Ultrastructural Localization of δ-Opioid Receptors in the Rat Caudate-Putamen Nucleus during Postnatal Development: Relation to Synaptogenesis

Hong Wang, Verginia C. Cuzon, Virginia M. Pickel

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


During development, δ-opioid receptors (DORs) in the rat caudate-putamen nucleus (CPN) appear later than μ-opioid receptors (MORs), whose developmental pattern specifically relates to synaptogenesis. We used electron microscopic immunocytochemistry to determine whether there are also age-related changes in subcellular localization of DORs in the rat CPN. Sections from postnatal day (P) 0-P30 and adult dorsomedial CPN were immunogold-silver labeled to examine the plasmalemmal and cytoplasmic distribution of these receptors. In addition, immunoperoxidase labeling was used to determine the numerical density of synapses relative to DOR-labeled profiles. Immunolabeling for DOR was undetectable at PO, light at P5, and dense from P10 onward. The labeling during P5-P10 was mainly localized in somatodendritic profiles but also was readily seen in axon terminals, most of which formed asymmetric synapses with dendrites. From P15, a few immunogold particles were seen in contact with postsynaptic densities in spines, and the proportion of these particles significantly increased in P30 and adult CPN. Other particles were localized in the cytoplasm of dendrites and terminals without significant age-related changes. Stereological analysis showed that compared with labeled dendritic shafts and spines, labeled axon terminals have a closer correlation with synapse formation. These results are in marked contrast with MORs, which show an age-related increase in association with dendritic plasma membrane and a good correlation in the developmental pattern of MOR-labeled spines with synapse formation (Wang et al. [2003] Neuroscience 118:695-708). Together, our results suggest receptor-type specific roles for endogenous opioids acting at both pre- and postsynaptic sides in the developing CPN.

Original languageEnglish (US)
Pages (from-to)343-353
Number of pages11
JournalJournal of Comparative Neurology
Issue number3
StatePublished - Dec 15 2003
Externally publishedYes


  • Development
  • Electron microscopic immunocytochemistry
  • Postsynaptic density
  • Striatum
  • Synaptogenesis
  • Ultrastructure

ASJC Scopus subject areas

  • Neuroscience(all)


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