UNESP, Fac Ciencias Farmaceut, Farmacol Lab, BR-14801902 Araraquara, SP - Brazil
 UNESP, UFSCar, Programa Interinst Posgrad Ciencias Fisiol, BR-14801902 Araraquara, SP - Brazil
 Washington State Univ Vancouver, Dept Psychol, Vancouver, WA 98686 - USA
 USP, FFCLRP, Programa Posgrad Psicobiol, BR-14040901 Ribeirao Preto, SP - Brazil
Total Affiliations: 4
SEP 30 2011.
Web of Science Citations:
Stress can enhance and inhibit nociception depending on the situation. Thus, simply shifting the context from the elevated plus maze (EPM) which has been shown to produce stress-induced antinociception to a different environment could produce drastic and rapid changes in nociception. The present experiment tested this hypothesis by assessing nociception in rats and mice during and immediately after removal from the maze. Experiment 1 found hyperalgesia in female and male rats tested on the hot plate immediately after exposure to the elevated plus maze. This hyperalgesia occurred with or without the added stress of a hind paw formalin injection and regardless of whether rats were exposed to an EPM with open (oEPM) or enclosed (eEPM) arms despite a clear antinociceptive effect while on the oEPM. Experiment 2 showed a similar shift from antinociception to nociception on the formalin test in mice immediately after removing them from the EPM. These data demonstrate that a mild stressor such as the EPM can produce both antinociception and hyperalgesia depending on the context. This shift from antinociception to hyperalgesia occurs rapidly and is evident in mice, male and female rats, and with the hot plate and formalin tests. (C) 2011 Elsevier B.V. All rights reserved. (AU)