Corticotropin-releasing factor innervation of the locus coeruleus region: distribution of fibers and sources of input

Neuroscience. 1992;48(3):689-705. doi: 10.1016/0306-4522(92)90412-u.

Abstract

Electrophysiologic studies support the hypothesis that corticotropin-releasing factor, the neurohormone that initiates adrenocorticotropin release during stress, also serves as a neurotransmitter in the pontine noradrenergic nucleus, the locus coeruleus. To elucidate the circuitry underlying proposed corticotropin-releasing factor neurotransmission in the locus coeruleus, the present study utilized immunohistochemical techniques to characterize corticotropin-releasing factor innervation of rat locus coeruleus and pericoerulear regions. Corticotropin-releasing factor-like immunoreactive fibers were identified in the locus coeruleus of colchicine- and non-colchicine-treated rats. However, corticotropin-releasing factor innervation of pericoerulear regions rostral and lateral to the locus coeruleus was more dense than that of the locus coeruleus proper. Double-labeling studies utilizing antisera directed against corticotropin-releasing factor and tyrosine hydroxylase indicated that corticotropin-releasing factor-like immunoreactive fibers overlap with tyrosine hydroxylase-like immunoreactive processes of locus coeruleus neurons, particularly in rostral medial and lateral regions. A group of corticotropin-releasing factor-like immunoreactive neurons was localized just lateral to the locus coeruleus and numerous corticotropin-releasing factor-like immunoreactive neurons were visualized just ventral to the rostral pole of the locus coeruleus in a region corresponding to Barrington's nucleus. None of these corticotropin-releasing factor-like immunoreactive neurons were tyrosine hydroxylase-positive. To determine the source of corticotropin-releasing factor-like immunoreactive fibers in the locus coeruleus, injections of the retrograde tracer [wheat germ agglutinin conjugated to inactivated (apo) horseradish peroxidase coupled to gold particles] were made into the locus coeruleus and sections were processed for corticotropin-releasing factor-like immunoreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

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

MeSH terms

  • Animals
  • Corticotropin-Releasing Hormone / physiology*
  • Electrophysiology
  • Horseradish Peroxidase
  • Immunohistochemistry
  • Locus Coeruleus / cytology
  • Locus Coeruleus / physiology*
  • Male
  • Nerve Fibers / physiology*
  • Rats
  • Rats, Inbred Strains
  • Tyrosine 3-Monooxygenase / biosynthesis
  • Tyrosine 3-Monooxygenase / metabolism
  • Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
  • Wheat Germ Agglutinins

Substances

  • Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
  • Wheat Germ Agglutinins
  • Corticotropin-Releasing Hormone
  • Horseradish Peroxidase
  • Tyrosine 3-Monooxygenase