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Autoradiographic distribution of radioactivity from 14 C‐GABA in the mouse
Author(s) -
Kuroda Eriko,
Watanabe Masahito,
Tamayama Takumi,
Shimada Masahisa
Publication year - 2000
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/(sici)1097-0029(20000115)48:2<116::aid-jemt7>3.0.co;2-p
Subject(s) - gabaa receptor , baclofen , medicine , endocrinology , chemistry , receptor , kidney , gabab receptor , biology , agonist
We investigated the distribution of radioactivity from 14 C‐labeled γ‐aminobutyric acid (GABA) in the mouse by in vivo autoradiography to clarify the tissues that show GABA uptake and/or GABA binding. Male mice were injected intravenously with 14 C‐GABA in both the absence and presence of an excess of unlabeled GABA, baclofen and isoguvacine. Whole‐body autoradiography of 3 H‐baclofen, a GABA B receptor agonist was also performed. At short intervals after 14 C‐GABA injection ( 3 and 6 minutes), very high radioactivity was detected in the kidney cortex, liver, pineal gland, hypophysis, median eminence of the hypothalamus, and cervical ganglion. The hyaline cartilage and glandular part of the stomach showed moderate radioactivity. In the presence of an excess amount of unlabeled GABA, radioactivity in most of tissues decreased significantly, but no significant difference in radioactivity was observed in the presence of baclofen and isoguvacine, agonists of GABA A and GABA B receptors, respectively. Autoradiography of 3 H‐baclofen showed that the kidney had high level of radioactivity, whereas the activity in other tissues and organs was similar or lower than in the blood except for the content of the urinary bladder and the pancreas at 15 minutes after injection. These data indicate that radioactivity from incorporated 14 C‐GABA into a variety of cells is much higher than that from bound 14 C‐GABA to the receptor sites. Our results suggest that GABA can be quickly localized in many organs of the mouse body after 3 minutes following injection, and GABA may serve multiple functions in those organs. Microsc. Res. Tech. 41:116–126, 2000. © 2000 Wiley‐Liss, Inc.