Vasopressin, Paarbindung und Aggression

Der Wikipedia-Artikel zu Vasopressin enthält einige interessante Stellen zu dessen Wirkungsweise, die in dem Artikel „Lust, Anziehung und Verbundenheit oder auch Liebe“ schon einmal angeklungen ist.

In recent years, there has been particular interest in the role of vasopressin in social behavior. It is thought that vasopressin, released into the brain during sexual activity, initiates and sustains patterns of activity that support the pair-bond between the sexual partners; in particular, vasopressin seems to induce the male to become aggressive towards other males.

Evidence for this comes from experimental studies in several species, which indicate that the precise distribution of vasopressin and vasopressin receptors in the brain is associated with species-typical patterns of social behavior. In particular, there are consistent differences between monogamous species and promiscuous species in the distribution of AVP receptors, and sometimes in the distribution of vasopressin-containing axons, even when closely-related species are compared.

Moreover, studies involving either injecting AVP agonists into the brain or blocking the actions of AVP support the hypothesis that vasopressin is involved in aggression towards other males. There is also evidence that differences in the AVP receptor gene between individual members of a species might be predictive of differences in social behavior. One study has suggested that genetic variation in male humans effects pair-bonding behavior. The brain of males uses vasopressin as a reward for forming lasting bonds with a mate, and men with one or two of the genetic alleles are more likely to experience marital discord. The partners of the men with two of the alleles affecting vasopressin reception state disappointing levels of satisfaction, affection, and cohesion. Vasopressin receptors distributed along the reward circuit pathway, to be specific in the ventral pallidum, are activated when AVP is released during social interactions such as mating, in monogamous prairie voles. The activation of the reward circuitry reinforces this behavior, leading to conditioned partner preference, and thereby initiates the formation of a pair bond.

Eine andere Studie geht in eine ähnliche Richtung:

Vasopressin/oxytocin and related peptides comprise a phylogenetically old superfamily of chemical signals in both vertebrates and invertebrates. Each peptide isoform has its own distinct receptor subtype and specific cellular action. The conservation and dispersion of vasopressin/oxytocin signalling systems across the animal kingdom attests to their functional significance in evolution. Indeed, they are involved in the physiology of fluid balance, carbohydrate metabolism, thermoregulation, immunity and reproduction. In addition, these peptides evolved a role in social behaviours related to aggression and affiliation. The focus of this chapter is the role of vasopressin/oxytocin as chemical signals in the brain altering aggressive responding in a context- and species-dependent manner. There is compelling evidence from several mammalian species including humans that vasopressin enhances aggression. The activity of the vasopressin appears linked to the serotonin system providing a mechanism for enhancing and suppressing aggressive behaviour.

Es könnte demnach eine Bindung gegenüber bestimmten Personen, aber Aggression gegenüber anderen Personen bewirkt werden. Auch die geschlechtsbezogene Seite finde ich natürlich sehr interessant. Hier könnte die Ursache für eine Vielzahl unterschiedlicher Verhaltensweisen liegen. Beispielsweise die Unterschiede bei den Big Five, nach denen Frauen bei der Verträglichkeit („Agreeableness“) im Schnitt besser abschneiden.