Sympathetic nervous system activity (SNS activity)

The **sympathetic nervous system** is one branch of the autonomic nervous system responsible for regulating involuntary physiological responses associated with stress ("fight-or-flight"), energy expenditure, cardiovascular tone, respiration, sweating, and metabolic functions. It operates through a network involving preganglionic neurons releasing acetylcholine onto nicotinic receptors in ganglia; postganglionic neurons then release norepinephrine onto adrenergic receptors on target tissues. Some exceptions exist—such as acetylcholine acting on muscarinic receptors in sweat glands and dopamine released by renal nerves. The effects are mediated by various receptor subtypes including alpha-, beta-adrenoceptors and muscarinic subtypes across different organs. While many drugs act on components within this network—such as beta-blockers targeting β-adrenoceptors—the term "sympathetic nervous system activity" refers to an overall physiological state/process rather than a discrete molecular target like a receptor or enzyme.[1][2][3][4] **Important note:** *"Sympathetic nervous system activity"* is **not** itself a therapeutic target but describes the functional status/output level of this neural network. Therapeutically relevant targets are specific molecules/receptors within this pathway such as *beta-adrenoceptor*, *alpha-adrenoceptor*, etc.[1]

Other names

Sympathetic nervous systemSNSSympathetic activationAdrenergic system (in some contexts)

Note: Mechanisms relate to modulation at adrenergic or cholinergic receptors within the SNS pathway. – Blockade or stimulation of adrenergic receptors to decrease/increase sympathetic outflow/effects[2][4] – Inhibition/enhancement of neurotransmitter release or reuptake in sympathetic neurons