Cage Control Research Articles

Effects of sleep deprivation on learning and memory and pCREB level in hippocampus of mice

Objective To observe the effects of sleep deprivation(SD)on learning and memory and phos-phorylated cyclic AMP responsive element binding protein(pCREB) expression in hippocampus of mice,and to explore the mechanism of cognitive change after SD. Methods Twenty female C57BL/6J mice were randomly divided into sleep deprivation group(SD, n = 10) and normal cage control group (CC,n = 10). Touch method was used to establish the sleep deprivation model. 30 days after SD,all the animals were subjected for Morris Water Maze (MWM) to test mean escape latency and percentage of time spent in the target quadrant. pCREB level in hippocampus was tested with Western blot. Results The mean escape latency in SD group in the second and third day of MWM was (29.31 ±4.93) s and (25.33 ±5.06)s, respectively, and was longer than that in CC group ((26.05 ±5.96)s and (19.35 ±7. 85)s,respectively). Mice in SD group spent less time in the target quadrant than that in CC group((23.61 ±9.86)% and (37.46 ±7. 51)%,.respectively, P<0.05). Results of Western blot for pCREB revealed that the pCREB level in hippocampus in sleep deprivation group was significantly lower than that in control group(0.71 ±0.03 and 0.82 ±0.06, respectively, P<0.01) . Conclusion The impairment of spatial learning and memory ability in sleep deprivation animals may be associated with the reduction of pCREB in hippocampus. Key words: Sleep deprivation; Learning; Memory; Phosphorylated cyclic AMP responsive element binding protein(pCREB)

Alendronate Inhibits Bone Formation Response To Simulated Resistance Training During Disuse

Previously, we have demonstrated that high intensity muscle contractions and the anti-resorptive agent alendronate (ALEN) independently abolish or mitigate, respectively, reductions in cancellous bone mass during rodent hindlimb unloading (HU). PURPOSE: To assess the separate and combined effects of a reduced frequency and intensity of muscle contractions simulating resistance training (SRT) and ALEN. METHODS: Male, Sprague-Dawley rats (6-mo-old) were randomly assigned to cage control (CC, n=12), HU (HU, n=12), HU plus either ALEN (HU+ALEN, n=12), SRT (HU+SRT, n=12), or ALEN and SRT (HU+SRT/ALEN, n=12). HU+SRT and HU+SRT/ALEN rats were subjected to muscle contractions while anesthetized once every 3 days during 28-d HU (75% peak isometric strength; 4 sets of 5 reps; 1000ms isometric + 1000ms eccentric). Additionally, HU+ALEN and HU+SRT/ALEN rats received 0.01 mg/kg BW ALEN 3×/week. RESULTS: Standard histomorphometry revealed a 56% reduction in periosteal bone formation rate (BFR) at mid-shaft tibia after 28-d HU, which was not rescued by ALEN treatment. However, we observed a 2.6- and 14-fold increase periosteal and endocortical (BFR), respectively, in HU+SRT vs. CC rats. These increases in diaphyseal BFR were significantly blunted (∼35-56%) in HU+SRT/ALEN rats. At the proximal tibia metaphysis (PTM), HU reduced cancellous BFR 80%, with no effect of ALEN treatment (-85% vs. CC). Similar to diaphyseal results, SRT during HU significantly increased cancellous BFR 123% vs. CC, whereas HU+SRT/ALEN inhibited the anabolic effect of SRT and reduced BFR (-33% vs. CC). SRT prevented negative effects of HU on PTM cancellous microarchitecture, resulting in increased bone volume (+19%) and trabecular thickness (+9%), respectively vs. CC. Additionally, osteoclast surface (OcS/BS) was reduced (-57%) and osteoid surface (OS/BS) significantly increased in HU+SRT rats vs. CC (32%). Adding ALEN to SRT during HU reduced OcS/BS (-75%), ObS/BS (-72%), and OS/BS (-61%) vs. CC, but did not affect microarchitecture. CONCLUSION: These results demonstrate the anabolic effect of high intensity muscle contractions during disuse and suggest that both bone resorption and formation are suppressed when SRT is combined with bisphosphonate treatment during HU. Funded by NSBRI through NASA Cooperative Agreement NCC 9-58.

