Difference in anxiety and sensitization of the acoustic startle response between the two inbred mouse strains BALB/cAN and DBA/2N

Abstract

The inbred mouse strain BALB has been proposed to be an animal model for pathological anxiety. BALB exhibits a stronger acoustic startle response (ASR) than the 'less emotional' inbred strain DBA. Four experiments were conducted to determine whether this strong ASR is due to a higher anxiety level and/or to greater sensitization in BALB than in DBA, with the following results: (1) The ASR to the very first startle stimulus was found to be much stronger in BALB than in DBA, and freezing behavior evoked by startle stimuli was more pronounced in BALB than in DBA. These findings indicate a higher level of anxiety in this strain.(2) ASR amplitudes of BALB initially rose much higher during consecutive startle stimuli and remained at a high level much longer than in DBA. Thereafter, ASR amplitude dropped more slowly and to a lesser degree than in DBA. Startle amplitudes decreased similarly in both strains (strong exponential decrease) only when a low sound pressure level (SPL) was used which elicited approximately the same low ASR in both strains. These results can only be explained by increased sensitization in BALB. (3) The slope of the i/ofunction, which represents the relation between sensory input and motor output, was steeper in BALB than in DBA. As it has been shown recently, sensitization increases the slope of the startle i/o-function indicating increased sensitization in BALB. It is discussed, however, whether anxiety also contributes to this effect. (4) Footshocks increased the ASR much less in BALB than in DBA, again showing increased sensitization in BALB. Both a higher level of anxiety and greater sensitization therefore determined the greater strength of the ASR in BALB than in DBA.

Acute anxiogenic-like effects of selective serotonin reuptake inhibitors are attenuated by the benzodiazepine diazepam in BALB/c mice

“…This study evaluated the anxiogenic–like effects of acute SSRI administration alone and in combination with the reference BZ, diazepam, in BALB/c mice, a strain previously shown to be sensitive to anxiogenic-like and anxiolytic-like effects of several classes of drugs (Belzung et al, 2001; Bouwknecht and Paylor, 2002; Dulawa et al, 2004; Griebel et al, 2000; Piappert and Pilz, 2002; Roy et al, 2001). Two SSRIs, fluoxetine and citalopram, were chosen for comparison in these studies due to their differing selectivity for the SERT and interaction with cytochrome P450 enzyme metabolism.…”

Acoustic startle modification as a tool for evaluating auditory function of the mouse: Progress, pitfalls, and potential

“…There are several caveats to the habituation phenomenon. The BALB/C strain has also been reported to show short term sensitization (reported as averages of 5-trial blocks; Plappert and Pilz 2002). Both long- and short-term habituation of the ASR can depend on age and sex interactions (Plappert et al 2005).…”

“…Both long- and short-term habituation of the ASR can depend on age and sex interactions (Plappert et al 2005). Additionally, some strains show sensitization of the ASR with repeated testing in sequential sessions (Typlt et al 2013a; Plappert and Pilz 2002). …”

Neural cell adhesion molecule (NCAM –/– ) null mice show impaired sensitization of the startle response

“…The startle apparatus is described in detail elsewhere (Plappert & Pilz 2002). Briefly, the SR was measured after placing the mouse in a wire mesh test cage (5 Â 9 Â 5 cm) fixed on a piezo accelerometer platform inside a sound-attenuating chamber.…”