KAINATE GLUTAMATE RECEPTORS (GLUR5-7) IN THE RAT ARCUATE NUCLEUS - RELATIONSHIP TO TANYCYTES, ASTROCYTES, NEURONS AND GONADAL-STEROID RECEPTORS

Glutamate action, through its ionotropic, kainate receptors, has been implicated in gonadal steroid-dependent mechanisms of the arcuate nucl eus. The objective of the present study was to determine the expressio n of kainate glutamate receptors in neural and glial elements of this area and their potential relationship to gonadal steroid receptors, Si ngle and double label, light and electron microscopic immunocytochemis try for kainate glutamate receptors and estrogen or androgen receptors revealed the existence of glutamate (GluR) 5-7 kainate receptors in t anycytes, astrocytes and neurons of the arcuate nucleus. In the arcuat e nucleus, subsets of GluR5-7-containing neurons were also immunoposit ive for estrogen (20%) and/or androgen receptors (23%). Glial elements , however, lacked labeling for gonadal steroid receptors, The coexiste nce of gonadal and kainate receptors in the same perikarya of arcuate nucleus cell populations suggests hormone regulation of excitatory neu rotransmission through ionotropic glutamate receptors in these regions . It is also indicated that a kainate receptor-mediated glutamate acti on may participate in neuro-glial interaction in the arcuate nucleus t hat, in turn, may underlie the morphological synaptic plasticity induc ed by gonadal steroids.