Open AccessRecent Advances in the Search for the N-Opioidergic System: Morphological Studies of the Endomorphinergic Neurons in the Central Nervous System
Author(s) -
Qingping Wang,
James E. Zadina,
JianLian Guan,
Seiji Shioda
Publication year - 2002
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.89.209
Subject(s) - opioidergic , brainstem , central nervous system , neuroscience , spinal cord , endogeny , opioid peptide , biology , endogenous opioid , receptor , chemistry , biophysics , opioid , biochemistry , (+) naloxone
Endomorphins (EMs) are newly found endogenous opioid peptides. Both endomorphin-1 (EM-1) and -2 (EM-2) are composed of four amino acids. Their high affinity and specificity for mu-opioid receptors have been confirmed by many physiological and pharmacological studies. In the present minireview, we discuss the distribution and localization of these peptides. While EM-2 is more prevalent in the spinal cord and lower brainstem, EM-1 is more widely and densely distributed throughout the brain than EM-2. We also discuss the possible coexistence of EM with other neurotransmitters. Finally, we introduce some new results regarding the ultrastructure and synaptic relationships of EM-2 obtained by the immunoelectron microscopic method.