D-AP5

Widely used, selective and competitive NMDA receptor antagonist which binds at the glutamate site. It is the more active form of DL-AP5.

D-AP5 blocks induction of LTP (long term potentiation) in a reversible manner and is frequently used to inhibit NMDAR-mediated synaptic plasticity. Also impairs spatial learning.

#Figure 1: D-AP5 inhibition of evoked NMDAR mediated EPSCs in mouse cortical neuron

D-AP5 is commonly used to inhibit NMDA mediated synaptic plasticity. It is often used at concentrations of 50 μM. D-AP5 from Hello Bio completely abolishes evoked NMDAR mediated currents at 50 μM and reduces NMDA currents at lower concentrations of 1 and 10 μM (see Fig 1 above).

#Protocol 1: Evoked NMDA receptor currents

• Whole cell voltage clamp recordings were obtained from layer V neurons of the mouse prelimbic cortex brain slice.
• NMDA currents were evoked via a stimulating electrode placed in layers II/III and evoked by a single square (150 μs) pulse every 10 sec at a stimulus intensity that gave a reliable NMDA current.
• Neurons were held a +40 mV to relieve NMDA currents from their voltage-dependent Mg²⁺ block.
• NMDA currents were continually stimulated and recorded in response to continual bath applications of D-AP5 until NMDA currents were completely abolished.
• All NMDAR recordings were made in the presence of GABA_A-R and AMPAR antagonists.

#Figure 2: D-AP5 inhibition of NMDAR mediated dendritic plateau potentials in rat CA1 pyramidal neurones.

D-AP5 is commonly used to inhibit NMDA mediated synaptic events such as dendritic plateau potentials. Figure 2 shows that D-AP5 from Hello Bio completely abolishes plateau potential formation at 50µM (see Fig 2 above).

#Protocol 2: Inhibition of NMDAR mediated dendritic plateau potentials in rat CA1 Pyramidal neurones

• Pyramidal neurones from adult Wistar rats were patched in CA1 using a KMeSO4 internal solution with addition of 1mM QX-314 (HB1030) to prevent action potentials.
• Cells were first held in V_clamp at -70mV for 10 minutes to wash out LTP before being transferred to I_clamp (again at -70mV) where they were stimulated sequentially every 15 seconds in the Schaffer collateral pathway.
• Stimulation consisted of one single stimulation followed 400ms later by 5 stimulations at 100Hz.
• Experiments took place in the presence of the GABA_B antagonist GCP55845 (1µM, HB0960) and 50µM PTX.
• Stimulation intensity was initially adjusted to evoke responses of approximately 1mV before stimulation was successively increased until robust plateau potentials were observed in all pathways.
• Stimulation was then turned off and 50µM DAPV was washed on to the slice for 10 minutes before another stimulation response was conducted in the same cell.
• Throughout the experiment input current was adjusted to maintain the cell at -70mV ± 0.5mV.