An Immunofluorescence Study of N-Acetylaspartylglutamate (NAAG) Localization at the Crayfish Neuromuscular Junction

Abstract

N-acetylaspartylglutamate (NAAG) is the most abundant neurotransmitter in the mammalian central nervous system (Neale et al., 2003). Recent studies have investigated the potential role of NAAG as a neurotransmitter in a variety of vertebrate organisms (Wroblewska, 2006), and have located it in nerves of invertebrates such as crayfish (Gafurov et. al. 2001). However, no research has been undertaken to locate NAAG specifically to the crayfish neuromuscular junction (NMJ). The crayfish NMJ serves as a simple glutamatergic model synapse that can be used to study the complex glutamatergic synapses in the human brain. Using indirect immunofluorescence, this study aimed to determine the presence and location of NAAG in the crayfish NMJ. Through the use of anti-NAAG and anti-synaptotagmin (a SNARE protein associated with neurotransmitter vesicles in the presynaptic terminal of an axon) antibodies (Cooper, 1995), we hypothesized that NAAG would be present in the pre-synaptic terminal in the NMJ. Inconsistent primary and secondary controls and synaptotagmin staining rendered our results inconclusive.