Behavioral methods to study anxiety in rodents

Figures & data

Figure 1 Assessment of the acoustic startle reflex in rodents. (A) Sprague-Dawley rat in an apparatus that quantifies startle responses. Rats are placed within a nonconfining holder to minimize restraint stress. Startle response is induced by a burst of white noise delivered via a speaker located behind the rat. The force displaced is quantified by an accelerometer beneath the holder. (B) Acute effects of the stress-peptide corticotropin-releasing factor (CRF; administered intracerebroventricularly [ICV]) or vehicle only (VEH) on acoustic startle in 150-minute test sessions. Data are expressed as (%) change from pretreatment tests. CRF produces a dosedependent increase in startle. *P<0.05;**P<0.01 ; Tukey's t-tests.

Figure 2 Electroencephalogram/electromyogram (EEG/EMG) telemetry in rodents as a potential index of stress. The use of telemetry in mice and rats allows derivation of numerous metrics, including sleep architecture and circadian rhythm. (A) C57BL/6 mouse next to a transmitter (manufacturer: Data Sciences International) that is subcutaneously implanted to allow remote measurements: EEG/EMG, activity, and body temperature. (B) Representative example of a brief period of EEG and EMG signal from awake, slow-wave sleep, or rapid eye movement (REM) sleep. (C) Regular circadian fluctuations of activity and temperature in C57BL/6J mice, where 0-12 h is the light phase and 12-24 h is the dark phase. These cycles can be dysregulated by stress. (D) Effects of the stress peptide pituitary adenylate cyclase-activating polypeptide (PACAP; administered intracerebroventricularly [ICV]) on exploratory behavior in the elevated plus maze (EPM) (left) and REM sleep (right) in C57BL/6J mice. PACAP decreased exploratory behavior and increased REM during the dark phase, au, arbitrary units; ZT, zeitgeber time