title: Oxytocin-induced yawning: sites of action in the brain and interaction with mesolimbic/mesocortical and incertohypothalamic dopaminergic neurons in male rats.
abstract: Oxytocin (80 ng) induces yawning when injected into the caudal part of the ventral tegmental area, the hippocampal ventral subiculum and the posteromedial nucleus of the amygdala of male rats. The behavioural response occurred concomitantly with an increase in the concentration of extracellular dopamine and its main metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the dialysate obtained from the shell of the nucleus accumbens and of the prelimbic medial prefrontal cortex by means of intracerebral microdialysis. Both oxytocin responses were significantly reduced by d(CH₂)₅Tyr(Me)²-Orn⁸-vasotocin, a selective oxytocin receptor antagonist, injected in the above brain areas 15 min before oxytocin. Similar results were obtained by activating central oxytocinergic neurons originating in the paraventricular nucleus of the hypothalamus and projecting to the ventral tegmental area, the hippocampus and the amygdala, with the dopamine agonist apomorphine given at a dose that induces yawning when injected into the paraventricular nucleus. Since oxytocin is considered a key regulator of emotional and social reward that enhances amygdala-dependent, socially reinforced learning and emotional empathy, mesolimbic and mesocortical dopamine neurons play a key role in motivation and reward, and yawning in mammals is considered a primitive, unconscious form of empathy, the present results support the hypothesis that oxytocinergic neurons originating in the paraventricular nucleus of the hypothalamus and projecting to the above brain areas and mesolimbic and mesocortical dopaminergic neurons participate in the complex neural circuits that play a role in the above mentioned functions.
authors.affiliation: Department of Biomedical Sciences, Neuroscience Section, and Centre of Excellence for the Neurobiology of Addictions, University of Cagliari, and Institute of Neuroscience, National Research Council, Cagliari Section, 09042 Monserrato Cagliari, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Sanna
authors.forename: Antonio
authors.initials: A
authors.lastname: Argiolas
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Melis
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D001931:Brain Mapping; D002450:Cell Communication / Q000187:drug effects* / Q000502:physiology; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D018491:Dopamine Agonists / Q000494:pharmacology; D059290:Dopaminergic Neurons / Q000187:drug effects* / Q000502:physiology; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D008032:Limbic System / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D008297:Male; D008954:Models, Biological; D010121:Oxytocin / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012737:Sex Factors; D015000:Yawning / Q000187:drug effects* / Q000502:physiology
chemical_list: D018491:Dopamine Agonists; D015102:3,4-Dihydroxyphenylacetic Acid; D010121:Oxytocin