The Effects And Mechanism Of Urocortin-2 On Behavioral And Learning-memory Function In Morphine Addiction Rats

This experiment mainly observed the effects of neuro-active peptide Urocortin-2(UCN-2)on striatum(STR)neuron discharge in morphine addicted rat,as well as the effects of behavior and learning memory function of UCN-2in morphine-addicted rats,and made a preliminary study of the mechanism,also provided the theoretical support and drug target for the treatment of detoxification of clinical opioid addiction.MethodsThe study selected Sprague-Dawley(SD)rats as experimental subjects,and the experiments were randomly divided into three groups,including the normal Group(NG group),morphine addiction model group,(MAG group),as well as the UCN-2+MAG group(morphine addiction plus given UCN-2),each group of experimental animals given 12 days,and then test results.After giving morphine to the addiction model,naloxone was used to induce the development of withdrawal symptoms,koobs symptom score was carried out,fatigue-to-stick experiment,force-exhausting swimming experiment,etc.were used to determine the effect of UCN-2 in morphine-addicted rat behavior.Using the Morris water maze experiment,the improvement of learning memory ability of UCN-2 in morphine-addicted rats was determined.In addition,a five-tube micro-electrode was used for micro-electrophoresion to observe the effects of spontaneous discharge of UCN-2 on striatum neurons.AST-2B andprotein kinase B(protein kinase B,PKB)inhibitors were given to identify possible mechanisms.After the above-mentioned experiment,the brain tissue of each group of experimental animals was taken for pathological testing,and the brain tissue homogenization was used to detect the expression of AKT and p-AKT by western blot method,and the relevant mechanism of the effects of UCN-2 on morphine-addicted rats was discussed.Results1.UCN-2 significantly reduced the morphine-addicted rat symptom score,improved withdrawal syndrome,and had a significant difference(P<0.05),compared to the MAG group.2.UCN-2 has anti-fatigue effects in morphine-addicted rats:(1)UCN-2can prolong the turn-to-bar time on clockwise mode and counterclockwise mode,compared to the MAG group,has a significant difference(P<0.05).(2)In the swimming exhaustion experiment,compared with the MAG group,the swimming time was extended,the time of struggle,the time of learning to swim was significantly shortened,with significant difference(P<0.05),indicating that UCN-2 can significantly improve the behavioral indicators of morphine-addicted rats,and improve learning ability.3.Effects of UCN-2 on learning memory in morphine-addicted rats: In Morris water maze behavioral experiments,UCN-2 was able to extend swimming time in the original platform quadrant,escape incubation period and swimming distance were shortened in morphine-addicted rats,with significant differences compared to the MAG group(P<0.05).4.Effect of UCN-2 on STR neuron discharge in morphine-addicted rats:UCN-2 slows down the discharge frequency of STR neurons in morphine-addicted rats,reduces the burst and discharge of neurons,which has significant differences compared to the MAG group(P<0.05).The inhibition of the discharge of STR neurons in UCN-2 morphine-addicted rats can be cancelled by PKB inhibitor and CRF-2R blocker AST-2B.5.Effects of UCN-2 on pathological changes in brain tissue in morphine-addicted rats: blue dyed neurons in each group,STR location is accurate.The UCN-2 group of neurons was arranged more regularly,the size of the neurons was lower than the normal,the denatured necrosis of nerve cells and the change of empty bubble synods.6.Effects of UCN-2 on AKT expression in morphine-addicted rats: AKT protein expression decreased in the UCN-2 group compared to the MAG group,while p-AKT expression increased,and the results were statistically significant and had significant differences(P<0.05).Conclusions1.UCN-2 could improve the withdrawal syndrome,improve the fatigue resistance,improve the learning and memory ability of morphine-addicted rats,and prove that UCN-2 has therapeutic effects on morphine addiction.2.UCN-2 could inhibit abnormal high-frequency discharge of STR neurons in morphine-addicted rats and improves the pathological structure of brain tissue.3.The possible mechanism of the improvement of behavior and learning memory in UCN-2 is by binding to CRF-2 receptors,which in turn affects the p-AKT-AKT signaling pathway in morphine-addicted rats.