In view of the possible involvement of the transient receptor potential vanilloid type-1 (TRPV1) in painful neuropathies such as headache, mouth burning syndrome and deep-tissue craniofacial pain disorders, we studied by immunohistochemistry the occurrence and localization of TRPV1 in the human trigeminal ganglion and spinal nucleus. Autoptic specimens from prenatal life to postnatal old age were examined. Several commercially available antibodies against TRPV1 were tested in human and rat tissue. Among them, only one, which in human brain homogenate western blot test revealed two bands corresponding to molecular weights congruent with those reported in literature, yielded a reliable immunostaining in human specimens. At all examined ages, in the trigeminal ganglion a subpopulation of small- to medium-sized neurons showed a distinct immunostaining in the perikaryon, sometimes extending to the proximal process; immunostained fiber tracts run isolated or in bundles across the ganglion. The percentage of positive neurons declined from early prenatal to full-term neonatal age, to rise again in adult life. Coexistence with CGRP was observed sporadically. Centrally, TRPV1-like immunoreactive material labeled fiber tracts and punctate terminal-like elements, which concentrated in the spinal tract and in lamina I, inner lamina II and deep magnocellular part of the caudal subnucleus. It was codistributed with CGRP and SP, but did not colocalize with SP. Neuronal cell bodies with peripheral membrane-like immunostaining were also detectable in the superficial layers of the nucleus. The density of positive elements was higher in newborn than in adult tissue. The results obtained extend previous data (Hou et al., Neurosci. Lett., 330, 223, 2002) and show that TRPV1 is expressed in human trigeminal primary sensory neurons and central caudal subnucleus from prenatal to postnatal old life with age-related changes. The localization observed both in the ganglion and in the caudal subnucleus, as well as the codistribution/colocalization with CGRP and SP are in agreement with those reported by Guo et al. (Eur. J. Neurosci., 11, 946, 1999) in the rat spinal ganglia and dorsal horn, which in turn differ from those reported there by Tominaga et al., (Neuron, 21, 531, 1998).
Transient receptor potential vanilloid type-1 (TRPV1) in the human trigeminal ganglion and spinal nucleus from prenatal life to old age
SERRA, MARIA PINA;QUARTU, MARINA;BOI, MARIANNA;
2010-01-01
Abstract
In view of the possible involvement of the transient receptor potential vanilloid type-1 (TRPV1) in painful neuropathies such as headache, mouth burning syndrome and deep-tissue craniofacial pain disorders, we studied by immunohistochemistry the occurrence and localization of TRPV1 in the human trigeminal ganglion and spinal nucleus. Autoptic specimens from prenatal life to postnatal old age were examined. Several commercially available antibodies against TRPV1 were tested in human and rat tissue. Among them, only one, which in human brain homogenate western blot test revealed two bands corresponding to molecular weights congruent with those reported in literature, yielded a reliable immunostaining in human specimens. At all examined ages, in the trigeminal ganglion a subpopulation of small- to medium-sized neurons showed a distinct immunostaining in the perikaryon, sometimes extending to the proximal process; immunostained fiber tracts run isolated or in bundles across the ganglion. The percentage of positive neurons declined from early prenatal to full-term neonatal age, to rise again in adult life. Coexistence with CGRP was observed sporadically. Centrally, TRPV1-like immunoreactive material labeled fiber tracts and punctate terminal-like elements, which concentrated in the spinal tract and in lamina I, inner lamina II and deep magnocellular part of the caudal subnucleus. It was codistributed with CGRP and SP, but did not colocalize with SP. Neuronal cell bodies with peripheral membrane-like immunostaining were also detectable in the superficial layers of the nucleus. The density of positive elements was higher in newborn than in adult tissue. The results obtained extend previous data (Hou et al., Neurosci. Lett., 330, 223, 2002) and show that TRPV1 is expressed in human trigeminal primary sensory neurons and central caudal subnucleus from prenatal to postnatal old life with age-related changes. The localization observed both in the ganglion and in the caudal subnucleus, as well as the codistribution/colocalization with CGRP and SP are in agreement with those reported by Guo et al. (Eur. J. Neurosci., 11, 946, 1999) in the rat spinal ganglia and dorsal horn, which in turn differ from those reported there by Tominaga et al., (Neuron, 21, 531, 1998).
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