Distribution of GABA immunoreactivity in the central and peripheral nervous system of amphioxus (Branchiostoma lanceolatum pallas)

Abstract

On the basis of labeling with an anti-gamma-aminobutyric acid (GABA) antibody, we report for the first time the presence and distribution of GABA-immunoreactive cells in the central and peripheral nervous system of amphioxus. In the nerve cord, there is a large dorsorostral group of cerebrospinal-fluid-contacting (CSFc) cells at the caudal end of the brain vesicle that gives rise to a large ventral commissure and neuropilar region. In the middle and caudal region of the brain, numerous commissural and CSFc neurons are situated below the region of large dorsal cells. In the spinal cord, several types of GABA-immunoreactive neurons of different size, appearance, and distribution were observed. In the dorsalmost region, very small commissural cells are scattered regularly along the cord. More ventrally in the cord, GABAergic neurons, both of commissural and CSFc cell types, form segmental groups, but scattered cells are observed throughout. These cells give rise to dense longitudinal fascicles of GABAergic fibers and to scattered commissural fibers. The caudal ampulla lacks GABAergic cells and fibers. Some of the fibers of the most rostral and caudal peripheral (sensory) nerves, as well as some sensory cells of the rostral and caudal epidermis, are GABA immunoreactive. The significance of these results for the understanding of the evolution of GABAergic systems of vertebrates is discussed.

A neurochemical map of the developing amphioxus nervous system

“…This is an advance over previous studies of amphioxus neurons, which were limited to elucidating only one neurotransmitter or neuropeptide at a time and which have demonstrated, for example, the occurrence in amphioxus of neurons containing cholecystokinin, oxytocin, vasopressin, luteinizing hormone and FMRFamide [31,32]. More recently, serotonergic, dopaminergic and cholinergic neurons have also been reported in B. floridae embryos and larvae [21-24], and the distribution of dopamine, serotonin and GABA has been described in amphioxus adults [33,34]. Moreover, by using HPLC, glutamate, aspartate, glycine, alanine, serine and GABA have been identified in the nervous system of the amphioxus B. lanceolatum [35].…”

Organization of the torus longitudinalis in the rainbow trout (Oncorhynchus mykiss): An immunohistochemical study of the GABAergic system and a DiI tract‐tracing study

“…After developing, sections were rinsed in TBS, dehydrated, and coverslipped. This polyclonal rabbit anti-GABA antibody was previously used for demonstrating the GABAergic systems in a number of species, including amphioxus, lampreys, dogfish, and trout (Yáñ ez et al, 1997;Anadón et al, 1998;Meléndez-Ferro et al, 2002;Sueiro et al, 2004).…”

Early Evolution of Ionotropic GABA Receptors and Selective Regimes Acting on the Mammalian-Specific Theta and Epsilon Subunits

“…GABA is also present in the nervous system of non-vertebrate taxa, for example, flatworms [7], arthropods [8], [9] and early chordates [10]. GABA synaptic transmission is achieved through membrane bound postsynaptic receptors.…”