Determining the functions of gad1 and gad2 in embryonic zebrafish using splice blocking morpholinos

GABA is a major inhibitory neurotransmitter in the central nervous system (CNS), which is synthesized from glutamate by the enzyme glutamic acid decarboxylase (GAD). There are two isoforms of GAD encoded by two genes gad1 and gad2. In mammals, gad1 encodes GAD67 and gad2 encodes GAD65. A decrease in GAD67 in the human brain is associated with schizophrenia and related neurological disorders. In mice, a loss of GAD65 causees spontaneous seizures. We studied the role of GAD in modulating neural activity in zebrafish. Splice blocking morpholinos were used to manipulate expression of gad in embryonic zebrafish. gad1-gad2 double morphants exhibited substantial reduction in GABA, leading to spontaneous seizures-like neural activity. Furthermore, gad1 and gad2 single morphants also exhibited seizure-like activity, suggesting that both GADs are important for the normal functioning of the brain.