The Nervous and Endocrine Systems During Panic: A Coordinated Response

Panic triggers a rapid, integrated response between the nervous and endocrine systems—the neuroendocrine stress axis.

Sequence of Activation

1. Threat detection (CNS): Amygdala processes sensory/emotional input → signals hypothalamus.
2. Sympathetic nervous system (SNS) activation: Locus coeruleus → norepinephrine release; preganglionic fibers → adrenal medulla → epinephrine (adrenaline) surge. Effects: ↑HR, ↑BP, ↑RR, bronchodilation, glycogenolysis, pupil dilation, blood shunting to muscles.
3. HPA axis activation: Hypothalamus → CRH → anterior pituitary → ACTH → adrenal cortex → cortisol. Cortisol: mobilizes glucose, modulates immune function, enhances vascular reactivity to catecholamines.
4. Thyroid axis modulation: Acute stress transiently alters TSH/thyroid hormones; chronic stress may suppress axis.
5. Parasympathetic rebound (recovery): Vagal activation → ↓HR, ↓BP, bronchoconstriction, GI restart. Requires threat resolution.

Integrated Effects

• Cardiovascular: ↑CO, ↑BP, ↑myocardial O₂ demand.
• Metabolic: Hyperglycemia, lipolysis, insulin resistance.
• Cognitive: Hypervigilance, narrowed attention, memory consolidation (amygdala-hippocampus).
• Immune: Acute enhancement → chronic suppression.

Clinical Relevance

Panic disorder involves dysregulation of this axis (hypersensitive amygdala, impaired prefrontal inhibition, HPA alterations). Treatment: CBT, SSRIs/SNRIs, breathing retraining, lifestyle modification.