Hindlimb unloading-induced reproductive suppression via Downregulation of hypothalamic Kiss-1 expression in adult male rats

Background Spaceflights-induced microgravity can alter various physiological processes in human’s body including the functional status of the reproductive system. Rodent model of tail-suspension hindlimb unloading is extensively used to stimulate the organs responses to the microgravity condition. This study explores the potential effects of hindlimb unloading on testicular functions and spermatogenesis in adult male rats and the underlying mechanism/s. Methods Twenty Sprague-Dawley rats were allotted into two groups: normally loaded group (control; all arms were in touch with the grid floor) and hindlimb unloaded group (HU; only the forearms were in contact with the grid floor). Results Following 30 days of exposure, the HU group saw a decline in body weight, testicular and epidydimal weights, and all semen parameters. The circulating concentrations of gonadotropin-releasing hormone (GnRH), follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone significantly decreased, while levels of kisspeptin, corticosterone, inhibin, prolactin and estradiol (E2) increased in the HU group. Intratesticular levels of 5α-reductase enzyme and dihydrotestosterone (DHT) were suppressed, while the levels of aromatase and kisspeptin were significantly elevated in the HU group. Hypothalamic kisspeptin (Kiss1) mRNA expression levels were downregulated while its receptors (Kiss1R) were upregulated in the HU group. On the contrary, the mRNA expression levels of testicular Kiss1 were upregulated while Kiss1R were downregulated. The pituitary mRNA expression levels of FSHβ and LHβ decreased in the HU group. The levels of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and nitric oxide (NO) concentrations, and total antioxidant capacity (TAC) were elevated while malondialdehyde (MDA) concentrations declined in the testes of HU group. The testes of the HU rats showed positive immunostaining of caspase-3, heat shock protein 70 (HSP70) and Bcl2. Conclusions Altogether, these results revealed an inhibitory effect of hindlimb unloading on kisspeptin signaling in the hypothalamic-pituitary-testicular axis with impaired spermatogenesis and steroidogenesis.

Curcumin to abrogate structural changes in the locus coeruleus following chronic sleep restriction in rats (Preprint)

UNSTRUCTURED This study examined the consequences of chronic sleep restriction (CSR) with or without curcumin treatment on quantitative histomorphological correlates of the locus coeruleus (LC) nucleus using stereological techniques. Male rats were assigned to five groups including: 1-control (C), 2- curcumin (CUR), 3- grid floor (GF), 4- CSR and 5- CSR+ curcumin (CUR) (100 mg/kg/day). Animals in the GF group were placed on wire-mesh grids while in the CSR box (modified multiple platform paradigm). After a period of 21 days, rats were sacrificed with their brains excised and assessed using stereological procedures. Our findings revealed a 22%, 45% and 47% reduction in the total volume, the total number of neurons and glial cells of LC in CSR group as compared to the control groups, respectively (p < 0.01). Such structural changes were abrogated in the CSR+CUR compared to the CSR group. The study outcome proposed potential neuroprotective effects of CUR in our sleep-restricted rat model. Further translational approaches would shed more light on the possible clinical significance of such finding in human subjects with chronic sleep loss including those with intensive shift-work schedules.

Vertical seismic response analysis of long-span composite open-web grid floor

PurposeThe purpose of this paper is to study the dynamic characteristics and seismic performance of the composite open-web grid floor structure.Design/methodology/approachStudied by using mode-superposition response spectrum method and time history analysis method.FindingsThe results show that the vertical mode-superposition response spectrum method is close to the time history analysis method. The floor has strong seismic performance, and the deflection and internal force are not large under vertical seism. The vertical seismic action suggested that 10% of the representative value of gravity load should be used to ensure the safety of the structure.Originality/valueIn the design, the mid-span section should be properly strengthened or the variable section design should be adopted.

