Distribution of dopamine immunoreactivity in the rat, cat, and monkey spinal cord

Abstract

In the present study, the distribution of dopamine (DA) was identified light microscopically in all segments of the rat, cat, and monkey spinal cord by using immunocytochemistry with antibodies directed against dopamine. Only fibers and (presumed) terminals were found to be immunoreactive for DA. Strongest DA labeling was present in the sympathetic intermediolateral cell column (IML). Strong DA labeling, consisting of many varicose fibers, was found in all laminae of the dorsal horn, including the central canal area (region X), but with the exception of the substantia gelatinosa, which was only sparsely labeled, especially in rat and monkey. In the motoneuronal cell groups DA labeling was also strong and showed a fine granular appearance. The sexually dimorphic cremaster nucleus and Onuf's nucleus (or its homologue) showed a much stronger labeling than the surrounding somatic motoneurons. In the parasympathetic area at sacral levels, labeling was moderate. The remaining areas, like the intermediate zone (laminae VI-VIII), were only sparsely innervated. The dorsal nucleus (column of Clarke) showed the fewest DA fibers, as did the central cervical nucleus, suggesting that cerebellar projecting cells were avoided by the DA projection. In all species, the descending fibers were located mostly in the dorsolateral funiculus, but laminae I and III also contained many rostrocaudally oriented fibers. It is concluded that DA is widely distributed within the spinal cord, with few differences between species, emphasizing that DA plays an important role as one of the monoamines that influences sensory input as well as autonomic and motor output at the spinal level.

Monoaminergic Control of Cauda-Equina-Evoked Locomotion in the Neonatal Mouse Spinal Cord

“…Qualitatively similar effects were observed when DA was applied in the presence of ␣ 2 antagonists. These results are consistent with reports of high levels of D 1 immunoreactive receptors in ventral horn neurons (Dubois et al 1986;Holstege et al 1996;Weil-Fugazza and Godefroy 1993) and with electrophysiological data that demonstrate that DA increases ventral neuronal excitability (Barasi and Roberts 1977;Smith et al 1995). However, our data suggest that D 1 actions are mainly on motoneurons and not on the network, which is contrary to reports that demonstrate that D 1 agonists either alone or in combination with 5-HT can evoke and modulate rhythms in the rat and mouse (Barriere et al 2004;Madriaga et al 2004;Whelan et al 2000).…”

Neurons of the Dopaminergic/Calcitonin Gene-Related Peptide A11 Cell Group Modulate Neuronal Firing in the Trigeminocervical Complex: An Electrophysiological and Immunohistochemical Study

“…As yet, there is no evidence linking specific dopaminergic nuclei and migraine, but since the A11 provides the only known source of descending dopaminergic innervation for the spinal gray matter (Holstege et al, 1996), we hypothesized that A11 projections would also have a descending modulatory effect on nociceptive trigeminovascular traffic. We used a durovascular model that has been highly predictive of translational outcomes in migraine (Bergerot et al, 2006) to test this question.…”

Spinal proerectile effect of apomorphine in the anesthetized rat

“…Immunocytochemical studies revealed that dopaminergic (DA) ®bers and terminals exist in virtually all laminae throughout the spinal cord. 7,8 Furthermore, studies using ligand binding techniques have shown the presence of D1 and D2 receptors in the spinal cord. 9 In male rats, D2 receptors identi®ed with immunochemistry and in situ hybridization have been located in the parasympathetic nucleus of the lumbosacral spinal cord, which contains the cellular bodies of the proerectile autonomic neurons innervating the penis.…”