Molecular and Metabolic Mechanism of Low-Intensity Pulsed Ultrasound Improving Muscle Atrophy in Hindlimb Unloading Rats.

Low-intensity pulsed ultrasound (LIPUS) has been proved to promote the proliferation of myoblast C2C12. However, whether LIPUS can effectively prevent muscle atrophy has not been clarified, and if so, what is the possible mechanism. The aim of this study is to evaluate the effects of LIPUS on muscle atrophy in hindlimb unloading rats, and explore the mechanisms. The rats were randomly divided into four groups: normal control group (NC), hindlimb unloading group (UL), hindlimb unloading plus 30 mW/cm2 LIPUS irradiation group (UL + 30 mW/cm2), hindlimb unloading plus 80 mW/cm2 LIPUS irradiation group (UL + 80 mW/cm2). The tails of rats in hindlimb unloading group were suspended for 28 days. The rats in the LIPUS treated group were simultaneously irradiated with LIPUS on gastrocnemius muscle in both lower legs at the sound intensity of 30 mW/cm2 or 80 mW/cm2 for 20 min/d for 28 days. C2C12 cells were exposed to LIPUS at 30 or 80 mW/cm2 for 5 days. The results showed that LIPUS significantly promoted the proliferation and differentiation of myoblast C2C12, and prevented the decrease of cross-sectional area of muscle fiber and gastrocnemius mass in hindlimb unloading rats. LIPUS also significantly down regulated the expression of MSTN and its receptors ActRIIB, and up-regulated the expression of Akt and mTOR in gastrocnemius muscle of hindlimb unloading rats. In addition, three metabolic pathways (phenylalanine, tyrosine and tryptophan biosynthesis; alanine, aspartate and glutamate metabolism; glycine, serine and threonine metabolism) were selected as important metabolic pathways for hindlimb unloading effect. However, LIPUS promoted the stability of alanine, aspartate and glutamate metabolism pathway. These results suggest that the key mechanism of LIPUS in preventing muscle atrophy induced by hindlimb unloading may be related to promoting protein synthesis through MSTN/Akt/mTOR signaling pathway and stabilizing alanine, aspartate and glutamate metabolism.

Reduction of knee joint load suppresses cartilage degeneration, osteophyte formation, and synovitis in early-stage osteoarthritis using a post-traumatic rat model.

The purpose of this study was to clarify the histological effect of reducing the loading to knee on cartilage degeneration, osteophyte formation, and synovitis in early-stage osteoarthritis (OA) using a post-traumatic rat model. Ten male rats were randomly allocated into two experimental groups: OA induction by surgical destabilization of medial meniscus (DMM, OA group) and hindlimb suspension after OA induction by DMM (OAHS group). The articular cartilage, osteophyte formation, and synovial membrane in the medial tibiofemoral joint were analyzed histologically and histomorphometrically at 2 and 4 weeks after surgery. The histological scores and changes in articular cartilage and osteophyte formation were significantly milder and slower in the OAHS group than in the OA group. At 2 and 4 weeks, there were no significant differences in cartilage thickness and matrix staining intensity between both the groups, but chondrocytes density was significantly lower in the OA group. Synovitis was milder in OAHS group than in OA group at 2 weeks. Reducing knee joint loading inhibited histological OA changes in articular cartilage, osteophyte formation, and synovial inflammation. This result supports the latest clinical guidelines for OA treatment. Further studies using biochemical and mechanical analyses are necessary to elucidate the mechanism underlying delayed OA progression caused by joint-load reduction.

Decrease in AQP4 expression level in atrophied skeletal muscles with innervation.