Effect of Repeated Exposure to Isoflurane on Nest Building and Burrowing in Mice

Nest building and burrowing are highly motivated natural behaviors in rodents, and changes in these behaviors can serve as welfare assessment tools. In this study, we investigated: 1) the limits of agreement between 2 observers for a refined scoring method for nest-building behavior; 2) the effect of repeated exposure to 15 min of isoflurane on nest-building behavior; 3) the effect of 24 h of grid-floor housing, repeated exposure to 15 min isoflurane, and daily intraperitoneal injection of 0.2 mL 0.9% isotonic saline for 3 d on burrowing behavior; and 4) the effect of exposure to grid-floor housing, isoflurane, and intraperitoneal injections on fecal corticosterone metabolites, body weight, fur status, and sucrose preference in mice. SPF C57BL/6NTac female mice (n = 27) were included in the study and were assessed first for burrowing behavior, followed by 2 wk of rest and then for nesting behavior. The refined scoring method for nest-building activity had good inter observer agreement. According to this method, a single exposure to anesthesia with isoflurane led to a decrease in nest-building activity and sucrose preference; a second exposure to anesthesia with isoflurane had no effect on nest building. Neither grid-floor housing nor repeated exposure to isoflurane anesthesia had any effect on burrowing behavior in mice. In contrast, intraperitoneal injections increased burrowing behavior. In conclusion, a refined scoring method for nest-building activity test that we developed for this study proved to be objective and sensitive to the effect of an initial exposure to anesthesia with isoflurane.

Effect of sleep deprivation on the liver, kidney and heart: histological and immunohistochemical study

<p class="abstract"><strong>Background:</strong> Sleep deprivation is verging on a public health epidemic. It induced mild organ injuries through oxidative stress. The present study aimed at evaluating possible histopathological and immunohistochemical alterations caused by sleep deprivation on the liver, heart and kidney.</p><p class="abstract"><strong>Methods:</strong> 36 Wistar senile male albino rats were divided into two groups; control and experimental. Experimental rats were placed in a plastic cage, with grid floor placed inside it. The cage was filled with water to 1 cm below the grid surface. The stainless-steel rods of the grid were set 2 cm apart from each other. Loss of muscle tone associated with sleep caused them to touch the water and wake up. At the end of the experiment, animals were sacrificed by decapitation on days 1, 3 and 5. Liver, kidney and heart were obtained and dissected. </p><p class="abstract"><strong>Results:</strong> In SSD1 group, liver cells showed early stage of hepatic steatosis while mucolipidosis within hepatocytes was detected in SSD3 and the degree of steatosis increased in SSD5. Renal glomerular congestion was detected in SSD1. In SSD3 vascular congestion of glomerular tufts and apoptosis of the lining tubular epithelium was seen. Renal casts were formed in SSD5. In SSD1 lysis of myocardial fibrils was seen. Myocardial fibers degeneration represented by increase sarcoplasmic eosinophilia in SSD3. Sarcoplasmic vacuolation and nuclear chromatolysis increased in SSD5. Staining with GFAP and P53 showed various results among the liver, heart and kidney.</p><p class="abstract"><strong>Conclusions:</strong> Sleep deprivation might induce multiple organ injury through oxidative stress causing altered histological appearance.</p>

Serviceability of a New Kind of Precast Hollow Cross-Grids Floor System

This paper proposed a new kind of precast hollow cross-grid floor system which is fabricated by several precast panels and post-poured concrete strips. As there is a lack of data related to the vibration serviceability of this new floor system which aim at being used in the large-span buildings, an experimental investigation was conducted. The data obtained from the experiment showed the new floor system meet existing China criteria under most pedestrian excitations. The resultsalso demonstrated thepacing rate influence the vibration performances most as the crowd effect least. Then the FEM analysis was taken to predict the peak acceleration of the new kind of floor system comparing to the experimental results using different coefficient of dynamic force.

