Neuroscience
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The dorsal diencephalic conduction system (DDC) is an important pathway of the brain reward circuitry, linking together forebrain and midbrain structures. The present work was aimed at describing the effect of a DDC lesion on the distribution of Fos-like immunoreactivity (FLIR) following intracranial self-stimulation (ICSS) of the lateral hypothalamus (LH). Rats were implanted with monopolar electrodes and divided into three groups; the first two groups were trained to self-stimulate at the LH, whereas the third group received no stimulation and served as a control. ⋯ As previously shown, a lesion at the DDC resulted in significant attenuations of the rewarding effectiveness of LH stimulation. Results also show a higher FLIR in several reward-related areas following LH stimulation, especially in the hemisphere ipsilateral to the stimulation electrode. Compared to non-lesioned rats, lesioned animals had lower FLIR in certain brain regions, suggesting that those regions that were activated by the rewarding stimulation may be functionally interconnected with the DDC.
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Anticholinergic medications can exert their effects by acting on muscarinic receptors, which mediates the function of acetylcholine in the central nervous system. Acetylcholine plays a number of roles, particularly in regard to the control of muscle activity and normal cognitive functioning. Eighteen subjects were recruited into the human, double-blind, placebo-controlled, four-way crossover study. ⋯ Promethazine was the only medication to influence the modified attention network test (ANT) by increasing the conflict effect and grand mean reaction time (RT). Pupil diameter and blink rate were both influenced by the central anticholinergics during performance of the cognitive test, thus highlighting the importance of central cholinergic pathways in the control of pupil diameter and blink rate. The collective effects of central anticholinergics on the modified ANT and on pupil diameter and blink rate during its performance, conveys the importance of central cholinergic pathways in cognitive function.
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Brain neurons of the deep-diving hooded seal (Cystophora cristata) are known to be inherently hypoxia tolerant. Here, we have used in vitro field potential recordings in hippocampal slices to compare effects of severe hypoxia on synaptic transmission in hooded seals vs. non-diving mammals. Synaptic responses of mice (Mus musculus) to hypoxia were in accordance with previously published data. ⋯ Paired pulse facilitation (PPF), typically associated with increased presynaptic calcium (Ca(2+)) levels, was significantly reduced in the seal slices. We propose that the build-up of Ca(2+) concentration is limited in seal presynaptic terminals, possibly due to a high Ca(2+) buffering capacity, which could explain both the attenuated PPF and the remarkable neural hypoxia tolerance of this species. Although we found no significant hypoxia-induced upregulation of mRNA for the Ca(2+) binding proteins calbindin d28k or parvalbumin in hooded seal hippocampal slices, a recent study reports very high transcript levels of the Ca(2+) binding protein S100B in this species, which is in support of the hypothesis.
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Brain aging is marked by a decline in cognitive abilities and associated with neurodegenerative disorders. Recent studies have shown, neurogenesis continues into adulthood but is known to be decreasing during advancing age and these changes may contribute to cognitive alterations. Advances, which aim to promote better aging are of paramount importance. ⋯ In contrast, DR shortened telomere lengths only in young animals. Neither age nor DR changed the differentiation patterns of glial cells. Our results suggest that the potential effects of DR could be mediated by telomere regulation and whether these are beneficial or negative remains to be determined.
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Anxiety disorders are more likely to occur in women than in men, usually emerge during adolescence and exhibit high comorbidity with alcohol use disorders (AUD). Adolescents with high levels of anxiety or heightened reactivity to stress may be at-risk for developing AUD. An approach to analyze if high levels of inborn anxiety predict greater ethanol drinking is to assess the latter variable in subjects classified as high- or low-anxiety responders. ⋯ Stress induced a significant increase in FOS immunoreactivity at the paraventricular nucleus, yet this effect was unaffected by level of anxiety response. Female adolescents with high levels of basal anxiety may be at-risk for exhibiting increased predisposition for ethanol intake and preference. The study also indicates that stress may exert differential effects on adolescent ethanol intake as a function of the level of anxiety response.