Localization, transport, and uptake of D-aspartate in the rat adrenal and pituitary glands

• Published in: Archives of biochemistry and biophysics Vol. 385; no. 2; pp. 242 - 249
• Main Authors: Lee, J A, Long, Z, Nimura, N, Iwatsubo, T, Imai, K, Homma, H
• Format: Journal Article
• Language: English
• Published: United States 15.01.2001
• Subjects: Adrenal Glands - cytology; Adrenal Glands - metabolism; Animals; Aspartic Acid - administration & dosage; Aspartic Acid - metabolism; Biological Transport; Endothelium - cytology; Endothelium - metabolism; Gene Expression Regulation, Developmental; Immunohistochemistry; Injections, Intraperitoneal; Injections, Intravenous; Male; Monosaccharide Transport Proteins - genetics; Monosaccharide Transport Proteins - metabolism; Pituitary Gland, Anterior - cytology; Pituitary Gland, Anterior - metabolism; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism
• ISSN: 0003-9861
• DOI: 10.1006/abbi.2000.2163

Large amounts of D-aspartate (D-Asp) are present in the rat adrenal and pituitary glands. D-Asp is thought to be synthesized in the mammalian body and also accumulates in various tissues following intraperitoneal or intravenous administration. This report examines the origins of D-Asp in the adrenal and pituitary glands. We administered D-Asp to male rats intraperitoneally and immunolocalized this exogenous D-Asp in adrenal and pituitary tissue, using an anti-D-Asp antiserum which was previously developed in our laboratory. D-Asp levels in the rat adrenal gland have been shown to undergo a transient increase at 3 weeks of age and to decrease rapidly thereafter. We found that in the adrenal gland, exogenous D-Asp administered intraperitoneally was incorporated into the same region of the adrenal cortex in which endogenous D-Asp was present. By Northern and Western blot analysis and immunohistochemistry of glutamate (Glu) transporter, we also found that expression of the Glu transporter (GLAST), which has an affinity for D-Asp, transiently increased at 3 weeks of age and that localization patterns of the Glu transporter within the tissue were almost coincident with those of endogenous D-Asp. These observations suggest that D-Asp in the adrenal cortex of 3-week-old male rats is primarily acquired by uptake from the vascular system. We have previously shown that D-Asp is specifically localized in prolactin (PRL)-containing cells in the anterior lobe of the adult rat pituitary gland. Here we report that in the pituitary gland, exogenous D-Asp accumulated in endothelial cells, but not in PRL-containing cells. Northern and Western blot analysis and immunohistochemistry of Glu transporter revealed that developmental changes in the Glu transporter (GLAST) expression did not correlate with tissue levels of D-Asp and that the Glu transporter was not expressed in PRL-containing cells. These observations suggest that, in contrast to the adrenal gland, most of the D-Asp in the pituitary gland of adult male rats originates inside the gland itself.