Functional interaction between the selective water channel AQP4 and several ion channels, such as TRPV4, NKCC1, and Na+ /K+ -ATPase, closely participate to regulate osmotic homeostasis. In the skeletal muscles, the decrease in APQ4 expression due to denervation was followed by the restoration of AQP4 expression during reinnervation. These findings raised the possibility that innervation status is an essential factor to regulate AQP4 expression in the skeletal muscles. This study investigated this hypothesis using disuse muscle atrophy model with innervation. Adult female Fischer 344 rats (8 weeks of age) were randomly assigned to either control (C) or cast immobilization (IM) groups (n = 6 per group). Two weeks after cast immobilization, the tibialis anterior muscles of each group were removed and the expression levels of some target proteins were quantified by western blot analysis. The expression level of AQP4 significantly decreased at 2 weeks post-immobilization (p < 0.05). Moreover, the expression levels of TRPV4, NKCC1, and Na+ /K+ -ATPase significantly decreased at 2 weeks post-immobilization (p < 0.05). This study suggested that innervation status is not always a key regulatory factor to maintain the expression of AQP4 in the skeletal muscles. Moreover, the transport of water and ions by AQP4 may be changed during immobilization-induced muscle atrophy.

Nox2 signaling and muscle fiber remodeling are attenuated by losartan administration during skeletal muscle unloading.

Reduced mechanical loading results in atrophy of skeletal muscle fibers. Increased reactive oxygen species (ROS) are causal in sarcolemmal dislocation of nNOS and FoxO3a activation. The Nox2 isoform of NADPH oxidase and mitochondria release ROS during disuse in skeletal muscle. Activation of the angiotensin II type 1 receptor (AT1R) can elicit Nox2 complex formation. The AT1R blocker losartan was used to test the hypothesis that AT1R activation drives Nox2 assembly, nNOS dislocation, FoxO3a activation, and thus alterations in morphology in the unloaded rat soleus. Male Fischer 344 rats were divided into four groups: ambulatory control (CON), ambulatory + losartan (40 mg kg-1  day-1 ) (CONL), 7 days of tail-traction hindlimb unloading (HU), and HU + losartan (HUL). Losartan attenuated unloading-induced loss of muscle fiber cross-sectional area (CSA) and fiber-type shift. Losartan mitigated unloading-induced elevation of ROS levels and upregulation of Nox2. Furthermore, AT1R blockade abrogated nNOS dislocation away from the sarcolemma and elevation of nuclear FoxO3a. We conclude that AT1R blockade attenuates disuse remodeling by inhibiting Nox2, thereby lessening nNOS dislocation and activation of FoxO3a.

Prolonged Immobilization Exacerbates the Loss of Muscle Mass and Function Induced by Cancer-Associated Cachexia through Enhanced Proteolysis in Mice.

We hypothesized that in mice with lung cancer (LC)-induced cachexia, periods of immobilization of the hindlimb (7 and 15 days) may further aggravate the process of muscle mass loss and function. Mice were divided into seven groups (n = 10/group): (1) non-immobilized control mice, (2) 7-day unloaded mice (7-day I), (3) 15-day unloaded mice (15-day I), (4) 21-day LC-cachexia group (LC 21-days), (5) 30-day LC-cachexia group (LC 30-days), (6) 21-day LC-cachexia group besides 7 days of unloading (LC 21-days + 7-day I), (7) 30-day LC-cachexia group besides 15 days of unloading (LC 30-days + 15-day I). Physiological parameters, body weight, muscle and tumor weights, phenotype and morphometry, muscle damage (including troponin I), proteolytic and autophagy markers, and muscle regeneration markers were identified in gastrocnemius muscle. In LC-induced cachexia mice exposed to hindlimb unloading, gastrocnemius weight, limb strength, fast-twitch myofiber cross-sectional area, and muscle regeneration markers significantly decreased, while tumor weight and area, muscle damage (troponin), and proteolytic and autophagy markers increased. In gastrocnemius of cancer-cachectic mice exposed to unloading, severe muscle atrophy and impaired function was observed along with increased muscle proteolysis and autophagy, muscle damage, and impaired muscle regeneration.

The involvement of PI3K/Akt/mTOR/GSK3ß signaling pathways in the antidepressant-like effect of AZD6765.

