Effects of intracerebroventricularly administered opioid peptide antagonists on tissue glycogen levels in rats after exercise

Background/aim: Physical exercise is a state of physiological stress that requires adaptation of the organism to physical activity. Glycogen is an important and essential energy source for muscle contraction. Skeletal muscle and liver are two important glycogen stores, and the energy required to maintain exercise in rodents are provided by destruction of this glycogen depot. In this study, the effects of endogenous opioid peptide antagonism at the central nervous system level on tissue glycogen content after exhaustive exercise were investigated. Materials and methods: Rats had intracerebroventricularly (icv) received nonspecific opioid peptide receptor antagonist, naloxone (50 µg/10 µL in saline) and δ-opioid receptor-selective antagonist naltrindole (50 µg/10 µL in saline) and then exercised till exhaustion. After exhaustion, skeletal muscle, heart, and liver were excised immediately. Results: Both opioid peptide antagonists decreased glycogen levels in skeletal muscle. Although, in soleus muscle, this decrease was not statistically significant (p > 0.05), in gastrocnemius muscle, it was significant in the icv naloxone administered group compared with control (p < 0.05). Heart glycogen levels increased significantly in both naloxone and naltrindole groups compared to control and sham-operated groups (p < 0.05). Heart glycogen levels were higher in the naloxone group than naltrindole (p < 0.05). Liver glycogen levels were elevated significantly with icv naloxone administration compared with the control group (p < 0.05). Glycogen levels in the naloxone group was also significantly higher than the naltrindole group (p < 0.05). Conclusion: Our findings indicate that icv administered opioid peptide antagonists may play a role in glycogen metabolism in peripheral tissues such as skeletal muscle, heart, and liver.

Dance and Movement Therapy Methods for Compassion Satisfaction, Burnout, and Compassion Fatigue in Nurses: A Pilot Study.

The current semi-experimental pilot study was conducted to investigate the effects of dance and movement therapy methods (DMTM) on compassion satisfaction, burnout, and compassion fatigue in nurses using a pre-/posttest design. Nurses (N = 8) with low compassion satisfaction, high burnout, and high compassion fatigue participated in eight sessions of DMTM. Upon completion of the program, average compassion satisfaction levels increased, and burnout and compassion fatigue levels decreased. Although further testing with larger samples is necessary, preliminary results indicate DMTM is effective for addressing compassion satisfaction, burnout, and compassion fatigue in nurses. [Journal of Psychosocial Nursing and Mental Health Services, 58(4), 43-51.].

Melatonin, aging, and COVID-19: Could melatonin be beneficial for COVID-19 treatment in the elderly?

The aim of this review is to summarize current studies on the relationship between melatonin and aging. Nowadays, age-related diseases come into prominence, and identifying age-related changes and developing proper therapeutic approaches are counted as some of the major issues regarding community health. Melatonin is the main hormone of the pineal gland. Melatonin is known to influence many biological processes in the body, including circadian rhythms, the immune system, and neuroendocrine and cardiovascular functions.Melatoninrhythms also reflect the biological process of aging. Aging is an extremely complex and multifactorial process. Melatonin levels decline considerably with aging and its decline is associated with several age-related diseases. Aging is closely associated with oxidative damage and mitochondrial dysfunction. Free radical reactions initiated by the mitochondria constitute the inherent aging process. Melatonin plays a pivotal role in preventing age-related oxidative stress. Coronavirus disease 2019 (COVID-19) fatality rates increase with chronic diseases and age, where melatonin levels decrease. For this reason, melatonin supplementation in elderly could be beneficial in COVID-19 treatment. Therefore, studies on the usage of melatonin in COVID-19 treatment are needed.

