Immunocytochemical localization of the renal neutral and basic amino acid transporter in rat adrenal gland, brainstem, and spinal cord

Abstract

A neutral and basic amino acid transporter (NBAT) cloned from rat kidney was recently localized to enteroendocrine cells and enteric neurons. We used an antibody directed against a synthetic peptide representing a putative extracellular domain of NBAT to determine whether this transporter was also present in other endocrine and neural tissues, including rat adrenal gland, brainstem, and spinal cord. Abundant, highly granular labeling for NBAT was observed in the cytoplasm of chromaffin and ganglion cells in the adrenal medulla. A small population of intensely labeled varicose processes was also seen in both the cortex and the medulla of the adrenal gland. More numerous, intensely labeled varicose processes were detected in brainstem and spinal cord nuclei, including the locus coeruleus, rostral ventrolateral medulla, nuclei of the solitary tract, dorsal motor nucleus of the vagus, and intermediolateral cell column of the thoracic spinal cord. Significant perikaryal labeling for NBAT was only detected in brainstem and spinal cord following intraventricular colchicine treatment, which increased the number, distribution, and intensity of NBAT-immunolabeled cells. These NBAT-immunoreactive perikarya were most numerous in the locus coeruleus, rostral ventrolateral medulla, nuclei of the solitary tract, and raphe nuclei. Ultrastructural examination of the nuclei of the solitary tract of normal rats showed that NBAT was localized predominantly to axon terminals. Within these labeled terminals, NBAT was associated with large dense core vesicles and discrete segments of plasma membrane. The observed localization of NBAT suggests that this renal specific amino acid transporter subserves a role as a vesicular or plasmalemmal transporter in monoamine-containing cells, including chromaffin cells and autonomic neurons.

Identification of Differentially Expressed Genes in Rat Hippocampus After Transient Global Cerebral Ischemia Using Subtractive cDNA Cloning Based on Polymerase Chain Reaction

“…It was suggested that NBAT subserved a role as a vesicular or plasmalemmal transporter in monoamine-containing cells, including chromaffin cells and autonomic neurons. 47 Taken together, on the basis of the knowledge of their own functions, these isolated genes were suggested to be involved in the molecular process of phenomena such as neural degenerative, neuroprotective, or reconstructive phenomena, which occur after global ischemia in the rat hippocampus. Further analyses on timely and spatial expression of the molecules and further clarification of their roles in molecular mechanisms underlying ischemic phenomena should be accomplished.…”

Oligomeric structure of a renal cystine transporter: implications in cystinuria

“…As in rat kidney, the relative amounts of the disulfide-linked species in different batches of the rabbit kidney BBMs also varied, and when NEM is included in buffers during BBM isolation, the 150 kDa species (presumably analogous to the 135 kDa to those found in these two organs. Such sites include certain enteroendocrine cells and enteric neurons [6], chromaffin cells of the adrenal medulla, and some of the catecholamine-containing neurons of brainstem and spinal chord [19]. Further studies are also required to determine whether the proteins found in association with NBAT can also occur on their own and/or in association with other proteins and, thus, possibly participate in additional transport and other functions.…”

Identification and Functional Characterization of a Novel Low Affinity Aromatic-preferring Amino Acid Transporter (arpAT)

“…In vivo, the LSHATs seem to heterodimerize only with one of the heavy subunits, although they can be less selective when overexpressed in heterologous systems (51), which may apply to arpAT in HeLa cells. arpAT mRNA localization in the small intestine and brain is compatible with both rBAT and 4F2hc binding, as both heavy chains have been localized to these tissues (26,50,(52)(53)(54). Another possibility is that arpAT may heterodimerize with both rBAT and 4F2hc in vivo, depending on its localization.…”