Vasopressin: Behavioral roles of an “original” neuropeptide

Abstract

Vasopressin (Avp) is mainly synthesized in the magnocellular cells of the hypothalamic supraoptic (SON) and paraventricular nuclei (PVN) whose axons project to the posterior pituitary. Avp is then released into the blood stream upon appropriate stimulation (e.g., hemorrhage or dehydration) to act at the kidneys and blood vessels. The brain also contains several populations of smaller, parvocellular neurons whose projections remain within the brain. These populations are located within the PVN, bed nucleus of the stria terminalis (BNST), medial amygdala (MeA) and suprachiasmatic nucleus (SCN).Since the 1950's, research examining the roles of Avp in the brain and periphery has intensified. The development of specific agonists and antagonists for Avp receptors has allowed for a better elucidation of its contributions to physiology and behavior. Anatomical, pharmacological and transgenic, including "knockout," animal studies, have implicated Avp in the regulation of various social behaviors across species.Avp plays a prominent role in the regulation of aggression, generally of facilitating or promoting it. Affiliation and certain aspects of pair-bonding are also influenced by Avp. Memory, one of the first brain functions of Avp that was investigated, has been implicated especially strongly in social recognition. The roles of Avp in stress, anxiety, and depressive states are areas of active exploration. In this review, we concentrate on the scientific progress that has been made on understanding the role of Avp in regulating of these and other behaviors across species, as well as discuss the implications for human behavior.

Tailless and Atrophin control Drosophila aggression by regulating neuropeptide signalling in the pars intercerebralis

“…However, together our results suggest that Tll and Atro are part of the transcription module that controls the activity of PI neurons affecting the release of neuropeptides that regulate aggressive behaviour. Our findings in flies suggest that three mechanisms that are involved in the regulation of aggression in mammalstranscriptional control by Nr2e1 (refs 19,27-29), electrical [33][34][35] or optogenetic 55 stimulation of hypothalamic neurons and neuropeptide release from the neurosecretory cells of the hypothalamus 44 -may in fact be a single mechanism that may represent a core aggression regulatory mechanism in all animals.…”

“…Our rationale was based on the idea that conserved transcription modules-which consist of a transcription factor with conserved co-factors, conserved binding site and conserved targets-exist in the evolutionarily conserved control of development 15 and behaviour 16,18 . We found that a conserved transcription factor, Tll, and its conserved co-repressor, Atro, indeed affect aggression in flies and that this transcriptional repressor complex acts through a set of adult neurosecretory cells known as the PI, which has remarkable similarity to the mammalian hypothalamus 31 , a brain region known for its critical role in the control of aggressive behaviour in mammals [33][34][35]44 . Moreover, we found that electrical activation of these neurons is sufficient to cause an increase in aggression in flies, just like electrical stimulation of the hypothalamus does in mammals [33][34][35] .…”

“…4), a brain region composed of B200 neurosecretory cells that has been suggested to be functionally equivalent to the hypothalamus based on molecular, structural and developmental data 31 . Interestingly, mouse Nr2e1 is expressed in the adult hypothalamus 28 , which is known for its important regulatory role in mammalian aggression 43,44 . To confirm that the signal observed in the PI was specific to Tll and not to its paralogue, Dsf, we immunostained flies in which the dsf locus is deleted.…”

“…In addition, we were able to block the behavioural effect of PI neuronal activation by blocking neuropeptide processing in these neurosecretory cells. Interestingly, neuropeptide release from the mammalian hypothalamus is also known to play a role in aggressive behaviour 44 . Thus, we have shown that three key mechanisms involved in the control of mammalian aggression are also involved in the control of fly aggression and that they may in fact be a single mechanism.…”

“…Electrical and optogenetic stimulation of the mammalian hypothalamus leads to a strong increase in aggression in a wide range of mammalian species [33][34][35] . Release of neuropeptides from the mammalian hypothalamus also plays an important role in aggression 44 . On the basis of these two mammalian mechanisms involved in aggression and the known similarity between these neurosecretory neuronal anatomies in mammals and flies, the Drosophila PI is an excellent candidate for a role in aggression regulation.…”