AZD6765 (lanicemine) is a non-competitive NMDA receptor antagonist that induces a fast-acting antidepressant effect without presenting psychotomimetic effects. However, the mechanisms underlying its effects remain to be established. In this context, we demonstrated that a single administration of AZD6765 (1 mg/kg, i.p.) was able to induce an antidepressant-like effect in mice submitted to tail suspension test (TST), an effect reversed by LY294002 (a reversible PI3K inhibitor, 10 nmol/site, i.c.v.), wortmannin (an irreversible PI3K inhibitor, 0.1 µg/site, i.c.v.) and rapamycin (a selective mTOR inhibitor, 0.2 nmol/site, i.c.v.). In addition, the administration of sub-effective doses of AZD6765 (0.1 mg/kg, i.p.) in combination with lithium chloride (non-selective GSK-3ß inhibitor, 10 mg/kg, p.o.) or AR-A014418 (selective GSK-3ß inhibitor, (0.01 µg/site, i.c.v.) caused a synergistic antidepressant-like effect. These results suggest the involvement of PI3K/Akt/mTOR/GSK3ß signaling in the AZD6765 antidepressant-like effect. In addition, western blotting analysis showed an increased immunocontent of synapsin in the prefrontal cortex and a tendency to an increased immunocontent of this protein in the hippocampus 30 min after AZD6765 administration, but no significant effect of AZD6765 was observed in P70S6K (Thr389) phosphorylation and GluA1 immunocontent. A single dose of AZD6765 (3 mg/kg, i.p.), similarly to ketamine (1 mg/kg, i.p.), decreased the latency to feed in the novelty suppressed feeding (NSF) test, a behavioral paradigm that evaluates depression/anxiety-related behavior. This effect was reversed by rapamycin administration, suggesting the activation of mTOR signaling in the effect of AZD in the NSF test. In addition, a single administration of AZD6765 (1 mg/kg, i.p.) or ketamine (1 mg/kg, i.p.) reversed the depressive-like behavior induced by chronic unpredictable stress (CUS). Altogether, the results provide evidence for the fast-acting antidepressant profile of AZD6765, by a mechanism likely dependent on PI3K/Akt/mTOR/GSK3ß.

Human umbilical cord mesenchymal stem cell-derived exosomes act via the miR-1263/Mob1/Hippo signaling pathway to prevent apoptosis in disuse osteoporosis.

Disuse osteoporosis (DOP) is a common complication resulting from the lack of or disuse of mechanical loading and has been unsatisfactorily treated. We hypothesized that exosomes derived from human umbilical cord mesenchymal stem cells (HUCMSCs) could reduce bone marrow mesenchymal stem cell (BMSC) apoptosis in rat DOP via the miR-1263/Mob1/Hippo signaling pathway. To evaluate the function of exosomes derived from HUCMSCs (HUCMSC-Exos) in DOP, hind limb unloading (HLU)-induced DOP rat models were prepared. In vitro, the proliferation of BMSCs were evaluated using CCK-8 assays. Further, the apoptosis of BMSCs were evaluated using annexin V-FITC assay and Western blots. In vivo, the protective effects of HUCMSC-Exos were evaluated using HE staining and microCT analysis. The underlying molecular mechanism of exosome action on BMSC apoptosis through the miR-1263/Mob1/Hippo pathway was also investigated by high-throughput RNA sequencing, luciferase reporter assays, RNA-pull down assays and Western blots. The RNA-seq and q-PCR results showed that the level of miR-1263 was most abundant among differentially expressed microRNAs. Exosomal miR-1263 could bind to the 3'untranslated region (3' UTR) of Mob1 and exert its function by directly targeting Mob1 in recipient cells. The inhibition of Mob1 could activate YAP expression. Hippo inhibition reversed the in vitro HLU-induced apoptotic effect on BMSCs. The microCT and HE staining results indicated that HUCMSC-Exos ameliorated DOP in vivo. Exosomes derived from HUCMSCs are effective at inhibiting BMSC apoptosis and preventing rat DOP. This mechanism is mediated by the miR-1263/Mob1/Hippo signaling pathway.

Effect of Collagen Peptide, Alone and in Combination with Calcium Citrate, on Bone Loss in Tail-Suspended Rats.

