See JAX Pipeline on the IMPC website for order of tasks for all mice tested

Project protocol: Auditory brainstem response

• Introduction
• Study design
• Workflow
• Equipment, software and supplies
• Procedure
• Measurements
• Experimental and technical parameters

Introduction

Tail suspension test monitors the immobility response to assess behavioral despair in mice, an induced depression model.

Study design

Paradigm: Baseline study

Panel: Collaborative Cross

Number of strains: 14

Sex: Both

Age: 10-12 wks

Sample size: Seven mice per sex

Number of cohorts: 1

Workflow

Step	Description	Equipment	Data collected
1	Mice are acclimated to testing room	-	-
2	Tail suspension test (5 min, 15 s)	Tail suspension apparatus, video equipment and software	Latency to immobility, duration of immobility

Equipment, software and supplies

• Tail suspension test apparatus [See Experimental and technical parameters]
  • Metal bar suspended on clamp stand 36.6 cm above lab bench
  • Neutral color background
  • Noldus Ethovision XT
  • Plastic cone with hole is placed around tail
  • Masking tape to attach tail to bar
• Ethovision detection software

Procedure

1. Mice are acclimated to the test room for 30 min.
2. The method of recording is set up:
   • Detection parameters appropriate to the coat color of the mice.
   • Time duration set at 5 min and 15 s.
   • A short (30 s) video of the tail suspension apparatus without a mouse is recorded at the beginning of each testing day. This ensures an accurate calibration background for the Ethovision detection software.
3. A single trial of the tail suspension test is performed on each mouse.
   • Recording begins before the mouse is suspended to guarantee that information is not lost in the first portion of the trial.
   • A plastic cone is placed around the tail of each mouse immediately before the test, with its tail extending through the tip, to prevent tail climbing behaviors.
   • The mouse is suspended at approximately one-third from the end of its tail; masking tape is used to secure the mouse to the bar.
   • Each trial is 5 min 15 s long and analyzed using the mobility detection module in EthoVision.
4. At the end of the 5 min 15 s trial, the mice are removed from the arena and returned to a holding cage until all mice within the homecage have been tested.
5. Analysis of the recording is done to measure latency to immobility and total time spent immobile.
6. Only the first 5 min of the recording after the experimenter has moved from view are analyzed.
7. An unscented 1% solution of Virkon S is used to clean the apparatus.

 

Data QC: Video from major outlier values should be reviewed for video tracking errors. These criteria should be evaluated periodically. The cone is in place to prevent tail climbing. Mice that climb are not included in the analysis.

 

Measurements

LIMS field name	MPD variable name	Description	Units	Series	Primary measurement	Series order	MPD computed	Calculation	Method	Data type
latency_to_immobility	immob_latency_TS	latency to immobility, 5 min test	s						tail suspension test	Float
time_immobile	immob_duration_TS	duration of immobility, 5 min test	s						tail suspension test	Float

Experimental and technical parameters

Equipment name	Tail suspension rod apparatus
Equipment manufacturer	The Jackson Laboratory - in house
Video tracking	Noldus
Software	Ethovision XT 7.1 and MPEG Recorder
Anesthesia	None