Meeting Abstract

P3.83  Jan. 6  EFFECTS OF 5-HYDROXYTRYPTOPHAN AND TRYPTOPHAN ADMINISTRATION ON BEHAVIOR AND SEROTONIN IMMUNOREACTIVITY IN CRAYFISH. TIERNEY, A.J.*; GUNARATNE, C.; MONROY, V.; DONNELLY, L.; Colgate University; Colgate University; Colgate University; Colgate University atierney@mail.colgate.edu

Serotonin (5-HT) is widely distributed in the crustacean nervous system and functions as both a neurotransmitter and a neurohormone. This monoamine is synthesized from tryptophan (TRYP) via the intermediary compound, 5-hydroxytryptophan (5-HTP). In vertebrates, TRYP and 5-HTP administration increase CNS synthesis of 5-HT, and both have been used to treat 5-HT-related disorders in humans. We investigated the effects of administering TRYP and 5-HTP on the performance of 5-HT-related behaviors and on 5-HT immunoreactivity in the nervous system of Procambarus clarkii. Adult male and female animals were injected with 5-HTP or TRYP (25 mg/kg of body weight) or control saline and transferred within 1-2 hrs to observation tanks where their behaviors were video-taped for 30 min. Observers blind to the animals� drug status recorded the amount of time crayfish spent Walking and in High Posture (a behavior elicited by 5-HT injection), and the number of tank quadrants entered. Tissue was subsequently processed for 5-HT immunoreactivity using standard procedures and matching each drug-injected animal with a saline-injected control. We found that 5-HTP-injected animals spent significantly more time in High Posture than did either TRYP or saline-injected animals; other behaviors did not differ significantly among groups. We also found that the relative intensity of 5-HT staining was greater in preparations treated with 5-HTP than either TRYP or control saline, suggesting that 5-HTP was taken up by neurons and converted to 5-HT. Our results indicate that 5-HTP administration may offer an effective way to manipulate 5-HT levels in this important crustacean model system.