GLS and nervous system disorder: Shen et al. (2020) found that the content of GAD65 can be reduced in the brain of PCPA insomniac rats. GLU is an excitatory neurotransmitter in the central nervous system which is produced by glutamine (GLN) under the action of glutaminase. GLU is released in the synaptic space to bind to the receptor, having an excitatory role. About 20% of the neurons in the human brain are GLU neurons. GLU has an excitatory effect on neurons, but excessive GLU will produce neurotoxicity, leading to neuronal death and nervous system diseases (Machado-Vieira et al., 2012).