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Updated: Apr 3, 2026

Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
Published on: July 29, 2014
Design, synthesis, and evaluation of new endomorphin analogs with enhanced central antinociception after peripheral
Xin Liu1, Long Zhao1, Yuan Wang1
1Department of pharmacology, Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, School of Life Science, Lanzhou University, Lanzhou 730000, PR China.
Abstract:
We synthesized two novel endomorphin-1 (EM-1) analogs by substituting the C-terminus residue with (thienyl)-α-methylene-β-amino acids (Map). Several in vitro and in vivo assays were used to determine the activity of the analogs. The two EM-1 analogs showed subnanomolar binding affinity and functional activity at the μ-opioid receptor in HEK293 cells. Tail-flick and formalin tests further revealed that the EM-1 analogs were very effective after intravenous administration. Our results indicate that compared to endomorphin-1, the (thienyl)Map modified peptides showed improved blood-brain barrier permeability.
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