A new metabotropic glutamate receptor agonist: developmental change of its sensitivity to receptors in the newborn rat spinal cord.

A novel metabotropic glutamate receptor agonist, (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG-IV), reduced the monosynaptic excitation in newborn rat spinal cord rather than polysynaptic discharges at the nanomolar range without causing postsynaptic depolarization of motoneurones. Its inhibitory action on the monosynaptic excitation reduced in due course of time after birth. On the contrary, the inhibitory action of a metabotropic GABAB receptor agonist, baclofen, did not show marked developmental change. DCG-IV should be expected to have the potential to provide further useful information on the physiological function of metabotropic glutamate receptors.