Traditionally, the spinal dorsal column and the gracile (GN) and cuneate (CN) nuclei are considered to convey somatic tactile and proprioceptive stimuli. However, clinical and experimental studies prove their involvement in visceral nociception. Early studies in our laboratory showed that, at variance with that of laboratory animals, the human CN contains discrete subregions strongly immunoreactive to substance P (SP), a neuropeptide classically involved in pain transmission. Here we provide further information on the chemical neuroanatomy of the human dorsal column nuclei and show that the SP-immunoreactive subregions of the CN retain the neurochemical features of the protopathic relay nuclei. Tissue distribution of neuropeptides SP, calcitonin gene-related peptide, leucine- and methionine-enkephalin, somatostatin, galanin and peptide histidine-isoleucine, trophins of the Neurotrophin and Glial-derived neurotrophic factor families and related receptors, transient receptor potential vanilloid type-1, and neuroplasticity-associated proteins growth-associated protein-43 and polysialylatedneural cell adhesion molecule was analyzed by immunohistochemistry in postmortem specimens of medulla oblongata from subjects aged 21 gestation weeks to 78 years, with no signs of neuropathology. Immunoreactivity to the examined molecules labels neuronal elements with similar aspect and density in the GN and main CN. By contrast, in restricted areas of the CN, located along its dorsal edge or embedded in the cuneate fasciculus, immunoreactive elements show aspect, density and reciprocal distribution strikingly similar to those detected in the superficial layers of the spinal dorsal horn and trigeminal subnucleus caudalis. We propose that, at variance with that of laboratory mammals, including primates, the human CN contains clear-cut, previously uncharacterized subregions with neurochemical features reminiscent of those present in the relay nuclei for protopathic and pain perception. Moreover, the peculiar localization of the examined substances suggests that the superficial layers of those regions may constitute a “gelatinous subnucleus”. The origin and functional involvement of such innervation remains to be elucidated.
Discovery Of Novel Subregions Of The Human Cuneate Nucleus Whose Neurochemical Features Match Those Of Nociceptive Sensory Nuclei
QUARTU, MARINA;SERRA, MARIA PINA;BOI, MARIANNA;PODDIGHE, LAURA;MELIS, TIZIANA
2012-01-01
Abstract
Traditionally, the spinal dorsal column and the gracile (GN) and cuneate (CN) nuclei are considered to convey somatic tactile and proprioceptive stimuli. However, clinical and experimental studies prove their involvement in visceral nociception. Early studies in our laboratory showed that, at variance with that of laboratory animals, the human CN contains discrete subregions strongly immunoreactive to substance P (SP), a neuropeptide classically involved in pain transmission. Here we provide further information on the chemical neuroanatomy of the human dorsal column nuclei and show that the SP-immunoreactive subregions of the CN retain the neurochemical features of the protopathic relay nuclei. Tissue distribution of neuropeptides SP, calcitonin gene-related peptide, leucine- and methionine-enkephalin, somatostatin, galanin and peptide histidine-isoleucine, trophins of the Neurotrophin and Glial-derived neurotrophic factor families and related receptors, transient receptor potential vanilloid type-1, and neuroplasticity-associated proteins growth-associated protein-43 and polysialylatedneural cell adhesion molecule was analyzed by immunohistochemistry in postmortem specimens of medulla oblongata from subjects aged 21 gestation weeks to 78 years, with no signs of neuropathology. Immunoreactivity to the examined molecules labels neuronal elements with similar aspect and density in the GN and main CN. By contrast, in restricted areas of the CN, located along its dorsal edge or embedded in the cuneate fasciculus, immunoreactive elements show aspect, density and reciprocal distribution strikingly similar to those detected in the superficial layers of the spinal dorsal horn and trigeminal subnucleus caudalis. We propose that, at variance with that of laboratory mammals, including primates, the human CN contains clear-cut, previously uncharacterized subregions with neurochemical features reminiscent of those present in the relay nuclei for protopathic and pain perception. Moreover, the peculiar localization of the examined substances suggests that the superficial layers of those regions may constitute a “gelatinous subnucleus”. The origin and functional involvement of such innervation remains to be elucidated.
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