J C Finley

Publications (6)15.74 Total impact

• Article: Galanin expression in carotid body afferent neurons.

  J C Finley, J T Erickson, D M Katz
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  ABSTRACT: The present study examined expression and plasticity of the neuropeptide, galanin, in carotid body afferent neurons in the petrosal ganglion of the adult rat. The pattern of galanin expression was compared with that of tyrosine hydroxylase, a selective marker of dopaminergic carotid body afferents in the petrosal ganglion. In normal animals, only 3% of tyrosine hydroxylase-containing petrosal ganglion neurons co-expressed galanin. Retrograde labeling studies, in which FluoroGold was injected into the vascularly isolated carotid body, demonstrated that all tyrosine hydroxylase-positive-galanin-positive cells in the petrosal ganglion project to this target. In addition, however, we unexpectedly found that galanin expression was markedly increased in the petrosal ganglion following FluoroGold injection into the carotid body. On the other hand, tyrosine hydroxylase expression was unchanged, indicating that monoaminergic and peptidergic traits can be differentially regulated in these cells. In summary, these data demonstrate that monoaminergic chemoafferent neurons can co-express a peptidergic trait, similar to catecholaminergic neurons within the central and autonomic nervous systems, and that these cells retain the potential for phenotypic plasticity in adulthood.
  Neuroscience 11/1995; 68(3):937-42. · 3.38 Impact Factor
• Article: BDNF supports mammalian chemoafferent neurons in vitro and following peripheral target removal in vivo.

  T Hertzberg, G Fan, J C Finley, J T Erickson, D M Katz
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  ABSTRACT: Chemoreceptor neurons innervating the rat carotid body were used as a model system to define target regulation of visceral sensory development in fetal and newborn animals. In vitro, chemoafferents were selectively supported by coculture with the carotid body or by treatment with trkB ligands [brain-derived neurotrophic factor (BDNF) and neurotrophin-4], whereas nerve growth factor and neurotrophin 3 had no effect. In vivo, chemoafferent neurons died following carotid body removal at birth, indicating a predominant role of peripheral, rather than central, targets in mediating survival at this stage. However, in the absence of target tissues, a large proportion of carotid body afferents could be rescued by implants containing BDNF. Moreover, BDNF mRNA was detected in the newborn carotid body by reverse transcriptase polymerase chain reaction. These data provide the first demonstration that BDNF can substitute for peripheral target support of sensory neuron survival in vivo and indicate that trkB ligands may be particularly important for development of visceral afferents involved in cardiorespiratory control.
  Developmental Biology 01/1995; 166(2):801-11. · 4.07 Impact Factor
• Article: Trophic regulation of carotid body afferent development.

  T Hertzberg, J C Finley, D M Katz
  Advances in experimental medicine and biology 02/1994; 360:305-7. · 1.09 Impact Factor
• Article: Dopaminergic and peptidergic sensory innervation of the rat carotid body: organization and development.

  D M Katz, J C Finley, J Polak
  Advances in experimental medicine and biology 02/1993; 337:43-9. · 1.09 Impact Factor
• Article: Transmitter diversity in carotid body afferent neurons: dopaminergic and peptidergic phenotypes.

  J C Finley, J Polak, D M Katz
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  ABSTRACT: Hypoxic stimulation of carotid body chemoreceptors is conveyed to the brainstem by primary sensory neurons whose peripheral axons run in the carotid sinus nerve. While considerable attention has focused on defining chemical neuroregulators released by glomus cells in the carotid body, our understanding of the morphology, distribution and transmitter phenotype of these carotid body afferent neurons remains limited. Carotid body afferent neurons were labeled by microinjection of the retrograde tracer, Fluorogold, into the vascularly isolated rat carotid body. In addition, immunoelectron microscopy was used to correlate transmitter phenotype with ultrastructural features of afferent terminals in the carotid body. Our results indicate that 41% of all carotid body afferent neurons express tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis, whereas 7% contain substance P. Tyrosine hydroxylase- and substance P-positive neurons constitute separate subpopulations of carotid body afferents, as these two phenotypes were not colocalized. Most of the tyrosine hydroxylase-containing carotid body afferent neurons were small- or medium-sized (mean cell diameter 15-20 microns) and located in the distal petrosal ganglion, whereas the majority of substance P-containing carotid body afferent neurons were medium- to large-sized (mean cell diameter 20-29 microns) and located in the proximal petrosal ganglion and jugular ganglion. These differences strengthen the notion that these catecholaminergic and peptidergic carotid body afferent neurons give rise to functionally distinct subsets of chemoafferent fibers. To further characterize the catecholaminergic phenotype expressed by tyrosine hydroxylase-positive cells in the petrosal ganglion, we examined the colocalization of tyrosine hydroxylase and DOPA decarboxylase, the dopamine-synthesizing enzyme. Eighty-six per cent of tyrosine hydroxylase-positive neurons in the distal petrosal ganglion also contained DOPA decarboxylase; as these cells do not express the norepinephrine-synthesizing enzyme, dopamine beta-hydroxylase, these data indicate that the catecholaminergic carotid body afferent neurons are dopaminergic. Finally, ultrastructural analysis of the peripheral processes of tyrosine hydroxylase-positive afferent terminals in the carotid body demonstrated endings in close opposition to Type I glomus cells, consistent with a role for dopaminergic afferent neurons in carotid body chemoreception. One possibility is that these cells, in addition to their role as afferents, constitute a morphologic substrate for dopaminergic "efferent" inhibition in the carotid body.
  Neuroscience 01/1993; 51(4):973-87. · 3.38 Impact Factor
• Article: The central organization of carotid body afferent projections to the brainstem of the rat.

  J C Finley, D M Katz
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  ABSTRACT: Despite increasing focus on brainstem respiratory control mechanisms in the rat, relatively little is known about the central organization of chemoreceptor pathways in this species. To approach this issue, the present study sought to selectively define the central projections of primary sensory neurons that innervate the carotid body. Afferent projections were visualized by horseradish peroxidase histochemistry following microinjection of wheat germ agglutinin-horseradish peroxidase into the vascularly isolated carotid body in situ. Labeled afferent fibers were found in several discrete regions of the dorsomedial and ventrolateral medulla. Heaviest labeling was seen bilaterally in the commissural and medial subnuclei of the caudal nucleus tractus solitarius (nTS); more moderate labeling was found bilaterally in the intermediate, interstitial, and dorsolateral subnuclei and ipsilaterally in the ventrolateral subnuclei. In addition, we observed a prominent projection to the caudal ventrolateral medulla in the region of the nucleus retroambigualis. Sparse labeling was also seen in the dorsal motor nucleus of the vagus nerve and the area postrema. These findings support the existence of multiple pathways by which peripheral chemoreceptor inputs may influence central respiratory neurons. In addition to the classically defined relay in nTS, carotid body afferents may also interact more directly with respiratory- or cardiovascular-related neurons in other regions such as the ventrolateral medulla.
  Brain Research 03/1992; 572(1-2):108-16. · 2.73 Impact Factor