PubMed · 6233844
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1984. Pain.. https://pubmed.ncbi.nlm.nih.gov/6233844/
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In anesthetized rats, the contribution of calcitonin gene-related peptide (CGRP) to antidromic vasodilation of skeletal muscle blood flow (MBF) following electrical stimulation of muscle afferent was investigated by measuring biceps femoris MBF using laser Doppler flowmetry. Repetitive antidromic electrical stimulation of unmyelinated C fibers in ipsilateral dorsal roots at the 3rd-5th lumbar segments for 30 s caused an increase in MBF for 3-15 min (mean 4.5 min) without significant change in systemic arterial blood pressure. The increase in skeletal MBF started about 10 s after the onset of stimulation, and peaked at approximately 130% of the control value at about 30 s after the end of the 30 s period of stimulation. The MBF response was totally abolished by topical application of hCGRP (8-37), a CGRP receptor antagonist. It is concluded that antidromic vasodilation in skeletal muscles following stimulation of unmyelinated C afferents in dorsal roots is independent of systemic blood pressure and is mediated essentially by CGRP. It is suggested that this CGRP-related antidromic vasodilation may be important in the clinical improvement of skeletal MBF produced by physical therapy, e.g. acupuncture.
The inferior olive climbing fibre projection to two somatotopically corresponding regions of the paravermal C1 zone in lobule V of the anterior lobe and the rostral folia of the paramedian lobule (PML) in the posterior lobe were investigated in cats by using a combined electrophysiological and retrograde double-labelling technique. In each experiment (n = 7), a small injection of rhodamine-tagged beads was made into the forelimb-receiving part of the C1 zone in one region of the cortex, and an injection of fluorescein-tagged beads was made into the other region. The two regions were found to receive olivary input from cells located in a partially overlapping territory within the rostromedial dorsal accessory olive (DAO). At progressively more rostral levels of DAO, the territory providing climbing fibres to the anterior lobe was centred more laterally than the territory projecting to the rostral PML. Where overlaps occurred, cells that provided climbing fibres to one or the other region were intermingled with a smaller population of double-labelled cells that had axons that branched to supply climbing fibres to both regions of the zone. The double-labelled cells represented on average 26% of the smaller total population of labelled cells within the area of overlap and 7% of the total population of neurones projecting to both regions of the zone. Overall, the findings suggested that the C1 zone within spatially separate but somatotopically corresponding regions of the paravermal cerebellar cortex receives at least partially independent olivary inputs, consistent with the presence of distinct microzones at different rostrocaudal levels of the zone.
The organization of the central lateral line pathways in the midshipman fish, Porichthys notatus, was identified following biotin injections into physiologically identified sites in the lateral line-recipient nucleus ventrolateralis in the midbrain. Retrogradely filled neurons are located primarily in nucleus medialis, the principal termination site of lateral line nerve afferents in the medulla, whereas terminal fields are mainly identified in isthmal (nucleus praeeminentialis) and diencephalic (posterior thalamic) nuclei. Compared to other teleosts, nucleus medialis has a distinctive cytoarchitecture in that most of its somata are confined to a dense cell plate adjacent to the fourth ventricle. Injections into nucleus ventrolateralis reveal a caudal (MEDc) and a rostral (MEDr) division of nucleus medialis which are separated by a dorsomedial division of the descending octaval nucleus. MEDc is further divisible into a caudal spherical and a more extensive rostral Purkinje-like cell division. MEDr includes a caudal division of Purkinje-like cells and a rostral division of round and fusiform-shaped cells that form a lateral band under the cerebellar crest. In addition to labeling terminals in nucleus ventrolateralis, biotin injections into MEDc and MEDr further distinguish intrinsic connectivity within nucleus medialis, and also label somata and terminals within other octavolateralis nuclei in the medulla. Injections into both nucleus ventrolateralis and nucleus medialis identify sites which may be processing information from both the auditory and lateral line systems, including the eighth nerve-recipient descending octaval nucleus, the acoustic division of the midbrain, and nucleus praeeminentialis which receives auditory input from the midbrain in midshipman.