Which pairing of endogenous opioid peptide family with its receptor of highest affinity is correct?

• A Enkephalins with kappa receptors
• B Dynorphins with delta receptors
• C Beta-endorphin with sigma receptors
• D Dynorphins with kappa receptors ✓

Explanation

The three classical endogenous opioid peptide families map onto receptors as follows: dynorphins show the highest affinity for kappa receptors, met- and leu-enkephalins preferentially bind delta receptors, and beta-endorphin binds mu receptors strongly. Sigma sites were once classed as opioid receptors but are now excluded from that family, which invalidates option C. This mapping is standard exam material and appears consistently across pharmacology texts.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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