1

peripheral hormones and central neuropeptides

Question 2

montane vole

Answer 2

solitary and promiscuous, uniparental

low selective aggression
low social contact

Question 3

prairie vole

Answer 3

mate for life, monogamous, biparental

high selective aggression
high social contact

Question 4

partner preference test?

Answer 4

females either side tethered, male can move freely, or vice versa.

measure time spent

Question 5

partner preference test for montane v prairie, stranger v partner

Answer 5

prairie spend more time with partner

montane rather spend time alone

Question 6

female pathways

Answer 6

Mating involves vaginal-cervical reflex arc to CNS to release OXYTOCIN in females

Question 7

ICV (intra ventricle) oxytocin during pre socialisation, partner preference testing without prior mating but familiar

Answer 7

increases partner preference only in prairie vole female.

montane dont care, spend time alone

Question 8

oxytocin given to females who are expose to male with no mating?

Answer 8

Expose to male but do not allow mating –> no bond

Expose to male, no mating, administer oxytocin –> Bonded

Question 9

allow female to mate, give OTR antagonist

Answer 9

no bond formed

therefore In females, oxytocin is crucial for partner bond formation

Question 10

oxytocin in males?

Answer 10

no effect on bonding

Question 11

AVP given to male prairie/montane?

Answer 11

icv administration of AVP leads to pair bond in male prairie voles

Question 12

male prairie/montane normal choice?

Answer 12

pairie choose previously bonded partner, montane done care either

Question 13

V1a antagonist in males?

Answer 13

AVP facilitates and AVP blocker prevents
paternal behaviour

avp key hormone for males

Question 14

AVP/OT summary sentence

Answer 14

Highly related peptides have similar role in mate bonding, but dramatic sex-specific action

Question 15

AVP receptor distribution in montane v prairie voles

Answer 15

dose of avp/ot the same, receptor vol different.

higher in prairie in VP NAc.

Question 16

OT receptor distribution in montane v prairie voles

Answer 16

Prairie:
NAc higher
Amygdala
BST - bed nucleus stria terminalisentral pallidum

Question 17

OT receptor expression in NAc correlating to maternal behaviour in prairie voles.
look at natural variation

Answer 17

positive linear correlation

Question 18

OT/AVP antagonist at different sites?

Answer 18

Prairie,
NAcc/PFC OT antagonist gives preference for stranger not partner (not sure what sex)

VP V1aRA gives preference for stranger not partner

Question 19

lil summary

Answer 19

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.

Question 20

blocking Dopamine in NAc in prairie male voles, also how it changes pre/post mating

Answer 20

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

Question 21

D1/D2 differences in prairie voles?

Answer 21

D1 formation of bond, D2 maintenance, look some studies up

Question 22

other species V1aR expression monog v non monog

Answer 22

different not sure how

Question 23

genetic differences between voles?

Answer 23

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

Question 24

changing V1a receptor distribution in voles using a virus transgenics

Answer 24

2. 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??

Question 25

changing V1a receptor distribution in voles using transgenic mice

Answer 25

1. 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.

Question 26

OT KO mice and V1aR KO mice

Answer 26

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.

Question 27

Gene transfer by virus to lateral septum in rats?

Answer 27

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.

Question 28

humans gene?

Answer 28

not as expanded as voles, more expanded than chimps promiscuous.

Question 29

human love?

Answer 29

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.