Preparations of synaptosomes (P2) from the telencephalon of the pigeon and rat were used to study the effects of α-methyl-m-tyramine (α-MMTA) and metaraminol on the efflux of radioactive serotonin (5-HT). The preparations were first incubated in the presence of 2.5 × 10-8 M [3H]-5-HT to selectively label serotonergic nerve endings. Both α-MMTA and metaraminol in combination at a concentration of 0.15, 0.030 and 0.006 mM each significantly increased the efflux of [3H]-5-HT over control values in preparations from both the pigeon and rat. These two compounds together at the two concentrations also appeared to decrease the efflux of [3H]-5-hydroxyindoleacetic acid. At a concentration of 0.012 mM, α-MMTA significantly increased the efflux of [3H]-5-HT whereas metaraminol when tested alone at this concentration did not appear to have an effect on the release of [3H]-5-HT. The results are discussed in terms of the behavioral effects produced by α-methyl-meta-tyrosine in pigeons working on a multiple FR 50 FI 10 schedule of reinforcement.
- 5-Hydroxyindoleacetic acid release
- Serotonin release
ASJC Scopus subject areas
- Behavioral Neuroscience