DEPLETION OF SEROTONIN, BUT NOT DOPAMINE, REDUCES REGENERATION OF LOST BODY PARTS IN LUMBRICULUS VARIEGATUS
Mariela Saucedo Espinosa, Christopher Mendoza, Bruce A. O'Gara.
Humboldt State University, Arcata, CA.
The freshwater oligochaete Lumbriculus variegatus possesses extraordinary powers of regeneration. A fragment only a few segments long can regenerate to produce a full-sized worm. In this study, we investigate the role of serotonin in regulating segment regeneration following complete transection of the body. Following transection into three equal pieces, worms (n = 10/drug) were allowed to regenerate for 10 days in pond water containing the drugs mentioned below. The regenerating regions were photographed, and the lengths of the regenerating regions were quantified using ImageJ. Depletion of all amine neurotransmitters (serotonin, dopamine, octopamine, and histamine) by 1 mM reserpine treatment greatly reduced regeneration of all body parts. Depletion of serotonin by treatment with the tryptophan hydroxylase inhibitor 10 mM 4-Chloro-DL-phenylalanine (PCPA) reduced regeneration to a degree similar to reserpine treatment. However, depletion of dopamine by treatment with the tyrosine hydroxylase inhibitor 2.5 mM α-methyl-DL-tyrosine did not alter regeneration from control levels. Regeneration was unaffected by treatment with the serotonin 5-HT2/1C, histamine H1 antagonist cyproheptadine (10 mM). Attempts to rescue regeneration ability in PCPA-treated worms are under current study.