system
Given the following post, respond as if you're commenting on Reddit:
human
Are neurotransmitters such as serotonin, dopamine, and GABA stored in the body like some vitamins and minerals are? Is it then possible to deplete them from chronic stress and/or bad diet? Furthermore is it possible to replenish them and cure things like anxiety and panic disorders?
gpt
Neurotransmitters are synthesized in the neuron and stored in the presynaptic terminal of nerve cells in small intracellular pockets called vesicles. When an action potential reaches the presynaptic terminal, voltage gated calcium channels open and the resulting influx of calcium ions into the neuron cause the vesicles to fuse into the neuronal membrane, releasing the contents of the vesicle into the synaptic cleft. Once in the cleft, the neurotransmitters can bind to specific receptors on the postsynaptic terminal, inducing a number of physiological effects in the next neuron. In this way, neurons are able to send biochemical signals throughout the brain creating thoughts and emotions as well as controlling the various functions of the body.

The the degree of the effects of various transmitters doesn't only rely on the concentration of the neurotransmitters but their ability to bind to  receptor proteins. Normally, once a neurotransmitter has been released into the synaptic cleft, it is either destroyed by various enzymes or taken back up by the presynaptic neuron. However, many drugs that modify the chemical balance of the brain don't just cause the body to produce more neurotransmitter, but also cause the neurons to remain in the synaptic cleft, either by reducing the activity of enzymes that destroy the neurotransmitter, or reducing the ability of the cell to re-uptake the neurotransmitter. 

Interestingly, cocaine and methamphetamines acts on the brain by "forcing" dopamine into the synaptic cleft and inhibiting the cell's ability to reuptake the neurotransmitter. This creates the "high" that drug abusers feel. These high levels of dopamine cause the brain to adapt by reducing then number of dopamine receptors in the postsynaptic neuron, so that without the drug, the effects of dopamine are considerably reduced (this causes withdrawal symptoms).

Minerals on the other hand are stored in the body in many different ways. For example, iron is stored in the body as ferritin, an intracellular protein that stores iron for future use. Bones are used as calcium reservoirs, and various hormonal and physiological changes cause the bone to lose calcium to the blood or cause calcium in the blood to bind to the bone.

Vitamins can also be stored in various ways. For example, vitamin D is produce from inactive vitamin D precursors in the skin. When UV-B radiation excites certain pigment molecules in the skin, this causes a series of reaction that "activates" the precursor into active vitamin D. This process is highly modulated by various hormonal systems in the body (since vitamin D can act as a hormone). Vitamin D also comes for dietary sources.

Neurotransmitters are synthesized in the soma (cell body) or directly in the presynaptic terminal of the neuron by various enzymes. The Golgi apparatus, the organelle responsible for packaging and distributing chemicals that the cell synthesizes, packages the neurotransmitter into a vesicle where it is transported to the presynaptic terminal where it waits to be released.

Unlike neurotransmitters, there is no universal way for minerals and vitamins to be stored in the body. The various minerals your body needs have widely varying functions, and each mineral has multiple functions. For example, as mentioned before, calcium is used by neurons to transmit signals throughout the brain. However, calcium is also used as an important structural element in bone and cartilage, as a hormonal messenger, and is vital for muscle contraction, among other things.