These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Effects of endomorphin on substantia gelatinosa neurons in rat spinal cord slices.
    Author: Wu SY, Ohtubo Y, Brailoiu GC, Dun NJ.
    Journal: Br J Pharmacol; 2003 Nov; 140(6):1088-96. PubMed ID: 14530213.
    Abstract:
    1. Whole-cell patch recordings were made from substantia gelatinosa (SG) neurons in transverse lumbar spinal cord slices of 15- to 30-day-old rats. 2. Endomorphin 1 (EM-1) or EM-2 (<or=10 microM) hyperpolarized or induced an outward current in 26 of the 66 SG neurons. The I-V relationship showed that the peptide activates an inwardly rectifying K+ current. 3. EM-1 or EM-2 (0.3-10 microM) suppressed short-latency excitatory postsynaptic currents (EPSCs) and long-latency inhibitory postsynaptic currents (IPSCs) in nearly all SG neurons tested or short-latency IPSCs in six of the 10 SG neurons. [Met5] enkephalin or [d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO) (1-10 microM) depressed EPSCs and IPSCs. EM-1 or EM-2 depressed synaptic responses without causing a significant change in holding currents or inward currents induced by glutamate. 4. Glutamate also evoked a short-latency outward current in five SG neurons or a biphasic current in two neurons; the outward current was blocked by tetrodotoxin (TTX, 0.3 microM) or bicuculline (10 microM). 5. EM-1 or DAMGO (1 or 5 microM) attenuated the glutamate-evoked outward or biphasic currents in four of the seven SG neurons. EM-1 (1 microm) reduced the frequency, but not the amplitude of miniature EPSCs or miniature IPSCs. 6.. Naloxone (1 microM) or the selective micro-opioid receptor antagonist beta-funaltrexamine (beta-FNA, 25 microM) antagonized the action of EM; EM-induced hyperpolarizations persisted in the presence of the kappa-opioid receptor antagonist (nor-binaltorphimine dihydrochloride, 1 microM) and/or sigma-opioid receptor antagonist (naltrindole hydrochloride, 1 microM). 7. It may be concluded that EM acting on micro-opioid receptors hyperpolarizes a population of SG neurons by activating an inwardly rectifying K+ current, and attenuates excitatory and inhibitory synaptic currents evoked in a population of SG neurons, probably by a presynaptic site of action.
    [Abstract] [Full Text] [Related] [New Search]