Effects of maternal separation on brain stress systems: Modulation by voluntary exercise in male rats

Early life stress (ELS) has been shown to predispose animals to anxiety- and depression-like behaviour in adulthood. Recent evidence suggests that repeated stress in adulthood dysregulates the hypothalamic orexin/hypocretin system. The current study examined the effects of maternal separation (MS), a well validated rodent model of ELS, on the expression of anxiety-like behaviour following the re-exposure to stress in adulthood. The pattern of Fos-expression in hypothalamic orexin neurons and stress sensitive brain regions was also characterised. Finally, this study examined whether the effects of this double-hit of stress could be reversed using a voluntary exercise intervention during early adulthood. Male rat pups (n=25) were removed from dams for 3hrs on postnatal days (PND) 2-14 (MS). Controls (C; n=25) remained undisturbed during this period except for weekly weighing. On PND 75, animals were randomly allocated to either a ‘stress’ (30min restraint stress) or ‘no stress’ condition (S or NS). A subset of MS animals (n=6) was allowed access to exercise wheels for 1hr/day from PND 40-70. Following this, all animals were behaviourally tested in the open field apparatus for 10mins. Two hours after initiation of restraint, animals were perfused and brains were processed for Fos-protein immunohistochemistry and co-labelled for orexin or tyrosine-hydroxylase (TH). Counts of Fos-positive neurons were made in the hypothalamus, paraventricular nucleus (PVN), paraventricular thalamus (PVT) and ventral tegmental area (VTA). MS-NS rats exhibited behaviour that was indistinguishable from C-NS rats. However, male MS-S rats exhibited decreased exploratory behaviour in the open field task compared to C-S rats. This was associated with a decrease in the percentage of Fos-positive orexin cells in the hypothalamus and reduced Fos-protein in the PVN, PVT and TH-positive VTA cells compared to C-S rats. Interestingly, the exercise intervention reversed the behavioural effects of MS following stress and normalized orexin cell and VTA-TH cell Fos-expression. In conclusion, MS resulted in altered open field behaviour and hypoactivation of the orexin system in response to adult stress. The current study indicates that changes in orexin system function may involve altered activity in stress-sensitive brain regions such as the VTA, PVN and PVT. Importantly, the behavioural and neural changes observed were reversed by voluntary exercise in early adulthood. These findings highlight the importance of non-pharmacological interventions in the treatment of stress-related disorders

Recruitment of hypothalamic orexin neurons after formalin injections in adult male rats exposed to a neonatal immune challenge

Exposure to early life physiological stressors, such as infection, is thought to contribute to the onset of psychopathology in adulthood. In animal models, injections of the bacterial immune challenge, lipopolysaccharide (LPS), during the neonatal period has been shown to alter both neuroendocrine function and behavioural pain responses in adulthood. Interestingly, recent evidence suggests a role for the lateral hypothalamic peptide orexin in stress and nociceptive processing. However, whether neonatal LPS exposure affects the reactivity of the orexin system to formalin-induced inflammatory pain in later life remains to be determined. Male Wistar rats (n=13) were exposed to either LPS or saline (0.05mg/kg, i.p) on postnatal days (PND) 3 and 5. On PND 80-97, all rats were exposed to a subcutaneous hindpaw injection of 2.25% formalin. Following behavioural testing, animals were perfused and brains processed for Fos-protein and orexin immunohistochemistry. Rats treated with LPS during the neonatal period exhibited decreased licking behaviours during the interphase of the formalin test, the period typically associated with the active inhibition of pain, and increased grooming responses to formalin in adulthood. Interestingly, these behavioural changes were accompanied by an increase in the percentage of Fos-positive orexin cells in the dorsomedial and perifornical hypothalamus in LPS-exposed animals. Similar increases in Fos-protein were also observed in stress and pain sensitive brain regions that receive orexinergic inputs. These findings highlight a potential role for orexin in the behavioural responses to pain and provide further evidence that early life stress can prime the circuitry responsible for these responses in adulthood

Epidural Auditory Event-Related Potentials in the Rat to Frequency and duration Deviants: Evidence of Mismatch Negativity?

