Co-localization of AMPA-type glutamate receptor immunoreactivity in neurons of the rat subthalamic nucleus

In order to determine the precise cellular localization of the α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA)-type glutamate receptor subunit immunoreactivity in the rat subthalamic nucleus, single and double immunofluorescence was performed. Intense level of GluR1, GluR2, GluR2/3 and GluR4 immunoreactivity was found in almost all neurons of the subthalamic nucleus. By double immunofluorescence, the subthalamic neurons in the same sections that displayed a strong immunoreactivity for GluR1 were found to display a robust GluR2 immunoreactivity and the subthalamic neurons that displayed GluR2 immunoreactivity were also found to express GluR4 immunoreactivity. The present results thus demonstrate that individual neurons of the subthalamic nucleus are likely to co-express GluR1 and GluR2, and GluR2 and GluR4 immunoreactivity. The native AMPA channels in the subthalamic neurons may, therefore, be composed of heteromeric subunits. The present results provide information of the neuroanatomical localization of AMPA receptor subunits in neurons of the subthalamic nucleus. The localization of AMPA receptor subunits may be related to functional characteristics of AMPA channels in the subthalamic neurons.