Intrinsic sensory neurons provide direct input to motor neurons and interneurons in mouse distal colon via varicose baskets
| Autor: | Marcello Costa, Dayan de Fontgalland, David Smolilo, David A. Wattchow, Nick J. Spencer, Timothy J. Hibberd |
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| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
Pathology medicine.medical_specialty animal structures Sensory Receptor Cells Colon Calcitonin gene-related peptide Biology Inhibitory postsynaptic potential Enteric Nervous System Guinea pig Mice 03 medical and health sciences Immunolabeling 0302 clinical medicine Interneurons Neural Pathways medicine Animals Myenteric plexus Motor Neurons General Neuroscience Colocalization Mice Inbred C57BL 030104 developmental biology nervous system Excitatory postsynaptic potential Calretinin 030217 neurology & neurosurgery |
| Zdroj: | Journal of Comparative Neurology. 528:2033-2043 |
| ISSN: | 1096-9861 0021-9967 |
| Popis: | Connections from intrinsic primary afferent neurons (IPANs), to ascending motor and interneurons have been described in guinea pig colon. These mono- and polysynaptic circuits may underlie polarized motor reflexes evoked by local gut stimulation. There is a need to translate findings in guinea pig to mouse, a species increasingly used in enteric neuroscience. Here, mouse distal colon was immunolabeled for CGRP, a marker of putative IPANs. This revealed a combination of large, intensely immunofluorescent axons in myenteric plexus and circular muscle, and thinner varicose axons with less immunofluorescence. The latter formed dense, basket-like varicosity clusters (CGRP+ baskets) that enveloped myenteric nerve cell bodies. Immunolabeling after 4-5 days in organ culture caused loss of large CGRP+ axons, but not varicose CGRP+ fibers and CGRP+ baskets. Baskets were characterized further by triple labeling with CGRP, nitric oxide synthase (NOS) and calretinin (CALR) antibodies. Approximately half (48%) of nerve cell bodies inside CGRP+ baskets lacked both NOS and CALR, while two overlapping populations containing NOS and/or CALR comprised the remainder. Quantitative analysis revealed CGRP+ varicosities were most abundant in baskets, followed by CALR+ varicosities, with a high degree of colocalization between the two markers. Few NOS+ varicosities occurred in baskets. Significantly higher proportions of CALR+ and CGRP+ varicosities colocalized in baskets than in circular muscle. In conclusion, CGRP+ baskets in mouse colon are formed by intrinsic enteric neurons with a neurochemical profile consistent with IPANs and have direct connections to both excitatory and inhibitory neurons. |
| Databáze: | OpenAIRE |
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