Parachlorophenylalanine - its three phase sequence of interactions with the two forms of brain tryptophan hydroxylase

Brain tryptophan hydroxylase: purification of, production of antibodies to, and cellular and ultrastructural localization in serotonergic neurons of rat midbrain.

“…The evidence is indirect and based on the reasonable assumption that those neurons in which 5HT can be visualized by their specific histofluorescence (4,5) should contain the enzyme. Consistent with the surmise are biochemical data demonstrating the presence of high levels of tryptophan hydroxylase activity in brain regions containing the cell bodies of 5HT neurons (3) or richly innervated by their processes (3). It has also been proposed, on indirect evidence, that tryptophan hydroxylase exists in different forms, differing either in susceptibility to inhibition by drugs (6)(7)(8) or possibly, in their relationship to subcellular organelles (3).…”

“…The observations that electrophoresis of highly purified tryptophan hydroxylase consistently produced three major protein bands, a highly active mobile C band, a less active, slowly moving A band, and the inactive band B, and that each band when isolated and resubjected to electrophoresis resulted in replication of the three bands suggests that tryptophan hydroxylase exists in multiple forms, as others have suggested (3,8). The nature of the multiple forms of the enzyme, however, is uncertain.…”

“…In brain, the enzyme has been presumed to be contained only within those specific neurons which synthesize, store, and release 5HT (3). The evidence is indirect and based on the reasonable assumption that those neurons in which 5HT can be visualized by their specific histofluorescence (4,5) should contain the enzyme.…”

Effects of PCPA and selective REM sleep deprivation on rotorod performance and open-field behavior in the rat

“…However, studies relating the effects of pcp A to sleep deprivation have failed to show a clear relation between the two variables. Rechtshaffen, Lovell, Freedman, Whitehead, and Aldrich (1973) were unable to demonstrate significant changes in sleep-waking with PCPA treatment in rats, and a similar failure has occurred in humans (Knapp & Mandell, 1972). Dement, Mitler, and Henriksen (1972) reported that chronic PCPA administration in cats produced only a transient insomnia lasting 3 to 4 days, despite continued marked cerebral serotonin depletion.…”

Taming effects of p-chlorophenylalanine on the aggressive behavior of septal rats

“…The rapidity of onset of the behavioral effects (30 min, [8]) suggests changes which might be occurring at the synapse and nerve terminal. One possible mechanism is suggested by Knapp and Mandell [14] who have shown that PCPA decreases the synaptic uptake of tryptophan, a serotonin precursor. If PCPA also interferes with the reuptake of serotonin, it may initially leave more functional serotonin available.…”