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Mu opioid receptor activation inhibits GABAergic inputs to basolateral amygdala neurons through Kv1.1/1.2 channels.
- Source :
-
Journal of neurophysiology [J Neurophysiol] 2006 Apr; Vol. 95 (4), pp. 2032-41. Date of Electronic Publication: 2005 Nov 23. - Publication Year :
- 2006
-
Abstract
- The basolateral amygdala (BLA) is the major amygdaloid nucleus distributed with mu opioid receptors. The afferent input from the BLA to the central nucleus of the amygdala (CeA) is considered important for opioid analgesia. However, little is known about the effect of mu opioids on synaptic transmission in the BLA. In this study, we examined the effect of mu opioid receptor stimulation on the inhibitory and excitatory synaptic inputs to CeA-projecting BLA neurons. BLA neurons were retrogradely labeled with a fluorescent tracer injected into the CeA of rats. Whole cell voltage-clamp recordings were performed on labeled BLA neurons in brain slices. The specific mu opioid receptor agonist, (D-Ala2,N-Me-Phe4,Gly5-ol)-enkephalin (DAMGO, 1 microM), significantly reduced the frequency of miniature inhibitory postsynaptic currents (mIPSCs) in 77% of cells tested. DAMGO also significantly decreased the peak amplitude of evoked IPSCs in 75% of cells examined. However, DAMGO did not significantly alter the frequency of mEPSCs or the peak amplitude of evoked EPSCs in 90% and 75% of labeled cells, respectively. Bath application of the Kv channel blockers, 4-AP (Kv1.1, 1.2, 1.3, 1.5, 1.6, 3.1, 3.2), alpha-dendrotoxin (Kv1.1, 1.2, 1.6), dendrotoxin-K (Kv1.1), or tityustoxin-Kalpha (Kv1.2) each blocked the inhibitory effect of DAMGO on mIPSCs. Double immunofluorescence labeling showed that some of the immunoreactivities of Kv1.1 and Kv1.2 were colocalized with synaptophysin in the BLA. This study provides new information that activation of presynaptic mu opioid receptors primarily attenuates GABAergic synaptic inputs to CeA-projecting neurons in the BLA through a signaling mechanism involving Kv1.1 and Kv1.2 channels.
- Subjects :
- Amygdala chemistry
Analgesics, Opioid pharmacology
Animals
Bicuculline pharmacology
Elapid Venoms pharmacology
Enkephalin, Ala(2)-MePhe(4)-Gly(5)- pharmacology
Excitatory Postsynaptic Potentials physiology
Kv1.1 Potassium Channel analysis
Kv1.1 Potassium Channel drug effects
Kv1.2 Potassium Channel analysis
Kv1.2 Potassium Channel drug effects
Limbic System physiology
Male
Neurons, Afferent drug effects
Patch-Clamp Techniques
Peptides pharmacology
Potassium Channel Blockers pharmacology
Rats
Rats, Sprague-Dawley
Receptors, Opioid physiology
Receptors, Opioid, mu agonists
Scorpion Venoms pharmacology
Signal Transduction physiology
Synaptic Transmission drug effects
Synaptic Transmission physiology
Synaptophysin analysis
Nociceptin Receptor
Amygdala physiology
Kv1.1 Potassium Channel physiology
Kv1.2 Potassium Channel physiology
Neurons, Afferent physiology
Receptors, Opioid, mu physiology
gamma-Aminobutyric Acid physiology
Subjects
Details
- Language :
- English
- ISSN :
- 0022-3077
- Volume :
- 95
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Journal of neurophysiology
- Publication Type :
- Academic Journal
- Accession number :
- 16306173
- Full Text :
- https://doi.org/10.1152/jn.01004.2005