title: Environmentally induced antinociception and hyperalgesia in rats and mice.
abstract: 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.
authors: Programa Interinstitucional de Pós-Graduação em Ciências Fisiológicas, UFSCar-UNESP, Rod. Araraquara-Jaú, km 01, 14801-902 Araraquara, SP, Brazil.
authors: Alianda Maira
authors: AM
authors: Cornélio
authors: Joyce
authors: J
authors: Mendes-Gomes
authors: Juliana Sayuri
authors: JS
authors: Fugimoto
authors: Michael M
authors: MM
authors: Morgan
authors: Ricardo Luiz
authors: RL
authors: Nunes-de-Souza
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004777:Environment; D005260:Female; D005557:Formaldehyde / Q000009:adverse effects; D006930:Hyperalgesia / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D018782:Maze Learning / Q000502:physiology; D051379:Mice; D059225:Nociception / Q000502:physiology*; D010146:Pain / Q000139:chemically induced / Q000517:prevention & control*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time; D012737:Sex Factors; D013045:Species Specificity
chemical_list: D005557:Formaldehyde