Brain research
-
The aim of this study was to elucidate physiological processes that are involved in the homeostatic regulation of REM sleep. Adult rats were chronically instrumented with sleep-wake recording electrodes. Following post-surgical recovery, rats were habituated extensively for freely moving polygraphic recording conditions. ⋯ During the last 2 h, after REM sleep deprivation, rats spent 51% more time in REM sleep compared to the BLD. Also during this period, the number of REM sleep episodes with the shortest (5-30 s) and longest (>120 s) duration increased during the RDD. These findings suggest that the REM sleep homeostatic process involves increased delta- and decreased theta-frequency wave activities in the cortical EEG.
-
Previously, we identified 14-3-3 beta and zeta isoforms and proteolytic fragments of alpha-spectrin as proteins released from degenerating neurons that also rise markedly in cerebrospinal fluid (CSF) following experimental brain injury or ischemia in rodents, but these proteins have not been studied before as potential biomarkers for ischemic central nervous system injury in humans. Here we describe longitudinal analysis of these proteins along with the neuron-enriched hypophosphorylated neurofilament H (pNFH) and the deubiquitinating enzyme UCH-L1 in lumbar CSF samples from 19 surgical cases of aortic aneurysm repair, 7 involving cardiopulmonary bypass with deep hypothermic circulatory arrest (DHCA). CSF levels of the proteins were near the lower limit of detection by Western blot or enzyme-linked fluorescence immunoassay at the onset of surgical procedures, but increased substantially in a subset of cases, typically within 12-24 h. ⋯ Six of 7 also exhibited marked increases in alpha-spectrin fragments generated by calpain, a protease known to trigger necrotic neurodegeneration. Among cases involving aortic cross-clamping but not DHCA, the proteins rose in CSF preferentially in the subset experiencing acute neurological complications. Our results suggest the neuron-enriched 14-3-3beta, 14-3-3zeta, pNFH, UCH-L1, and calpain-cleaved alpha-spectrin may serve as a panel of biomarkers with clinical potential for the detection and management of ischemic central nervous system injury, including for mild damage associated with surgically-induced circulation arrest.
-
Memory impairment is common following traumatic brain injury. However, the specific processes underlying the impairments remain unknown. Traumatic brain injury may interfere with several of the stages of the learning and memory process. ⋯ However, after the reminding procedure, injured animals displayed sham-level performance during the second probe trial. The results of these experiments suggest that with anterograde memory impairment induced by traumatic brain injury, the primary deficit lies in task acquisition, not the retention of information within long-term memory. Retrograde memory impairment following injury appears to be mediated primarily by deficits in memory retrieval.