The researchers studied how removing the pituitary gland or adrenal glands affects a hormone called CRF in the brain of rats. They found that two weeks after surgery, the levels of CRF in the brain were much higher than in normal rats. This increase was likely due to the long-term absence of feedback signals from other hormones. One week after surgery, there was a small decrease in CRF levels, which may be linked to the removal of these feedback signals. Overall, the results show that removing certain glands can lead to significant changes in CRF levels in the brain.