Distinct NMDA and AMPA receptor-mediated responses in mouse and human Cajal-Retzius cells

This study examined glutamate-activated current responses of mouse and huma n Cajal-Retzius (C-R) cells. Thin cortical slices were prepared from the br ains of mice 4-6 days after birth and from those of midgestational human fe tuses. Both human and mouse C-R cells displayed glutamate-induced whole-cel l current responses that were voltage-dependent and included an N-methyl-D- aspartate (NMDA) receptor-mediated component that was differentially sensit ive to blockade by the NMDA receptor antagonists 2-amino-5-phosphonovaleric acid and ifenprodil. alpha -Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), a non-NMDA glutamate receptor agonist, induced current respons es in human but not in mouse C-R cells. These results, taken together, lead us to conclude that human C-R cells express both NMDA and AMPA types of gl utamate receptors very early during development of the cortex. In contrast, mouse C-R cells express only the NMDA type of glutamate receptor. Thus we demonstrate a species-dependent sensitivity of C-R cells to glutamate and p ostulate that this differential sensitivity may account in part for a speci es-dependent difference in the persistence of C-R cells during cortical dev elopment.