Persistent effects of a serotonin depletor (p-chlorophenylalanine) in regenerated planaria (Dugesia dorotocephala).

p-Chlorophenylalanine (pCPA) caused an increase in looping and locomotion speed in planaria (Dugesia dorotocephala). These effects dissipated quickly after treatment, except in animals that regenerated from worms surgically sectioned after treatment. Planaria that regenerated from head sections showed more looping 6 and 11 days later than tail regenerates, regenerates from untreated worms, and uncut worms. After the initial acceleration, pCPA animals, especially regenerates from tail sections, slowed down compared with untreated controls. Tail regenerates showed reduced speed 6 and 11 days later in comparison with head regenerates, regenerates from untreated animals, and uncut animals. The speed effect may have been due to pathogenesis in the eye spots in pCPA animals. The looping effect, however, may have been due to persisting serotonin depletion in the head regenerates. It is suggested that research on this problem might profitably be pursued with sexually reproducing planaria, to examine the possibility of genetic recoding due to serotonin depletion.