Methamphetamine abuse impairs motor cortical plasticity and function.

Exposure to addictive drugs triggers synaptic plasticity in reward-related brain regions, such as the midbrain, nucleus accumbens and the prefrontal cortex. Effects of chronic drug exposure on other brain areas have not been fully investigated. Here, we characterize synaptic plasticity in motor cortex after methamphetamine self-administration in rats. We show that this causes a loss of corticostriatal plasticity in rat brain slices and impaired motor learning in the rotarod task. These findings are paralleled by the observation of a lack of transcranial magnetic stimulation-induced potentiation or depression of motor evoked potentials in human patients with addiction, along with poor performance in rotary pursuit task. Taken together, our results suggest that chronic methamphetamine use can affect behavioral performance via drug-evoked synaptic plasticity occluding physiological motor learning.

[Neurogenesis as a therapeutic strategy to regenerate central nervous system]. / Neurogénesis como estrategia terapéutica para regenerar el sistema nervioso central.

INTRODUCTION: In the past few years, it has been demonstrated that the adult mammalian brain maintains the capacity to generate new neurons from neural stem/progenitor cells. These new neurons integrate into pre-existing systems through a process referred to as 'neurogenesis in the adult brain'. DEVELOPMENT: This discovery has modified our understanding of how the central nervous system functions in health and disease. Until today, a great effort has been made attempting to decipher the mechanisms regulating adult neurogenesis, which might help to induce neuronal endogenous cell replacement in various neurological diseases. CONCLUSIONS: In this revision, we will attempt to shed some light on the neurogenesis process with respect to diseases of the central nervous system and we will describe some therapeutic potentials in relation to neurodegenerative diseases.

[Neurogenesis in the adult brain]. / Neurogénesis en el cerebro adulto.

INTRODUCTION: The discovery that new neurons continue to be generated in the adult brain has modified the concept of brain plasticity and has brought to light new mechanisms that ensure the homeostasis of the nervous system. DEVELOPMENT: Neurogenesis, that is to say, the process involving the generation of new neurons, has been shown to occur in the hippocampus and in the olfactory bulb in adult mammals, which suggests that neuronal stem cells persist throughout the entire lifespan. The primary precursors have been identified in specialised regions called neurogenic niches. Interestingly, the cells that give rise to the new neurons in the adult brain express markers for glial cells, a cell lineage that is a long way from that of neurons. Studies conducted during the development of the brain have shown that radial glial cells not only give rise to astrocytes but also neurons, oligodendrocytes and ependymal cells. In addition, it is known that radial glial cells are also the precursors of neuronal stem cells in the adult brain. CONCLUSIONS: Overall, these data support the idea that stem cells develop from a neuroepithelial-glial radial-astrocytic lineage. Thus, identifying the primary precursors, both in the developing brain and in the adult brain, is essential to understand the functioning of the nervous system and, from there, to develop strategies for neuronal replacement in the adult brain when needed.

Vagus nerve stimulation in treating depression: A tale of two stories.

Vagus nerve stimulation (VNS) has been widely used to treat different neurological disorders, especially epilepsy. Accumulating evidence also suggests its potential application in antidepressive therapy, given that VNS has been confirmed by several clinical trials to exert long-term effects on mitigating depression and reducing the risk of relapse in depressed patients. Likewise, VNS has also proven to ameliorate the behavioral deficits in a rat model of depression. While the influences of VNS on monoamine metabolism and mood improvement are well-recognized, the underlying mechanisms mediating its antidepressive action remain poorly understood. Recent findings suggest that VNS-enhanced proliferation of hippocampal neural progenitor cells (NPCs) and synaptic transmission might serve as a monoamine-independent pathway contributive to the beneficial effects of VNS on depression. Here we briefly reviewed the recent progress in this field, based on which we propose that there might be, at least, two little-overlapped, and yet interactive pathways mediating the antidepressive action of VNS.

Retracted: Hypocretin (orexin) cell transplantation diminishes narcoleptic-like sleep behavior in rats.

Arias-Carrión, O.; Drucker-Colín, R.; Murillo-Rodríguez, E. "Hypocretin (orexin) cell transplantation diminishes narcoleptic-like sleep behavior in rats." CNS Neurol. Disord. Drug Targets, 2011,11(7). The above-cited paper has been retracted from CNS & Neurological Disorders-Drug Targets at the request of the authors. The authors advised the Journal of their intention to perform additional experiments in order to strengthen their initial results, at which time an amended manuscript may be submitted.

Neurogenesis in the subventricular zone following transcranial magnetic field stimulation and nigrostriatal lesions.

Neurogenesis continues at least in two regions of the mammalian adult brain, the subventricular zone (SVZ) and the subgranular zone in hippocampal dentate gyrus. Neurogenesis in these regions is subjected to physiological regulation and can be modified by pharmacological and pathological events. Here we report the induction of neurogenesis in the SVZ and the differentiation after nigrostriatal pathway lesion along with transcranial magnetic field stimulation (TMFS) in adult rats. Significant numbers of proliferating cells demonstrated by bromodeoxyuridine-positive reaction colocalized with the neuronal marker NeuN were detected bilaterally in the SVZ, and several of these cells also expressed tyrosine hydroxylase. Transplanted chromaffin cells into lesioned animals also induced bilateral appearance of subependymal cells. These results show for the first time that unilateral lesion, transplant, and/or TMFS induce neurogenesis in the SVZ of rats and also that TMFS prevents the motor alterations induced by the lesion.