Saline as a vehicle control does not alter ventilation in male CD-1 mice

Breathing and Oxygen Carrying Capacity in Ts65Dn and Down Syndrome

Individuals with Down syndrome (Ds) are at increased risk of respiratory infection, aspiration pneumonia, and apnea. The Ts65Dn mouse is a commonly used model of Ds, but there have been no formal investigations of awake breathing and respiratory muscle function in these mice. We hypothesized that breathing would be impaired in Ts65Dn vs. wild-type (WT), and would be mediated by both neural and muscular inputs. Baseline minute ventilation was not different at 3, 6, or 12 mo of age. However, VT/Ti, a marker of the neural drive to breathe, was lower in Ts65Dn vs. WT and central apneas were more prevalent. The response to breathing hypoxia was not different, but the response to hypercapnia was attenuated, revealing a difference in carbon dioxide sensing, and/or motor output in Ts65Dn. Oxygen desaturations were present in room air, demonstrating that ventilation may not be sufficient to maintain adequate oxygen saturation in Ts65Dn. We observed no differences in arterial PO2 or PCO2, but Ts65Dn had lower hemoglobin and hematocrit. A retrospective medical record review of 52,346 Ds and 52,346 controls confirmed an elevated relative risk of anemia in Ds. We also performed eupneic in-vivo electromyography and in-vitro muscle function and histological fiber typing of the diaphragm, and found no difference between strains. Overall, conscious respiration is impaired in Ts65Dn, is mediated by neural mechanisms, and results in reduced hemoglobin saturation. Oxygen carrying capacity is reduced in Ts65Dn vs. WT, and we demonstrate that individuals with Ds are also at increased risk of anemia.

NADPH Oxidase: a Possible Therapeutic Target for Cognitive Impairment in Experimental Cerebral Malaria

Long-term cognitive impairment associated with seizure-induced hippocampal damage is the key feature of cerebral malaria (CM) pathogenesis. One-fourth of child survivors of CM suffer from long-lasting neurological deficits and behavioral anomalies. However, mechanisms on hippocampal dysfunction are unclear. In this study, we elucidated whether gp91^phox isoform of nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) (a potent marker of oxidative stress) mediates hippocampal neuronal abnormalities and cognitive dysfunction in experimental CM (ECM). Mice symptomatic to CM were rescue treated with artemether monotherapy (ARM) and in combination with apocynin (ARM + APO) adjunctive based on scores of Rapid Murine Come behavior Scale (RMCBS). After a 30-day survivability period, we performed Barnes maze, T-maze, and novel object recognition cognitive tests to evaluate working and reference memory in all the experimental groups except CM. Sensorimotor tests were conducted in all the cohorts to assess motor coordination. We performed Golgi-Cox staining to illustrate cornu ammonis-1 (CA1) pyramidal neuronal morphology and study overall hippocampal neuronal density changes. Further, expression of NOX2, NeuN (neuronal marker) in hippocampal CA1 and dentate gyrus was determined using double immunofluorescence experiments in all the experimental groups. Mice administered with ARM monotherapy and APO adjunctive treatment exhibited similar survivability. The latter showed better locomotor and cognitive functions, reduced ROS levels, and hippocampal NOX2 immunoreactivity in ECM. Our results show a substantial increase in hippocampal NeuN immunoreactivity and dendritic arborization in ARM + APO cohorts compared to ARM-treated brain samples. Overall, our study suggests that overexpression of NOX2 could result in loss of hippocampal neuronal density and dendritic spines of CA1 neurons affecting the spatial working and reference memory during ECM. Notably, ARM + APO adjunctive therapy reversed the altered neuronal morphology and oxidative damage in hippocampal neurons restoring long-term cognitive functions after CM.

Activation of Astrocytes in the Persistence of Post-hypoxic Respiratory Augmentation

