Serotonin synthesis in the nerve-terminals of rat brain regions

ABSTRACT

Isolated nerve-terminals [synaptosomes] have been used to investigate serotonin synthesis in rat brain regions. The rate of serotonin production by the synaptosomal preparations from hypothalamus, striatum, midbrain and frontal cortex was measured before and after incubation of the synaptosomes in the presence of a monoamine oxidase inhibitor. The hypothalamic area and the synaptosomes isolated from this brain region contained a higher storage capacity of serotonin and displayed a higher rate of serotonin production compared with other parts of the brain. The lowest level of serotonin is stored in the frontal cortex, which is consistent with a lower rate of amine synthesis by the nerve-terminals obtained from this brain region. The data indicated that there is a close relationship between the rate of serotonin production by synaptosomes and the endogenous serotonin content of the brain regions. It is concluded that, synaptosomes preparations preserve many of the physiological properties of the synoptic region of the neurons and may be used for studying neurochemical characteristics of neurotransmitters in the brain