neurochemistry

Neurochemistry is the study of the chemical processes that underlie nervous system function, focusing on the synthesis, release, binding, and metabolism of signaling molecules that mediate communication among neurons and between neurons and other cell types. It encompasses neurotransmitters, neuromodulators, and neurohormones, integrating chemistry with physiology, pharmacology, and molecular biology.

In synaptic transmission, presynaptic neurons synthesize neurotransmitters, package them in vesicles, and release them in response to action potentials. The neurotransmitter released into the synaptic cleft binds to receptors on the postsynaptic membrane, triggering ionic or metabolic responses that influence neuronal excitability and signaling. Neurotransmitters are then cleared by reuptake transporters, enzymatic breakdown, or diffusion, allowing termination of signaling and recycling of components. This cycle is tightly regulated by enzymes, vesicular transport, and various signaling cascades.

Major transmitter systems include amino acids such as glutamate (excitatory) and GABA and glycine (inhibitory); monoamines such as dopamine, norepinephrine, and serotonin; acetylcholine; neuropeptides; and other signaling molecules like endocannabinoids and nitric oxide. Receptors are diverse, including ionotropic and metabotropic types, which activate multiple intracellular pathways that modulate synaptic strength, plasticity, and network dynamics.

Techniques in neurochemistry combine chemistry and neuroscience, including microdialysis, voltammetry, and mass spectrometry for chemical measurement, as well as imaging methods like PET and SPECT. Genetic and pharmacological tools help establish causal roles of specific chemicals. Clinically, neurochemical alterations are implicated in disorders such as depression, schizophrenia, Parkinson's disease, and Alzheimer's disease, guiding pharmacotherapies that affect synthesis, release, receptor activity, or degradation of signaling molecules.