Sympathetic fibers of autonomic nervous system

Sympathetic fibers of the autonomic nervous system are bundles of neuronal axons that transmit signals from the central nervous system to peripheral organs and tissues as part of the sympathetic division of the autonomic nervous system[1][3][5][7][8]. These fibers are subdivided into: - **Preganglionic sympathetic fibers:** Short, myelinated axons that originate in the thoracolumbar spinal cord and release acetylcholine onto nicotinic acetylcholine receptors in sympathetic ganglia. - **Postganglionic sympathetic fibers:** Long, unmyelinated axons that extend from sympathetic ganglia to target organs; they mostly release norepinephrine onto adrenergic (alpha and beta) receptors on effector cells, except for sweat glands (acetylcholine, muscarinic receptors) and some renal fibers (dopamine receptors)[2][5][7][8]. Drugs therapeutically target the neurotransmitters or receptors (e.g., adrenergic receptors) involved in sympathetic transmission, not the fibers themselves. Thus, "sympathetic fibers" are not considered a druggable molecular target, but rather a component of neuroanatomical circuitry[2][5][7][8]. This entry is not specific or structured enough to represent a molecular target; use the specific neurotransmitter receptor or transporter (e.g., "Beta-1 adrenergic receptor") for that purpose.

Other names

sympathetic nerve fibersympathetic postganglionic fibersympathetic preganglionic fibersympathetic efferent