MESSRIPOUR M, CLARK J. EFFECTS OF CATECHOLAMINES ON DOPAMINE AND SEROTONIN SYNTHESIS IN RAT BRAIN STRIATAL SYNAPTOSOMES: THE ROLE OF PRESYNAPTIC RECEPTORS AND THE SYNAPTOSOMAL REUPTAKE MECHANISM.. Med J Islam Repub Iran 1989; 2 (4) :287-292
URL:
http://mjiri.iums.ac.ir/article-1-1237-en.html
From the Biochemistry Department, Isfahan University of Medical Sciences, Isfahan, Islamic Republic of Iran
Abstract: (4490 Views)
The regulation of dopamine and serotonin synthesis in rat brain striatal
synaptosomes has been studied using HPLC methods. Noradrenaline was
shown to markedly inhibit both the synthesis of dopamine and serotonin.
The response of the synaptosomes to the concentrations of noradrenaline
appeared to be biphasic, a very effective inhibition occurring at low
concentrations (1-5 µm) and a relatively ineffective further inhibition
occurring at high concentrations (up to 100 µM). The inhibition of dopamine
and serotonin synthesis by noradrenaline was also studied in the presence of
phenoxybenzamine (alpha adrenergic receptor blocker) and imipramine
(reuptake inhibitor). Phenoxybenzamine changed the pattern of inhibition
of both dopamine and serotonin synthesis by noradrenaline by preventing
the very effective inhibition previously seen at low (1-5 µM) noradrenaline
concentrations. Imipramine, whilst showing marked inhibition of dopamine
synthesis on its own, prevented any inhibition by noradrenaline. In the case
of serotonin synthesis, however, imipramine alleviated some of the inhibition
seen in the presence of noradrenaline alone. The results are discussed
with respect to the role that presynaptic receptors and reuptake mechanisms
play in the regulation of catecholamine and serotonin synthesis at the nerve
ending.