Morphological studies of the endomorphinergic neurons in the central nervous system.
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.
Department of Anatomy, Showa University School of Medicine, Tokyo, Japan.
Qing-Ping
QP
Wang
James E
JE
Zadina
Jian-Lian
JL
Guan
Seiji
S
Shioda
D000818:Animals; D002490:Central Nervous System / Q000737:chemistry / Q000166:cytology / Q000648:ultrastructure*; D006801:Humans; D009474:Neurons / Q000737:chemistry / Q000166:cytology / Q000648:ultrastructure*; D009842:Oligopeptides / Q000032:analysis*; D013569:Synapses / Q000737:chemistry / Q000648:ultrastructure
D009842:Oligopeptides; C105293:endomorphin 1; C105294:endomorphin 2