Distribution of catecholamines in the brain stem and spinal cord of the lizard Varanus exanthematicus: an immunohistochemical study based on the use of antibodies to tyrosine hydroxylase.
Antibodies to tyrosine hydroxylase were used to study the distribution of nerve cells, fibers and terminals, containing catecholamines, in the lizard Varanus exanthematicus, by means of the indirect immunofluorescence technique. Tyrosine hydroxylase-containing cell bodies occurred in the hypothalamus, the ventral and dorsal tegmentum mesencephali, the substantia nigra, the isthmic reticular formation, in and ventrolaterally to the locus coeruleus, in the nucleus tractus solitarii and in a lateral part of the nucleus reticularis inferior. In addition tyrosine hydroxylase-containing cell bodies were found throughout the spinal cord, ventral to the central canal. Tyrosine hydroxylase-immunoreactive terminal areas in the brain stem were seen in the nucleus interstitialis of the fasciculus longitudinalis medialis, the nucleus raphes superior, the locus coeruleus, several parts of the reticular formation and the nucleus descendens nervi trigemini. Ascending catecholaminergic pathways could be traced from the ventral mesencephalic tegmentum as well as from the dorsal isthmic tegmentum rostralwards, through the lateral hypothalamus. These pathways correspond to the mesostriatal and isthmocortical projections respectively, as described in mammals. Furthermore, ascending catecholaminergic fibers could be traced from the catecholaminergic cell groups in the medulla oblongata to the isthmus, where they intermingle with the locus coeruleus neurons. These pathways correspond to the medullohypothalamic projection and to the dorsal periventricular system in mammals. Descending catecholaminergic fibers to the spinal cord pass via the dorsomedial part of the lateral funiculus, and mainly terminate in the dorsal horn. The results obtained in the present study have been placed in a comparative perspective, which illustrates the constancy of catecholaminergic innervation throughout phylogeny.
D000818:Animals; D001933:Brain Stem / Q000201:enzymology / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism*; D004027:Diencephalon / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D008116:Lizards / Q000378:metabolism*; D008636:Mesencephalon / Q000378:metabolism; D009434:Neural Pathways / Q000378:metabolism; D013116:Spinal Cord / Q000201:enzymology / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
D002395:Catecholamines; D014446:Tyrosine 3-Monooxygenase