Neuroprotective role of delta opioid receptors in hypoxic preconditioning

Background/aim: The purpose of the present study was to explore the neuroprotective role of delta opioid receptors (DOR) in the rat cortex in hypoxic preconditioning. Materials and methods: Rats were randomly divided into 8 groups: control (C), sham (S), hypoxic preconditioning (PC), severe hypoxia (SH), PC + SH, PC + SH + Saline (PS), PC + SH + DPDPE (DPDPE, selective DOR agonist), PC + SH + NT (NT, Naltrindole, selective DOR antagonist). Drugs were administered intracerebroventrically. Twenty four h after the end of 3 consecutive days of PC (10% O2, 2 h/day), the rats were subjected to severe hypoxia (7% O2 for 3 h). Bcl-2 and cyt-c were measured by western blot, and caspase-3 was observed immunohistochemically. Results: Bcl-2 expressions in the PC group were higher than in control, SH, and PC + SH groups. Even though there were no significant differences between the groups in terms of cyt-c levels, caspase-3 immunoreactivity of cortical neurons and glial cells in the severe hypoxia and NT groups were higher than in the control, sham, and hypoxic preconditioning groups. DPDPE administration diminished caspase-3 immunoreactivity compared with all of the severe hypoxia groups. Conclusions: These results suggest that cortical cells are resistant to apoptosis via increased expression of Bcl-2 and decreased immunoreactivity of caspase-3 in the cortex, and that DOR is involved in neuroprotection induced by hypoxic preconditioning via the caspase-3 pathway in cortical neurons.

The combined effect of morin and hesperidin on memory ability and oxidative/nitrosative stress in a streptozotocin-induced rat model of Alzheimer's disease.

Alzheimer's disease (AD), the most frequent neurodegenerative disease within dementias, affects the CNS, leading to gradual memory issues and cognitive dysfunction. Oxidative stress in AD contributes to ongoing neuronal loss and hastens disease progression. Notably, the potent antioxidant compounds morin and hesperidin have demonstrated significant effectiveness in addressing oxidative stress. This study explores the impact of morin and hesperidin on behavior and oxidative stress in the streptozotocin (STZ)-induced AD rat model. The experiment involved five groups: control, STZ, STZ+morin, STZ+hesperidin, and STZ+morin+hesperidin. The rat model of AD was created by injecting STZ with the stereotaxic surgery. Morin and hesperidin were applied to the groups for 7-days. After the applications, the Morris water maze (MWM) and novel object recognition (NOR) tests were used and the rats were sacrificed. Malondialdehyde (MDA), glutathione (GSH), nitric oxide (NOx), and protein carbonyl (PC) levels were measured. In the STZ group, the levels of NOx and PC exhibited a noteworthy increase compared to the control. Conversely, the application of morin and/or hesperidin treatments reduced NOx and PC levels compared to the STZ group. The co-administration of morin and hesperidin improved the antioxidant status and decreased lipid peroxidation in STZ-induced rats. In the STZ group, serum advanced oxidation protein products (AOPP) levels were statistically elevated compared to the control. However, in the treatment groups, morin and/or hesperidin successfully decreased AOPP levels to those observed in the control. The combined use of these flavonoids may have a neuroprotective effect regarding memory problems and decreasing oxidative/nitrosative stress.

Protective effect of melatonin and 1,25-dihydroxyvitamin D3 on renal ischemia-reperfusion injury in rats.

Ischemia-reperfusion (I/R) injury induces the generation of reactive oxygen species (ROS) which affect many organs. This study was designed to investigate the roles of melatonin and 1,25-dihydroxyvitamin D3 (VD3) on renal I/R injury. Thirty male Wistar albino rats were divided into five groups: group 1, control; group 2, right nephrectomy (RN) +  I/R in the contralateral kidney; group 3, melatonin + RN + I/R; group 4, VD3 + RN + I/R; and group 5, melatonin + VD3 + RN + I/R. Melatonin (10 mg/kg), VD3 (0.5 µg/kg), and melatonin plus VD3 were injected intraperitoneally for 7 days before renal I/R. After 7 days, right nephrectomy was initially performed and left renal artery was clamped for 45 min. After 45-min reperfusion, the serum and kidney tissue samples were obtained for assays. Melatonin and VD3 had an ameliorative effect on biochemical parameters such as serum creatinine (SCr) and blood urea nitrogen (BUN). Renal tissue malondialdehyde (MDA), glutathione (GSH), nitric oxide (NO) levels, and superoxide dismutase (SOD) activity were determined. Renal I/R decreased the kidney tissue GSH levels and SOD activity and increased the NO levels as compared with control group. However, melatonin and VD3 and melatonin plus VD3 treatment significantly increased the tissue GSH levels and SOD activity and decreased the NO levels compared with those of I/R group. Meanwhile, MDA levels were not different between the control and I/R groups. But, MDA levels decreased in all treated groups compared to I/R and control groups. These data support that melatonin and VD3 have beneficial effects on renal injury.

