The functional status of dopaminergic nerve terminals has been studied with a method that allows the simultaneous determination of the specific activities of dopamine (DM), tyrosine (Tyr), 3 methoxytyramine (3 MT) and 3,4 dihydroxyphenylacetic acid (DOPAC), after administration of [ 3H]tyrosine ([ 3H]Tyr). Combined fluorimetric, mass fragmentographic and radiometric techniques have been used. [ 3H]Tyrosine was given intraventricularly to unanesthetized rats and the animals were killed by exposure for 4 sec to high energy microwave radiations. The specific activities of 3 MT and DOPAC measured 5 and 20 min after administration of [ 3H]Tyr, i.e. at time intervals in which the specific activity of DM is rising, are much higher than those of their physiological precursor, suggesting that they are generated by more than 1 DM compartment. This hypothesis seems to be supported by the finding that in animals killed by decapitation instead of microwave radiations the post mortem accumulation of 3 MT occurs to a much smaller extent for the radioactive fraction than for the endogenous one, indicating that 3 MT formed after death may be mainly derived from DM coming from a compartment where this monoamine has been poorly labeled by the radioactive precursor.
|Number of pages||5|
|Journal||Journal of Neurochemistry|
|Publication status||Published - 1977|
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience