Oxytocin is a hormone peptide of 9 aminoacids produced from hypothalamic nuclei and secreted by theneurohypophysis. Its main action is to stimulate contractions of the smooth muscle of the uterus, especially in the last stage of pregnancy when it plays an important role in the initiation and maintenance of labor and delivery. It seems that the gene structure and the phenotypic expression of the basis of this neuropeptide are stable and phylogenetically very old, while the genetic regulation of its receptors would present an extreme variability. This wealth of receptor expression seems to be the basis of differences in social behavior is different between animal species and between individuals of the same species. Animal experiments have demonstrated the importance of this hormone in coupling and behavior towards offspring. Although many human studies are beginning to explore the role of this neuropeptide in cognitive skills with relational implications. The first results confirm that changes in genes coding for its receptor can alter brain function and contribute to the characterization of individual social behaviors. Particularly interesting are the findings of induction of increased brain function and a simultaneous increase of the capacity for empathy, relationship with others and self-esteem. Hence the definition of 'trust hormone' or 'hormone of falling'. The journal Neuropsychopharmacology has just published the results of a survey in which the nasal application of oxytocin has been shown to influence the neural and behavioral processing of social stimuli. These effects are probably mediated by genetic variations. A potential candidate is the CD38 gene, which encodes a transmembrane protein involved in processes of oxytocin secretion. A common variant of this gene, called rs3796863, was recently found with high frequency in autistic spectrum disorders (ASD). The research, led by Dr. Sauer and his colleagues of the Central Institute of Mental Health of the University of Heidelberg, investigated in 55 healthy young men, the different effect of intranasal application of oxytocin on the processing of social stimuli on the basis of the change CD38 gene. Individuals who have a mutation in both alleles showed slower reaction times and greater activation in left fusiform gyrus during visual processing of social stimuli. The differences between genotypes have become more obvious under stimulation with oxytocin, even if they have not reach statistical significance. The results indicate that the variant rs3796863 may significantly affect the activation of the fusiform gyrus, a part of the mesial temporal lobe of the brain associated with perception of emotions in the faces of others and widely regarded in the research on the causes of ASD. Oxytocin seems to modulate this effect by amplifying the activation differences between different allelic groups. This suggests an interaction between genetic structure and availability of oxytocin in the activation of the fusiform gyrus and supports some recent proposals to use this neuropeptide as a basis for possible pharmacological treatment of symptoms of ASD.
This article has been translated and adapted to English (American) by Courtney Diamond
REFERENECES
- Donaldson Z.R. and Young L.J. Oxytocin, Vasopressin, and the Neurogenetics of Sociality. Science, 2008, 7, 5903: 900-904
- Sauer C, Montag C, Wörner C, Kirsch P, Reuter M. Effects of a Common Variant in the CD38 Gene on Social Processing in an Oxytocin Challenge Study: Possible Links to Autism. Neuropsychopharmacology, January 2012; doi:10.1038/npp.2011.333.