Corticotropin-releasing factor innervation of the locus coeruleus region: distribution of fibers and sources of input.
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)
Valentino
R J
RJ
Department of Mental Health Science, Hahnemann University, Philadelphia, PA 19102.
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D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000502:physiology*; D004594:Electrophysiology; D006735:Horseradish Peroxidase; D007150:Immunohistochemistry; D008125:Locus Coeruleus / Q000166:cytology / Q000502:physiology*; D008297:Male; D009412:Nerve Fibers / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis / Q000378:metabolism; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins
D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins; D003346:Corticotropin-Releasing Hormone; D006735:Horseradish Peroxidase; D014446:Tyrosine 3-Monooxygenase