Yolanda García-Mesa1, Jorge García-Piqueras1, Patricia Cuendias1, Ramón Cobo1, José Martín-Cruces1, Jorge Feito2, Olivia García-Suarez1, Benjamín Martín Biedma3, J A Vega4. 1. Departamento de Morfología y Biología Celular - Grupo SINPOs, Universidad de Oviedo, Oviedo, Spain. 2. Departamento de Morfología y Biología Celular - Grupo SINPOs, Universidad de Oviedo, Oviedo, Spain; Servicio de Anatomía Patológica, Complejo Hospitalario Universitario, Salamanca, Spain. 3. Departamento de Cirugía y Especialidades Médico-Quirúrgicas, Universidad de Santiago de Compostela, Spain. 4. Departamento de Morfología y Biología Celular - Grupo SINPOs, Universidad de Oviedo, Oviedo, Spain; Facutad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago de Chile, Chile. Electronic address: javega@uniovi.es.
Abstract
BACKGROUND: Small clear synaptic-like vesicles fill axon terminals of mechanoreceptors. Their functional significance is controversial and probably includes release of neurotransmitters from afferent axon terminals. Synaptophysin, a major protein of the synaptic vesicle membrane, is present in presynaptic endings of the central and peripheral nervous systems. It is also expressed in mechanosensory neurons which extend into skin forming sensory corpuscles. Nevertheless, synaptophysin occurrence in these structures has never been investigated. METHODS: Here we used immunohistochemistry to detect synaptophysin in adult human dorsal root ganglia, cutaneous Meissner and Pacinian corpuscles and Merkel cell-neurite complexes from foetal to elderly period. Moreover, we analyzed whether synaptophysin co-localizes with the mechano-gated protein PIEZO2. RESULTS: Synaptophysin immunoreactivity was observed in primary sensory neurons (36 ± 6%) covering the entire soma size ranges. Axons of Meissner's and Pacinian corpuscles were positive for synaptophysin from 36 and 12 weeks of estimated gestational age respectively, to 72 years old. Synaptophysin was also detected in Merkel cells (from 14 weeks of estimated gestational age to old age). Additionally in adult skin, synaptophysin and PIEZO2 co-localized in the axon of Meissner and Pacinian corpuscles, Merkel cells as well as in some axons of Merkel cell-neurite complexes. CONCLUSION: Present results demonstrate that a subpopulation of primary sensory neurons and their axon terminals forming cutaneous sensory corpuscles contain synaptophysin, a typical presynaptic vesicle protein. Although the functional relevance of these findings is unknown it might be related to neurotransmission mechanisms linked to mechanotransduction.
BACKGROUND: Small clear synaptic-like vesicles fill axon terminals of mechanoreceptors. Their functional significance is controversial and probably includes release of neurotransmitters from afferent axon terminals. Synaptophysin, a major protein of the synaptic vesicle membrane, is present in presynaptic endings of the central and peripheral nervous systems. It is also expressed in mechanosensory neurons which extend into skin forming sensory corpuscles. Nevertheless, synaptophysin occurrence in these structures has never been investigated. METHODS: Here we used immunohistochemistry to detect synaptophysin in adult human dorsal root ganglia, cutaneous Meissner and Pacinian corpuscles and Merkel cell-neurite complexes from foetal to elderly period. Moreover, we analyzed whether synaptophysin co-localizes with the mechano-gated protein PIEZO2. RESULTS: Synaptophysin immunoreactivity was observed in primary sensory neurons (36 ± 6%) covering the entire soma size ranges. Axons of Meissner's and Pacinian corpuscles were positive for synaptophysin from 36 and 12 weeks of estimated gestational age respectively, to 72 years old. Synaptophysin was also detected in Merkel cells (from 14 weeks of estimated gestational age to old age). Additionally in adult skin, synaptophysin and PIEZO2 co-localized in the axon of Meissner and Pacinian corpuscles, Merkel cells as well as in some axons of Merkel cell-neurite complexes. CONCLUSION: Present results demonstrate that a subpopulation of primary sensory neurons and their axon terminals forming cutaneous sensory corpuscles contain synaptophysin, a typical presynaptic vesicle protein. Although the functional relevance of these findings is unknown it might be related to neurotransmission mechanisms linked to mechanotransduction.
Authors: Katarzyna Michalak-Micka; Dominic Rütsche; Luca Mazzone; Vanessa L Büchler; Ueli Moehrlen; Agnes S Klar; Thomas Biedermann Journal: Front Bioeng Biotechnol Date: 2022-09-15