Effect of cannabinoids on synaptic transmission in the rat hippocampal slice is temperature-dependent.
We have previously reported that the synthetic cannabinoid R-(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazin-yl]-(1-naphthalenyl)methanone mesylate (WIN55,212-2) causes a selective inhibition of paired pulse depression of population spikes recorded from the CA1 region of rat hippocampal slices maintained at 28-30 degrees C. We now show that this effect is highly temperature-dependent and that WIN55,212-2 actually increases paired pulse depression of population spikes recorded from slices maintained at 35 degrees C. This temperature dependence was found to correlate with the effects of the known gamma-amino butyric acid (GABA)-uptake inhibitors, nipecotic acid and guvacine, which were without effect at 28-30 degrees C, but increased paired pulse depression at 35 degrees C. The results show that the effects of cannabinoids on synaptic transmission in the hippocampal slice are highly temperature-dependent and it is suggested that this is due to the presence of increased GABA uptake at higher temperatures.
Al-Hayani
Abdulmonem
A
Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, UK.
Davies
Stephen N
SN
D000818:Animals; D048588:Benzoxazines; D002186:Cannabinoids / Q000494:pharmacology*; D005260:Female; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D009025:Morpholines / Q000494:pharmacology*; D009281:Naphthalenes / Q000494:pharmacology*; D009539:Nicotinic Acids / Q000494:pharmacology; D009557:Nipecotic Acids / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects*; D013696:Temperature; D005680:gamma-Aminobutyric Acid / Q000187:drug effects / Q000378:metabolism
D048588:Benzoxazines; D002186:Cannabinoids; D009025:Morpholines; D009281:Naphthalenes; D009539:Nicotinic Acids; D009557:Nipecotic Acids; D011720:Pyrazoles; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; C030278:nipecotic acid; C015910:guvacine; D005680:gamma-Aminobutyric Acid; C070417:(3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone; C109925:AM 281