Oral administration of bovine collagen peptide (CP) combined with calcium citrate (CC) has been found to inhibit bone loss in ovariectomized rats. However, the protective effects of CP and CP-CC against bone loss have not been investigated in a tail-suspension simulated microgravity (SMG) rat model. Adult Sprague-Dawley rats (n = 40) were randomly divided into five groups (n = 8): a control group with normal gravity, a SMG control group, and three SMG groups that underwent once-daily gastric gavage with CP (750 mg/kg body weight), CC (75 mg/kg body weight) or CP-CC (750 and 75 mg/kg body weight, respectively) for 28 days. After sacrifice, the femurs were analyzed by dual-energy X-ray absorptiometry, three-point bending mechanical tests, microcomputed tomography, and serum bone metabolic markers. Neither CP nor CP-CC treatment significantly inhibited bone loss in SMG rats, as assessed by dual-energy X-ray absorptiometry and three-point bending mechanical tests. However, both CP and CP-CC treatment were associated with partial prevention of the hind limb unloading-induced deterioration of bone microarchitecture, as demonstrated by improvements in trabecular number and trabecular separation. CP-CC treatment increased serum osteocalcin levels. Dietary supplementation with CP or CP-CC may represent an adjunct strategy to reduce the risk of fracture in astronauts.

Antidepressant-Like Activity of Typical Antidepressant Drugs in the Forced Swim Test and Tail Suspension Test in Mice Is Augmented by DMPX, an Adenosine A2A Receptor Antagonist.

Unsatisfactory therapeutic effects of currently used antidepressants force to search for new pharmacological treatment strategies. Recent research points to the relationship between depressive disorders and the adenosinergic system. Therefore, the main goal of our studies was to evaluate the effects of DMPX (3 mg/kg, i.p.), which possesses selectivity for adenosine A2A receptors versus A1 receptors, on the activity of imipramine (15 mg/kg, i.p.), escitalopram (2.5 mg/kg, i.p.), and reboxetine (2 mg/kg, i.p.) given in subtherapeutic doses. The studies carried out using the forced swim and tail suspension tests in mice showed that DMPX at a dose of 6 and 12 mg/kg exerts antidepressant-like effect and does not affect the locomotor activity. Co-administration of DMPX at a dose of 3 mg/kg with the studied antidepressant drugs caused the reduction of immobility time in both behavioral tests. The observed effect was not associated with an increase in the locomotor activity. To evaluate whether the observed effects were due to a pharmacokinetic/pharmacodynamic interaction, the levels of the antidepressants in blood and brain were measured using high-performance liquid chromatography. It can be assumed that the interaction between DMPX and imipramine was exclusively pharmacodynamic in nature, whereas an increased antidepressant activity of escitalopram and reboxetine was at least partly related to its pharmacokinetic interaction with DMPX.

Protective effects of Brazilian propolis supplementation on capillary regression in the soleus muscle of hindlimb-unloaded rats.

The protective effects of Brazilian propolis on capillary regression induced by chronically neuromuscular inactivity were investigated in rat soleus muscle. Four groups of male Wistar rat were used in this study; control (CON), control plus Brazilian propolis supplementation (CON + PP), 2-week hindlimb unloading (HU), and 2-week hindlimb unloading plus Brazilian propolis supplementation (HU + PP). The rats in the CON + PP and HU + PP groups received two oral doses of 500 mg/kg Brazilian propolis daily (total daily dose 1000 mg/kg) for 2 weeks. Unloading resulted in a decrease in capillary number, luminal diameter, and capillary volume, and an increase in the expression of anti-angiogenic factors, such as p53 and TSP-1, within the soleus muscle. Brazilian propolis supplementation, however, prevented these changes in capillary structure due to unloading through the stimulation of pro-angiogenic factors and suppression of anti-angiogenic factors. These results suggest that Brazilian propolis is a potential non-drug therapeutic agent against capillary regression induced by chronic unloading.

