**1. Introduction**

Depression is a weakening disease and it is mostly affecting modern society. The world health organization forecasts that in 2022 depression will become the major common cause of loss of interest in the working in the entire world. Thus the research of depression is one of the most important way through which we can obtain new treatment of depression and improve the developed drugs which can work better for depressive individuals. It will also assist to develop and create new approaches that will be used for better treatment of depression. Chemical transmission is the major tool through which nerves communicate with each other. Now it is well known that the presynaptic and postsynaptic events are responsible for the plasticity and learning within the Central nervous system. Chemical transmission requires different types of steps including synthesis of the neurotransmitters, their storage in secretary vesicles, and their release into the synaptic cleft between presynaptic and postsynaptic cleft. The initial step of the synthesis of neurotransmitters is the facilitated transport of amino acids from blood to the brain, in the brain precursors are converted into neurotransmitters enzymatically. These are stored in the synaptic vesicles, and finally released into the synaptic cleft via calcium dependent process. The release rate of neurotransmitters determined the rate of firing of neurons which means that the drug alter the firing rate of neurons. This modification of neurons carried out the alteration of release of neurotransmitters. After this released neurotransmitters bind with somatodendritic auto receptors. Thus binding of neurotransmitter to auto-receptors is responsible for reducing the synthesis of neurotransmitters or additional release from the presynapse. The synaptic results of neurotransmitter are ceased via binding with specific receptors and reuptake into the pre-synapse. Neurotransmitters metabolized by monoamine oxidase enzymes in the presynapse [1].