The capacity of the human brain to detect deviance in the acoustic environment pre-attentively is reflected in a brain event-related potential (ERP), mismatch negativity (MMN). MMN is observed in response to the presentation of rare oddball sounds that deviate from an otherwise regular pattern of frequent background standard sounds. While the primate and cat auditory cortex (AC) exhibit MMN-like activity, it is unclear whether the rodent AC produces a deviant response that reflects deviance detection in a background of regularities evident in recent auditory stimulus history or differential adaptation of neuronal responses due to rarity of the deviant sound. We examined whether MMN-like activity occurs in epidural AC potentials in awake and anesthetized rats to high and low frequency and long and short duration deviant sounds. ERPs to deviants were compared with ERPs to common standards and also with ERPs to deviants when interspersed with many different standards to control for background regularity effects. High frequency (HF) and long duration deviant ERPs in the awake rat showed evidence of deviance detection, consisting of negative displacements of the deviant ERP relative to ERPs to both common standards and deviants with many standards. The HF deviant MMN-like response was also sensitive to the extent of regularity in recent acoustic stimulation. Anesthesia in contrast resulted in positive displacements of deviant ERPs. Our results suggest that epidural MMN-like potentials to HF sounds in awake rats encode deviance in an analogous manner to the human MMN, laying the foundation for animal models of disorders characterized by disrupted MMN generation, such as schizophrenia

Long-term effects of a protein-enriched diet on blood pressure in older women

Short-term randomised, controlled trials have found that dietary protein relative to carbohydrate can reduce blood pressure. Our objective was to investigate the effects on blood pressure of an increase in protein intake from whey over 2 years in women aged over 70 years. From the general population, 219 women aged between 70 and 80 years were recruited to a 2-year randomised, double-blind, placebo-controlled parallel-design trial: 181 women completed the trial to the end of year 2. Participants were randomly assigned to consume a daily whey protein-based beverage (protein) or an energy-matched low-protein high-carbohydrate beverage (control). Blood pressure measurements were performed at baseline, year 1 and year 2. For protein relative to control, the estimated mean net differences in protein and carbohydrate intakes were 18 (95 % CI 13, 23) and − 22 (95 % CI − 9, − 35) g/d at year 1, and 22 (95 % CI 17, 28) and − 18 (95 % CI − 6, − 31) g/d at year 2. Intention-to-treat analysis found no overall differences between groups in blood pressure (P>0.5). Net differences in systolic and diastolic blood pressure were – 2.3 (95 % CI – 5.3, 0.7) and – 1.5 (95 % CI – 3.6, 0.6) mmHg at year 1, and 1.6 (95 % CI – 1.5, 4.7) and 0.3 (95 % CI – 1.9, 2.4) mmHg at year 2. Similar differences in systolic and diastolic blood pressure at years 1 and 2 were observed with per-protocol analysis. Therefore, the present study did not provide evidence that a higher whey protein intake in older women can have prolonged effects on blood pressure

Clinical and Experimental Applications of NIR-LED Photobiomodulation

This review presents current research on the use of far-red to near-infrared (NIR) light treatment in various in vitro and in vivo models. Low-intensity light therapy, commonly referred to as “photobiomodulation,” uses light in the far-red to near-infrared region of the spectrum (630–1000 nm) and modulates numerous cellular functions. Positive effects of NIR–light-emitting diode (LED) light treatment include acceleration of wound healing, improved recovery from ischemic injury of the heart, and attenuated degeneration of injured optic nerves by improving mitochondrial energy metabolism and production. Various in vitro and in vivo models of mitochondrial dysfunction were treated with a variety of wavelengths of NIR-LED light. These studies were performed to determine the effect of NIR-LED light treatment on physiologic and pathologic processes. NIRLED light treatment stimulates the photoacceptor cytochrome c oxidase, resulting in increased energy metabolism and production. NIR-LED light treatment accelerates wound healing in ischemic rat and murine diabetic wound healing models, attenuates the retinotoxic effects of methanol-derived formic acid in rat models, and attenuates the developmental toxicity of dioxin in chicken embryos. Furthermore, NIR-LED light treatment prevents the development of oral mucositis in pediatric bone marrow transplant patients. The experimental results demonstrate that NIR-LED light treatment stimulates mitochondrial oxidative metabolism in vitro, and accelerates cell and tissue repair in vivo. NIR-LED light represents a novel, noninvasive, therapeutic intervention for the treatment of numerous diseases linked to mitochondrial dysfunction

