Interessante Forschung zur Wirkung von Oxytocin:
Oxytocin is the focus of intense scrutiny for its apparent roles in establishing trust between people, and has been administered to children with autism spectrum disorders in clinical trials. The new study, to be published Sept. 12 in Nature, pinpoints a unique way in which oxytocin alters activity in a part of the brain that is crucial to experiencing the pleasant sensation neuroscientists call „reward.“ The findings not only provide validity for ongoing trials of oxytocin in autistic patients, but also suggest possible new treatments for neuropsychiatric conditions in which social activity is impaired. „People with autism-spectrum disorders may not experience the normal reward the rest of us all get from being with our friends,“ said Robert Malenka, MD, PhD, the study’s senior author. „For them, social interactions can be downright painful. So we asked, what in the brain makes you enjoy hanging out with your buddies?“ Some genetic evidence suggests the awkward social interaction that is a hallmark of autism-spectrum disorders may be at least in part oxytocin-related. Certain variations in the gene that encodes the oxytocin receptor – a cell-surface protein that senses the substance’s presence – are associated with increased autism risk.
Oxytocin wäre also dafür zuständig, soziale Interaktionen zu belohnen. Interessant auch die weiteren Ausführung zur Bindung:
In the 1970s, biologists learned that in prairie voles, which mate for life, the nucleus accumbens is replete with oxytocin receptors. Disrupting the binding of oxytocin to these receptors impaired prairie voles‘ monogamous behavior. In many other species that are not monogamous by nature, such as mountain voles and common mice, the nucleus accumbens appeared to lack those receptors. „From this observation sprang a dogma that pair bonding is a special type of social behavior tied to the presence of oxytocin receptors in the nucleus accumbens. But what’s driving the more common group behaviors that all mammals engage in – cooperation, altruism or just playing around – remained mysterious, since these oxytocin receptors were supposedly absent in the nucleus accumbens of most social animals,“ said Dölen. The new discovery shows that mice do indeed have oxytocin receptors at a key location in the nucleus accumbens and, importantly, that blocking oxytocin’s activity there significantly diminishes these animals‘ appetite for socializing. Dölen, Malenka and their Stanford colleagues also identified, for the first time, the nerve tract that secretes oxytocin in the region, and they pinpointed the effects of oxytocin release on other nerve tracts projecting to this area.
Und zu der Wirkungsweise:
As the Stanford team found, oxytocin acting at the nucleus accumbens wasn’t simply squirted into general circulation, as hormones typically are, but was secreted at this spot by another nerve tract originating in the hypothalamus, a multifunction midbrain structure. Oxytocin released by this tract binds to receptors on the dorsal Raphe projections to the nucleus accumbens, in turn liberating serotonin in this key node of the brain’s reward circuitry. The serotonin causes changes in the activity of yet other nerve tracts terminating at the nucleus accumbens, ultimately resulting in altered nucleus accumbens activity – and a happy feeling. „There are at least 14 different subtypes of serotonin receptor,“ said Dölen. „We’ve identified one in particular as being important for social reward. Drugs that selectively act on this receptor aren’t clinically available yet, but our study may encourage researchers to start looking at drugs that target it for the treatment of diseases such as autism, where social interactions are impaired.“
Demnach wäre Autismus eine Folge davon, dass man nicht hinreichend für soziale Interaktionen belohnt wird, was mal wieder zeigt, wie biochemisch unser Gehirn arbeitet: Funktioniert eines der Systeme nicht, dann verändert es das gesamte Denken