Table 5.

Summary of rodent studies exploring the link between the HPA axis and anxiety-related behaviors. In general, manipulations that increase HPA axis tone promote anxious behaviors, whereas manipulations that limit HPA axis tone reduce or prevent them. OFT= open field test (includes interaction tests); EPM= elevated plus maze; STR= startle reflex; LDB= light-dark box; CRH = corticotropin releasing hormone; GC = glucocorticoid.

HPA manipulation	Test	Behavioral Outcome	References
Increased CRH or GC signaling (Receptor agonist, transgenic mice)	OFT EPM STR LDB	↓ open exploration ↓ open exploration ↑ magnitude ↓ light exploration ↑ light exploration (only in animals that are inherently high- anxiety)	(68, 141, 192, 262, 381, 520) (141, 186, 192, 492, 520) (141, 262, 282, 381, 530) (168, 192, 381, 514) (514)
Acute stress-induced increases in CRH and GC signaling (diverse stressors)	OFT EPM STR LDB	↓ open exploration ↓ open exploration ↑ magnitude ↓ light exploration	(1, 566, 579) (5, 266, 321, 335, 566, 579, 612) (187) (579)
Chronic stress-induced increases in CRH and GC signaling (homotypic and heterotypic stress paradigms)	OFT EPM STR	↓ open exploration ↓ open exploration ↑ magnitude	(49, 207, 272, 409) (227, 272, 617) (207, 227, 272, 617)
Reduced CRH or GC signaling during/after chronic stress (or in animals that are inherently high-anxiety) (Receptor antagonists, adrenalectomy, transgenic mice)	OFT EPM STR LDB	↑ open exploration ↑ open exploration ↓ magnitude ↑ light exploration	(240, 501, 543, 579) (63, 208, 262, 501, 502, 549, 579) (262) (63, 502, 543, 549)