[The presynaptic metabolic modulation of the impulse-dependent release of 3H-serotonin from rat brain slices by ipsapirone (TVX Q 7821) and other serotonin agonists].

: The experiments with thin slices of the cortex and dorsal raphe nucleus of rat midbrain which were incubated with [3H]-hydroxytryptamine ([3H-]HT) have established that serotonin and its agonists inhibit 3H-HT release from the electrically stimulated slices. The serotonin agonists ipsapirone (TVX Q 7821), buspirone, gepirone, and 8-OH-DPAT which mainly stimulate the Type 1A serotonin receptors of somatodendritic synapses inhibit the release of [3H]-HT from the dorsal raphe nucleus slices to a greater extent rather from those of the cortex. On the contrary, the serotonin agonists TFMPP, mCPP, and Ru 24969 which predominantly affect 1B-HT receptors largely inhibit [3H]-HT release from the electrically stimulated cortical slices. Ipsapirone-induced inhibition of the impulse-dependent release of [3H]-HT has been found to be associated with changes in intracellular cAMP levels and protein kinase activity. The nature of serotonin agonist-induced modulation of the impulse-dependent release of [3H]-HT from serotoninergic neurons is discussed in the paper.