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Ultrastructural localization of delta‐1 opioid receptor in the dorsal raphe nucleus of the rat
Author(s) -
Wang QingPing,
Ochiai Hidehiko,
Guan JianLian,
Nakai Yasumitsu
Publication year - 1997
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/(sici)1098-2396(199707)26:3<243::aid-syn6>3.0.co;2-7
Subject(s) - postsynaptic potential , axon , chemistry , dorsal raphe nucleus , dendrite (mathematics) , immunocytochemistry , biophysics , nucleus , synapse , ultrastructure , synaptic vesicle , vesicle , raphe nuclei , anatomy , membrane , receptor , microbiology and biotechnology , neuroscience , biology , endocrinology , serotonergic , biochemistry , serotonin , geometry , mathematics
The ultrastructural localization of delta‐1 opioid receptor in the rat dorsal raphe nucleus was studied by the preembedding avidin‐biotin‐peroxidase complex technique. With application of a low concentration of the first antiserum in incubation and control of short‐time reaction to 3,3′‐diaminobenzidine, the immunoreaction seemed to be faint at the light microscopic level. At the electron microscopic level, however, delta‐1 opioid receptor immunoreaction products were found to be localized specifically on the postsynaptic membrane of dendrites, dense‐cored vesicles, and the surface of the small, clear vesicles in axon terminals with strong immunoreactivity. Of the total 659 immunopositive profiles observed, up to 62.4% (411/659) were dendrites, whereas 33.8% (223/659) were axon terminals. The immunostained myelinated axons and perikarya were relatively rare, with the frequencies 0.8% (5/659) and 3.0% (20/659), respectively. Most of the immunopositive dendrites (338/411, 82.2%) were immunostained only at the postsynaptic membranes. Other immunoreactive dendrites showed their immunoreaction products also in some other contents besides the postsynaptic membranes (44/411, 10.7%) or only in those contents but not the postsynaptic membranes (25/411, 6.1%). Only four dendrites showed their immunoreactive results only at the membrane not related to synapse (4/267, 1.0%). No dendrite was found immunostained in all the contents. About half of the immunopositive axon terminals (125/223, 56.1%) were found to make synapse with nonimmunoreactive dendrites (76/223, 34.1%) or immunoreactive dendrites (49/223, 22.0%), while only one was found to make contact with immunoreactive perikarya. The present study showed that delta‐1 opioid receptor in the dorsal raphe nucleus is mostly localized on postsynaptic membrane; the main function of the delta‐1 receptor in the dorsal raphe nucleus is to receive signals from the opioid‐containing axon terminals through synapses. Synapse 26:243–253, 1997. © 1997 Wiley‐Liss Inc.