Neuroscience 2002 Abstract
| Presentation Number: | 737.10 |
|---|---|
| Abstract Title: | EFFECT OF CANNABINOID COMPOUNDS ON LOCUS COERULEUS NEURONS IN ANAESTHETIZED RATS. |
| Authors: |
Ruiz-Ortega, J.*1
; Mendiguren, A.1
; Areso, P.1
; Ugedo, L.1
1Department of Pharmacology, Faculty of Medicine, University of the Basque Country, Bizkaia, Leioa, Spain |
| Primary Theme and Topics |
Synaptic Transmission and Excitability - Neurotransmitters -- Cannabinoids |
| Session: |
737. Neurotransmitters: cannabinoids I Poster |
| Presentation Time: | Wednesday, November 6, 2002 2:00 PM-3:00 PM |
| Location: | Hall A2-B3 C-48 |
| Keywords: | electrophysiology, WIN 55,212, CP 55,940, SR 141716A |
The CB1 cannabinoid receptor is widely distributed in the Central Nervous System and participates in several central functions. The aim of this study was to investigate whether cannabinoid compounds modulate the activity of locus coeruleus (LC) neurons by using single-unit extra-cellular recordings in anaesthetized rats.
The cannabinoid agonists WIN 55,212 (31.2-1000 µg/kg, i.v.), CP 55,940 (62.5-1000 µg/kg, i.v.) and Δ9 THC (0.5-6 mg/kg, i.v.) caused a dose-dependent increase of LC neuron firing rate in vagotomized rats with a maximum effect of 79.2±50.4%, 43.7±23.5% and 29.8±10.4% respectively and an order of potency of WIN 55,212>CP 55,940>Δ9 THC. However, when WIN 55,212 (31-66 pmol) was applied locally into the LC there was not changed in the firing rate. On the other hand, the effect of the agonist WIN 55,212 was abolished by pre-treatment (30 min before the experiment) with the antagonist SR 141716A (2 mg/kg i.p.; this dose did not modify the firing rate of the neurons of the LC) whereas pre-treatment with naloxone (5 mg/kg i.p.) failed to modify WIN 55,212 effect.
We conclude therefore that cannabinoid compounds stimulate LC neurons through CB1 receptors but these receptors are not localized on LC neurons.
The cannabinoid agonists WIN 55,212 (31.2-1000 µg/kg, i.v.), CP 55,940 (62.5-1000 µg/kg, i.v.) and Δ9 THC (0.5-6 mg/kg, i.v.) caused a dose-dependent increase of LC neuron firing rate in vagotomized rats with a maximum effect of 79.2±50.4%, 43.7±23.5% and 29.8±10.4% respectively and an order of potency of WIN 55,212>CP 55,940>Δ9 THC. However, when WIN 55,212 (31-66 pmol) was applied locally into the LC there was not changed in the firing rate. On the other hand, the effect of the agonist WIN 55,212 was abolished by pre-treatment (30 min before the experiment) with the antagonist SR 141716A (2 mg/kg i.p.; this dose did not modify the firing rate of the neurons of the LC) whereas pre-treatment with naloxone (5 mg/kg i.p.) failed to modify WIN 55,212 effect.
We conclude therefore that cannabinoid compounds stimulate LC neurons through CB1 receptors but these receptors are not localized on LC neurons.
Supported by Supported by UPV/EHU 9/UPV/ 00026-327-13590/20001 and SAF 990046.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2002 Neuroscience Meeting Planner. Orlando, FL: Society for Neuroscience, 2002. Online.
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