The distribution of serotonin in the CNS of an elasmobranch fish: Immunocytochemical and biochemical studies in the atlantic stingray, Dasyatis sabina

Abstract

The distribution of serotonin (5HT) in the brain of the Atlantic stingray was studied with peroxidase-antiperoxidase immunocytochemistry and high-pressure liquid chromatography. The regional concentrations of 5HT determined for this stingray fell within the range of values previously reported for fishes. A consistent trend in vertebrates for the hypothalamus and midbrain to have the highest concentrations and the cerebellum the lowest was confirmed in stingrays. Neuronal cell bodies and processes exhibiting 5HT-like immunoreactivity were distributed in variable densities throughout the neuraxis. Ten groups of 5HT cells were described: (I) spinal cord, (II-IV) rhombencephalon, (V, VI) mesencephalon, (VII, VIII) prosencephalon, (IX) pituitary, and (X) retina. There were three noteworthy features of the 5HT system in the Atlantic stingray: (1) 5HT cells were demonstrated in virtually every location in which 5HT-containing cells have been described or alluded to in the previous literature. The demonstration of immunopositive cells in the spinal cord, the retina, and the pars distalis of the pituitary suggests that 5HT may be an intrinsic neurotransmitter (or hormone) in these regions. (2) The distribution of 5HT cells in the brainstem shared many similarities with that in other vertebrates. However, there were many 5HT cells outside of the raphe nuclei, in the lateral tegmentum. It appears that the hypothesis that "lateralization" of the 5HT system is an advanced evolutionary trend cannot be supported. (3) 5HT fibers and terminals were more widely distributed in the Atlantic stingray brain than has been reported for other nonmammalian vertebrates on the basis of histofluorescence. It appears that this feature of the 5HT system arose early in phylogeny, and that the use of immunohistochemistry might reveal a more general occurrence of widespread 5HT fibers and terminals.

New Insights on Saccus vasculosus Evolution: A Developmental and Immunohistochemical Study in Elasmobranchs

“…No 5-HT-ir cells were observed in the SV of either developing or adult sharks. As reported in the batoid Dasyatis sabina [Ritchie et al, 1983], a few 5-HT-ir fibers innervated the shark SV, suggesting that they are saccopetal, probably arising from serotoninergic cells of the posterior recess nucleus.…”

Organization of the Serotonergic System in the Central Nervous System of Two Basal Actinopterygian Fishes: the Cladistians <b><i>Polypterus senegalus</i></b> and <b><i>Erpetoichthys calabaricus</i></b>

“…This absence of 5-HT-ir cells and presence of extensive serotonergic innervation in the olfactory bulbs and pallial/subpallial telencephalic areas seems to be a shared feature across vertebrates, with the exception of chondrosteans, which showed immunoreactive cells in the olfactory bulbs and in the medioventral wall of the telencephalic ventricle, rostral to the anterior commissure [Adrio et al, 1999], and the marine teleost Micropogonias undulatus that possesses 5-HT-ir cells in the olfactory bulbs [Khan and Thomas, 1993]. Summary of the distribution of 5-HT-ir cells and fibers in different areas of the CNS of the main vertebrate groups studied 2 Ritchie et al [1983Ritchie et al [ , 1984, Cruce [1991, 1992], Stuesse et al [1990Stuesse et al [ , 1991aStuesse et al [ , b, 1995, Schuette and Chappel [1998], Carrera et al [2008].…”

Serotonergic systems in the spinal cord of the amphibian urodele Pleurodeles waltl

“…In mammals, 5-HT-containing intraspinal neurons were detected following pharmacological pretreatment to increase the level of 5-HT expression (Lamotte et al, 1982), whereas other studies have reported that serotonergic innervation is derived only from supraspinal structures (Kojima and Sano, 1983). It has thus been proposed that spinal cord 5-HT-ir cells were present early in phylogeny and have subsequently been lost in a number of species (Ritchie et al, 1983).…”