24 research outputs found
MPTP Neurotoxicity and Testosterone Induce Dendritic Remodeling of Striatal Medium Spiny Neurons in the C57Bl/6 Mouse
Nigrostriatal damage is increased in males relative to females. While estrogen is neuroprotective in females, less is known about potential protective effects of testosterone in males. We determined if castration enhances neuronal injury to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Castrates or sham-castrated mice were sacrificed 1 week following injection of MPTP (4 × 20 mg/kg) or saline (n = 11-12/group). The right striatum was immunostained for tyrosine hydroxylase (TH). The left hemisphere was stained by Golgi Cox to quantify neuronal morphology in medium spiny neurons (MSNs) of the dorsolateral striatum. MPTP reduced TH, but there was no effect of castration and no interaction. For MSN dendritic morphology, MPTP decreased the highest branch order and increased spine density on 2nd-order dendrites. Castrated males had shorter 5th-order dendrites. However, there was no interaction between gonadal status and MPTP. Thus, castration and MPTP exert nonoverlapping effects on MSN morphology with castration acting on distal dendrites and MPTP acting proximally
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Noradrenergic mechanisms of arousal’s bidirectional effects on episodic memory
Arousal’s selective effects on cognition go beyond the simple enhancement of emotional stimuli, sometimes enhancing and other times impairing processing of proximal neutral information. Past work shows that arousal impairs encoding of subsequent neutral stimuli
regardless of their top-down priority via the engagement of β-adrenoreceptors. In contrast, retrograde amnesia induced by emotional arousal can flip to enhancement when preceding neutral items are prioritized in top-down attention. Whether β-adrenoreceptors also contribute to
this retrograde memory enhancement of goal-relevant neutral stimuli is unclear. In this pharmacological study, we administered 40mg of propranolol or 40mg of placebo to healthy young adults to examine whether emotional arousal’s bidirectional effects on declarative
memory relies on β-adrenoreceptor activation. Following pill intake, participants completed an emotional oddball task in which they were asked to prioritize a neutral object appearing just before an emotional or neutral oddball image within a sequence of 7 neutral objects. Under placebo, emotional oddballs impaired memory for lower priority oddball+1 objects but had no effect on memory for high priority oddball-1 objects. Propranolol blocked this anterograde amnesic effect of arousal. Emotional oddballs also enhanced selective memory trade-offs significantly more in the placebo than drug condition, such that high priority oddball-1 objects
were more likely to be remembered at the cost of their corresponding lower priority oddball+1 objects under arousal. Lastly, those who recalled more high priority oddball-1 objects preceding an emotional versus neutral oddball image showed greater increases in salivary alpha-amylase, a biomarker of noradrenergic system activation, across the task. Together these findings suggest that different noradrenergic mechanisms contribute to the anterograde and retrograde mnemonic effects of arousal on proximal neutral memoranda
The Oxygen Paradox, the French Paradox, and age-related diseases
open46openDavies, Joanna M. S.; Cillard, Josiane; Friguet, Bertrand; Cadenas, Enrique; Cadet, Jean; Cayce, Rachael; Fishmann, Andrew; Liao, David; Bulteau, Anne-Laure; Derbré, Frédéric; Rébillard, Amélie; Burstein, Steven; Hirsch, Etienne; Kloner, Robert A.; Jakowec, Michael; Petzinger, Giselle; Sauce, Delphine; Sennlaub, Florian; Limon, Isabelle; Ursini, Fulvio; Maiorino, Matilde; Economides, Christina; Pike, Christian J.; Cohen, Pinchas; Salvayre, Anne Negre; Halliday, Matthew R.; Lundquist, Adam J.; Jakowec, Nicolaus A.; Mechta-Grigoriou, Fatima; Mericskay, Mathias; Mariani, Jean; Li, Zhenlin; Huang, David; Grant, Ellsworth; Forman, Henry J.; Finch, Caleb E.; Sun, Patrick Y.; Pomatto, Laura C. D.; Agbulut, Onnik; Warburton, David; Neri, Christian; Rouis, Mustapha; Cillard, Pierre; Capeau, Jacqueline; Rosenbaum, Jean; Davies, Kelvin J. A.Davies, Joanna M. S.; Cillard, Josiane; Friguet, Bertrand; Cadenas, Enrique; Cadet, Jean; Cayce, Rachael; Fishmann, Andrew; Liao, David; Bulteau, Anne-Laure; Derbré, Frédéric; Rébillard, Amélie; Burstein, Steven; Hirsch, Etienne; Kloner, Robert A.; Jakowec, Michael; Petzinger, Giselle; Sauce, Delphine; Sennlaub, Florian; Limon, Isabelle; Ursini, Fulvio; Maiorino, Matilde; Economides, Christina; Pike, Christian J.; Cohen, Pinchas; Salvayre, Anne Negre; Halliday, Matthew R.; Lundquist, Adam J.; Jakowec, Nicolaus A.; Mechta-Grigoriou, Fatima; Mericskay, Mathias; Mariani, Jean; Li, Zhenlin; Huang, David; Grant, Ellsworth; Forman, HENRY J.; Finch, Caleb E.; Sun, Patrick Y.; Pomatto, Laura C. D.; Agbulut, Onnik; Warburton, David; Neri, Christian; Rouis, Mustapha; Cillard, Pierre; Capeau, Jacqueline; Rosenbaum, Jean; Davies, Kelvin J. A