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Localization of oxytocin binding sites in the human brainstem and upper spinal cord: an autoradiographic study

Department of Physiology, University Medical Center, Geneva, Switzerland.
Brain Research (Impact Factor: 2.83). 11/1989; 500(1-2):223-30. DOI: 10.1016/0006-8993(89)90317-X
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ABSTRACT Two different ligands, tritiated oxytocin and a newly synthesized and monoiodinated oxytocin antagonist, were used to reveal sites which bind oxytocin in the brainstem and upper spinal cord of 12 human subjects. Tissue sections were incubated with either ligand at a concentration close to their respective dissociation constants determined in human uterus and rat brain. Specificity of binding was assessed in presence of unlabelled oxytocin in excess. Comparable results were obtained using tritiated or iodinated ligand. Labelling was most intense in the substantia nigra pars compacta, the substantiae gelatinosae of the caudal spinal trigeminal nucleus and of the dorsal horn of the upper spinal cord, as well as in the medio-dorsal region of the nucleus of the solitary tract. Binding was also detected in the rest of the nucleus of the solitary tract and in other areas, including the oral and interpolar parts of the spinal trigeminal nucleus, the hypoglossal nucleus and the area postrema. Presence of oxytocin binding sites in regions concerned with sensory, autonomic and motor processing suggests that oxytocin could act as a neurotransmitter or neuromodulator in the human central nervous system.

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    • "Consequently each radioligand binds to both OXTR and AVPR1a, making it difficult to discriminate with confidence the distribution of the two receptors . This lack of selectivity of the radioligands for the primate receptors brings into question the specificity of the receptor binding results in earlier OXTR and AVPR1a mapping studies in human (Loup et al., 1989, 1991) and rhesus macaque (Macaca mulatta) brain tissue (Toloczko et al., 1997). These issues also highlight the importance of overcoming the promiscuous binding profile of the radioligands in primate tissue by using a competitive binding design. "
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    Neuroscience 07/2014; 273:12–23. DOI:10.1016/j.neuroscience.2014.04.055 · 3.33 Impact Factor
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    • "Neuroscience 253 (2013) 155–164 amygdala or the hippocampus. However, the validity of the Loup et al. (1989, 1991) studies has been brought into question by evidence that 125 I-OTA binds V1a as potently as OTRs in the rhesus monkey brain (Toloczko et al., 1997). "
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    • "Research has demonstrated that activation of the brainstem is significantly attenuated following oxytocin administration (Baumgartner et al., 2008), likely through the mediation of activity via these amygdalar projections (Huber et al., 2005). Complementing this indirect influence of oxytocin on brainstem activity, functional oxytocin receptors have been identified within the human central gray, among other brainstem regions (Loup et al., 1989), suggesting that the neuropeptide directly affects brainstem structure and function. Indeed, direct administration of oxytocin into the periaqueductal gray has been shown to attenuate anxiety-related behaviors in postpartum rats (Figueira et al., 2008). "
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