Sigma-1 Receptor - Characteristics

Characteristics

The sigma-1 receptor is defined by its unique pharmacological profile. In 1976 Martin reported that the effects of N-allylnormetazocine (SKF-10,047) could not be due to activity at the μ and κ receptors (named from the first letter of their selective ligands morphine and ketazocine, respectively) and a new type of opioid receptor was proposed; σ (from the first letter of SKF-10,047). However, ligands acting at this new “opioid” receptor were not blocked by the classical opioid antagonists naloxone and naltrexone. Consequently, the opioid classification was eventually dropped and the receptor was later termed the sigma-1 receptor. It was found to have affinity for the (+)-stereoisomers of several benzomorphans (e.g., (+)-pentazocine and (+)-cyclazocine), various structurally and pharmacologically distinct psychoactive chemicals such as haloperidol and cocaine, and neuroactive steroids like progesterone.