A simple rat model of mild traumatic brain injury: a device to reproduce anatomical and neurological changes of mild traumatic brain injury

Mild traumatic brain injury typically involves temporary impairment of neurological function. Previous studies used water pressure or rotational injury for designing the device to make a rat a mild traumatic brain injury model. The objective of this study was to make a simple model of causing mild traumatic brain injury in rats. The device consisted of a free-fall impactor that was targeted onto the rat skull. The weight (175 g) was freely dropped 30 cm to rat’s skull bregma. We installed a safety device made of acrylic panel. To confirm a mild traumatic brain injury in 36 Sprague-Dawley rats, we performed magnetic resonance imaging (MRI) of the brain within 24 h after injury. We evaluated behavior and chemical changes in rats before and after mild traumatic brain injury. The brain MRI did not show high or low signal intensity in 34 rats. The mobility on grid floor was decreased after mild traumatic brain injury. The absolute number of foot-fault and foot-fault ratio were decreased after mild traumatic brain injury. However, the difference of the ratio was a less than absolute number of foot-fault. These results show that the device is capable of reproducing mild traumatic brain injury in rats. Our device can reduce the potential to cause brain hemorrhage and reflect the mechanism of real mild traumatic brain injury compared with existing methods and behaviors. This model can be useful in exploring physiology and management of mild traumatic brain injury.

A simple rat model of mild traumatic brain injury: device to reproduce anatomical and neurological changes of mild traumatic brain injury

Mild traumatic brain injury typically involves temporary impairment of neurological function. Previous studies used the water pressure or rotational injury for designing the device to make a rat mild traumatic brain injury model. The objective of this study was to make a simple model of mild traumatic brain injury in rat. The device consisted of a free-fall impactor that was targeted onto the rat skull. The weight (175g) was freely dropped 30cm to rat’s skull bregma. We installed a safety device made of acrylic panel. To confirm a mild traumatic brain injury in 36 Sprague–Dawley rats, we performed the brain magnetic resonance image(MRI) within 24 hours after injury. We evaluated behavior and chemical changes in rats before and after mild traumatic brain injury. The brain MRI did not show high or low signal intensity in 34 rats. The mobility on grid floor was decreased after mild traumatic brain injury. Absolute number of foot-fault and foot-fault ratio were decreased after mild traumatic brain. But the difference of ratio was lesser than absolute number of foot-fault. These results show that the device is capable of reproducing mild traumatic brain injury in rat. Our device can reduce the potential to cause brain hemorrhage and reflect the mechanism of real mild traumatic brain injury compared with existing methods and behaviors. This model can be useful in exploring physiology and management of mild traumatic brain injury.

A simple rat model of mild traumatic brain injury: device to reproduce anatomical and neurological changes of mild traumatic brain injury

Mild traumatic brain injury typically involves temporary impairment of neurological function. Previous studies used the water pressure or rotational injury for designing the device to make a rat mild traumatic brain injury model. The objective of this study was to make a simple model of mild traumatic brain injury in rat. The device consisted of a free-fall impactor that was targeted onto the rat skull. The weight (175g) was freely dropped 30cm to rat’s skull bregma. We installed a safety device made of acrylic panel. To confirm a mild traumatic brain injury in 36 Sprague–Dawley rats, we performed the brain magnetic resonance image(MRI) within 24 hours after injury. We evaluated behavior and chemical changes in rats before and after mild traumatic brain injury. The brain MRI did not show high or low signal intensity in 34 rats. The mobility on grid floor was decreased after mild traumatic brain injury. Absolute number of foot-fault and foot-fault ratio were decreased after mild traumatic brain. But the difference of ratio was lesser than absolute number of foot-fault. These results show that the device is capable of reproducing mild traumatic brain injury in rat. Our device can reduce the potential to cause brain hemorrhage and reflect the mechanism of real mild traumatic brain injury compared with existing methods and behaviors. This model can be useful in exploring physiology and management of mild traumatic brain injury.