Effect of 30-Day Hindlimb Unloading and Hypergravity on Bone Marrow Stromal Progenitors in C57Bl/6N Mice.

We studied the effect of 30-day hindlimb unloading and subsequent simulated hypergravity on the cellularity and proliferative, clonogenic, and differentiation potential of bone marrow stromal progenitors in mice. Clonogenic and differentiation activity of stromal cells decreased after unloading; proliferative and differentiation activity of bone marrow stromal progenitors increased after hypergravity simulation. Our findings demonstrated negative effect of unloading on functional activity of mouse bone marrow stromal progenitors. Short-term hypergravity after unloading produced a stimulating effect on the bone marrow stromal progenitors.

Long-term hindlimb unloading causes a preferential reduction of medullary thymic epithelial cells expressing autoimmune regulator (Aire).

Hindlimb unloading (HU) of rodents has been used as a ground-based model of spaceflight. In this study, we investigated the detailed impact of 14-day HU on the murine thymus. Thymic mass and cell number were significantly reduced after 14 days of hindlimb unloading, which was accompanied by an increment of plasma corticosterone. Although corticosterone reportedly causes selective apoptosis of CD4+CD8+ thymocytes (CD4+CD8+DPs) in mice treated with short-term HU, the reduction of thymocyte cellularity after the 14-day HU was not selective for CD4+CD8+DPs. In addition to the thymocyte reduction, the cellularity of thymic epithelial cells (TECs) was also reduced by the 14-day HU. Flow cytometric and RNA-sequencing analysis suggested that medullary TECs (mTECs) were preferentially reduced after HU. Moreover, immunohistochemical staining suggested that the 14-day HU caused a reduction of the mTECs expressing autoimmune regulator (Aire). Our data suggested that HU impacts both thymocytes and TECs. Consequently, these data imply that thymic T cell repertoire formation could be disturbed during spaceflight-like stress.

The neuroprotective and antidepressant-like effects of Hcyb1, a novel selective PDE2 inhibitor.

AIMS: Depression is currently the most common mood disorder. Regulation of intracellular cyclic adenosine monophosphate (cAMP) and/or cyclic guanosine monophosphate (cGMP) signaling by phosphodiesterase (PDE) inhibition has been paid much attention for treatment of depression. This study aimed to investigate the neuroprotective effects of Hcyb1, a novel PDE2 inhibitor, in HT-22 cells and antidepressant-like effects in mouse models of depression. METHODS: Hcyb1 was synthesized and its selectivity upon PDE2 was tested. Moreover, HT-22 hippocampal cells were used to determine the effects of Hcyb1 on cell viability, cyclic nucleotide levels, and the downstream molecules related to cAMP/cGMP signaling by neurochemical, enzyme-linked immunosorbent, and immunoblot assays in vitro. The antidepressant-like effects of Hcyb1 were also determined in the forced swimming and tail suspension tests in mice. RESULTS: Hcyb1 had a highly selective inhibition of PDE2A (IC50  = 0.57 ± 0.03 µmol/L) and over 250-fold selectivity against other recombinant PDE family members. Hcyb1 at concentrations of 10-10 and 10-9  mol/L significantly increased cell viability after treatment for 24 hours. At concentrations of 10-9 ~10-7  mol/L, Hcyb1 also increased cGMP levels by 1.7~2.3 folds after 10-minute treatment. Furthermore, Hcyb1 at the concentrations of 10-9  mol/L increased both cGMP and cAMP levels 24 hours after treatment. The levels of phosphorylation of CREB and BDNF were also increased by Hcyb1 treatment in HT-22 cells for 24 hours. Finally, in the in vivo tests, Hcyb1 (0.5, 1, and 2 mg/kg, i.g.) decreased the immobility time in both forced swimming and tail suspension tests, without altering locomotor activity. CONCLUSION: These results suggest that the novel PDE2 inhibitor Hcyb1 produced neuroprotective and antidepressant-like effects most likely mediated by cAMP/cGMP-CREB-BDNF signaling.