Dietary inflammatory index and the aging kidney in older women: a 10‑year prospective cohort study

Purpose: Chronic inflammation plays a role in the pathogenesis of age-related renal disease and the diet can moderate systemic inflammation. The primary objective of this study was to examine the associations between a dietary inflammatory index ( DII®) score and renal function, the trajectory of renal function decline, and renal disease-related hospitalizations and/or mortality over 10 years. Methods: The study was conducted in 1422 Western Australian women without prevalent chronic kidney disease and aged ≥ 70 years. Baseline dietary data, obtained from a validated food frequency questionnaire, were used to calculate a DII score for each individual. Results: In this cohort, the mean [range] DII score was 0.19 [− 6.14 to 6.39]. A higher DII score was associated with poorer renal function at baseline and a greater renal function decline over 10 years; after multivariable adjustments, a one unit higher DII score was associated with a 0.55 mL/min/1.73 m2 lower eGFR at baseline (p = 0.01) and a 0.06 mL/min/1.73 m2 greater annual decline in eGFR over 10 years (p = 0.05). Restricted cubic splines provide evidence of a non-linear association between baseline DII score and risk of a renal disease-related event. Compared to participants in the lowest quintile, those in the highest quintile of DII score were at a higher risk of experiencing a renal disease-related event (adjusted HR 2.06, 95% CI 0.97, 4.37). Conclusion: Recommending an increased consumption of foods with a higher anti-inflammatory potential could form part of a multifaceted approach to reduce the risk of renal disease through diet and lifestyle changes

De novo designed peptide and protein hairpins self‐assemble into sheets and nanoparticles

AFM, TEM, fluorescence microscopy image files and spectral data published in DOI:10.1002/smll.202100472. Preprint of this is available at bioRxiv DOI:10.1101/2020.08.14.25146

Decorating Self-Assembled Peptide Cages with Proteins

An ability to organize and encapsulate multiple active proteins into defined objects and spaces at the nanoscale has potential applications in biotechnology, nanotechnology, and synthetic biology. Previously, we have described the design, assembly, and characterization of peptide-based self-assembled cages (SAGEs). These ≈100 nm particles comprise thousands of copies of <i>de novo</i> designed peptide-based hubs that array into a hexagonal network and close to give caged structures. Here, we show that, when fused to the designed peptides, various natural proteins can be co-assembled into SAGE particles. We call these constructs pSAGE for protein-SAGE. These particles tolerate the incorporation of multiple copies of folded proteins fused to either the N or the C termini of the hubs, which modeling indicates form the external and internal surfaces of the particles, respectively. Up to 15% of the hubs can be functionalized without compromising the integrity of the pSAGEs. This corresponds to hundreds of copies giving mM local concentrations of protein in the particles. Moreover, and illustrating the modularity of the SAGE system, we show that multiple different proteins can be assembled simultaneously into the same particle. As the peptide–protein fusions are made <i>via</i> recombinant expression of synthetic genes, we envisage that pSAGE systems could be developed modularly to actively encapsulate or to present a wide variety of functional proteins, allowing them to be developed as nanoreactors through the immobilization of enzyme cascades or as vehicles for presenting whole antigenic proteins as synthetic vaccine platforms