VAAT functionality in cholinergic and dopaminergic neurons

SLC10A4 (Solute carrier family 10 member 4) is a member of the sodium/bile acid cotransporter protein family. Previous studies indicated that this protein is a molecular link between two subpopulations of neurons i.e the monoaminergic and cholinergic. These neural subpopulations are widespread in the central nervous system (CNS) and are involved in most processes of our behaviour related to motivation, perseverance, reward system as well as all of the motor output. In this research study the focus has been on using Slc10a4 wild type (WT), knockout (KO) and Slc10a4 over expressing mouse, to characterize the function of a Vesicular Aminergic Associated transporter (VAAT) in cholinergic and dopaminergic neurons in the brain. Increased motor activity and increased drug-induced hyperactivity have been observed in KO mice. At subcellular level VAAT co-localizes with Vesicular Acetylcholine Transporter (VAChT) and Vesicular monoamine transporter (Vmat-2) on small synaptic vesicles (SV) at axon-termini in the brain. Experiments were performed to understand the significance of VAAT in cholinergic and dopaminergic systems, investigate VAChT distribution in neuromuscular junctions (NMJ) in VAAT mutant mice, study dopamine (DA) uptake efficiency in vesicles, investigate the epileptic link of VAAT and understand motor behavior of mutant mice. It was observed that VAAT colocalizes with VAChT in NMJ’s of diaphragm and gastrocnemius mouse muscles. The protocol for vesicular uptake studies was optimized under different conditions. Results illustrated that VAAT over-expressing mice show higher DA uptake compared to WT, while KO mice show less vesicular uptake. RNA expression analysis of muscarinic, nicotinic and dopaminergic receptors in striatum and hippocampus brain regions was performed. RT-qPCR results indicated no significant difference in expression levels; in both control and KO VAAT samples.