Circadian Rhythm of Pain in Male Mice

Mildly Increased Mechanical Nociceptive Sensitivity in REV-ERBα Knock-out Mice

“…Both WT and KO mice showed altered acute nociceptive sensitivity in accordance with circadian rhythm in the hot plate test. Therefore, our hot plate test results support a previous study showing that thermal nociceptive sensitivity of male mice undergoes daily variation [3]. On the other hand, in the tail flick test, both WT and KO mice did not show altered acute nociceptive sensitivity in relation to the circadian rhythm, and this discrepancy may stem from the differences between the methods.…”

“…Clinical trials have demonstrated significant differences in nociceptive sensitivities depending on the circadian rhythm in various diseases, such as burning mouth syndrome [1] and symptomatic knee osteoarthritis [2]. In animal studies, the thermal nociceptive sensitivity of male mice shows daily variation [3]. These findings suggest that pain perception could be affected by circadian rhythm.…”

Daily rhythm of nociception in rats

“…Another study in rats suggested the occurrence of greater sensitivity during the light phase [4], but this was probably an artifact of the experimental procedure, as only two time points during the day were reported. A study on mice suggested the occurrence of two daily peaks in sensitivity, one during the light phase and one during the dark phase [5]. The amplitude of the daily variation in latencies was much smaller in that study than in ours, and it is possible that random oscillations were interpreted as a daily rhythm.…”

“…Yet, few studies have investigated the daily rhythmicity in nociception. Although studies on rats [2] and golden hamsters [3] have indicated the occurrence of greater pain sensitivity during the dark phase of the light-dark cycle, another study on rats indicated the occurrence of greater sensitivity during the light phase [4], and a study on mice indicated the occurrence of two daily peaks in sensitivity, one during the light phase and one during the dark phase [5]. Therefore, a re-evaluation of the daily rhythmicity in nociception seemed warranted.…”

Acute behavioural responses to nicotine and nicotine withdrawal syndrome are modified in GABAB1 knockout mice

“…This discrepancy could be due to different laboratory environment factors (Chesler et al, 2002) such as experimenter, season, cage density, sex, humidity and order of testing. In addition, other influencing factors can be the hot-plate temperature (Imamachi et al, 2009), the animal's age (Tajima et al, 2009;Berry et al, 2007), the time day of testing (Jeong et al, 2000;Konecka and Sroczynska, 1998) and the fact that nociceptive threshold in the tail-flick, paw-pressure and formalin tests could be different. The present results also provide clear evidence for the involvement of GABA B receptors in the effects induced by NIC on anxietyrelated responses.…”