Distribution of glycine immunoreactivity in the brain of the Siberian sturgeon (Acipenser baeri): Comparison with γ-aminobutyric acid

Abstract

Glycine and γ-aminobutyric acid (GABA) are the main inhibitory neurotransmitters in the central nervous system (CNS) of vertebrates. Studies on the distribution of glycinergic neurons and fibers have been carried out mainly in rodents and lampreys. With the aim of discovering more about the early evolution of this system in vertebrates, we analyzed the distribution of glycine-immunoreactive (Gly-ir) neurons and fibers in the CNS of a basal ray-finned fish, the Siberian sturgeon (Chondrostei, Acipenseriformes), by use of immunohistochemical techniques. We also compared the distribution of glycine and GABA by the use of double-immunofluorescence techniques and confocal microscopy. Our results revealed the presence of Gly-ir cells in different regions of the CNS, such as olfactory bulbs, preoptic area, hypothalamus, thalamus, pretectum, optic tectum, tegmentum and rostral spinal cord, although most of the Gly-ir cells and the most intensely immunoreactive cells were located in the rhombencephalon, mainly in the octavolateral area and reticular formation. In addition, coronet cells of the basal hypothalamus and saccus vasculosus were Gly-ir. Glycinergic fibers coursed along most brain regions and were more abundant in the thalamus, hypothalamus, optic tectum, tegmentum, isthmic region, and basal rhombencephalon. The Mauthner cell perikaryon was richly innervated by Gly-ir boutons, as reported for teleosts. With regard to the colocalization of glycine and GABA, double-immunoreactive cells were located mainly in the rhombencephalon. The results enable us to conclude that the distribution of glycine in the sturgeon brain is more similar to that observed in lampreys than that observed in mammals.

The brain of the tree pangolin (Manis tricuspis). IV. The hippocampal formation

“…The pattern of neuronal staining was similar to that seen in other mammals (e.g. Adrio et al, ; Bhagwandin et al, ; Gritti et al, ).…”

Organization of the sleep‐related neural systems in the brain of the harbour porpoise (Phocoena phocoena)

“…To reveal neurons containing the calcium‐binding protein CR, we used the 7699/3H anti‐CR rabbit polyclonal antibody from Swant (7699/3H; RRID AB_10000321) at a dilution of 1:10,000. The pattern of staining within the neurons of the basal forebrain, diencephalon, and pons of the harbor porpoise was similar to that seen in other mammals (Gritti et al, ; Adrio et al, ; Bhagwandin et al, ).…”

Glycine‐immunoreactive neurons in the brain of a shark (Scyliorhinus canicula L.)

“…The polyclonal rabbit antiglycine antibody (Immunosolution; code IG1003) was raised against a glycine–porcine thyroglobin conjugate and tested by the supplier in sections of retina and cerebellum from various mammals and other vertebrates as well as in dot blot immunoassays with a variety of amino acid conjugates: the standard 20 amino acids found in proteins; the nonprotein amino acids D‐serine, D‐alanine, and D‐aspartate; GABA; and the glycine‐containing tripeptide glutathione, which did not yield significant reactivity. This antibody, developed by Dr. David V. Pow (University of Newcastle, Newcastle, New South Wales, Australia), has been used in a number of studies on glycinergic neurons of the brain and spinal cord, including fishes (Villar‐Cerviño et al, , ; Adrio et al, ; Barreiro‐Iglesias et al, ). The monoclonal mouse anti‐GABA antibody (Sigma) was raised against GABA conjugated to BSA with glutaraldehyde and was evaluated by the supplier for activity and specificity by dot‐blot immunoassay.…”

“…The GABA immunostaining pattern observed in the cerebellum of S. canicula with this antiserum was the same as with a polyclonal antiserum raised against GABA (Alvarez‐Otero et al, 1995) and with an antiserum raised against glutamate decarboxylase, the GABA‐synthesizing enzyme (Anadón et al, ). This antiserum was used in studies of brains of sea lamprey and Siberian sturgeon (Villar‐Cerviño et al, , ; Adrio et al, ). The glycine and GABA antibodies have also been characterized in our laboratory by Western blotting with brain protein extracts from sea lamprey and Siberian sturgeon (Villar‐Cerviño et al, , ; Adrio et al, ).…”

“…This antiserum was used in studies of brains of sea lamprey and Siberian sturgeon (Villar‐Cerviño et al, , ; Adrio et al, ). The glycine and GABA antibodies have also been characterized in our laboratory by Western blotting with brain protein extracts from sea lamprey and Siberian sturgeon (Villar‐Cerviño et al, , ; Adrio et al, ). These blots showed that the antibodies did not recognize any native protein band.…”