Opioid actions on rat anterior cingulate cortex neurons in vitro

J Neurosci. 1994 Mar;14(3 Pt 1):1106-13. doi: 10.1523/JNEUROSCI.14-03-01106.1994.


Intracellular recordings were made from layer V pyramidal neurons in slices of rat anterior cingulate cortex, using electrodes that contained potassium methylsulfate and biocytin. [Met5]enkephalin (300 nM to 30 microM) reversibly reduced the amplitude of EPSPs evoked by stimulation of the subcortical white matter; the half-maximal concentration was about 800 nM. These EPSPs were blocked by (+/-)-2-amino-5-phosphonovaleric acid and 6-cyano-7-nitroquinoxaline-2,3-dione. [Met5]enkephalin also reduced the amplitude of bicuculline-sensitive IPSPs evoked by stimulation within layer V; the half-maximal concentration was about 60 nM. Both these actions of [Met5]enkephalin were mimicked by the delta-selective agonist DPDPE (Tyr-D-Pen-Gly-Phe-D-Pen) but not by the mu-selective agonist DAMGO (Tyr-D-Ala-Gly-MePhe-Gly-ol); they were blocked by the delta-selective antagonist naltrindole (apparent dissociation constant of about 0.3 nM) but not by the mu-selective antagonist CTOP (D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2). [Met5]enkephalin did not change the amplitudes of depolarizations evoked by direct application of glutamate or hyperpolarizations evoked by direct application of muscimol (at -55 mV). Fifty percent (22 of 45) of pyramidal cells were hyperpolarized by [Met5]enkephalin; this resulted from an increase in potassium conductance, and it was mimicked by DPDPE and blocked by naltrindole. Five of seven nonpyramidal cells were hyperpolarized by [Met5]enkephalin; this was mimicked by DAMGO and blocked by CTOP.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
  • Enkephalin, D-Penicillamine (2,5)-
  • Enkephalin, Methionine / pharmacology*
  • Enkephalins / pharmacology
  • Glutamates / pharmacology
  • Glutamic Acid
  • Gyrus Cinguli / metabolism
  • Gyrus Cinguli / physiology*
  • Naloxone / pharmacology
  • Narcotic Antagonists
  • Narcotics / pharmacology*
  • Neurons / drug effects
  • Neurons / physiology
  • Neurotransmitter Agents / metabolism
  • Rats
  • Receptors, Opioid / drug effects
  • Receptors, Opioid / physiology
  • Somatostatin / analogs & derivatives
  • Somatostatin / pharmacology
  • Synapses / metabolism
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology


  • Enkephalins
  • Glutamates
  • Narcotic Antagonists
  • Narcotics
  • Neurotransmitter Agents
  • Receptors, Opioid
  • Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
  • phenylalanyl-cyclo(cysteinyltyrosyl-tryptophyl-ornithyl-threonyl-penicillamine)threoninamide
  • Naloxone
  • Glutamic Acid
  • Somatostatin
  • Enkephalin, Methionine
  • Enkephalin, D-Penicillamine (2,5)-