SEROTONIN SYNAPSE. Serotoninergic synapse The nerve impulse is transmitted between two synapses thanks to serotonin garnet balls contained in the vescicles of the presynaptic neuron. In the synaptic cleft, these vesicles release the serotonin, that fixes to the receptors of the synaptic button´s postsynaptic neuron. The presynaptic neuron possess two types of membrane receptors that control the concentration of serotonin in the synaptic cleft : the autoreceptor in pink and the carrier of the ser