查看文章

Memantine is reported to improve symptoms in moderate cases of Alzheimer's disease and Parkinson's disease, but is also known to trigger psychosis in some Parkinson patients. Because these clinical features suggested a possible dopamine component of memantine action, we measured the potency of memantine on the functional high‐affinity state of dopamine D2 receptors, or D2^High. Using [³H]domperidone to label D2 receptors, the memantine dissociation constant at D2^High was 917 ± 23 nM for rat striatal D2 receptors and 137 ± 19 nM for human cloned D2Long receptors. The memantine dissociation constant for striatal N‐methyl‐D‐aspartate (NMDA) receptors labeled by [³H]MK 801 was 2200 ± 400 nM. Memantine stimulated the incorporation of [³⁵S]GTP‐γ‐S into D2‐expressing Chinese Hamster Ovary cells with a dissociation constant of 1200 ± 400 nM. Memantine, between 200 and 2000 nM …