Experimental neurology
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Experimental neurology · Sep 2013
Increased SMA-M1 coherence in Parkinson's disease - Pathophysiology or compensation?
Parkinson's disease (PD) is a common neurodegenerative disorder owing to loss of dopaminergic cells. Akinesia - one of the core symptoms of PD - is associated with exaggerated oscillations at beta frequency (13-30 Hz) within the subthalamic nucleus (STN). Thus, enhanced oscillations below 30 Hz are assumed to represent a pathophysiological marker of PD. ⋯ During rest a significant positive correlation between disease duration and SMA-M1 coherence was found ON but not OFF medication. Conversely, during isometric contraction SMA-M1 coherence and UPDRS III were inversely correlated OFF but not ON medication explaining more than 80% of variance. The results favor the hypothesis that OFF medication exaggerated cortical coherence at beta frequency represents a compensatory mechanism rather than a pathophysiological marker per se.
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Experimental neurology · Sep 2013
Cutaneous noradrenaline measured by microdialysis in complex regional pain syndrome during whole-body cooling and heating.
Complex regional pain syndrome (CRPS) is characterised by autonomic, sensory, and motor disturbances. The underlying mechanisms of the autonomic changes in CPRS are unknown. However, it has been postulated that sympathetic inhibition in the acute phase with locally reduced levels of noradrenaline is followed by an up-regulation of alpha-adrenoceptors in chronic CRPS leading to denervation supersensitivity to catecholamines. ⋯ CRPS pain and the perceived skin temperature were measured every 5 min during thermal exposure, while noradrenaline was determined from cutaneous microdialysate collected every 20 min throughout the study period. Cooling induced peripheral sympathetic activation in patients and controls with significant increases in dermal noradrenaline, vasoconstriction, and reduction in skin temperature. The main findings were that the noradrenaline response did not differ between patients and controls or between the CRPS hand and the contralateral unaffected hand, suggesting that the evoked noradrenaline release from the cutaneous sympathetic postganglionic fibres is preserved in chronic CRPS patients.
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Experimental neurology · Sep 2013
Environmental enrichment promotes robust functional and histological benefits in female rats after controlled cortical impact injury.
Environmental enrichment (EE) consistently induces marked benefits in male rats after traumatic brain injury (TBI), but whether similar efficacy extends to females is not well established. Hence, the aim of this study was to reassess the effect of EE on functional and histological outcome in female rats after brain trauma. Twenty-four normal cycling adult female rats underwent verification of estrous stage prior to controlled cortical impact (CCI) or sham injury and then were assigned to EE or standard (STD) housing. ⋯ EE also provided significant histological protection as confirmed by increased CA(1/3) cell survival and decreased cortical lesion size vs. STD. These data demonstrate that EE confers robust benefits in female rats after CCI injury, which parallels numerous studies in males and lends further credence for EE as a preclinical model of neurorehabilitation.
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Electrolytic lesion of the medial septum, a basal forebrain nucleus that projects to the hippocampus, prolonged the emergence from general anesthesia in rats. Septal lesioned rats required a longer time to recover from a loss of righting reflex (LORR) and a loss of tail-pinch response after injectable (20 mg/kg i.p. pentobarbital, 5mg/kg i.v. propofol) or volatile (1.5% halothane, 2% isoflurane) anesthetic. When incremental doses of propofol were given i.p., septal lesioned rats as compared to control rats showed LORR at a lower dose of propofol. ⋯ Medial septal lesion resulted in a near complete loss of hippocampal theta rhythm during walking and a general decrease in power of the hippocampal EEG at all frequencies (0-100 Hz), during walking or immobility. It is concluded that lesion of medial septum, in part through a loss of septohippocampal cholinergic afferents, increased the anesthesia response to volatile and injectable general anesthetics, during both induction and emergence. It is suggested that the septohippocampal system participates in many components of general anesthesia including hypnosis, immobility, and analgesia.
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Experimental neurology · Sep 2013
Functional consequences of ethidium bromide demyelination of the mouse ventral spinal cord.
Ethidium bromide (EB) has been extensively used in the rat as a model of spinal cord demyelination. However, this lesion has not been addressed in the adult mouse, a model with unlimited genetic potential. Here we characterize behavioral function, inflammation, myelin status and axonal viability following bilateral injection of 0.20 mg/mL ethidium bromide or saline into the ventral white matter (VWM) of female C57Bl/6 mice. ⋯ As these data suggest that EB-injection in the mouse spinal cord is a non-remyelinating lesion, we sought to ask whether wheel running could promote recovery by enhancing plasticity of local lumbar circuitry independent of remyelination. This did not occur as BMS and Treadscan assessment revealed no significant effect of wheel running on recovery. However, this study defines the importance of descending ventral motor pathways to locomotor function in the mouse as VWM loss results in a chronic hindlimb deficit.