title: The effect of chronic thienorphine administration on long-term potentiation and synaptic structure in rat hippocampus.
abstract: Thienorphine is a new nonselective partial agonist of opioid receptors, which is currently under a Phase II clinical trial in China as a new treatment for opioid dependence. In this study, we compared the effect of thienorphine with morphine on long-term potentiation (LTP) in the lateral perforant path (LPP)-granule cell synapse of the rat dentate gyrus (DG). Furthermore, the effect of thienorphine on the synaptic structure of the CA1 hippocampal region and the expression of synaptophysin was investigated. Results indicated interesting differences between thienorphine and morphine on the modulation of hippocampal synaptic plasticity. Chronic thienorphine treatment facilitated LTP in the LPP-DG cell synapses more than chronic morphine treatment. Morphometric measurement and analysis showed that chronic thienorphine administration decreased the length of the active zone and reduced the thickness of CA1 postsynaptic densities compared with the saline group (control), but were elevated compared with the morphine group. Furthermore, the expression of hippocampal synaptophysin was increased with chronic thienorphine administration but reduced with chronic morphine treatment. Taken together, our study clearly demonstrates that chronic thienorphine treatment enhances LTP, modulates hippocampal synaptic structure, and increases the expression of hippocampal synaptophysin. Therefore, further study is warranted to investigate thienorphine as a new treatment for opioid dependence.
authors.affiliation: Beijing Institute of Pharmacology and Toxicology, Beijing, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Yong
authors.forename: Lingdi
authors.initials: L
authors.lastname: Yan
authors.forename: Zhaoqi
authors.initials: Z
authors.lastname: Dong
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.forename: Ruibin
authors.initials: R
authors.lastname: Su
authors.forename: Zehui
authors.initials: Z
authors.lastname: Gong
mesh_terms: D000818:Animals; D002047:Buprenorphine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D056547:CA1 Region, Hippocampal / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018891:Dentate Gyrus / Q000187:drug effects* / Q000502:physiology; D017774:Long-Term Potentiation / Q000187:drug effects*; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D057907:Post-Synaptic Density / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D016708:Synaptophysin / Q000235:genetics / Q000378:metabolism
chemical_list: D009292:Narcotic Antagonists; D016708:Synaptophysin; C512397:thienorphine; D002047:Buprenorphine; D009020:Morphine
keywords: LTP; hippocampus; synaptic structure; synaptophysin; thienorphine