Sources of noradrenergic afferents to the hypoglossal nucleus in the rat

Brain Res Bull. 1992 Dec;29(6):931-42. doi: 10.1016/0361-9230(92)90168-w.

Abstract

The sources of noradrenergic (NA) innervation to the hypoglossal nucleus (nXII) in the rat were investigated with double-labeling histochemical/immunocytochemical and lesion/degeneration techniques. Following injection of wheat germ-agglutinin conjugated to horseradish peroxidase into nXII, brain stem sections were reacted with tetramethylbenzidine, stabilized, and incubated in antiserum to tyrosine hydroxylase (TH). Double-labeled neurons were observed in three pontine sites bilaterally, although mainly ipsilaterally, that included the nucleus subceruleus (nSC; 68.75%) and the A7 (21.09%) and A5 (10.15%) cell groups. Confirmation of the above results and identification of the course taken by descending NA-nXII projections was accomplished by lesioning the rostral pons, the nSC, or the medullary catecholamine bundle (MB), the suspected route by which NA afferents reach nXII. Quantitative estimates of the reduction of TH immunoreactivity on the lesioned compared to nonlesioned side of nXII were made densitometrically. In each case, TH immunostaining was significantly decreased (75%) in the ipsilateral caudoventromedial district of nXII, the predominant target area of NA input. The results from this study establish that multiple NA sources in the pons project to nXII in the rat, the majority of NA-nXII afferents are derived from the nSC, and descending NA-nXII projections course in the MB. These data are discussed relative to tongue control.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Afferent Pathways / anatomy & histology*
  • Afferent Pathways / cytology
  • Afferent Pathways / physiology
  • Animals
  • Brain Stem / anatomy & histology*
  • Brain Stem / cytology
  • Brain Stem / physiology
  • Catecholamines / analysis*
  • Female
  • Horseradish Peroxidase
  • Hypoglossal Nerve / anatomy & histology*
  • Hypoglossal Nerve / cytology
  • Hypoglossal Nerve / physiology
  • Immunohistochemistry
  • Nerve Fibers / ultrastructure
  • Neurons / cytology*
  • Neurons / physiology
  • Pons / anatomy & histology
  • Pons / cytology
  • Pons / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Tyrosine 3-Monooxygenase / analysis*
  • Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
  • Wheat Germ Agglutinins

Substances

  • Catecholamines
  • Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
  • Wheat Germ Agglutinins
  • Horseradish Peroxidase
  • Tyrosine 3-Monooxygenase