ABSTRACT
Background@#Synaptic plasticity contributes to nociceptive signal transmission and modulation, with calcium/ calmodulin-dependent protein kinase II (CaMK II) playing a fundamental role in neural plasticity. This research was conducted to investigate the role of CaMK II in the transmission and regulation of nociceptive information within the nucleus accumbens (NAc) of naïve and morphine-tolerant rats. @*Methods@#Randall Selitto and hot-plate tests were utilized to measure the hindpaw withdrawal latencies (HWLs) in response to noxious mechanical and thermal stimuli. To induce chronic morphine tolerance, rats received intraperitoneal morphine injection twice per day for seven days. CaMK II expression and activity were assessed using western blotting. @*Results@#Intra-NAc microinjection of autocamtide-2-related inhibitory peptide (AIP) induced an increase in HWLs in naïve rats in response to noxious thermal and mechanical stimuli. Moreover, the expression of the phosphorylated CaMK II (p-CaMK II) was significantly decreased as determined by western blotting. Chronic intraperitoneal injection of morphine resulted in significant morphine tolerance in rats on Day 7, and an increase of p-CaMK II expression in NAc in morphine-tolerant rats was observed. Furthermore, intra-NAc administration of AIP elicited significant antinociceptive responses in morphine-tolerant rats. In addition, compared with naïve rats, AIP induced stronger thermal antinociceptive effects of the same dose in rats exhibiting morphine tolerance. @*Conclusions@#This study shows that CaMK II in the NAc is involved in the transmission and regulation of nociception in naïve and morphine-tolerant rats.
ABSTRACT
BACKGROUND: This team modified the arthroscopic reduction and internal fixation with canulated screw through very high-posteromedial portal approach to perform direct compression. Thus, the pressure of the fracture block is evenly distributed on the healing line, and the operation is convenient and fixed firmly, but its clinical effect remains to be further confirmed. OBJECTIVE: To compare the clinical outcome of arthroscopic reduction and internal fixation with canulated screw through very high-posteromedial portal approach and double bundle suture fixation for avulsion fracture of the tibial attachment of posterior cruciate ligament. METHODS: From January 2011 to May 2017, 60 cases of the avulsion fracture of posterior cruciate ligament (transverse diameter of fracture block > 10 mm) were treated operatively at the Orthopedics and Arthroscopic Ward Two, First Hospital of Qinhuangdao, China. According to different modes of operation in different periods, patients were assigned to two groups. In the canulated screw group (n=31), patients were treated with canulated screw through very high-posteromedial portal approach. In the suture group (n=29), patients were treated with double bundle suture fixation through posteromedial portal approach. General conditions were compared between the two groups. Knee function was assessed with the Intemational Knee Documentation Committee and Lysholm scores. Knee stability was evaluated with KT-2000 and posterior drawer test. RESULTS AND CONCLUSION: (1) All the patients were followed up (range 6-12 months). (2) The average operation time was (63.49±3.97) minutes in the canulated screw group and (87.28±3.46) minutes in the suture group (P < 0.05). At 3 months after surgery, all the patients were healed. (3) At the final follow-up, in the canulated screw group, the negative rate of posterior drawer test was 90%. Lysholm scores were 94.89±4.75. IKDC scores were 94.01±3.25. In the suture group, the negative rate of posterior drawer test was 90%. Lysholm scores were 95.56±3.63. IKDC scores were 95.52±4.72. No significant difference was determined between the two groups (P > 0.05). (4) KT-2000 measurement results revealed that there were no significant differences between the surgical knee and the normal knee in both groups (canulated screw group:(2.53±1.02)mm versus(2.12±0.83)mm;suture group:(2.65±0.82)mm versus(2.19±0.63)mm (P > 0.05). Moreover, no significant difference was detected in the affected knee of KT-2000 results between the two groups. (5) Both arthroscopic reduction with canulated screw through very high-posteromedial portal approach and double bundle suture fixation can achieve satisfactory clinical outcomes, but arthroscopic reduction with canulated screw through very high-posteromedial portal approach in patients with fracture block diameter > 10 mm can result in shorter operation time, more reliable fixation, and thus permit an early postoperative functional exercise.