LACK OF M(2) MUSCARINIC ACETYLCHOLINE-RECEPTOR MESSENGER-RNA IN RAT LYMPHOCYTES

The presence of muscarinic acetylcholine receptors on lymphocytes has been demonstrated by radioligand binding experiments. Although the specific subtype(s) of muscarinic acetylcholine receptors expressed in lymphocytes is still unknown, some reports suggest the presence of the m(2) subtype. In this study we analyzed the expression of m(2) subtype mRNA in rat mononuclear cells, B lymphocytes and T lymphocytes by Northern blot hybridization and reverse transcription-polymerase chain reaction. Positive signals for the presence of m(2) mRNA were found in rat heart, brainstem, cerebral cortex, corpus striatum and hippocampus, which were used as positive controls. On the other hand, no expression of m(2) was detected in lymphocytes. These results indicate that mRNA for the m(2) subtype is absent in rat lymphocytes and that one or more other subtypes may be responsible for the reported results in binding experiments.