FUNCTIONAL ALPHA(3)-GLYCINE RECEPTORS IN RAT ADRENAL

The adrenal medulla contains high-affinity strychnine binding sites, p resumed to be receptors for glycine. In this study, glycine injection (400 pmol) via a cannula attached to a microdialysis probe increased i n vivo concentrations of catecholamines in the adrenal microdialysate in anesthetized rats. Strychnine perfusion (20 pmol/20 min) blocked th ese responses. To identify receptors potentially mediating this effect , we tested for RNA transcripts of the three known alpha subunits of s trychnine binding site, using the reverse transcription-polymerase cha in reaction. Only mRNA encoding the alpha(3) isoform was found in the rat adrenal. The findings suggest that in the rat adrenal, glycine sti mulates catecholamine release by binding to strychnine binding sites a nd that those sites probably contain the alpha(3) isoform.