(a) : Neurotransmitters are chemicals that are used to relay, amplify and modulate electrical signals between a neuron and another cell. Substances that act as neurotransmitters can be categorized into three major groups: (1) amino acids (primarily glutamic acid, GABA, aspartic acid and glycine), (2) peptides (vasopressin, somatostatin, neurotensin, etc.), and (3) monoamines (norepinephrine, dopamine and serotonin) plus acetylcholine. Cortisone is a glucocorticoid steroid hormone, produced by the adrenal glands and has anti-inflammatory and immune-system suppressing properties.