Investigation Covering the Effect of Boron plus Taurine Application on Protein Carbonyl and Advanced Oxidation Protein Products Levels in Experimental Alzheimer Model.

Alzheimer's disease (AD) is the most common form of dementia that occurs in the brain. This is a chronic neurodegenerative disease which is valid in 60-70% of all dementia patients. Boron, regarded as a potential antioxidant, has the effect of reducing oxidative stress. Taurine, as one of the thiol-containing amino acids, exists at different concentrations in both the neurons and glial cells of the central nervous system. It plays an important role in the protective and adjuvant therapies as an antioxidant due to its characteristics of maintaining the oxidant-antioxidant balance of the body as well as cell integrity and increasing body resistance. Based on this information, our objective was to reveal the effect of boron alone, taurine alone plus co-administration of taurine and boron application on brain tissue protein carbonyls (PC) and serum advanced oxidation protein products (AOPP) levels in the experimental Alzheimer's model. For this purpose, 5 groups were formed in our study which consisted of 30 Wistar albino male rats. The rats were given a single dose of STZ stereotaxically. At the end of this period, the rats were decapitated, plus their brain tissues and blood were removed. Our findings suggested that taurine alone and co-administration of boron and taurine had a decreasing effect on AOPP and PC levels of the experimental Alzheimer model of the rats.

Melatonin with 1,25-dihydroxyvitamin D3 protects against apoptotic ischemia-reperfusion injury in the rat kidney.

This study was designed to evaluate the preventive role of melatonin (Mel) and 1,25-dihydroxyvitamin D3 (VD3) in biochemical and apoptotic events leading to tissue injury and renal dysfunction after ischemia-reperfusion (I/R). Thirty male Wistar rats were divided into five groups: sham-operated, I/R, Mel + I/R, VD3 + I/R, and Mel + VD3 + I/R. The rats were intraperitoneally administered with Mel (10 mg/kg), VD3 (0.5 µg/kg), or Mel (10 mg/kg) plus VD3 (0.5 µg/kg) each day at 1 week prior to ischemia. Right nephrectomy was initially performed and left renal I/R injury was induced by 45 min of bilateral renal ischemia followed by 45 min of reperfusion. After reperfusion, kidneys and blood were obtained for histopathologic and biochemical evaluation. Mel and VD3 had an ameliorative effect on biochemical parameters such as serum creatinine, blood urea nitrogen, alanine aminotransferase, aspartate aminotransferase, and apoptosis (caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining) in the kidneys against renal I/R injury in rats. Additionally, VD3 combined with Mel significantly reduced apoptotic and histological alterations when compared with Mel or VD3 alone. This preventive effect on renal tubular apoptosis was remarkable when Mel was combined with VD3.

Age-related changes in the rat brain mitochondrial antioxidative enzyme ratios: modulation by melatonin.

Oxidative stress is an important factor for aging. The antioxidative enzymes glutathione peroxidase (GPx), glutathione reductase (GRd) and superoxide dismutase (SOD) play a crucial role protecting the organism against the age-dependent oxidative stress. Glutathione (GSH) is present in nearly all living cells. GSH is one of the main antioxidants in the cell and it serves several physiological functions. Our purpose was to evaluate the age-related changes in mitochondrial GPx, GRd and SOD activities, and mitochondrial GSH pool in the brains of young (3 months) and aged rats (24 months). We also investigated whether melatonin administration influences these brain mitochondrial enzyme activities and GSH levels in young and aged rats. The results showed that GPx activity increased with age, whereas melatonin treatment decreased GPx activity in the aged rats at levels similar to those in young and young+melatonin groups. The activities of GRd and SOD, however, did not change with age. But, melatonin treatment increased SOD activity in the aged rats. GSH levels, which also increased with age, were not modified by melatonin treatment. The reduction in the SOD/GPx and GR/GPx ratios with age was prevented by melatonin administration. Together, our results suggest that the age-related oxidative stress in rat brain mitochondria is more apparent when the antioxidant enzyme ratios are analyzed instead of their absolute values. The antioxidative effects of melatonin were also supported by the recovery of the enzyme ratios during aging.

