Amphioxus GABA

    "amphioxus GABA"  
        PubMed = 5       
        Google = 119,000   

Distribution of GABA immunoreactivity in the central and peripheral nervous
system of amphioxus (Branchiostoma lanceolatum Pallas).    
Only abstract available online for free.  
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."  
    158 Related citations
See the Abstract.         

The nervous system of amphioxus: structure, development, and evolutionary significance
    - Canadian Journal of Zoology   (Goog)      
The nervous system of amphioxus: structure, development, and evolutionary significance 

Note: The purple link is to the original article which is no longer available to the general public for free. The green link is to the PDF which I was able to download at the local university library.   See:   Amphioxus PDFs

Searched for "GABA"
     "Little is known about the neurotransmitters released by peripheral neurons, but there is evidence that at least some type I cells are GABAergic (Anadón et al. 1998)".   
GABA, neuropeptide Y, and several other neuropeptides have been detected in various cells loosely classified as interneurons (Uemura et al. 1994; Anadón et al. 1998; Castroet al. 2003)"   
Second, a novel class of interneurons, Anadón’s cells, has been identified in the vicinity of the ventral expansion of the central canal (Anadón et al. 1998; see Fig. 5).   These are very small GABAergic cells interspersed between the cell bodies of SM and VM neurons (cf. Figs. 4, 5).   Anadón et al. (1998) have suggested that they might be comparable to the inhibitory Renshaw cells of vertebrates. "   
Whether by light microscopy (e.g., Edinger 1906; Franz 1923; Ekhart et al. 2003) or EM (Meves 1973), it is difficult to discern much about the neuronal and glial cells of the anterior
vesicle, since most cells are small and rather densely stained and have few visible distinguishing features. Franz (1923, 1927) therefore concluded that the entire anterior vesicle consisted only of glial cells. However, GABAergic (Anadón et al. 1998) and serotoninergic neurons (Moret et al. 2004) have since been identified in this region in adult specimens
Then, just ventral to the Joseph cells and surrounding the dorsal expansion of the
central canal, there are bilateral, longitudinal bands of neurons immunoreactive for urotensin and FMRFamide (Uemura et al. 1994), GABA (Anadón et al. 1998), neuropeptide Y (Castro et al. 2003), and catecholamines (the catecholaminergic population I of Moret et al. (2004)).
Serotonin-containing neurons are absent in this region (Moret et al. 2004), but a relatively large number of GABAergic and peptidergic cells (Uemura et al. 1994; Anadón et al. 1998; Castro et al. 2003) do occur. In addition, there are four relatively large catecholaminergic cells (population III of Moret et al. 2004) with translumenal processes in the vicinity of the roots of the fifth dorsal nerves."