Acute hypoxia increases ventilation. After cessation of hypoxia loading, ventilation decreases but remains above the pre-exposure baseline level for a time. However, the mechanism of this post-hypoxic persistent respiratory augmentation (PHRA), which is a short-term potentiation of breathing, has not been elucidated. We aimed to test the hypothesis that astrocytes are involved in PHRA. To this end, we investigated hypoxic ventilatory responses by whole-body plethysmography in unanesthetized adult mice. The animals breathed room air, hypoxic gas mixture (7% O₂, 93% N₂) for 2min, and again room air for 10min before and after i.p. administration of low (100mg/kg) and high (300mg/kg) doses of arundic acid (AA), an astrocyte inhibitor. AA suppressed PHRA, with the high dose decreasing ventilation below the pre-hypoxic level. Further, we investigated the role of the astrocytic TRPA1 channel, a putative ventilatory hypoxia sensor, in PHRA using astrocyte-specific Trpa1 knockout (asTrpa1^−/−) and floxed Trpa1 (Trpa1^f/f) mice. In both Trpa1^f/f and asTrpa1^−/− mice, PHRA was noticeable, indicating that the astrocyte TRPA1 channel was not directly involved in PHRA. Taken together, these results indicate that astrocytes mediate the PHRA by mechanisms other than TRPA1 channels that are engaged in hypoxia sensing.

Ginger (Zingiber officinale roscoe) extract could upregulate the renal expression of NRF2 and TNFα and prevents ethanol-induced toxicity in rat kidney

OBJECTIVE

Ginger has protective effects on the kidney, however the molecular mechanism of this effect has not yet been fully elucidated. Therefore, this work studied molecular mechanisms of ginger effects on ethanol-induced kidney injury.

MATERIALS AND METHODS

Twenty-four male Sprague-Dawley rats were randomly divided into four groups: control, ginger (1 g/kg/day ginger extract by oral gavage), ethanol (4 g/kg/day ethanol by oral gavage) and ginger-ethanol group and treated daily for 28 days. Kidney function, expression of nuclear factor erythroid 2-related factor 2 (NRF2) and tumor necrosis factor (TNF)-α genes and oxidative stress parameters in kidney tissue, were evaluated. Total phenolic content (TPC) and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of ginger extract were also evaluated.

RESULTS

Hydroethanolic extract of ginger showed a good level of DPPH scavenging activity and TPC. In the ethanol group, serum level of urea, creatinine and uric acid and the expression of NRF2 and TNF-α significantly increased compared to control group, while co-treatment with ginger in ginger+ethanol group significantly ameliorated them compared to the ethanol group. Ethanol exposure significantly reduced the activity of superoxide dismutase  (SOD), glutathione peroxidase (GPx) and catalase (CAT) compared to the control values ,while the level of malondialdehyde (MDA) significantly increased. Ginger significantly ameliorated the level of MDA and activity of SOD, GPx and CAT in the ginger-ethanol group compared to the ethanol group.

CONCLUSION

The results showed that ginger's protective effects against ethanol renotoxicity were mediated via enhancing the NRF2 and TNF-α expression.

Volatile Composition, Toxicity, Analgesic, and Anti-Inflammatory Activities ofMucuna pruriens

The volatile constituents, toxicity, antinociception, and anti-inflammatory activities of the essential oil obtained from the leaf of Mucuna pruriens utilis collected from Nigeria are reported. The essential oil was analyzed comprehensively utilizing gas chromatography (GC)-flame ionization detector and GC coupled with mass spectrometry (MS) using the HP-5 column. The antinociceptive and anti-inflammatory assays were analyzed by a hot plate, formalin, and carrageenan-induced edema assays, respectively. The essential oil was obtained in a yield of 0.2% (v/w) calculated on a dry weight basis. A total of 36 compounds representing 94.8% of the oil contents were identified. The oil contained a high content of ( E)-2-hexenal (19.0%), linalool (8.9%), 1-hexanol (6.6%), and trans-dehydroxylinalool oxide (5.2%). The analgesic property of the essential oil was slightly significant ( P < 0.5) only at the third hour for the 400 mg/kg while other doses are less active. The rate of inhibition was moderate (24.1%-54%) during the analgesic phase of the formalin assay. The rate of inhibition at the anti-inflammatory phases of both formalin and carrageenan were significantly high (100%) and P < 0.001 for all the doses during the reaction duration. The potential proinflammatory mechanism might be due to effects on several proinflammatory mediators, including, histamine, serotonin, and bradykinin, and the ability of the essential oils to act as centrally mediated opioid analgesic. Mucuna pruriens essential oils displayed a high anti-inflammation potential and can be used as a potential centrally mediated opioid antagonist against analgesia.

