| Mice anesthetized and ovariectomy or sham surgery performed
||Mice allowed to recover for 17 days
||Open field test
||Open field arena
||Locomotor activity, exploratory and anxiety-like behavior
||Forced swim test
||Cylinder filled halfway with water
- Surgical tools
- Sutures (Med Rep Express, Prescott AZ)
- Open field arena and software (VersaMax Animal Activity Monitoring System, AccuScan Instruments Inc., Columbus OH)
- 42 x 42 x 30 cm arena consisting of a white Plexiglas floor and clear Plexiglas walls
- 16 photocells on each side of the arena, dividing it into 256 equal squares that allow for tracking of horizontal and vertical activity
- In a sound-attenuating chamber
- Forced swim test apparatus (Noldus, Wageningen, The Netherlands)
- 25-cm high glass-polycarbonate cylinder 17 cm in diameter, filled halfway with water maintained at room temperature
- Noldus Ethovision 7.0 software (Noldus, Wageningen, The Netherlands)
- Tribromoethanol (Sigma-Aldrich, St. Louis MO)
- Buprenorphine HCl (Patterson Veterinary, Devens MA)
Procedure: Ovariectomy and sham surgeries
- Mice are anesthesized with a 1.2% solution of tribromoethanol administered by intraperitoneal injection at a dose of 0.2 mL/10g body weight.
- A dorsal midline incision is made in the skin caudal to the posterior border of the ribs.
- An incision is made in the muscle, and the fat pad located just beneath the muscles is pulled out to expose the ovary.
- The fallopian tube is clamped off, the ovary removed and muscle and skin are sutured.
- This procedure is performed bilaterally.
- The procedure for sham surgery is identical except for clamping and tying off fallopian tubes and removal of ovaries.
- Buprenorphine HCl is administered subcutaneously at a dose of 0.05 mg/kg body weight after surgery as needed during the recovery period.
- Mice are allowed to recover for 17 days.
Procedure: Open field test
- Mice are placed in the open field arena individually for a 10-min test.
- Behavioral measures are recorded and analyzed in five 2-min bins using the VersaMax activity monitor and analyzer software.
Procedure: Forced swim test
- Mice are placed in the apparatus for a 6-min test.
- Test sessions are video recorded and analyzed using Noldus Ethovision software.
- Immobility is defined as no movements other than those required to stay afloat.
- NOTE: C58/J mice were not tested due to an inability to remain above water.
- Open field test
- distance traveled
- movement time
- center distance
- margin distance (thigmotaxis)
- vertical movement
- percent time spent in the center of the arena
- Forced swim test