On the fifth day after chamber implantation, animals were sacrificed and tumor-angiogenesis was evaluated.
At the one-hour contextual retention test, when the mice were brought back to the original conditioning chamber, the animals exhibited significant freezing during the 5-min contextual recall (Fig. 1E), indicating robust contextual fear memory.
Our behavioral results indicate that contextual fear conditioning can reliably occur in a single trial even when delivery of footshock is delayed for 26 min after introduction to a novel chamber (DS animals).
Briefly, after being anesthetized with 5% isoflurane and ∼98% oxygen in a gas chamber, the animals where endotracheal intubated and the cannula was connected to a volume cycled rodent ventilator (Harvard Apparatus) on supplement of a mixture of ∼1.75% isoflurane and ∼98% oxygen.
After removing the needle from the anterior chamber, the animals were observed until full recovery which occurred within 5 min.
Following habituation in the operant chamber, the animals were trained to lever-press and then run for additional sessions to strengthen the newly learned behaviour.
When kept in the described 12 cage isolation chambers, individual animals have to be removed from the chamber in their cages and be placed under an illumination screen for the time of the light exposure.
In a typical feed evaluation study using a respiration chamber, the animal variation of CH4 production is minimized by a fixed amount of feed provided to the animals.
