Abstract
The neurotransmitter glutamate plays an essential role in excitatory neurotransmission; however, excessive glutamate leads to excitotoxicity, which is the most common pathogenic feature of numerous brain disorders. This study aimed to investigate the role of butyl 2-[2-(2-fluorophenyl)acetamido]benzoate (HFP034), a synthesized anthranilate derivative, in the central glutamatergic system. We used rat cerebrocortical synaptosomes to examine the effect of HFP034 on glutamate release. In addition, we used a rat model of kainic acid (KA)-induced glutamate excitotoxicity to evaluate the neuroprotective potential of HFP034. We showed that HFP034 inhibited 4-aminopyridine (4-AP)-induced glutamate release from the synaptosomes, and this inhibition was abolished in the absence of extracellular calcium. HFP034-mediated inhibition of glutamate release was associated with a decreased 4-AP-evoked Ca2+ level elevation, and had no effect on synaptosomal membrane potential. The inhibitory effect of HFP034 on evoked glutamate release was suppressed by blocking P/Q-type Ca2+ channels and protein kinase C (PKC). Furthermore, HFP034 inhibited the phosphorylation of PKC and its substrate, myristoylated alanine-rich C kinase substrate (MARCKS), in the synaptosomes. We also observed that HFP034 pretreatment reduced neuronal death, glutamate concentration, glial activation, and the levels of endoplasmic reticulum stress-related proteins, calpains, glucose-regulated protein 78 (GRP 78), C/EBP homologous protein (CHOP), and caspase-12 in the hippocampus of KA-injected rats. We concluded that HFP034 is a neuroprotective agent that prevents glutamate excitotoxicity, and we suggest that this effect involves the inhibition of presynaptic glutamate release by suppressing P/Q‐type Ca2+ channels and PKC/MARCKS pathways.