Lecture 17 - Vasopressin Flashcards
What does vasopressin do
Now we are moving onto vasopressin, the hormone that is thought to contribute to males bonding as oxytocin contributes in females. Like oxytocin it is a ratio thing – males have oxytocin but lower level and thus less effect. Females have vasopressing, but lower levels and lower effects. No black and white here, but vasopressin effects are greater in males.
What does it do?
Arginine-Vasopressin: pituitary hormone that promotes water retention in kidneys
Vasopressin made in PVN and SupraOpticNucleus, cause released from pituitary (same as OXT)
SAO = water balance
Water balance regulated in close proximity to MPOA:
Interconnections and similar activation of pituitary
Vasopressin: Territorial Marking
Control of body fluids all related to control of territory
Urine commonly used to demonstrate ownership in animals
Maintaining territory is male role in many species. True in humans from an evolutionary standpoint
Linking territory and love
Argenine-vasopressin linked to fluid balance and thus territorial marking
Also linked to male social behaviours
Territory and sociality overlap in males
Protect territory including offspring and partners
Mate guarding:
Voles: aggressive behaviour positive correlation
with vasopressin in the hypothalamus
oxytocin is critical for maternal behaviour, and coopted to form human pair bonds in females. Treat romantic partner a bit like child – protect, care, etc….
Contrast males have vasopressing to mediate territoriality and relations with other individuals considered his. This is not intended as a discussion of feminism and males owning women, we have had quite enough of that this week following the American election. However, from a neuro perspective Young proposes that males social interactions based in this territory neural network, with males treating their young and partners well by protecting them like territory, ensuring others cannot access to prevent maltreatment.
Vasopressin: bonding in males
Prairie voles:
Central AVP (Vasopressin injected centrally) facilitates a partner preference in the absence of mating
Partner preference is blocked by a selective V1aR antagonist
increasing vasopressin, either in the entire body or only in the brain results in increased pair bonds, and pair bonds in the absence of sex, which is important in the development of these bonds
Further evidence comes from blocking vasopressin using antagonist drugs
Vasopressin receptor: key in pair bond
Vasopressin has greater effect in male prairie voles compared to montane voles
Same as oxytocin in females
No difference in vasopressin release during sex in male prairie and Montane voles
Same as oxytocin in females
Difference in vasopressin V1a receptor in ventral pallidum output of NAc (oxytocin)
Effectively the montagne vole has more vasopressin receptors than the parie one.
Vasopressin V1 action is needed for partner preference formation nd expression
Vasopressin affects which part of partner preference formation?
During interaction, just afterwards, or before testing?
V1a receptor antagonist AVPA infused into ventricles at different times
- Premating treatment group
- Postmating group
- Pretesting group
- Control group
Injections at each time point, but only injected with AVPA once
24 hours with sexually receptive female partner
should induce a pair bond
6 hours with non-receptive female
24 hours typically induces a pair bond
6 hours does not
Controls showed partner preference
AVPA prior to mating or partner preference test blocks the display of a partner preference
Vasopressin must bind during interaction and testing for partner preference
Inn the case where vasopressin receptors were blocked pre mating or pre testing, the voles did not learn or express a preference
AVPA immediately after mating period did not disrupt partner preference
Vasopressin not necessary after the interaction
In voles, what is vasopressin needed for
V1aR activation is necessary for pair bond formation and expression
Vasopressin released during pair bonding and test – binds to V1a
V1aR for two temporally dissociable processes in bond formation
Involved in formation of preference and expression of preference
Microsatellites on genes
Tract of repetitive DNA (2-5 base pairs repeated)
Higher mutation rate than the rest of DNA (and so more genetic variability)
Length change in microsatellite can affect protein production
Vole strains differ in microsatellite on the gene encoding V1aR (avpr1a)
Monogamous prairie voles often have longer version
More V1aR
Mechanism for strain difference or even individual difference?
Variation within strain too
Some prairie voles long, some prairie voles short
Explains individual differences
Prairie voles selected by length of microsatellite of avpr1a gene
Male and female
Parental and pair bond behaviour assessed
Longer avpr1a results in significantly higher V1aR (vasopressin receptors)
higher in ventral pallidum which is major input to Nac, the amygdala, the hypothalamus, and the lateral septum which is major input to MPOA in the hypothalamus
-How do these changes in receptor distribution affect changes in behaviour?
