Differentiation Between Rat Brain and Mouse Vas Deferens Delta Opioid Receptors
Format of Original
European Journal of Pharmacology
Original Item ID
Certain enkephalin analogues, including those which contain the conformationally restricted amino acid E-(2R,3S)-cyclopropylphenylalanine ((2R,3S)-▿EPhe), have been shown to have high affinity for brain δ opioid receptors but are much less active in mouse vas deferens bioassays. To investigate whether there are differences between δ opioid receptors in brain and mouse was deferens, the ability of a selective δ opioid compound. [D-Pen2,pCl-Phe4,D-Pen5]enkephalin (pCl-DPDPE), and [D-Ala2,(2R,3S)-▿EPhe4,Leu5]enkephalin methyl ester (CP-OMe), to inhibit [3H]pCl-DPDPE binding in both rat brain and mouse vas deferens were measured. pCl-DPDPE recognized brain and mouse vas deferences binding sites with equal affinity, however, CP-OMe showed 33 fold lower affinity in mouse vas deferens compared to brain. This suggests that mouse vas deferens δ opioid receptors may be distinct from brain δ opioid receptors.