Endogenous opioid peptides as neurotransmitters in the rat hippocampus
The role of endogenous opioid peptides as neurotransmitters in the rat hippocampus was investigated by using extracellular recording and radioligand binding techniques in the hippocampal slice preparation. Synaptic conductances from endogenously released opioid peptides have been difficult to detect. This problem was approach by designing a novel assay of opioid peptide release, in which release was detected by measuring binding competition between endogenous opioids and added radioligand. Membrane depolarization displaced ({sup 3}H)-diprenorphine binding in a transient, calcium-dependent, and peptidase-sensitive manner. Autoradiographic localization of the sites of ({sup 3}H)-diprenorphine binding displacement showed that significant opioid peptide release and receptor occupancy occurred in each major subregion of the hippocampal slices. This assay method can not be used to define optimal electrical stimulation conditions for releasing endogenous opioids. The binding displacement method was extended to the study of the sigma receptor. Depolarization of hippocampal slices was found to reduce the binding of the sigma-selective radioligand ({sup 3}H)-ditolylguanidine in a transient and calcium-dependent manner with no apparent direct effects on sigma receptor affinity.
- Research Organization:
- Washington Univ., Seattle, WA (USA)
- OSTI ID:
- 6533660
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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HIPPOCAMPUS
ELECTROPHYSIOLOGY
PEPTIDES
BIOLOGICAL FUNCTIONS
RECEPTORS
BIOCHEMICAL REACTION KINETICS
AUTORADIOGRAPHY
CELL MEMBRANES
LIGANDS
RATS
TRITIUM COMPOUNDS
ANIMALS
BODY
BRAIN
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
FUNCTIONS
HYDROGEN COMPOUNDS
KINETICS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANS
PHYSIOLOGY
PROTEINS
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RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques