aced126
Bluelighter
- Joined
- May 18, 2015
- Messages
- 1,047
Do antagonists/inverse agonists ever get close to increasing neural activity because the amount of auto receptors out number the regular receptors? It seems at some times a partial agonist can work as an antagonist because it's displacing a more efficacious ligand..
To your second point, I'd say that it'd depend on some factors including concentration of the partial agonist (which results in the specific receptor saturation). The endogenous ligand is by definition a full agonist, and so assuming that all the receptors are saturated with endogenous ligands, introducing a partial agonist in necessary concentrations to achieve complete displacement of all the endogenous ligands to the receptor (we're of course assuming the partial agonist has a much higher affinity for the receptor so that displacement takes place easily) would mean that the overall response is reduced, and in that case the partial agonist would actually kind of be an antagonist (assuming the antagonist doesn't achieve full receptor saturation; if so, then by definition there would be 0 response overall; if partial saturation is achieved then only partial response is suppressed). As belligerent mentioned, this can happen if the "endogenous ligand" is something one continually administers in high concentrations (full mu opioid agonists).
But in most situations, I think the endogenous ligand is in concentrations such that most of the receptors are not occupied, and so introducing a partial agonist will bind to the unoccupied receptors (and occupied ones if the affinity is high enough) will result in an overall increased response.