Measuring pain in the (knockout) mouse: big challenges in a small mammal

The increasing popularity of the mouse as a subject in basic science studie s of pain can largely be attributed to the development of transgenic 'knock out' technology in this species only. To take advantage of this biological technique, many investigators are rushing to adapt to the mouse experimenta l protocols that were designed for the rat. However. the myriad physiologic al and behavioral differences between these two rodent species render such adaptations non-trivial and in many cases seriously problematic. Tn this ar ticle we review the basic nociceptive assays used in behavioral pain resear ch (thermal, mechanical, electrical and chemical), and highlight how specie s differences affect their proper application. In addition. some of the iss ues specifically pertaining to the interpretation of such data in knockout studies are addressed. (C) 2001 Elsevier Science B.V. All rights reserved.