Preconditioning with cobalt chloride modifies pain perception in mice.

Cobalt chloride (CoCl2) modifies mitochondrial permeability and has a hypoxic-mimetic effect; thus, the compound induces tolerance to ischemia and increases resistance to a number of injury types. The aim of the present study was to investigate the effects of CoCl2 hypoxic preconditioning for three weeks on thermonociception, somatic and visceral inflammatory pain, locomotor activity and coordination in mice. A significant pronociceptive effect was observed in the hot plate and tail flick tests after one and two weeks of CoCl2 administration, respectively (P<0.001). Thermal hyperalgesia (Plantar test) was present in the first week, but recovered by the end of the experiment. Contrary to the hyperalgesic effect on thermonociception, CoCl2 hypoxic preconditioning decreased the time spent grooming the affected area in the second phase of the formalin test on the orofacial and paw models. The first phase of formalin-induced pain and the writhing test were not affected by CoCl2 preconditioning. Thus, the present study demonstrated that CoCl2 preconditioning has a dual effect on pain, and these effects should be taken into account along with the better-known neuro-, cardio- and renoprotective effects of CoCl2.

Motor cortex plasticity--from physiology to clinical neurology.

Neurophysiologic, neuroanatomic and neuroimaging studies conducted over the past two decades reveal that the cerebral cortex is functionally and structurally dynamic. The functional topography of the motor cortex can be modified by a variety of experimental manipulations, including peripheral or central injury, electrical stimulation, pharmocologic treatment or behavioral experience. Recent evidence demonstrates that functional alterations in motor cortex organization are accompanied by changes in dendritic and synaptic structure, as well as alterations in the regulation of cortical neurotransmitter systems. This article describes the state of the science regarding the main mechanisms implicated in the motor cortex plasticity, the main tools used for its investigation and the consequence of the recent discoveries on the therapeutic and rehabilitation procedures for the brain-injured persons.