Summary
In slices of mouse hypothalamus labelled in vitro with 3H-noradrenaline (3H-NA), the deaminated metabolite 3H-3,4-dihydroxyphenylglycol (3H-DOPEG), represented 40.2±2.6% of the total outflow of radioactivity and was the main fraction in the sponteneous efflux. Inhibition of neuronal monoamine oxidase by exposure to 60 μM bretylium, reduced the outflow of 3H-DOPEG to 9.7±0.3%. At the same time, the proportion of 3H-normetanephrine (3H-NMN) was significnatly increased. On the other hand, an increased outflow of 3H-DOPEG and a lower proportion of 3H-NMN was obtained in the presence of 2.9 μM of the reserpine like agent Ro 4-1284.
It is suggested that in the mouse hypothalamus, the deaminated metabolite, DOPEG, is formed inside the nerve terminals, while the O-methylated metabolite, NMN, might result from the activity of extraneuronal catechol O-methyltransferase.
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Adler-Graschinsky, E. Metabolic fate of 3H-noradrenaline released from the mouse hypothalamus. Naunyn-Schmiedeberg's Arch. Pharmacol. 302, 337–339 (1978). https://doi.org/10.1007/BF00508305
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DOI: https://doi.org/10.1007/BF00508305