The clinically available NMDA receptor antagonist, memantine, exhibits relative safety in the developing rat brain

The N-methyl-d-aspartate glutamate receptor (NMDAR) has been implicated in preterm brain injury (periventricular leukomalacia (PVL)) and represents a potential therapeutic target. However, the antagonist dizocilpine (MK-801) has been reported to increase constitutive neuronal apoptosis in the developing rat brain, limiting its clinical use in the developing brain. Memantine is another use-dependent NMDAR antagonist with shorter binding kinetics and has been demonstrated to be protective in a rat model of PVL, without effects on normal myelination or cortical growth. To further evaluate the safety of memantine in the developing brain, we demonstrate here that, in contrast to MK-801, memantine at neuroprotective doses does not increase neuronal constitutive apoptosis. In addition, there are no long-term alterations in the expression of NMDAR subunits, AMPAR subunits, and two markers of synaptogenesis, Synapsin-1 and PSD95. Evaluating clinically approved drugs in preclinical neonatal animal models of early brain development is an important prerequisite to considering them for clinical trial in preterm infants and early childhood.