**2. Vasopressin (arginine-vasopressin, AVP), oxytocin and behaviors**

The two neuro-hormones are nona-peptides closely related each other, while their functions are sometimes in opposite directions, e.g. facial cognition and responses to stress [14]. Also, there is a suggestion that oxytocin is responsible for maternal behavior whereas male-typical social behavior is associated with AVP [2]. As a neuromodulator, AVP has been suggested to play a role in some of the cognitive abilities, including social memory, as well as emotionality (Fig 2). Neurotransmissions by AVP are mediated by three receptor subtypes, namely, V1A, V1B, and V2 receptors, all of which are coupled to G-proteins [2]. Information about oxytocin is reviewed elsewhere in this Book [3]

Impaired social abilities have been particularly implicated in subjects with developmental disorders, such as autism. Thus, Fries et al (2005) [15] reported decreased urine levels of AVP and oxytocin, in children reared in orphanage settings compared to those in infants who received normal care-giving from their parents. Previously institutionalized children have been suggested to frequently experience problems in establishing social bonds and regulating social behavior [15]. Accordingly, infants who experienced early neglect showed lower basal levels of AVP than family-reared children [15]. These observations support the growing evidence for the role of the neuropeptidergic systems in social behaviors in mammals (e.g. [16; 17; 18]: see [19] for review).

**Figure 1.** Sagittal (A) and coronal (B) views of the pituitary gland manually traced (in blue). The pituitary stalk was excluded from the tracings. (Takahashi T et al. *Prog Neuropsychopharmacol Biol* 

**2. Vasopressin (arginine-vasopressin, AVP), oxytocin and behaviors** 

The two neuro-hormones are nona-peptides closely related each other, while their functions are sometimes in opposite directions, e.g. facial cognition and responses to stress [14]. Also, there is a suggestion that oxytocin is responsible for maternal behavior whereas male-typical social behavior is associated with AVP [2]. As a neuromodulator, AVP has been suggested to play a role in some of the cognitive abilities, including social memory, as well as emotionality (Fig 2). Neurotransmissions by AVP are mediated by three receptor subtypes, namely, V1A, V1B, and V2 receptors, all of which are coupled to G-proteins [2]. Information

Impaired social abilities have been particularly implicated in subjects with developmental disorders, such as autism. Thus, Fries et al (2005) [15] reported decreased urine levels of AVP and oxytocin, in children reared in orphanage settings compared to those in infants who received normal care-giving from their parents. Previously institutionalized children have been suggested to frequently experience problems in establishing social bonds and regulating social behavior [15]. Accordingly, infants who experienced early neglect showed lower basal levels of AVP than family-reared children [15]. These observations support the growing evidence for the role of the neuropeptidergic systems in social behaviors in

*Psychiatry* 35;177-83, 2011 (Permission obtained from Elsevier)

about oxytocin is reviewed elsewhere in this Book [3]

mammals (e.g. [16; 17; 18]: see [19] for review).

**Figure 2.** Arginine-vasopressin in the brain and periphery. Extracted from Frank E and Landgraf R. *Eur J Psychopharmacol* 583;226-42, 2008 (Permission obtained from Elsevier)
