Anxiolytic effects of administration of a commercially available prebiotic blend of galacto-oligosaccharides and beta glucans in Sprague-Dawley rats.

Prebiotics are nondigestible food agents that stimulate the growth of bacteria in the gut, whereas probiotics are live microorganisms that replace or restore beneficial bacteria in the digestive tract. Both agents have been shown to have beneficial qualities within the microbiota-gut-brain axis, but the behavioural effects of prebiotics have been less studied than probiotics. Whereas several studies have shown that prebiotics reduce inflammation and modulate anxiety in animals that are injected with lipopolysacccharides or chronically stressed animals, respectively, it is not yet known how they affect a healthy organism. Here, we tested the behavioural effects of galacto-oligosaccharides and beta glucan as a commercially available prebiotic blend in healthy, naïve Sprague-Dawley rats. We used the open field test and elevated plus maze to assess anxiety-like behaviour in controls and in rats that ingested the prebiotic blend in their drinking water. We also used the Morris Water Maze to assess spatial memory performance in controls and prebiotic treated rats. Rats treated with prebiotics spent more time in the intermediate zone of the open field test and in the open arms of the elevated plus maze, and exhibited a shorter latency to enter each of these zones. No significant differences between groups were found in the Morris Water Maze. Our results suggest that whereas prebiotics significantly reduced anxiety-like behaviours, it had no effect on spatial memory performance. Altogether, our data indicate that commercially available prebiotic beta glucan blends have anxiolytic effects in healthy rats.

QTc interval in survivors of out of hospital cardiac arrest.

BACKGROUND: QTc interval (QTc) prolongation is seen on the post-arrest electrocardiogram (ECG) of many out of hospital cardiac arrest (OHCA) survivors. It remains unclear whether this is a transient phenomenon or a manifestation of an underlying arrhythmic substrate. This observational study assessed the trend of QTc in an unselected group of patients presenting with OHCA. We sought to identify any relationship between QTc, gender and aetiology of arrest. We observed whether targeted temperature management (TTM) is associated with malignant arrhythmia. METHOD: We analysed 60 patients presenting with OHCA to the Bristol Heart Institute during a 20-month period. We measured QTc on admission and assessed for persistence, development and resolution of prolongation at up to 5 time points post-OHCA. Aetiology of arrest was divided into coronary, non-coronary or primary arrhythmic to investigate for patterns in QTc behaviour. RESULTS: 81.7% (49/60) of arrests were attributed to an acute coronary event. 55% (33/60) had QTc prolongation on admission, of which 79% resolved. There were no significant differences in QTc behaviour by aetiology. One patient presenting with a normal QTc, developed prolongation during admission and received a genetic diagnosis of Long QT Syndrome. TTM was employed in 57/60, with no increased incidence of malignant arrhythmia. CONCLUSIONS: Prolonged QTc on admission does not imply a primary arrhythmic aetiology and resolves in the majority pre-discharge. However, an initial normal QTc post-OHCA does not preclude a diagnosis of Long QT syndrome, highlighting the importance of thorough investigations in these patients. TTM appears safe from a cardiac perspective.

Day-night differences in neural activation in histaminergic and serotonergic areas with putative projections to the cerebrospinal fluid in a diurnal brain.

In nocturnal rodents, brain areas that promote wakefulness have a circadian pattern of neural activation that mirrors the sleep/wake cycle, with more neural activation during the active phase than during the rest phase. To investigate whether differences in temporal patterns of neural activity in wake-promoting regions contribute to differences in daily patterns of wakefulness between nocturnal and diurnal species, we assessed Fos expression patterns in the tuberomammillary (TMM), supramammillary (SUM), and raphe nuclei of male grass rats maintained in a 12:12 h light-dark cycle. Day-night profiles of Fos expression were observed in the ventral and dorsal TMM, in the SUM, and in specific subpopulations of the raphe, including serotonergic cells, with higher Fos expression during the day than during the night. Next, to explore whether the cerebrospinal fluid is an avenue used by the TMM and raphe in the regulation of target areas, we injected the retrograde tracer cholera toxin subunit beta (CTB) into the ventricular system of male grass rats. While CTB labeling was scarce in the TMM and other hypothalamic areas including the suprachiasmatic nucleus, which contains the main circadian pacemaker, a dense cluster of CTB-positive neurons was evident in the caudal dorsal raphe, and the majority of these neurons appeared to be serotonergic. Since these findings are in agreement with reports for nocturnal rodents, our results suggest that the evolution of diurnality did not involve a change in the overall distribution of neuronal connections between systems that support wakefulness and their target areas, but produced a complete temporal reversal in the functioning of those systems.