A pharmacological characterization of the serotonin autoreceptor in the rat spinal cord

The purpose of these studied was to correlate the receptor which is responsible for the modulation of [3H]5-HT release with a specific 5-HT receptor subtype. Changes in [3H]5-HT release were examined using synaptosomes prepared from rat spinal cord homogenates. The synaptosomes were allowed to accumulate [3H]5-HT and the spontaneous as well as potassium-evoked release of [3H]5-HT release can be evaluated. Using this procedure, drugs capable of modulating [3H]5-HT release can be evaluated. In the present studies, the nonselective agonists 5-HT and LSD induced a concentration-dependent decrease in potassium-stimulated [3H]5-HT release. In a manner similar to the nonselective drugs, the 5-HT1B preferring compounds TFMPP and mCPP also produced a concentration-dependent decrease in potassium-stimulated [3H]5-HT release. In contrast, the 5-HT1A agonist 8-OH-DPAT did not alter release. A second group of studies was aimed at confirming the presynaptic distribution of the 5-HT1B receptor site. For these studies, a 5-HT neurotoxin was used to destroy 5-HT nerve terminals and changes in receptor binding to the 5-HT1B and 5-HT1A site were examined