Tauroursodeoxycholic acid produces antidepressant-like effects in a chronic unpredictable stress model of depression via attenuation of neuroinflammation, oxido-nitrosative stress, and endoplasmic reticulum stress.

Depression is a common psychiatric disorder with heavy economic and social burdens. Searching new agents with better antidepressant-like activities is of great significance for depression therapy. Tauroursodeoxycholic acid (TUDCA), a clinical drug for gallstone treatment, possesses neuroprotective effects in different brain disorders. However, whether it affects depression remains unclear. We addressed this issue by evaluating the effect of TUDCA on depression induced by chronic unpredictable stress (CUS). Results showed that TUDCA treatment at 200 but not 100 mg/kg prevented the 5 weeks of CUS-induced increases in the immobile time of C57BL6/J mice in the experiments of forced swimming test and tail suspension test as well as the CUS-induced decrease in sucrose intake and crossing numbers in the open-field test, and did not enhance the antidepressant-like effect of fluoxetine. Attenuation of neuroinflammation may be involved in the antidepressant-like effect of TUDCA, as TUDCA treatment (200 mg/kg) normalized the levels of tumor necrosis factor-α and interleukin-6 in both hippocampus and prefrontal cortex. The increases in inflammasome and microglial activation markers, including interleukin-ß, nod-like receptor protein 3, and Iba-1, in CUS-treated mice were reduced by TUDCA treatment (200 mg/kg). TUDCA treatment (200 mg/kg) also normalized the changes in markers reflecting the oxidative-nitrosative and endoplasmic reticulum (ER) stress induced by CUS, such as nitric oxide, reduced glutathione, malondialdehyde, glucose-regulated protein 78, and C/EBP homologous protein. These results revealed that TUDCA improved the CUS-induced depression-like behaviors likely through attenuation of neuroinflammation, oxido-nitrosative, and ER stress.

Human Neural Stem Cell Extracellular Vesicles Improve Tissue and Functional Recovery in the Murine Thromboembolic Stroke Model.

Over 700 drugs have failed in stroke clinical trials, an unprecedented rate thought to be attributed in part to limited and isolated testing often solely in "young" rodent models and focusing on a single secondary injury mechanism. Here, extracellular vesicles (EVs), nanometer-sized cell signaling particles, were tested in a mouse thromboembolic (TE) stroke model. Neural stem cell (NSC) and mesenchymal stem cell (MSC) EVs derived from the same pluripotent stem cell (PSC) line were evaluated for changes in infarct volume as well as sensorimotor function. NSC EVs improved cellular, tissue, and functional outcomes in middle-aged rodents, whereas MSC EVs were less effective. Acute differences in lesion volume following NSC EV treatment were corroborated by MRI in 18-month-old aged rodents. NSC EV treatment has a positive effect on motor function in the aged rodent as indicated by beam walk, instances of foot faults, and strength evaluated by hanging wire test. Increased time with a novel object also indicated that NSC EVs improved episodic memory formation in the rodent. The therapeutic effect of NSC EVs appears to be mediated by altering the systemic immune response. These data strongly support further preclinical development of a NSC EV-based stroke therapy and warrant their testing in combination with FDA-approved stroke therapies.

Long-Term High-Dose Resveratrol Supplementation Reduces Bone Mass and Fracture Strength in Rats.

