Neuroscience 2005 Abstract
| Presentation Number: | 987.3 |
|---|---|
| Abstract Title: | Role of subthalamic nucleus in the Δ<sup>9</sup>-tetrahydrocannabinol effect on nigral dopamine neuron activity. |
| Authors: |
Morera, T.*1
; Ruiz-Ortega, J.1
; Ugedo, L.1
1Pharmacology, Univ. of the Basque Country, Leioa, Spain |
| Primary Theme and Topics |
Sensory and Motor Systems - Basal Ganglia -- Systems physiology and behavior |
| Session: |
987. Basal Ganglia Cellular Physiology Poster |
| Presentation Time: | Wednesday, November 16, 2005 3:00 PM-4:00 PM |
| Location: | Washington Convention Center - Hall A-C, Board # FF26 |
| Keywords: | CANNABINOIDS, BASAL GANGLIA, PARKINSON |
The active principle of marijuana, delta-9-tetrahydrocannabinol (Δ9-THC), exerts its pharmacological effects throught selective cannabinoid receptors. The cannabinoid receptor CB1 is expressed in the nervous system and is densely located in basal ganglia, a group of brain nuclei that includes substantia nigra compacta and subthalamic nucleus and is involved in motor activity. The present study sought to determine the role of subthalamic nucleus in the Δ9-THC effect on nigral dopamine neuron activity by extracellular recording techniques in anaesthetized rats.
Systemic administration of Δ9-THC (0.25-2 mg/kg) stimulated substantia nigra compacta neurons (by a 33.54 ± 8.63% n= 8). This stimulatory effect was completely abolished by previous blockage of excitatory amino acid receptors after kynurenic acid application (0.5 µM, i.c.v.; n=5). Similarly, destruction of the ipsilateral subthalamic nucleus by chemical lesion with ibotenic acid (10 µg/ml, 5 µl) completely blocked Δ9-THC effect (n=5). Neither kynurenic acid administration nor ibotenic lesion modified basal firing rate (mean basal firing rate was 4.23±0.88 Hz before and 4.73 ± 0.99 Hz after kynurenic application and 3.87 ± 0.61 Hz in control rats and 4.05 ± 0.73 Hz ibotenic lesioned rats).
These results suggest that the effect of Δ9-THC on substantia nigra compacta neurons is an indirect effect which may be the consequence of excitatory amino acids released from subthalamic terminals on substantia nigra compacta.
Systemic administration of Δ9-THC (0.25-2 mg/kg) stimulated substantia nigra compacta neurons (by a 33.54 ± 8.63% n= 8). This stimulatory effect was completely abolished by previous blockage of excitatory amino acid receptors after kynurenic acid application (0.5 µM, i.c.v.; n=5). Similarly, destruction of the ipsilateral subthalamic nucleus by chemical lesion with ibotenic acid (10 µg/ml, 5 µl) completely blocked Δ9-THC effect (n=5). Neither kynurenic acid administration nor ibotenic lesion modified basal firing rate (mean basal firing rate was 4.23±0.88 Hz before and 4.73 ± 0.99 Hz after kynurenic application and 3.87 ± 0.61 Hz in control rats and 4.05 ± 0.73 Hz ibotenic lesioned rats).
These results suggest that the effect of Δ9-THC on substantia nigra compacta neurons is an indirect effect which may be the consequence of excitatory amino acids released from subthalamic terminals on substantia nigra compacta.
Supported by UPV/EHU 9/UPV /00026-327-13590/2001 and FIS PI021600
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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