BACKGROUND: Clusterin has many biological functions, especially the great protection effects on histiocytes in pathological conditions. It will be helpful to discuss the expression of clusterin in the spinal cord injury tissue to further identify the mechanism of secondary spinal cord injury and to provide possible treatments.OBJECTIVE: To observe the expression of clusterin in acute spinal cord injury tissue.DESIGN: Randomized controlled animal study.SETTING: Department of Orthopaedics, First Affiliated Hospital, China Medical University.MATERIALS: The experiment was performed in Experimental Animal Department, China Medical University from January 2003 to January 2006.A total of 65 adult healthy SD rats of 250-300 g provided by Experimental Animal Department, China Medical University were selected. METHODS: All the rat models by modified Allen assay for acute spinal cord injury were randomized into injury group, sham operation group and normal control group with 30, 30 and 5 rats in each group, respectively.The rat injury models in dorsal spinal cord were prepared by modified Allen assay: the target injury site was T10 segment; the sham operation group was given T10 total laminectomy. The normal control group received no operation. Rats in the injury group and sham operation group were killed at hour 12, days 1, 3, 7, 14 and 21 after spinal injury and operation with 5 rats at each time point, respectively. Frozen sections of the injury part were made at different time point after injury. Degeneration and necrosis of spinal cord injury tissues were observed with hematoxylin-eosin (HE) staining. Deposition and disposition of positive reactants of clusterin were observed with clusterin immunohistochemical staining. Average gray value of positive reactants of clusterin was detected with semi-quantitative image analysis (went with the intensity of clusterin immunoreaction in inverse ratio).MAIN OUTCOME MEASURES: ①Degeneration and necrosis as well as positive expression of clusterin of spinal cord injury tissues of rats in each group. ②Average gray value of clusterin positive reactants in spinal cord injury tissues of rats in each group.RESULTS: A total of 65 rats were involved in the result analysis, without dropout. ①In the injury group, positive expression of clusterin began to increase at day 1 after injury, reached peak at about day 7, declined gradually at day 14 and tended to be stable at day 21 after injury. This dynamic course of change was along with the prolongation of time. The expression of clusterin appeared in the sham operation group and normal control group at each time point, and the expression was stable. There was no dynamic change with the prolongation of time. ②In the injury group average gray value of positive reactants of clusterin was significantly lower at days 1, 3,7, 14 and 21 as compared with that in the sham operation group and normal control group (t=6.33-15.57, P ＜ 0.01 ). There was no significant difference in average gray value of positive reactants of clusterin at each time point in the sham operation group as compared with the normal control group (P ＞ 0.05).CONCLUSION: The expression of clusterin increases greatly in acute spinal cord injury tissues, and has dynamic change, which is the same with spinal cord injury.

Methcathinone (MCAT) belongs to the designer drugs called synthetic cathinones, which are abused worldwide for recreational purposes. It has strong stimulant effects, including enhanced euphoria, sensation, alertness, and empathy. However, little is known about how MCAT modulates neuronal activity in vivo. Here, we evaluated the effect of MCAT on neuronal activity with a series of functional approaches. C-Fos immunostaining showed that MCAT increased the number of activated neurons by 6-fold, especially in sensory and motor cortices, striatum, and midbrain motor nuclei. In vivo single-unit recording and two-photon Ca²⁺ imaging revealed that a large proportion of neurons increased spiking activity upon MCAT administration. Notably, MCAT induced a strong de-correlation of population activity and increased trial-to-trial reliability, specifically during a natural movie stimulus. It improved the information-processing efficiency by enhancing the single-neuron coding capacity, suggesting a cortical network mechanism of the enhanced perception produced by psychoactive stimulants.
Mice ; Animals ; Reproducibility of Results ; Neurons ; Sensation ; Perception