【Animal modeling】-The role of phosphokinase Czeta in the anterior cingulate cortex in emotional responses in rats with inflammatory pain induced by Freund

  Objective: To observe the emotional response of CFA-induced inflammatory pain model rats, and to explore the relationship between the anterior cingulate cortex (ACC) phosphokinase Czeta (PKCzeta) and the emotional response of inflammatory pain rats.

  Methods: Twenty-four clean-grade male SD rats were randomly divided into blank control group and model control group. A chronic inflammatory pain model was established by subcutaneous injection of Freund's complete adjuvant into the foot. The changes of body weight and pain threshold of rats in each group before modeling (base), 3, 7, 14, 21 and 28 days after modeling were observed dynamically; Total travel distance, open arm travel distance, number of open arm entries, and percentage of open arm dwell time in . The total movement distance in the open field, the movement distance in the central quadrant, the times of entering the central quadrant and the stay time in the central quadrant of all rats were observed 14 and 29 days after modeling. Western blotting was used to detect the expression of PKCzeta protein in the ACC region of the contralateral and affected sides at 14 and 29 days after modeling.

  RESULTS: There was no significant difference in body weight between the two groups at each time point (P>0.05). Before modeling, there was no significant difference in pain threshold between the two groups (P>0.05); 1 day after modeling, the pain threshold of rats in the model control group was significantly decreased (P<0.05), and it was significantly lower in the whole experimental process. compared with the blank control group (P<0.05). Compared with the blank control group, the open arm movement distance and the percentage of open arm stay time of the rats in the model control group were significantly reduced on 28 d after the model (P<0.05), and the central quadrant movement distance and the number of times of entering the central quadrant on the 29 d after the model were significantly reduced. (P<0.05). At 29 days after modeling, the expression of PKCzeta protein in the ACC region of the affected side of the rats in the model control group was significantly higher than that in the blank control group (P<0.05). And open arm movement distance, open arm stay time percentage, central quadrant movement distance, central quadrant entry times were negatively correlated with the changes of PKCzeta protein expression on the affected side.

  Conclusion: CFA-induced chronic inflammatory pain rats can exhibit abnormal emotional behaviors; chronic inflammatory pain emotional-like behaviors may be related to the high expression of PKCzeta in the ACC region.