="an ">&ensp;</span>P <span  title="" class="an ">&ensp;</span>X <span  title="" class="an ">&ensp;</span>receptors <span  title="" class="an ">&ensp;</span>Metabotropic <span  title="" class="an ">&ensp;</span>P <span  title="" class="an ">&ensp;</span>Y <span  title="" class="an ">&ensp;</span>receptors <span  title="" class="an ">&ensp;</span>some <span  title="" class="an ">&ensp;</span>of <span  title="" class="an ">&ensp;</span>which <span  title="" class="an ">&ensp;</span>bind <span  title="" class=