Sympathetic nervous system activation (SNS activation)

Sympathetic nervous system activation refers to the physiological process by which the **sympathetic branch** of the autonomic nervous system increases its output in response to stressors—physical or psychological. This process is not a single molecule or receptor but rather a coordinated network involving neurotransmitters such as **norepinephrine** and **epinephrine**, released from nerve endings and adrenal glands respectively. Activation leads to classic "fight-or-flight" responses including increased heart rate, elevated blood pressure, bronchodilation, pupil dilation, enhanced glucose release from glycogen stores in liver/muscle tissue, reduced digestive activity, sweating, and heightened alertness. These changes are mediated through adrenergic receptors distributed throughout various organs.[1][2][3][4] Chronic or excessive sympathetic activation is implicated in several diseases—most notably hypertension and cardiac arrhythmias such as atrial fibrillation—and can be targeted therapeutically by drugs that block adrenergic signaling at different points in this pathway.[5][9] However, "sympathetic nervous system activation" itself is not a discrete molecular target like a receptor or enzyme; it describes an integrated physiological state resulting from upstream neural signaling cascades. Because this entry refers broadly to a physiological process rather than a specific molecular entity suitable for direct drug targeting (such as "beta 1 adrenergic receptor"), it should be flagged as incorrect for use as a canonical therapeutic target name.

Other names

Sympathetic activationSNS overactivityFight-or-flight responseSympatho-adrenal response

Inhibition of adrenergic receptors to reduce sympathetic effects[5][9] - Beta-blockade to decrease heart rate and contractility[5] - Alpha-blockade to reduce vascular resistance and blood pressure[9] - Central inhibition to decrease overall sympathetic outflow[9]