Length of avar1a microsatellite affects paternal behaviour
Longer licking and grooming
No effect on maternal behaviour
Greater social odor investigation in males with long alleles
Vasopressin receptor density linked to social behavior
Length of microsatellite has no effect on non-social behaviour
Gave 24hour mating experience between male and a receptive
Bonding should occur in prairie voles
Male prairie voles with the long avpr1a microsatellite show pair bonding
Short ones do not later express preference for one or other vole when re presented
V1aR increases linked to more parental, social, and bonding behaviour
V1aR and male voles
V1aR increases linked to more parental, social, and bonding behaviour
Vasopressin’s role in male human’s behaviour
Vasopressin extends social recognition abilities
Manipulation of vasopressin systems in the ventral pallidum and hypothalamus alter social behavior
Parental, social, bonding
Avpr1a length difference determines V1aR in the VP
Neural substrate for strain and individual differences in social behaviour.
Similar to oxytocin, these social effects of vasopressin on romantic and non-romantic bonds challenging to study. Some evidence that same mechanisms are at play in human males, even if studies not as well controlled and clearcut as the research e are able to do with voles.
Humans avpr1a microsatellites
Humans have a similar variation in avpr1a, suggesting this could mediate individual differences in social behavior in men as well as voles
Variation in the AVPR1A locus (RS3) may also contribute to socio- behavioral diversity in humans.
Two long versions of microsatellite region associated with more VP1aR
These alleles have been linked to human social behaviour.
100 males and females
Genotyped for RS3 avpr1a promoter region length
Divided into long and short group so that each group had ~ n=100
Does altruistic behavior differ??
Dictator game online
Player 1 has shekels and Player 2 doesn’t, you are randomly assigned (lies!)
How much of your 50 shekels will you give?
(computer game used by economists to measure altruism) can give proportion of money that you want to your people – told to take it seriously – how much would you share with those in need. Also key to note that you are told it is randomly assigned, so you could easily be the “have not” person in need. “Luckily” all participants in the study were randomly assigned to Player 1 to see how they would allocate money
Also good that it is online – relative anonymity means that you feel more comfortable acting in a less generous, or altruistic way.
2 short versions of allele
Less altruistic
Gave less money in dictator game than s/l or l/l
On self reported benevolence and universality
-Shorter microsatellite region associated with less altruistic behavior
Shorter microsatellite region linked to lower hippocampal V1aR expression which might explain the mechanism
Humans avpr1a and pair bonding
Twin and Offspring Study in Sweden: 552 same-sex twins and their spouses/partners
Indices of quality of the marital including Partner Bonding Scale (PBS)
Three vasopressin allelic variations (short-short, short-long, long-long)
On the bonding scale: l/l was reported as having a stronger bond
85% of l/l were married, 68% of s/s/. They cohabited but did not get married which might indicate a lower level of commitment
Humans avpr1a and social recognition
Access to multimodal visual/auditory information = social recognition
Processed in cortical areas such as temporoparietal junction (TPJ) and prefrontal cortex
Unfamiliar faces activate the left TPJ
Does vasopressin affect speed at which faces become “familiar”
Compared TPJ activation to faces and scenes
Very familiar faces and faces viewed once before
Placebo group – elevated TJP activity for less familiar faces
Not with vasopressin: non-familiar faces made familiar more rapidly?
Suggest that vasopressing increases social cognition in humans, similar to voles
Avpr1a and altruism, social recognition and pair bonding
Vasopressin activates critical sites for social recognition
Humans:
Multimodal visual/auditory information - temporoparietal junction and prefrontal cortex
Rodents:
Olfactory information - lateral septum, connected to the olfactory system
Vasopressin is critical for social behavior in males
Humans are like voles:
Two versions of microsatellite regions of AVPR1A gene
Long version
Better social recognition, higher altruism, more likely to form successful pair bond
Short version
Slower social recognition, less altruistic, less chance of pairbond and worse quality of bond
Vasopressin for male territoriality, parental behavior, pair bonding, and mate-guarding
Oxytocin plays lesser role in males
