Neuroscience
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This study examined the relationship between head and trunk sway during quiet stance and compared this relationship with that of the pelvis to the trunk. Sixteen younger and 14 elderly subjects participated, performing four different sensory tasks: standing quietly on a firm or foam support surface, with eyes open or closed. Roll and pitch angular velocities were recorded with six body-worn gyroscopes; a set of two mounted at the upper trunk, an identical set at the hips, and another set on a head band. ⋯ These data indicate that during quiet stance body motion increases in the order of pelvis, trunk, head and quiet stance involves control of at least two separate links: trunk on pelvis and head on trunk dominated by head resonance. The head is locked to the trunk for low-frequency motion possibly because motion is just supra-vestibular threshold. The head is not stabilised in space during stance, rather the pelvis is.
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The periaqueductal gray (PAG) is part of a descending pain modulatory system that, when activated, produces widespread and profound antinociception. Microinjection of either opioids or cannabinoids into the PAG elicits antinociception. Moreover, microinjection of the cannabinoid 1 (CB1) receptor agonist HU-210 into the PAG enhances the antinociceptive effect of subsequent morphine injections, indicating a direct relationship between these two systems. ⋯ Eight percent (8%) of PAG neurons that were MOP receptor-immunoreactive (-ir) received CB1 receptor-ir appositions. Ultrastructural analysis confirmed the presence of CB1 receptor-ir somata, dendrites and axon terminals in the PAG. These results indicate that behavioral interactions between cannabinoids and opioids may be the result of cellular adaptations within PAG neurons co-expressing CB1 and MOP receptors.
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Cholinergic activities affect olfactory bulb (OB) information processing and associated learning and memory. However, the presence of intrinsic cholinergic interneurons in the OB remains controversial. As a result, morphological and functional properties of these cells are largely undetermined. ⋯ Additionally, we quantitatively determined the density of VAChT labeled cholinergic nerve fibers in various layers of the OB, as well as the intensity of VAChT immunoreactivity within the GL, suggesting primary sites of cholinergic actions. Taken together, our results provide clear evidence showing the presence of a significant number of cholinergic interneurons and that these morphologically and distributionally diverse interneurons make up complex local cholinergic networks in the OB. Thus, our results suggest that olfactory information processing is modulated by dual cholinergic systems of local interneuron networks and centrifugal projections.
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Preclinical as well as limited clinical studies indicate that ketamine, a non-competitive glutamate N-methyl-D-aspartate (NMDA) receptor antagonist, may exert a quick and prolonged antidepressant effect. It has been postulated that ketamine action is due to inhibition of NMDA and stimulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors. Here, we sought to determine whether ketamine would exert antidepressant effects in Wistar-Kyoto (WKY) rats, a putative animal model of depression and whether this effect would be associated with changes in AMPA/NMDA receptor densities in the hippocampus. ⋯ These results indicate a rapid and lasting antidepressant-like effect of a low ketamine dose in WKY rat model of depression. Moreover, the increase in AMPA/NMDA receptor density in the hippocampus could be a contributory factor to behavioral effects of ketamine. These findings suggest potential therapeutic benefit in simultaneous reduction of central NMDA and elevation of AMPA receptor function in treatment of depression.
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X-linked adrenoleukodystrophy (X-ALD) and pseudo neonatal adrenoleukodystrophy (P-NALD) are neurodegenerative demyelinating diseases resulting from the functional loss of the peroxisomal ATP-binding cassette transporter D (ABCD1) and from single peroxisomal enzyme deficiency (Acyl-CoA oxidase1: ACOX1), respectively. As these proteins are involved in the catabolism of very long chain fatty acids (VLCFA: C24:0, C26:0), X-ALD and P-NALD patients are characterized by the accumulation of VLCFA in plasma and tissues. Since peroxisomes are involved in the metabolism of reactive oxygen species (ROS) and nitrogen species (RNS), we examined the impact of VLCFA on the oxidative status of 158N murine oligodendrocytes expressing or not Abcd1 or Acox1. ⋯ SiRNA knockdown of Abcd1 or Acox1 increased ROS and RNS production even in the absence of VLCFA, and especially potentialized VLCFA-induced ROS overproduction. Moreover, mainly in cells with reduced Acox1 level, the levels of VLCFA and neutral lipids were strongly enhanced both in untreated and VLCFA - treated cells. Our data obtained on 158N murine oligodendrocytes highlight that VLCFA induce an oxidative stress, and demonstrate that Abcd1 or Acox1 knockdown contributes to disrupt RedOx equilibrium supporting a link between oxidative stress and the deficiency of Abcd1 or Acox1 peroxisomal proteins.