Neuroscience letters
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Neuroscience letters · Aug 2013
Alterations of mean diffusivity in brain white matter and deep gray matter in Parkinson's disease.
Although Parkinson's disease is a neurodegenerative disease primarily involving basal ganglia and midbrain, the deficit of white matter is also involved during the disease progression. As the diffusion tensor imaging method is sensitive to the microstructural changes, we investigated the microstructural alterations in white matter and deep gray matter in patients with Parkinson's disease. Brain images of 64 patients and sex- and age-matched 64 healthy controls were obtained from a 3T MRI scanner. ⋯ There were white matter deficits in the corticofugal tract, cingulum, uncinate fasciculus, crus of fornix or stria terminalis, corpus callosum, external capsule, superior longitudinal fasciculus, posterior thalamic radiation including optic radiation, and the tracts adjacent to the precuneus and supramarginal gyrus, as indicated by higher mean diffusivity in Parkinson's disease patients than in controls. There were also deficits in the left putamen, pallidum, thalamus, and caudate as indicated by higher mean diffusivity in Parkinson's disease patients than in controls. Using diffusion tensor imaging and multi-methods of image analysis, we successfully characterized and visualized brain white matter and deep gray matter areas with microstructural deficits in Parkinson's disease patients.
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Neuroscience letters · Aug 2013
The inhibition of cocaine-induced locomotor activity by CART 55-102 is lost after repeated cocaine administration.
CART peptide is known for having an inhibitory effect on cocaine- and dopamine-mediated actions after acute administration of cocaine and dopamine. In this regard, it is postulated to be a homeostatic, regulatory factor on dopaminergic activity in the nucleus accumbens (NAc). ⋯ The loss of CART peptide's inhibitory effect did not return for up to 9 weeks after stopping the repeated cocaine administration. It may not be surprising that homeostatic regulatory mechanisms in the NAc are lost after repeated cocaine administration, and that this may be a mechanism in the development of addiction.
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Neuroscience letters · Aug 2013
Involvement of the dorsal hippocampal dopamine D2 receptors in histamine-induced anxiogenic-like effects in mice.
Anxiety-related behaviors increase histamine and dopamine release in the brain. On the other hand, central histamine counteracts reward and reinforcement processes mediated by the mesolimbic dopamine system. We investigated the effects of the histaminergic system and dopamine D2 receptors agents and their interactions on anxiety-related behaviors using the elevated plus-maze (EPM). ⋯ Histamine can decrease dopaminergic tone in the dorsal hippocampus through decreasing the endogenous dopamine release, whereas quinpirole does the same via the postsynaptic DA receptors' activation. Sulpiride however renders the same effect through autoreceptors' blockade and potentiated dopamine transmission. Thus, quinpirole and sulpiride seem to compensate the effects of the intra-CA1 injection of exogenous histamine, and tend to exert anxiolytic effects in the presence of histamine.
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Neuroscience letters · Aug 2013
Mammal retinal distribution of ENKergic amacrine cells and their neurochemical features: evidence from the PPE-GFP transgenic mice.
The neuroactive peptide enkephalin (ENK) has been postulated to play important roles in modulating visual information. The retinal presence of ENKergic cells has been revealed with conventional morphological protocols targeting ENK molecule especially in avian, however, the detailed distribution of ENKergic cells and their specific neurochemical features in the mammal retina remain unclear because of the difficulties in visualizing ENKergic cells efficiently and reliably. To address this question, we took advantage of the preproenkephalin-green fluorescent protein (PPE-GFP) transgenic mice previously generated and identified in our group, and identified the neurochemical characteristics of retinal ENKergic cells. ⋯ However, some of them also utilized excitatory glutamate as the primary neurotransmitter. The present findings suggest that the retinal ENKergic cells fall into a subpopulation of amacrine cells and show predominantly inhibitory as well as less dominantly excitatory neurochemical features. Our findings offered comprehensive morphological evidence for the function of ENKergic amacrine cells of mammal species.
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Neuroscience letters · Aug 2013
Choline, an alpha7 nicotinic acetylcholine receptor agonist, alleviates hyperalgesia in a rat osteoarthritis model.
It has been suggested that activation of alpha7 nicotinic acetylcholine receptors (α7nAChR) could alleviate acute and chronic pain in various abnormal pain models. However, it is unclear whether the stimulation of α7nAChRs has anti-hyperalgesic effects on osteoarthritis. Therefore, we tested whether choline, an α7nAChR agonist, could alleviate chronic inflammatory pain in an osteoarthritis model. ⋯ Intrathecal choline increased PWT and PWL. The anti-hyperalgesic effect of intraperitoneal choline was completely blocked by methyllycaconitine when it was injected intrathecally 10 min before the choline treatment. These results show that choline could alleviate mechanical and heat hyperalgesia via spinal α7nAChR in the MIA-induced inflammation pain model.