Zebrafish Larvae Carrying a Splice Variant Mutation in cacna1d: A New Model for Schizophrenia-Like Behaviours?

Abstract

Persons with certain single nucleotide polymorphisms (SNPs) in the CACNA1D gene (encoding voltage-gated calcium channel subunit alpha 1-D) have increased risk of developing neuropsychiatric disorders such as bipolar, schizophrenia and autism. The molecular consequences of SNPs on gene expression and protein function are not well understood. Thus, the use of animal models to determine genotype-phenotype correlations is critical to understanding disease pathogenesis. Here, we describe the behavioural changes in larval zebrafish carrying an essential splice site mutation (sa17298) in cacna1da. Heterozygous mutation resulted in 50% reduction of splice variants 201 and 202 (haploinsufficiency), while homozygosity increased transcript levels of variant 201 above wild type (WT; gain-of-function, GOF). Due to low homozygote viability, we focused primarily on performing the phenotypic analysis on heterozygotes. Indeed, cacna1dasa17298/WT larvae displayed hyperlocomotion—a behaviour characterised in zebrafish as a surrogate phenotype for epilepsy, anxiety or psychosis-like behaviour. Follow-up tests ruled out anxiety or seizures, however, as neither thigmotaxis defects nor epileptiform-like discharges in larval brains were observed. We therefore focused on testing for potential “psychosis-like” behaviour by assaying cacna1dasa17298/WT larval locomotor activity under constant light, during light-dark transition and in startle response to dark flashes. Furthermore, exposure of larvae to the antipsychotics, risperidone and haloperidol reversed cacna1da-induced hyperactivity to WT levels while valproate decreased but did not reverse hyperactivity. Together, these findings demonstrate that cacna1da haploinsufficiency induces behaviours in larval zebrafish analogous to those observed in rodent models of psychosis. Future studies on homozygous mutants will determine how cacna1d GOF alters behaviour in this context.

Antidepressant Screening Demonstrated Non-Monotonic Responses to Amitriptyline, Amoxapine and Sertraline in Locomotor Activity Assay in Larval Zebrafish

“…The observed effects of antidepressants with decreased swimming activity on zebrafish larvae are also consistent with other recent studies [85][86][87]. Other behavioral changes were also displayed from burst and rotation movement that implied fear, predator avoidance, seizure, and movement orientation [88,89]. Burst count was considered as the rapid simultaneous movement, which helps evaluate the locomotion activity.…”

“…The sudden increase in the acceleration of swimming movement is indicated as the startle response [74], which presented within the transition of light and dark cycles. Meanwhile, the rotation movement indicated a swimming orientation varied depending on various factors [64,89]. The variation in body rotation produces an escape kinematic response depending on the stimulus.…”

Calcium channelopathies and intellectual disability: a systematic review

“…MiR-135b could inhibit cardiomyocyte hypertrophy [ 148 ]. Nifedipine can block Cav1.2 current [ 146 ] Oxidative stress pathway for affective disorders [ 156 ] Apoptotic pathway in Timothy syndrome [ 153 ] Apoptotic pathway in dilated cardiomyopathy [ 154 ] CACNA1D Calcium voltage-gated channel subunit alpha1 D Cav1.3 L-type None Zebrafish larvae for schizophrenia [ 251 ]. Animal model of epilepsy [ 252 ] None Oxidative stress pathway in hearing loss [ 157 ] CACNA1E Calcium voltage-gated channel subunit alpha1 E Cav2.3 R-type Mouse model of Fragile X Syndrome [ 253 ] Sprague–Dawley rats for epilepsy [ 254 ].…”

A Mini-Review Regarding the Modalities to Study Neurodevelopmental Disorders-Like Impairments in Zebrafish—Focussing on Neurobehavioural and Psychological Responses

“…Thus, genetic models, such as cntnap2 knock down model (relevant to ASD seizures), nbea mutant model (GABAergic synaptic plasticity impairments, impaired locomotor activity, and decreased startle reflex), and DIA1/DIA1R transgenic models (cognitive retardation) were successfully described [ 8 , 11 ]. Also, the neurodevelopmental impairments in schizophrenia, such as cerebellar neurons loss of function, demyelination, and oligodendrocytes development defects can be studied using disc1, nrg1, and cacna1d mutant zebrafish larvae [ 114 ]. The newer model of Xie et al [ 115 ] studied the implication of pdzk1 gene in both schizophrenia and ASD, the knock-out individuals showing increased spatial frequency tuning functions, thus abnormal visual behavior.…”