välittäjäaineista

Välittäjäaineet, known in English as neurotransmitters, are chemical substances that transmit signals across synapses between neurons. In the nervous system, they are released from the presynaptic terminal into the synaptic cleft and bind to specific receptors on the postsynaptic membrane, initiating physiological responses such as changes in ion flow, secondary messenger systems, or alterations in gene expression. Neurotransmitters include small molecules such as acetylcholine, dopamine, norepinephrine, serotonin, gamma‑aminobutyric acid (GABA), glutamate, and glycine, as well as peptidergic substances like enkephalins and oxytocin. Each type is distinguished by its chemical structure, sites of synthesis, and the neural circuits in which it predominates. The removal of released neurotransmitter is achieved by reuptake transporters, enzymatic degradation, or diffusion, which helps terminate the signal and maintain neurotransmitter homeostasis.

The functional diversity of neurotransmitters underlies processes ranging from motor control and sensory perception to mood regulation and endocrine signaling. Dysregulation of neurotransmitter systems is implicated in psychiatric disorders such as depression, schizophrenia, and anxiety, as well as in neurological conditions like Parkinson’s disease and epilepsy. Pharmacological agents that modulate neurotransmitter activity—including inhibitors, agonists, antagonists, and reuptake blockers—are important therapeutic tools. Ongoing research seeks to clarify how specific neurotransmitter pathways contribute to behavior and disease, with implications for drug development, neuropsychiatric treatment, and understanding of brain–body interactions.