Meeting Abstract

55.2  Thursday, Jan. 5  The role of glutamate in insect locomotion: A glutamate agonist causes hyperactivity and loss of climbing ability in adult fruit flies. MEKDARA, Nalong T.*; CHOUDHURY, Songita; MEKDARA, Prasong J.; BERG, Otto; GOTO, Joy J.; MULLER, Ulrike K. ; Cal. State Univ. of Fresno; Cal. State Univ. of Fresno; Cal. State Univ. of Fresno; Cal. State Univ. of Fresno; Cal. State Univ. of Fresno; Cal. State Univ. of Fresno nmekdara@csufresno.edu

L-Glutamate controls insect locomotion both at the level of the peripheral and the central nervous system. We study the effects of excess glutamate on the walking behavior of adult Drosophila melanogaster. Feeding the flies high concentrations of glutamate or N-Betamethyl-amino-L-alanine L-BMAA, a glutamate agonist (concentrations: 0, 12.5, 25, 50 mM) and recording the flies’ ability to climb for 10 minutes for three consecutive days. Overstimulation of glutamate receptors at the neuromuscular junctions should result in loss of climbing ability. Overstimulation of the central pattern generator should lead to hyperactivity (walking faster and longer). We used two behavioral assays (climbing up a vertical incline after the tap-down and spontaneous climbing up a gradual incline) to assess motor behavior. The spontaneous-climbing assay was developed by our team to detect subtle differences in climbing ability by assessing use of space in an arena with a lenticular floor. We quantified walking speed, walking bout duration, walking bout frequency, stumble frequency and climbing height. We observed that excess glutamate causes no significant loss of climbing ability and only causes a significant increase in walking speed at the highest dose. L-BMAA causes an increase in walking speed and walking activity even at the lowest dose. L-BMAA causes significant loss of climbing ability at all doses. We observe a clear dosage and progression effect in L-BMAA: higher doses and prolonged exposure cause an increase in the severity of the symptoms.