The effects of N-methyl- d-aspartate (NMDA) and non-NMDA receptor agonist and antagonists on hypothalamic neurones in the anaesthetized rat which respond to changes in scrotal skin temperature

Abstract

There are neurons in the pre-optic anterior hypothalamus of the anaesthetised rat which respond to changes in scrotal skin temperature. Neuronal firing rate can be increased by raising the scrotal skin temperature above 36°C, and also by ionophoretic application of either N-methyl- d-aspartate (NMDA) or α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) (a non-NMDA receptor agonist). The increase in neuronal firing evoked by thermal stimulation was prevented or diminished by concurrent application of either d-2-amino-5-phosphonopentanoic acid (D-AP5) (an NMDA receptor antagonist) or 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo( F)quinoxaline (a non-NMDA receptor antagonist) at doses which were sufficient to abolish or significantly diminish the effect of the specific agonist. It is probable that both NMDA and non-NMDA receptors are involved in the scrotal thermoafferent pathway in the rat.