Indicators of anxiety and nociceptive sensitivity in female rats with temporomandibular joint dysfunction
Abstract
The aim: to study the perceptual component of pain sensitivity, as well as the level of anxiety and exploratory activity of female rats on the model of temporomandibular joint dysfunction.
Material and methods. Studies were conducted on 18 female Wistar rats. Temporomandibular joint (TMJ) dysfunction was modeled by intra-articular injection of sodium monoiodacetate at a dose of 16 mg/kg. In the elevated cruciate maze (ECM) test, total sitting time and number of entries into closed or open arms, number of overhangs and upright stances were recorded. Testing was performed at baseline and 14 days from the beginning of the experiments. The perceptual component of animal nociception was studied by the latent period of tail withdrawal during light-thermal stimulation using the "tail-flick" method. Measurements were performed in the diestrus phase determined by microscopy of vaginal swabs. Pain sensitivity was evaluated at baseline, in the 2nd and 3rd estrous cycle after the beginning of the experiment.
Results. The latent period of tail withdrawal of rats receiving sodium monoiodacetate during nociceptive stimulation decreased by the second and third estrous cycle compared to the initial state. In the dynamics of observations of PCL, animals with temporomandibular joint dysfunction were characterized by a decrease in the time of exit from the central platform, a decrease in the number of vertical stands and overhangs compared to the initial value. Under these conditions, it was revealed that rats with pain syndrome differed from control individuals by the following parameters: longer duration of staying in closed arms, lower number of overhangs.
Conclusion. Female rats with experimental TMJ dysfunction are characterized by strengthening of the perceptual component of nociception. The development of pain syndrome in the maxillofacial region is accompanied by suppression of exploratory activity and increased anxiety level of animals.
