lack of σ1 receptor. Clinical significance Mutations in sigma-1 receptor have been associated with distal spinal muscular atrophy type 2. Ligands The following ligands have high affinity for the σ1 receptor and possess high binding selectivity over the subtype σ2: Agonists: PRE-084 ANAVEX2-73 Donepezil Selegiline D-Deprenyl Fluvoxamine Fluoxetine Citalopram Amitriptyline L-687,384 SA-4503 Dipentylamine Dextromethorphan Dimethyltryptamine (+)-pentazocine (the "unnatural" enantiomer, which lacks affinity for the μ-opioid and κ-opioid receptors.) Opipramol Antagonists: Sertraline S1RA FTC-146 1-benzyl-6′-methoxy-6′,7′-dihydrospiro[piperidine-4,4′-thieno[3.2-c]pyran]: putative antagonist, selective against 5-HT1A, 5-HT6, 5-HT7, α1A and α2 adrenergic, and NMDA receptors NE-100 Positive allosteric modulators (PAMs): Methylphenylpiracetam SOMCL-668 Uncategorized: 4-IPBS PD 144418 spipethiane RHL-033 3-[[1-[(4-chlorophenyl)methyl]-4-piperidyl]methyl]-1,3-benzoxazol-2-one: very high affinity and subtype selectivity 1'-[(4-fluorophenyl)methyl]spiro[1H-isobenzofuran-3,4'-piperidine] 1'-benzyl-6-methoxy-1-phenyl-spiro[6H-furo[3,4-c]pyrazole-4,4'-piperidine] (−)-(S)-4-methyl-1-[2-(4-chlorophenoxy)-1-methylethyl]piperidine Agents exist that have high σ1 affinity but either lack subtype selectivity or have high affinity at other binding sites, thus being more or less dirty/multifunctional, like haloperidol. Furthermore, there is a wide range of agents with an at least moderate σ1 involvement in their binding profile. See also Sigma-2 receptor References External links