Resveratrol (RSV) is a natural polyphenolic compound. A recent study suggests a positive effect on BMD in men; however, the underlying changes in microstructure and strength remain unknown. We aimed to investigate the effects of RSV on the skeleton in hindlimb-immobilized and non-immobilized rats. Seventy-two female Wistar rats were divided into six groups. Two baseline (BSL) groups underwent short-term diet intervention for 4 weeks before sacrifice [phytoestrogen-deficient diet (PD) (BSL + PD) or RSV diet (600 mg/kg body weight/day) (BSL + RSV)]. Four groups were injected in the right hindlimb with botulinum toxin (BTX) (immobilized) or saline (non-immobilized), and fed either PD diet or RSV diet 4 weeks pre-injection and 6 weeks post-injection before sacrifice (BTX + PD, BTX + RSV, PD, and RSV, respectively). DXA, µCT, dynamic histomorphometry, and mechanical tests were performed. Short-term RSV treatment did not affect bone parameters, whereas long-term RSV exposure had a consistent negative impact on non-immobilized rats (RSV vs. PD); whole femoral aBMD (p = 0.01) and distal femoral metaphyseal Tb.N (p = 0.01), Tb.Sp (p = 0.02), and BV/TV (p = 0.07). At the femoral mid-diaphysis, RSV increased periosteal resorption (p = 0.01) and increased endosteal formation (p = 0.02), while mineralization was unaffected. In addition, RSV reduced femoral mid-diaphyseal three-point bending strength (p = 0.03) and stiffness (p = 0.04). BTX-induced immobilization resulted in significant bone loss and reduced bone strength; however, RSV supplementation was unable to prevent this. In conclusion, long-term high-dose RSV reduced bone mass and fracture strength and did not prevent immobilization-induced bone loss in rats.

Simulated space radiation sensitizes bone but not muscle to the catabolic effects of mechanical unloading.

Deep space travel exposes astronauts to extended periods of space radiation and mechanical unloading, both of which may induce significant muscle and bone loss. Astronauts are exposed to space radiation from solar particle events (SPE) and background radiation referred to as galactic cosmic radiation (GCR). To explore interactions between skeletal muscle and bone under these conditions, we hypothesized that decreased mechanical load, as in the microgravity of space, would lead to increased susceptibility to space radiation-induced bone and muscle loss. We evaluated changes in bone and muscle of mice exposed to hind limb suspension (HLS) unloading alone or in addition to proton and high (H) atomic number (Z) and energy (E) (HZE) (16O) radiation. Adult male C57Bl/6J mice were randomly assigned to six groups: No radiation ± HLS, 50 cGy proton radiation ± HLS, and 50 cGy proton radiation + 10 cGy 16O radiation ± HLS. Radiation alone did not induce bone or muscle loss, whereas HLS alone resulted in both bone and muscle loss. Absolute trabecular and cortical bone volume fraction (BV/TV) was decreased 24% and 6% in HLS-no radiation vs the normally loaded no-radiation group. Trabecular thickness and mineral density also decreased with HLS. For some outcomes, such as BV/TV, trabecular number and tissue mineral density, additional bone loss was observed in the HLS+proton+HZE radiation group compared to HLS alone. In contrast, whereas HLS alone decreased muscle mass (19% gastrocnemius, 35% quadriceps), protein synthesis, and increased proteasome activity, radiation did not exacerbate these catabolic outcomes. Our results suggest that combining simulated space radiation with HLS results in additional bone loss that may not be experienced by muscle.

Modulatory Role of Rutin Supplement on Open Space Forced Swim Test Murine Model of Depression.

Flavonoids have been demonstrated to possess an anti-depressant effect and less adverse effects than tricyclic anti-depressants. For this reason, flavonoids in natural products have attracted growing attention. Rutin is a glycoside flavonoid which belongs to an important class of flavonoids, abundantly found in plants, such as buckwheat seeds, asparagus, red pepper, apples, citrus fruits and leaves of many herbs such as rosemary, dandelion or sage, and black and green tea.  It is a vital nutritional component of food stuff. This study aimed at investigating the antidepressant potential of the rutin supplement on Swiss albino mice. For assessment of antidepressant activity, Open Space Forced Swim Test (OSFST), Tail Suspension Test (TST), Open-Field Test (OFT) and Novel Object Recognition Test (NORT) were used. Twenty-five Swiss albino mice were used for the study and divided into five groups. Group I received 10 mg/kg distilled water, group II received fluoxetine 20 mg/kg while group III, IV and V received rutin (30 mg/kg, 60 mg/kg and 120 mg/kg respectively) for sixteen days. The administration of the rutin supplement for sixteen days produced a reduction of immobility time in the TST (at 30 mg/kg, 60 mg/kg and 120 mg/kg), p<0.05. Likewise, a statistically significant difference was observed in line crossing in OFT, p<0.05. However, no significant effect was observed in percentage novel object preference in NORT. This study revealed that oral administration of rutin has an antidepressant potential in a dose dependent manner in OSFST mouse model of depression.

