Distribution of tyrosine hydroxylase, serotonin, and leu-enkephalin immunoreactive cells in the brainstem of a shark, Squalus acanthias.

Title

Distribution of tyrosine hydroxylase, serotonin, and leu-enkephalin immunoreactive cells in the brainstem of a shark, Squalus acanthias.

Creator

Stuesse S L; Cruce W L

Publisher

Brain, behavior and evolution

Date

1992
1992

Description

The central nervous system location of neurochemicals that are widely distributed among extant animals may give us clues to changes that occurred in the brains of these animals during evolution. We have been studying the brains of cartilaginous fishes, a heterogeneous group whose central nervous system varies considerably. Squalus acanthias, the spiny dogfish shark, was chosen to represent the squalomorphs, a group of living sharks known to possess many primitive characters. The distribution of tyrosine hydroxylase (TH+), serotonin (5-HT+), and leu-enkephalin (LENK+) positive cells within the brainstem of Squalus was determined by use of antibodies to these substances. All the major raphe groups described for mammals were found in Squalus. The 5-HT+ cells in raphe nuclei were more uniformly distributed in Squalus than in Heterodontus, the horn shark. Other nuclei that were 5-HT+ and LENK+, and that have been identified in mammals, included reticularis paragigantocellularis lateralis, a B9 cell group, and reticularis magnocellularis. The postcommissural nucleus and pretectal area contained 5-HT+ and LENK+ cells. These cells have been described in a holocephalian, in teleosts, and in reptiles but not in other elasmobranchs or in mammals. Cells that were TH+ were located in prominent A1/A2, A6 (locus coeruleus), A9 (substantia nigra), and A10 (ventral tegmental area) cell groups, and in a very small A5 group. We conclude that the variation in chondrichthian brainstems exceeds that in mammals, and we suggest that this variation is related to life-style and the long evolutionary history of these fishes.

Subject

Animals; Brain Mapping; Brain Stem/*anatomy & histology; Diencephalon/anatomy & histology; Dogfish/*anatomy & histology; Enkephalin; Immunoenzyme Techniques; Leucine/*analysis; Mesencephalon/anatomy & histology; Nerve Fibers/ultrastructure; Neurons/ultrastructure; Rhombencephalon/anatomy & histology; Serotonin/*analysis; Spinal Cord/anatomy & histology; Tyrosine 3-Monooxygenase/*analysis

Identifier

Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

77–92

Issue

2

Volume

39

Citation

Stuesse S L; Cruce W L, “Distribution of tyrosine hydroxylase, serotonin, and leu-enkephalin immunoreactive cells in the brainstem of a shark, Squalus acanthias.,” NEOMED Bibliography Database, accessed February 2, 2023, https://neomed.omeka.net/items/show/4723.

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