henry copeland:

Keeping up the pressure: New neural mechanism is found to regulate the chronic stress response -- ScienceDaily

The newly discovered nerve cells express a receptor, CRFR1, on their outer walls, which enables them to take in the message of the CRF neurotransmitter. The scientists' experiments showed that, in mice, the cortisol actually increases the number of CRFR1 receptors on these nerve cells, suggesting a positive feedback loop that could be self-renewing, rather than abating.
- www.sciencedaily.com