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Title: Catecholaminergic innervation of the cat spinal cord
Author: Doyle, Christopher Alfred
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1994
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The organisation of catecholamine (CA)-containing nerve terminals in the cat spinal dorsal horn was examined in an immunocytochemical study employing antisera against tyrosine hydroxylase & dopamine-β-hydroxylase. Light microscopic analysis revealed that varicose axons were concentrated in laminae I, II & IV. Correlated ultrastructural analysis showed that these terminals usually formed single synapses with dendrites of somata, but not with other axon terminals. This suggests that descending catecholaminergic axons regulate sensory transmission through the dorsal horn via a postsynaptic action upon dorsal horn neurons. Using the retrograde tracer horseradish peroxidase to label particular groups of dorsal horn neurons, it was shown that the postsynaptic dorsal column (PSDC) pathway, is a major protection target of CA-containing axons. Over 60% of these cells were found to have dopamine-β-hydroxylase immunostained varicosities closely apposed to their somata and/or proximal dendrites, and correlated ultrastructural analysis confirmed that many of these contacts were regions of synaptic association. In contrast, the cells of the spinocervical tract (SCT) did not receive a major innervation from these axons. The lateral cervical nucleus (LCN), the termination site of SCT cells, was found to possess a dense innervation from CA-containing axons. These fibres were present throughout the nucleus and synapsed with dendrites and somata, including those of large cells in the lateral region, but not with other axon terminals. This suggests that catecholaminergic axons in the LCN regulate the activity of LCN neurons but not the terminals of SCT cells. It has been suggested that many catecholaminergic axons in the dorsal horn may contain neuropeptide Y (NPY), and an examination was made of NPY-immunoreactive axons to test this hypothesis. Light microscopy revealed a heavy concentration of NPY-positive profiles in laminae I & II, but only low to moderate numbers in III-VI.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available