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Biology subjects

Lithen, A.

Publications and source records attributed to Lithen, A..

2 recordsLinked to original sources

Ketosis Elevates Antioxidants and Enhances Neural Function Through Improved Bioenergetics: A 1H MR Spectroscopy Study

Ketosis is known to alter the balance of neuroactive amino acids and enhance neural function when compared to a glycolytic condition. However, its influence on other metabolites, such as antioxidants and neural energy markers, and the mechanisms by which ketosis improves neural function remain unclear. Here, we measure the neurochemical effects of acute ketosis on the human brain using ultra-high-field 1H MR Spectroscopy (MRS) and investigate the subsequent impact on neural function through resting-state functional magnetic resonance imaging (rsfMRI). In a within-subjects design, N = 63 healthy adults from across the lifespan underwent 1H MRS and rsfMRI scans before and after consuming individually weight-dosed and calorically-matched ketone monoester or glucose drinks. Ketone monoester administration, but not glucose, significantly elevated cerebral antioxidants and energy markers while decreasing GABA, glutamate, and glutamine levels in the posterior cingulate cortex (PCC). Notably, increased bioenergetics, specifically an increase in total creatine, correlated with greater improvements in neural function as measured using rsfMRI. Our results integrate metabolic and functional neuroimaging findings, offering a comprehensive understanding of ketosis-induced changes in brain chemistry and functional network dynamics, yielding valuable insights into potential mechanisms by which ketosis imparts its neural benefits.

neuroscience↗

Development of an MRI Compatible Nasal Drug Delivery Method: Probing Nicotine Addiction Dynamics

BackgroundSubstance abuse is a fundamentally dynamic disease, characterized by repeated oscillation between craving, drug self-administration, reward, and satiety. To model nicotine addiction as a control system, an MR-compatible nicotine delivery system is needed to elicit cyclical cravings. MethodUsing a concentric nebulizer, inserted into one nostril, we delivered each dose--each equivalent to a single cigarette puff--using a syringe pump by nebulizing the nicotine solution using pressurized medical air. A control mechanism permits dual modes: one delivers puffs on a fixed interval programmed by researchers; with the other, subjects press a button to self-administer each nicotine dose. Subjects were therefore able to intuitively "smoke" the equivalent of a cigarette, one "puff" at a time. We dosed each "puff" such that one cigarette would be equal, in nicotine content, to 10 puffs. ResultsWe tested the viability of this delivery method for studying the brains response to nicotine addiction in three steps. First, we established the pharmacokinetics of nicotine delivery, using a dosing scheme designed to gradually achieve saturation, as with a cigarette. Second, we lengthened the time between micro-doses to elicit craving cycles, using both fixed-interval and subject-driven behavior. Finally, we confirmed that the fixed-interval protocol reliably activates brain circuits linked to addiction. ConclusionOur MR-compatible nasal delivery method enables the measurement of neural circuit responses to drug doses on a single-subject level, allowing the development of data-driven predictive models to quantify individual dysregulations of the reward control circuit causing addiction.

neuroscience↗