A simple analytical expression for the gradient induced potential on active implants during MRI.

During magnetic resonance imaging, there is an interaction between the time-varying magnetic fields and the active implantable medical devices (AIMD). In this study, in order to express the nature of this interaction, simplified analytical expressions for the electric fields induced by time-varying magnetic fields are derived inside a homogeneous cylindrical volume. With these analytical expressions, the gradient induced potential on the electrodes of the AIMD can be approximately calculated if the position of the lead inside the body is known. By utilizing the fact that gradient coils produce linear magnetic field in a volume of interest, the simplified closed form electric field expressions are defined. Using these simplified expressions, the induced potential on an implant electrode has been computed approximately for various lead positions on a cylindrical phantom and verified by comparing with the measured potentials for these sample conditions. In addition, the validity of the method was tested with isolated frog leg stimulation experiments. As a result, these simplified expressions may help in assessing the gradient-induced stimulation risk to the patients with implants.

Dexamethasone prevents transport inhibition by hypoxia in rat lung and alveolar epithelial cells by stimulating activity and expression of Na+-K+-ATPase and epithelial Na+ channels.

Hypoxia inhibits Na and lung fluid reabsorption, which contributes to the formation of pulmonary edema. We tested whether dexamethasone prevents hypoxia-induced inhibition of reabsorption by stimulation of alveolar Na transport. Fluid reabsorption, transport activity, and expression of Na transporters were measured in hypoxia-exposed rats and in primary alveolar type II (ATII) cells. Rats were treated with dexamethasone (DEX; 2 mg/kg) on 3 consecutive days and exposed to 10% O(2) on the 2nd and 3rd day of treatment to measure hypoxia effects on reabsorption of fluid instilled into lungs. ATII cells were treated with DEX (1 muM) for 3 days before exposure to hypoxia (1.5% O(2)). In normoxic rats, DEX induced a twofold increase in alveolar fluid clearance. Hypoxia decreased reabsorption (-30%) by decreasing its amiloride-sensitive component; pretreatment with DEX prevented the hypoxia-induced inhibition. DEX increased short-circuit currents (ISC) of ATII monolayers in normoxia and blunted hypoxic transport inhibition by increasing the capacity of Na(+)-K(+)-ATPase and epithelial Na(+) channels (ENaC) and amiloride-sensitive ISC. DEX slightly increased the mRNA of alpha- and gamma-ENaC in whole rat lung. In ATII cells from DEX-treated rats, mRNA of alpha(1)-Na(+)-K(+)-ATPase and alpha-ENaC increased in normoxia and hypoxia, and gamma-ENaC was increased in normoxia only. DEX stimulated the mRNA expression of alpha(1)-Na(+)-K(+)-ATPase and alpha-, beta-, and gamma-ENaC of A549 cells in normoxia and hypoxia (1.5% O(2)) when DEX treatment was begun before or during hypoxic exposure. These results indicate that DEX prevents inhibition of alveolar reabsorption by hypoxia and stimulates the expression of Na transporters even when it is applied in hypoxia.

Measuring local RF heating in MRI: Simulating perfusion in a perfusionless phantom.

PURPOSE: To overcome conflicting methods of local RF heating measurements by proposing a simple technique for predicting in vivo temperature rise by using a gel phantom experiment. MATERIALS AND METHODS: In vivo temperature measurements are difficult to conduct reproducibly; fluid phantoms introduce convection, and gel phantom lacks perfusion. In the proposed method the local temperature rise is measured in a gel phantom at a timepoint that the phantom temperature would be equal to the perfused body steady-state temperature value. The idea comes from the fact that the steady-state temperature rise in a perfused body is smaller than the steady-state temperature increase in a perfusionless phantom. Therefore, when measuring the temperature on a phantom there will be the timepoint that corresponds to the perfusion time constant of the body part. RESULTS: The proposed method was tested with several phantom and in vivo experiments. Instead, an overall average of 30.8% error can be given as the amount of underestimation with the proposed method. This error is within the variability of in vivo experiments (45%). CONCLUSION: With the aid of this reliable temperature rise prediction the amount of power delivered by the scanner can be controlled, enabling safe MRI examinations of patients with implants.