Neuroscience
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Rotenone is a pesticide that inhibits mitochondrial complex I activity, thus creating an environment of oxidative stress in the cell. Many studies have employed rotenone to generate an experimental animal model of Parkinson's disease (PD) that mimics and elicits PD-like symptoms, such as motor and cognitive decline. Cytoprotective proteins including parkin and heat shock proteins (HSPs) play major roles in slowing PD progression. ⋯ These protective proteins help maintain cellular homeostasis and may be capable of rescuing cells from death. Therefore, we assessed the levels of different HSPs in the rotenone-treated animals. Collectively, our studies indicated the following findings in the striatum and substantia nigra following chronic rotenone exposure in an experimental PD model: (i) behavioral deficit that correlated with histopathological changes and down regulation of TH signaling, (ii) decreased levels of the cytoprotective proteins parkin, DJ1 and Hsp70 and robust expression of mitochondrial chaperone Hsp60 according to Western blot, (iii) increased immunoreactivity for caspase 9, caspase 3 and ubiquitin and decreased parkin immunoreactivity.
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The perifornical-lateral hypothalamic area (PF-LHA) is a major wake-promoting structure. It predominantly contains neurons that are active during behavioral and cortical activation. Nitric oxide (NO) is a gaseous neurotransmitter that has been implicated in the regulation of sleep. ⋯ We found that NOC-18-induced suppression in the discharge activity of PF-LHA neurons was significantly attenuated during the blockade of adenosine A(1) receptor-, GABA(A) receptor-, and sGC-cGMP-mediated signaling. These findings suggest that NO-evoked inhibition of PF-LHA neurons involves a complex mechanism including, but may not be limited to, adenosinergic, GABAergic and sGC-cGMP signaling pathways. The findings are consistent with a generalized sleep-promoting role of NO within the PF-LHA and, given the sleep-promoting roles of adenosinergic and GABAergic systems in this area, further suggest that this effect may be mediated through nitrergic interactions with other neurotransmitters and neuromodulators.
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Dementia, especially Alzheimer's disease, is a rapidly increasing medical condition that presents with enormous challenge for treatment. It is characterized by impairment in memory and cognitive function often accompanied by changes in synaptic transmission and plasticity in relevant brain regions such as the hippocampus. We recently synthesized TH-9, a conjugate racetam-methylxanthine compound and tested if it had potential for enhancing synaptic function and possibly, plasticity, by examining its effect on hippocampal fast excitatory synaptic transmission and plasticity. ⋯ Conversely, induction of LTP or LTD completely occluded the ability of TH-9 to enhance fEPSPs. Thus, TH-9 utilizes cholinergic and adenosinergic mechanisms to cause long-lasting enhancement in fEPSPs which were occluded by LTP and LTD. TH-9 may therefore employ similar or convergent mechanisms with frequency-dependent synaptic plasticities to produce the observed long-lasting enhancement in synaptic transmission and may thus, have potential for use in improving memory.
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Activating transcription factor 3 (ATF3) is a stress-induced transcription factor that has been shown to repress inflammatory gene expression in multiple cell types and diseases. This study was conducted to investigate the role of ATF3 in the pathological processes of cerebral ischemia and its influence on post-ischemic inflammation. ⋯ Our study demonstrated that ATF3 was markedly induced by brain ischemia. ATF3 deficiency exacerbated the inflammatory response and brain injury after cerebral ischemia, potentially through further activation of the NF-κB signaling pathway. ATF3 is likely an important protective regulator in cerebral ischemic injury.
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The Ts65Dn (TS) mouse model of Down syndrome (DS) displays a number of behavioral, neuromorphological and neurochemical phenotypes of the syndrome. Altered GABAergic transmission appears to contribute to the mechanisms responsible for the cognitive impairments in TS mice. Increased functional expression of the trisomic gene encoding an inwardly rectifying potassium channel, subfamily J, member 6 (KCNJ6) has been reported in DS and TS mice, along with the consequent impairment in GAB Aergic function. ⋯ Also, ETH and GAB did not induce anxiety in the open field or plus maze tests, did not alter performance in the Morris water maze, and did not affect cued - or context - fear conditioning. Our results thus suggest that KCNJ6 may not be a promising drug target candidate in DS. As a corollary, they also show that long-term use of ETH and GAB is devoid of adverse behavioral and cognitive effects.