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Ultrastructural localization of mu‐1 opioid receptor in the dorsal raphe nucleus of the rat
Author(s) -
Wang QingPing,
Ochiai Hidehiko,
Guan JianLian,
Nakai Yasumitsu
Publication year - 1998
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(199807)29:3<240::aid-syn6>3.0.co;2-6
Subject(s) - postsynaptic potential , axon , dorsal raphe nucleus , chemistry , raphe nuclei , immunocytochemistry , biophysics , nucleus , dendritic spine , anatomy , receptor , biology , neuroscience , endocrinology , serotonergic , serotonin , biochemistry , hippocampal formation
A simple pre‐embedding avidin‐biotin‐peroxidase complex technique was used to study the ultrastructural localization of mu‐1 opioid receptor in the rat dorsal raphe nucleus. Using low concentrations of the first antiserum for incubation with a short reaction time to 3,3′‐diaminobenzidine, the immunostaining was faint at the light microscopic level. However, at the electron microscopic level strong immunoreaction was observed. Mu‐1 opioid receptors were found to be localized on the postsynaptic membrane of dendrites, extra‐synaptic plasma membrane, and the surface of the small, clear vesicles in axon terminals. Of the total 407 immunopositive profiles observed, 76.4% (311/407) were dendrites and 18.9% (77/407) were axon terminals. The immunostained myelinated axons and perikarya were relatively rare, with frequencies of 1.0% (4/407) and 3.7% (15/407), respectively. About 50.8% of the immunopositive dendrites (158/311) were immunostained having their MOR‐LI results beneath the postsynaptic membrane, although about 19.6% of them (31/158) also exhibited MOR‐LI on other components, including the extrasynaptic plasma membrane. Other immunopositive dendrites showed staining in some other contents, including extrasynaptic plasma membrane (82/311, 26.4%) or not on the plasma membranes (71/311, 22.8%). Less than half of the immunopositive axon terminals (35/77, 45.5%) were found to make synapses with nonimmunoreactive dendrites (31/77, 40.3%) or immunopositive dendrites (4/77, 5.2%); none were found to make synapses with immunoreactive perikarya. The present study shows that mu‐1 opioid receptor in the dorsal raphe nucleus plays a role at both synapse or not. Synapse 29:240–247, 1998. © 1998 Wiley‐Liss, Inc.