anisomycin and Spinal-Cord-Injuries

The study aimed to determine the effects of protease-activated receptor-2 (PAR-2) on glial scar formation after spinal cord injury (SCI) in Sprague-Dawley (SD) rats and the underlying mechanisms. Rivlin and Tator's acute extradural clip compression injury (CCI) model of severe SCI was established in this study. Animals were divided into four groups: 1) sham group (laminectomy only); 2) model group, treated with normal saline; 3) PAR-2 inhibitor group; 4) PAR-2 activator group. Enhanced GFAP and vimentin expression were the markers of glial scar formation. To determine whether JNK was involved in the effects of PAR-2 on GFAP and vimentin expression, we administered anisomycin (a JNK activator) in the presence of PAR-2 inhibitor and SP600125 (a JNK inhibitor) in the presence of PAR-2 activator. At 1, 7, 14 and 28 day after SCI, Basso, Beattie, and Bresnahan (BBB) locomotor score test was used to assess the locomotor functional recovery; immunofluorescence and western blot analysis were used to assess the expression level of GFAP, vimentin and p-JNK. Double immunofluorescence staining with GFAP and tubulin beta was used to assess the glial scar formation and the remaining neurons. Results suggested that PAR-2 is involved in glial scar formation and reduces neurons residues which can cause a further worsening in the functional outcomes after SCI via JNK signaling. Therefore, it may be effective to target PAR-2 in the treatment of SCI.

Topics: Animals; Anisomycin; Anthracenes; Cicatrix; Female; MAP Kinase Signaling System; Rats; Rats, Sprague-Dawley; Receptor, PAR-2; Spinal Cord Injuries

Previous research has shown that spinally transected rats will learn to maintain a flexion response when administered shock contingent upon leg position. In short, a contingency is arranged between shock delivery and leg extension so that Master rats exhibit an increase in flexion duration that lasts throughout the training session. Furthermore, when Master rats are later tested they reacquire the flexion response in fewer trials, indicative of some savings. As a control, a second group of spinal rats (Yoked rats) are given shock irrespective of leg position (noncontingent shock). These animals fail to show the same increase in leg flexion duration. Interestingly, when Yoked rats are later tested with a shock contingency in place, they still fail to learn (learning deficit). The present experiments were designed to determine whether both forms of instrumental learning in spinal animals require de novo protein synthesis. As such, we administered various doses of anisomycin intrathecally prior to training. Additionally, spinal rats were trained and tested either immediately or 24 h after test. We found that only the highest dose of anisomycin (125 microg/microl) had an effect in Yoked animals that were tested 24 h after training. Specifically, the highest dose of anisomycin reversed the learning deficit in those animals. Moreover, anisomycin had a similar effect when administered prior to training and immediately following training, but not 6 h after training. Finally, the results demonstrated that the observed effect of anisomycin was not due to state-dependency.

Topics: Animals; Anisomycin; Behavior, Animal; Conditioning, Operant; Dose-Response Relationship, Drug; Hindlimb; Injections, Spinal; Male; Protein Synthesis Inhibitors; Rats; Rats, Sprague-Dawley; Reflex; Spinal Cord Injuries; Time Factors