Neuronal responses to cannabinoid receptor ligands in the solitary tract nucleus

Our previous study showed many neurons in the subpostremal division of the nucleus tractus solitarii to be cannabinoid-sensitive. In order to further investigate this sensitivity, single unit activity was recorded extracellularly in rat hindbrain slices, and the effects of bath application of delta9-tetrahydrocannabinol and of two synthetic cannabinoid receptor agonists were analysed and compared to each other. Approximately half the recorded neurons responded to agonists, and most of the neurons exposed to two of the agonists reacted similarly to both. The involvement of cannabinoid CB receptors in neuronal sensitivity to delta9-tetrahydrocannabinol is supported by these data and by the effects of N-piperidin-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-3-p yrazole-carboxamide, hydrochloride (SR 141716A), a compound which is considered to be a selective antagonist and/or a selective inverse agonist of this receptor type.