Modulation of PKA, PKC, CAMKII, ERK 1/2 pathways is involved in the acute antidepressant-like effect of (octylseleno)-xylofuranoside (OSX) in mice.

RATIONALE: (Octylseleno)-xylofuranoside (OSX) is an organoselenium compound from the class of alkylseleno carbohydrates possessing a C8 alkyl chain. Members of this class of organoselenium compounds have promising pharmacological activities, among them are antioxidant and acute antidepressant-like activities with the involvement of monoaminergic system, as previously presented by our research group. OBJECTIVE: The objective of the study was to investigate the possible involvement of cellular signalling pathways in the antidepressant-like effect caused by OSX (0.01 mg/kg, oral route (p.o.) by gavage) in the tail suspension test (TST) in mice. METHODS: Mice were treated by intracerebroventricular (i.c.v.) injection either with vehicle or with H-89 (1 µg/site i.c.v., an inhibitor of protein kinase A-PKA), KN-62 (1 µg/site i.c.v., an inhibitor of Ca2+/calmodulin-dependent protein kinase II-CAMKII), chelerythrine (1 µg/site i.c.v., an inhibitor of protein kinase C-PKC) or PD098059 (5 µg/site i.c.v., an inhibitor of extracellular-regulated protein kinase 1/2-ERK1/2). Fifteen minutes after, vehicle or OSX was injected, and 30 min later, the TST and open field tests (OFT) were carried out. RESULTS: The antidepressant-like effect of orally administered OSX was blocked by treatment of the mice with H-89, KN-62, chelerythrine and PD098059; all inhibitors of signalling proteins involved with neurotrophic signalling pathways. The number of crossings in the OFT was not altered by treatment with OSX and/or signalling antagonists. CONCLUSIONS: The results demonstrated that OSX showed an antidepressant-like effect in the TST in mice through the activation of protein kinases PKA, PKC, CAMKII and ERK1/2 that are involved in intracellular signalling pathways.

Activation of HIF-1α and its downstream targets in rat hippocampus after long-term simulated microgravity exposure.

Microgravity has many detrimental impact on brain functions, however the underlying mechanism remain unclear. In present study, 28 days of tail-suspension (30°) was used to simulate microgravity in rats. We showed that oxidative stress in hippocampus was increased after 28 days of simulated microgravity in consideration of the decreased expression of NF-E2-related factor 2 (Nrf2) and the declined activities of total superoxide dismutase (T-SOD), CuZn-SOD, glutathione peroxidase (GSH-PX) and total antioxidant capacity (T-AOC). Using RNA-seq, we further investigated the effect of simulated microgravity on the expression of genes in hippocampus, and 849 genes were found to be differentially expressed. According to pathway analysis, the differentially expressed genes involved in cytoskeleton, metabolism, immunity, transcription regulation, etc. It is interesting to note that the differentially expressed genes were involved in hypoxia-associated pathway. In agreement with this, the expression of hypoxia induced factor-1α (HIF-1α), the master regulator of oxygen homeostasis, was significantly increased. Meanwhile, HIF-2α, a HIF-1α paralog, was elevated compared with the control group. The expression of pyruvate dehydrogenase kinase 1 (PDK1), lactate dehydrogenase A (LDHA) and vascular endothelial growth factor (VEGF), three well-defined downstream targets of HIF-1α, were up-regulated in hippocampus after 28 days of simulated microgravity exposure. Additionally, brain oxygen saturation (SO2) and blood flow analyzed by the tissue oxygen analysis system were also significantly reduced. These findings indicate that simulated microgravity might cause an alteration in oxygen homeostasis, providing novel insight into better understanding of how simulated microgravity affects the function of hippocampus and a new direction to the development of countermeasure for brain dysfunction during spaceflight (actual microgravity).