Neurobiology of disease
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Neurobiology of disease · Nov 2014
Regulation of alternative VEGF-A mRNA splicing is a therapeutic target for analgesia.
Vascular endothelial growth factor-A (VEGF-A) is best known as a key regulator of the formation of new blood vessels. Neutralization of VEGF-A with anti-VEGF therapy e.g. bevacizumab, can be painful, and this is hypothesized to result from a loss of VEGF-A-mediated neuroprotection. The multiple vegf-a gene products consist of two alternatively spliced families, typified by VEGF-A165a and VEGF-A165b (both contain 165 amino acids), both of which are neuroprotective. ⋯ Exogenous VEGF-A165b also ameliorated neuropathic pain. We conclude that the relative levels of alternatively spliced VEGF-A isoforms are critical for pain modulation under both normal conditions and in sensory neuropathy. Altering VEGF-Axxxa/VEGF-Axxxb balance by targeting alternative RNA splicing may be a new analgesic strategy.
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Neurobiology of disease · Nov 2014
Deep brain stimulation in rats: different targets induce similar antidepressant-like effects but influence different circuits.
Recent studies in patients with treatment-resistant depression have shown similar results with the use of deep brain stimulation (DBS) in the subcallosal cingulate gyrus (SCG), ventral capsule/ventral striatum (VC/VS) and nucleus accumbens (Acb). As these brain regions are interconnected, one hypothesis is that by stimulating these targets one would just be influencing different relays in the same circuitry. We investigate behavioral, immediate early gene expression, and functional connectivity changes in rats given DBS in homologous regions, namely the ventromedial prefrontal cortex (vmPFC), white matter fibers of the frontal region (WMF) and nucleus accumbens. ⋯ In regard to functional connectivity, DBS in all targets decreased intercorrelations among cortical areas. This is in contrast to the clear differences observed in subcortical connectivity, which was reduced after vmPFC DBS but increased in rats receiving Acb or WMF stimulation. In conclusion, results from our study suggest that, despite similar antidepressant-like effects, stimulation of the vmPFC, WMF and Acb induces distinct changes in regional brain activity and functional connectivity.
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Neurobiology of disease · Nov 2014
Disease modifying effect of chronic oral treatment with a neurotrophic peptidergic compound in a triple transgenic mouse model of Alzheimer's disease.
Besides the presence of amyloid beta (Aβ) plaques and neurofibrillary tangles, neurogenesis and synaptic plasticity are markedly impaired in Alzheimer's disease (AD) possibly contributing to cognitive impairment. In this context, neurotrophic factors serve as a promising therapeutic approach via utilization of regenerative capacity of brain to shift the balance from neurodegeneration to neural regeneration. However, besides more conventional "bystander" effect, to what extent can neurotrophic compounds affect underlying AD pathology remains questionable. ⋯ This disease modifying effect was probably via increased brain derived neurotrophic factor (BDNF) expression mediated decrease in glycogen synthase kinase-3-β (GSK3β) activity we found in P021 treated 3xTg-AD mice. P021 treatment also rescued deficits in cognition, neurogenesis, and synaptic plasticity in 3xTg-AD mice. These findings demonstrate the potential of the neurotrophic peptide mimetic as a disease modifying therapy for AD.
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Neurobiology of disease · Nov 2014
Dynamic changes in pro- and anti-inflammatory cytokines in microglia after PPAR-γ agonist neuroprotective treatment in the MPTPp mouse model of progressive Parkinson's disease.
Neuroinflammatory changes play a pivotal role in the progression of Parkinson's disease (PD) pathogenesis. Recent findings have suggested that activated microglia may polarize similarly to peripheral macrophages in the central nervous system (CNS), assuming a pro-inflammatory M1 phenotype or the alternative anti-inflammatory M2 phenotype via cytokine production. A skewed M1 activation over M2 has been related to disease progression in Alzheimer disease, and modulation of microglia polarization may be a therapeutic target for neuroprotection. ⋯ The results show that the dopaminergic degeneration was associated with a gradual microglia polarization to the inflammatory over the anti-inflammatory phenotype in a chronic mouse model of PD. Neuroprotective treatment with rosiglitazone modulated microglia polarization, boosting the M2 over the pro-inflammatory phenotype. PPAR-γ agonists may offer a novel approach to neuroprotection, acting as disease-modifying drugs through an immunomodulatory action in the CNS.
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Neurobiology of disease · Nov 2014
Loss of dopamine disrupts circadian rhythms in a mouse model of Parkinson's disease.
Although a wide range of physiological functions regulated by dopamine (DA) display circadian variations, the role of DA in the generation and/or modulation of these rhythms is unknown. In Parkinson's disease (PD) patients, in addition to the classical motor symptoms, disturbances of the pattern of daily rest/wake cycles are common non-motor symptoms. We investigated daily and circadian rhythms of rest/activity behaviors in a transgenic MitoPark mouse model with selective inactivation of mitochondrial transcription factor A (Tfam) resulting in a slow and progressive degeneration of DA neurons in midbrain structures. ⋯ Re-exposure to a light/dark cycle completely restores daily locomotor rhythms. MitoPark mice and control littermates express similar masking behaviors under a 1h light/1h dark regime, suggesting that the maintenance of a daily pattern of rest/activity in arrhythmic MitoPark mice can be attributed to the acute inhibitory and stimulatory effects of light and darkness. These results imply that, in addition to the classical motor abnormalities observed in PD, the loss of the midbrain DA neurons leads to impairments of the circadian control of rest/activity rhythms.