FIGURE 1.

Properties of presynaptic N-methyl-D-aspartate receptors (preNMDARs) in the superficial dorsal horn (SDH). 1. GluN2A and GluN2B-containing preNMDARs in primary afferents have been implicated in pain models. Low Mg²⁺ sensitivity suggests a potential role of GluN2D or GluN3-containing preNMDARs. 2. PreNMDARs may contribute to signaling in the SDH by either direct cation influx, or 3. By metabotropic signaling. 4. To date, preNMDARs have been found to contribute to both neuropathic pain and opioid-induced hyperalgesia, but not to non-pathological nociception. Figure was created using BioRender.com.