Tzu Chi Medical Journal
Volume 19, Issue 4 , Pages 181-185, December 2007

Cellular Heterogeneity Within the Solitary Tract Nucleus and Visceral Afferent Processing—Electrophysiological Approaches to Discerning Pathway Performance

  • Michael C. Andresen

      Affiliations

    • Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, USA
    • Corresponding Author InformationCorresponding author. Department of Physiology and Pharmacology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239-3098, USA
    • ,
  • Timothy W. Bailey

      Affiliations

    • Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, USA
    • ,
  • Young-Ho Jin

      Affiliations

    • Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, USA
    • ,
  • Stuart J. McDougall

      Affiliations

    • Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, USA
    • ,
  • James H. Peters

      Affiliations

    • Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, USA
    • ,
  • Sue A. Aicher

      Affiliations

    • Institute of Neurological Sciences, Oregon Health and Science University, Portland, Oregon, USA

Received 12 June 2007; received in revised form 17 September 2007; accepted 20 September 2007.

Article Outline

Abstract 

Many homeostatic reflexes depend on autonomic central nervous system mechanisms to systemically coordinate visceral organ function. The nucleus of the solitary tract (NTS) is the common entry of cranial visceral afferents into these regulatory pathways. Such NTS neurons initiate adjustments in cardiovascular, respiratory, gastrointestinal and other visceral systems. Diversity of neurons within the NTS appears integral to such pro cessing but is daunting to approach experimentally. This review outlines three experimental approaches to understanding cellular heterogeneity within NTS and its relation to function. Brainstem slice preparations coupled with patch recordings afford cellular–molecular resolution with substantial links to the more intact system. Pharmacological approaches based on visceral afferent phenotype have helped identify myelinated and unmyelinated solitary tract inputs to NTS neurons. An interesting outcome has been the robust association of A-type potassium currents with NTS neurons receiving unmyelinated afferents. Neuroanatomical tracers offer a second, complementary approach. Anterograde transport of fluorescent dye identifies cranial visceral afferent terminals on second order neurons that cluster on or proximal to the soma—a highly unusual distribution in the central nervous system. Thus, second order baroreceptive neurons can be identified neuroanatomically in vitro. Equally helpful has been identification of NTS projection neurons by retrograde tracers injected into target regions of the hypothalamus or brainstem and this approach indicates substantial specialization—relative homogeneous neurons within the overall heterogeneity of NTS. Lastly, transgenic mouse strains, particularly those expressing marker chromophores, have identified phenotypic subtypes such as GABAergic inhibitory neurons within NTS. Combined methodologies are forging new understanding of NTS and autonomic regulation.

keywords:  C-fiber , Parasympathetic , Paraventricular nucleus , Sensory , Vagus

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PII: S1016-3190(10)60014-6

doi:10.1016/S1016-3190(10)60014-6

Tzu Chi Medical Journal
Volume 19, Issue 4 , Pages 181-185, December 2007

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