Chronic intake of caffeine during gestation down regulates metabotropic glutamate receptors in maternal and fetal rat heart.

Caffeine is the most widely consumed substance in the world which antagonizes adenosine effects. Adenosine acting through A(1) receptors inhibits glutamate release which binds to metabotropic glutamate receptors (mGluRs). Recently, we have shown that maternal caffeine intake during gestation causes down-regulation of A(1) and metabotropic glutamate receptors in the brain of both rat mothers and fetuses. In the present work we provide evidence that caffeine also affects receptors in hearts, causing a decrease in mGluRs from both maternal and fetal hearts. A decrease in G(q/11) and PLC beta(1) proteins level was also observed in both tissues. However, phospholipase C activity was only affected in fetal heart, being significantly decreased. These results suggest an in vivo cross-talk mechanism between adenosine and glutamate receptors in peripheral tissues. Therefore, special attention should be paid to caffeine ingestion during gestation.