No evidence of neural adaptations following chronic unilateral isometric training of the intrinsic muscles of the hand: a randomized controlled study

Purpose: To test whether long-term cortical adaptations occur bilaterally following chronic unilateral training with a simple motor task. / Methods: Participants (n = 34) were randomly allocated to a training or control groups. Only the former completed a 4-week maximal-intensity isometric training of the right first dorsal interosseus muscle through key pinching. Maximal strength was assessed bilaterally in four different movements progressively less similar to the training task: key, tip and tripod pinches, and handgrip. Transcranial magnetic stimulation was used to probe, in the left and right primary hand motor cortices, a number of standard tests of cortical excitability, including thresholds, intra-cortical inhibition and facilitation, transcallosal inhibition, and sensory-motor integration. / Results: Training increased strength in the trained hand, but only for the tasks specifically involving the trained muscle (key +8.5 %; p < 0.0005; tip +7.2 %; p = 0.02). However, the effect size was small and below the cutoff for meaningful change. Handgrip and tripod pinch were instead unaffected. There was a similar improvement in strength in the untrained hand, i.e., a cross-education effect (key +6.4 %; p = 0.02; tip +4.7 %; p = 0.007). Despite these changes in strength, no significant variation was observed in any of the neurophysiological parameters describing cortico-spinal and intra-cortical excitability, inter-hemispheric inhibition, and cortical sensory-motor integration. / Conclusions: A 4-week maximal-intensity unilateral training induced bilaterally spatial- and task-specific strength gains, which were not associated to direct or crossed cortical adaptations. The observed long-term stability of neurophysiological parameters might result from homeostatic plasticity phenomena, aimed at restoring the physiological inter-hemispheric balance of neural activity levels perturbed by the exercise. / Trial registration number: ClinicalTrials.gov identifier NCT02010398

Bottarga di muggine come fonte di acidi grassi n-3: stabilità ossidativa e modulazione del profilo lipidico in cellule epiteliali intestinali Caco-2

The importance of n-3 polyunsaturated fatty acids (n-3 PUFA) intake has long been recognized in human nutrition, lowering the incidence of atherosclerosis, coronary heart disease, inflammatory disease and cancer. Although health benefits, n-3 PUFA are subject to rapid and/or extensive oxidation during processing and storage, resulting in potential alteration in nutritional composition and quality of food. Bottarga, the salted and semidried mullet (Mugil cephalus) ovary product, is proposed as important source of n-3 PUFA, having high levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In this work we investigated the extent of lipid oxidation of grated bottarga samples during 7 months at different storage conditions (-20°C, 2°C, room temperature under light/dark exposure). Cell viability, lipid composition and lipid peroxidation were measured in intestinal epithelial Caco-2 cell monolayers after 6-48 h incubation with lipid and hydrophilic extracts obtained from bottarga samples at different storage conditions. Storage of bottarga did not affect the n-3 PUFA level, but significant differences were observed in hydroperoxide and malondialdeyde levels of samples from different storage conditions. Bottarga extracts did not show a toxic effect on cell viability. Epithelial cells incubated with bottarga oil had significant changes in fatty acid composition with an accumulation of EPA, DHA, and 22: 5, however, did not accumulate more cholesterol than control cells

H2O2 oxidative activity: modulatory effect of hydroxytyrosol

Hydroxytyrosol (HT) is the major o-diphenol present in extra-virgin olive oil, either in free or esterified form, once absorbed, is present in high amount in the kidney, where it may exert a proctetive action. In this study we monitored the ability of HT to protect renal cells (LLC-PK1) against oxidative damage induced by H2O2. The peroxidation of lipid represents a primary consequences of cellular oxidative stress, leading to biophysical changes that disrupt membrane and organelle function; moreover oxidative stress is a process that may stimulate cellular signalling pathways, usually associated with the promotion of cellular death. HT exerted a significant antioxidant action, inhibiting the production of fatty acids hydroperoxides and 7-ketocholesterol induced by H2O2 treatment and thus preserving the membrane lipids. It has been shown that oxidative stress in LLC-PK1 cells is related also to the changes in the phosphorylation state of pro-death signalling pathways ERK1/2 and the pro-survival signalling Akt/PKB. Pretreatment with HT is able to modulate H2O2-induced changes in the phosphorylation state of ERK1/2 and Akt/PKB. We suggest that one potential protective mechanism of olive oil polyphenols in kidney cells may be attributed to interactions with intracellular signalling pathways activated in response to oxidative stress