Physiological arousal

Physiological arousal is a complex biological state characterized by increased responsiveness to sensory stimuli, alertness, and readiness for action. It is primarily governed by the ascending reticular activating system (ARAS) in the brainstem, which projects to the thalamus and cortex to regulate wakefulness and consciousness (StatPearls, Physiology, Arousal [https://www.ncbi.nlm.nih.gov/books/NBK539830/]). This state involves the integrated activity of the autonomic nervous system and the endocrine system, resulting in physical changes such as increased heart rate and blood pressure. While not a single molecular target, arousal is modulated by several neurotransmitter systems including the adrenergic, cholinergic, dopaminergic, and histaminergic pathways (Saper et al., 2005, Nature [https://doi.org/10.1038/nature04194]). Abnormalities in arousal regulation are central to various conditions, including insomnia, anxiety disorders, and post-traumatic stress disorder (PTSD). Pharmacological agents typically influence this state by acting on specific receptors like GABA, adrenergic, or orexin receptors to either stimulate or sedate the central nervous system.

Other names

Arousal stateAlertnessWakefulnessSympathetic activationPhysiological reactivity

Drugs modulate physiological arousal by acting as agonists or antagonists on molecular targets such as the GABA-A receptor (sedation), adrenergic receptors (autonomic modulation), or by increasing the synaptic concentration of monoamines like dopamine and norepinephrine (stimulation).