Young and middle-aged mouse breathing behavior during the light and dark cycles

Unrestrained barometric plethysmography is a common method used for characterizing breathing patterns in small animals. One source of variation between unrestrained barometric plethysmography studies is the segment of baseline. Baseline may be analyzed as a predetermined time‐point, or using tailored segments when each animal is visually calm. We compared a quiet, minimally active (no sniffing/grooming) breathing segment to a predetermined time‐point at 1 h for baseline measurements in young and middle‐aged mice during the dark and light cycles. Additionally, we evaluated the magnitude of change for gas challenges based on these two baseline segments. C57BL/6JEiJ x C3Sn.BliA‐Pde6b⁺/DnJ male mice underwent unrestrained barometric plethysmography with the following baselines used to determine breathing frequency, tidal volume (VT) and minute ventilation (VE): (1) 30‐sec of quiet breathing and (2) a 10‐min period from 50 to 60 min. Animals were also exposed to 10 min of hypoxic (10% O₂, balanced N₂), hypercapnic (5% CO₂, balanced air) and hypoxic hypercapnic (10% O₂, 5% CO₂, balanced N₂) gas. Both frequency and VE were higher during the predetermined 10‐min baseline versus the 30‐sec baseline, while VT was lower (P < 0.05). However, VE/V_O2 was similar between the baseline time segments (P > 0.05) in an analysis of one cohort. During baseline, dark cycle testing had increased VT values versus those in the light (P < 0.05). For gas challenges, both frequency and VE showed higher percent change from the 30‐sec baseline compared to the predetermined 10‐min baseline (P < 0.05), while VT showed a greater change from the 10‐min baseline (P < 0.05). Dark cycle hypoxic exposure resulted in larger percent change in breathing frequency versus the light cycle (P < 0.05). Overall, light and dark cycle pattern of breathing differences emerged along with differences between the 30‐sec behavior observational method versus a predetermined time segment for baseline.

Method to Obtain Pattern of Breathing in Senescent Mice through Unrestrained Barometric Plethysmography

Unrestrained barometric plethysmography (UBP) is a method for quantifying the pattern of breathing in mice, where breathing frequency, tidal volume, and minute ventilation are routinely reported. Moreover, information can be collected regarding the neural output of breathing, including the existence of central apneas and augmented breaths. An important consideration for UBP is obtaining a breathing segment with a minimal impact of anxious or active behaviors, to elucidate the response to breathing challenges. Here, we present a protocol that allows for short, quiet baselines to be obtained in aged mice, comparable to waiting for longer bouts of quiet breathing. The use of shorter time segments is valuable, as some strains of mice may be increasingly excitable or anxious, and longer periods of quiet breathing may not be achieved within a reasonable timeframe. We placed 22 month-old mice in a UBP chamber and compared four 15 s quiet breathing segments between minutes 60-120 to a longer 10 min quiet breathing period that took 2-3 h to acquire. We also obtained counts of central apneas and augmented breaths prior to the quiet breathing segments, following a 30 min familiarization period. We show that 10 min of quiet breathing is comparable to using a much shorter 15 s duration. Additionally, the time leading up to these 15 s quiet breathing segments can be used to gather data regarding apneas of central origin. This protocol allows investigators to collect pattern-of-breathing data in a set amount of time and makes quiet baseline measures feasible for mice that may exhibit increased amounts of excitable behavior. The UBP methodology itself provides a useful and noninvasive way to collect pattern-of-breathing data and allows for mice to be tested over several time points.

Minute ventilation during hypoxia is augmented with capsaicin supplementation in aged mice

Capsaicin is an agonist for transient receptor potential vanilloid 1 (TRPV1), and acute injection results in an increased frequency and tidal volume in young rats. It is unknown how capsaicin influences breathing in aged mice. We tested the hypothesis that capsaicin supplementation would elicit an augmented pattern of breathing in old mice compared to controls. Male 22-month old C57BL/6 J mice consumed a diet containing capsaicin (50 ppm) or lecithin control for one month. Breathing patterns were obtained prior to/following the dietary supplementation period using unrestrained barometric plethysmography. Frequency, tidal volume (VT), minute ventilation (VE), VE to expelled carbon dioxide ratio (VE/VCO₂) and VT divided by inspiratory time (VT/T_i) were analyzed at baseline and during a 15-minute hypoxic exposure (10% O₂). Capsaicin supplemented mice showed greater VE, VE/VCO₂ and TV/T_i during hypoxic exposure compared to controls, with no change at baseline. Overall, these findings suggest an acute augmented response to hypoxia following capsaicin administration in older mice.