TY - JOUR
T1 - Opioid inhibition of spontaneously active neurons of the rat arcuate nucleus in vitro
AU - Loose, Michael D.
AU - Kelly, Martin J.
N1 - Funding Information:
ACKNOWLEDGEMENTS The authors wish to thank Martha Bosch for technical assistancea nd Joan Vaughan for typing the manuscript.T his work was supportedb y PHS grants DA 05158, HD 19905 and a grant from the Eli Lilly Foundation. Dr. Michael Loose was supported by an NRSA (HD 07133). and Dr. Martin Kelly by an RCDA (HD 00718).
PY - 1989/5
Y1 - 1989/5
N2 - The effects of opioid agonists were determined on single-unit activity recorded from the arcuate nucleus (ARC) in perfused, coronal slices of hypothalamus taken from proestrous rats., The selective, μ-receptor agonist Tyr-D-Ala-Gly-MePhe-Gly-ol enkephalin (DAGO) produced a concentration-dependent decrease in the firing rate of 70-78% of the units tested. The concentration of DAGO that induced maximal inhibition of firing was approximately 0.5 μM. This inhibition of firing frequency occurred irrespective of cell location, firing pattern or baseline firing frequency. The effect of DAGO was antagonized by the opioid antagonist naloxone (0.1 μM). The selective κ-receptor agonist trans-(+)-34 dichloro-N-methyl-[2-(1-pyrrolidinyl) cyclohexyl] benzeneacetamide methane sulfonate (U50,488H) did not decrease the firing rate in cells which did respond to DAGO. Blockade of synaptic activity decreased the level of spontaneous activity but did not prevent the inhibitory action of DAGO. These data support the hypothesis that opioids through activation of μ-receptors, inhibit neuronal activity in the arcuate nucleus. Furthermore, the opioid inhibition occurs in part via a direct postsynaptic action.
AB - The effects of opioid agonists were determined on single-unit activity recorded from the arcuate nucleus (ARC) in perfused, coronal slices of hypothalamus taken from proestrous rats., The selective, μ-receptor agonist Tyr-D-Ala-Gly-MePhe-Gly-ol enkephalin (DAGO) produced a concentration-dependent decrease in the firing rate of 70-78% of the units tested. The concentration of DAGO that induced maximal inhibition of firing was approximately 0.5 μM. This inhibition of firing frequency occurred irrespective of cell location, firing pattern or baseline firing frequency. The effect of DAGO was antagonized by the opioid antagonist naloxone (0.1 μM). The selective κ-receptor agonist trans-(+)-34 dichloro-N-methyl-[2-(1-pyrrolidinyl) cyclohexyl] benzeneacetamide methane sulfonate (U50,488H) did not decrease the firing rate in cells which did respond to DAGO. Blockade of synaptic activity decreased the level of spontaneous activity but did not prevent the inhibitory action of DAGO. These data support the hypothesis that opioids through activation of μ-receptors, inhibit neuronal activity in the arcuate nucleus. Furthermore, the opioid inhibition occurs in part via a direct postsynaptic action.
KW - Opioids μ-Receptor Arcuate Hypothalamus DAGO
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U2 - 10.1016/0361-9230(89)90024-5
DO - 10.1016/0361-9230(89)90024-5
M3 - Article
C2 - 2548677
AN - SCOPUS:0024383120
SN - 0361-9230
VL - 22
SP - 819
EP - 823
JO - Journal of Electrophysiological Techniques
JF - Journal of Electrophysiological Techniques
IS - 5
ER -