Synaptic properties of serotonergic growth cones in developing rat brain

摘要: In order to gain insight into the events that take place when serotonergic growth cones are remodeled synapses, we tested hypothesis neurotransmitter-related properties of presynaptic terminals already present in these before synaptogenesis begins. The ontogeny markers for specific reuptake 5-HT and 5-HT-storing synaptic vesicles was studied isolated cone (IGC) fractions from developing rat brain. High-affinity 3H-imipramine binding (a marker plasma membrane transporter) significantly enriched IGC prepared beginning cortical [embryonic day 15 (E15) E20]. Radioautography with or 3H-paroxetine (another confirmed transporter is cerebral cortex it contains cones, but not synapses. Specific uptake 3H-5-HT found as early E15; this inhibited by fluoxetine. Electron microscopic radioautography demonstrated directly were structures took up 3H-5-HT. vesicle protein synaptophysin a 45 kDa specifically vesicles, serotonin-binding (SBP), each E15 postnatal 5; SBP immunoreactivity increased approximately 10-fold between E20. Endogenous detected at amount development proceeded. ratio 5-hydroxyindole acetic acid suggested within protected catabolism monoamine oxidase. Reserpine-induced depletion 5-HT, vesicular carrier apparent E20, E15. These data suggest characterize components mature synapses develop formed. may permit neurotransmission be established rapidly during or, alternatively, enable play role ontogeny.