Reuptake is the reabsorption of a secreted substance by the same cell that originally secreted it. It is essential in regulating the level of neurotransmitter in the synapse and therefore controls the time during which the substance is available for synaptic transmission. When a nerve releases a neurotransmitter, the neurotransmitter either travels to a receptor of a nearby cell or, in the case of reuptake, reattaches to the receptor of the cell that produced it. In this case, the neurotransmitter is taken back into the cell and recycled. The efficiency of the reuptake mechanism is often used to treat and regulate many psychological conditions that involve neurotransmitters, including depression and anxiety.