MOLECULAR-PROPERTIES OF THE GLUTAMATE-RECEPTOR MEDIATING SYNAPTIC EXCITATION IN RAT HYPOTHALAMIC NEURONS

AMPA-type glutamate receptors (GluRs) mediate synaptic excitation in n etworks of cultured rat hypothalamic neurons [18, 25]. Under voltage c lamp the agonists quisqualate and AMPA induce current responses which consist of a maintained and/or transient component depending on the co ncentrations applied. The current-voltage relationship for both compon ents is linear. The biphasic response patterns are due to receptor des ensitization which is fast and does not require intracellular second m essengers for its activation. Several GluR-subtype-encoding transcript s were found in these neurons using polymerase chain reaction (PCR) me thods. While mRNAs encoding the GluR2 and 3 flip forms are expressed e arly, mRNAs encoding the GluR1, 2 and 3 flop forms and the GluR4 flip form appear only in cultures older than 3 weeks. By comparison to reco mbinant receptors, the properties of the native receptor can be accomo dated by a heteromeric receptor containing GluR2 as one of the subunit s.