Treadmill Exercise And IL-6-induced Cachexia In The ApcMin/+ Mouse

Cancer cachexia is a condition associated with the loss of skeletal muscle and adipose tissue mass. The ApcMin/+ mouse is an established model of colorectal cancer that also develops cachexia. IL-6 is necessary for the development of cachexia in the ApcMin/+ mouse. While endurance exercise can reduce polyp number and systemic inflammation in the ApcMin/+ mouse, the affect of exercise on IL-6-induced cachexia in the ApcMin/+ mouse is not known. PURPOSE: The purpose of this study was to determine if 8 weeks of treadmill exercise could repress IL-6-induced cachexia in the ApcMin/+ mouse. METHODS: ApcMin/+ mice were assigned to either 8 weeks of treadmill (6 days/week, 18m/s, 5% grade) exercise or cage control treatments at 6 weeks of age. After 6 weeks of exercise training, circulating IL-6 over-expression was induced by electroporation of a plasmid into the quadriceps while an empty vector served as the control. Body weight, muscle and fat pad weights were recorded at 14 weeks of age. RESULTS: Electroporation increased circulating plasma IL-6 in sedentary control mice (6.7 vs 141 pg/ml) and the exercise group (10.4 vs 111 pg/ml). Sedentary ApcMin/+ mice over-expressing IL-6 lost 10.2% (p < 0.001) of their body mass during the 2 week period. The loss in body weight corresponded to a 13% reduction (p = 0.04) in soleus muscle wet weight and a 45% (p = 0.002) reduction in epididymal fat pad weight. Exercise training prevented the IL-6 induced loss in body weight and maintained soleus muscle and epididymal fat pad weights. CONCLUSION: These data show chronic moderate treadmill exercise in the ApcMin/+ mouse prevents cachexia induced by IL-6 over-expression. Funded by R01CA121249-01A2

Abstract 3270: Environmental stress results in an earlier onset of tumors in a HER2/Neu breast cancer model

Abstract Introduction Possible environmental effects on the development of HER2+ breast cancer have received relatively little research attention. Here we used the well-established MMTV-neu mouse model, which overexpresses mammary ErbB2 (HER2-neu) and stochastically develops primary tumors over 6-12 months, to test the hypothesis that chronic exposure to environmental stressors may result in an earlier onset of tumors. Experimental Procedures Female mice (FVB/N-Tg(MMTVneu)202Mul/J) were purchased from Jackson Labs at age 4-5 weeks, housed in standard cages in an isolation chamber in a controlled-access animal room, and randomly assigned to one of four experimental exposure conditions in a factorial design that was maintained for the course of the study: 1) Restraint stress (RS) 90 min - 1x/wk (n=24); 2) Social disruption stress (SD) (via cage mate switching across home cages) 2x/wk (n=23); 3) RS&amp;SD (n=22); 4) home cage control (HC)(n=20). Mice were visually inspected and palpated for tumor development 1x/wk (blinded as to treatment group). All mammary glands from each mouse were processed for histologic evaluation one week following positive tumor palpation. All palpated tumors were histologically confirmed by a pathologist's evaluation of H&amp;E sections (blinded as to treatment group). Results Consistent with the study hypothesis, the results indicated that mice chronically exposed to the two environmental stressors (RS&amp;SD) developed primary tumors at a significantly (p&amp;lt;0.002, Cox regression) younger age (mean +/− se: 29.8 +/− 0.7 wk) than the controls (HC) (34.4 +/− 0.8 wk). The mice chronically exposed to just one of the stressors developed tumors at an intermediate age (RS = 32.0 +/− 0.8; SD = 32.3 +/− 0.8 wk), suggesting a possible additive pattern of stress responses. Consistent with stress effects early in the process of tumorigenesis, evidence of mammary hyperplasia in the H&amp;E sections was also significantly (p&amp;lt;0.04) more frequent in mice exposed to both stressors (RS&amp;SD) compared with the control group (HC). Body weights increased significantly over the entire course of the study and did not differ across groups, suggesting that the group differences in tumor development were not due to a failure to thrive. Conclusions Exposure to environmental stressors may speed the development of tumors in this transgenic model of HER2+ breast cancer. These novel findings suggest the importance of further investigation to determine the mechanisms responsible for these effects of exposure to environmental stressors. (Support: CA120795) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3270.

Habitual aerobic exercise reverses age‐associated increases in transforming growth factor beta 1 in carotid arteries of mice

Aging increases carotid artery stiffness and adventitial collagen in mice. These events are reversed by voluntary wheel running (VR). Transforming growth factor β1 (TGF‐β1) modulates extracellular matrix proteins with aging, but the effect of habitual exercise on TGF‐β1 expression in large elastic arteries is unknown. Carotid artery stiffness was greater in old (O, 31 mo, n=4) vs. young (Y, 7 mo, n=4) adult cage‐control B6D2F1 mice (8.53 ± 2.00 vs. 3.015 ± 1.19 AU, p &lt; 0.05), but not in O (n=4) given access to running wheels (mean distance = 1 km/d) for 12 weeks (3.61 ± 0.83 AU, p &lt; 0.05). Immunohistochemical analysis of carotid arteries from Y (n=6) and O (n=8) cage control mice revealed increases in adventitial TGF‐β1 with aging (5.7E‐05 ± 5.9E‐06 vs. 3.6E‐05 ± 3.5E‐06 AU, P &lt; 0.05), which were reversed by VR in O (n=4) (3.6E‐05 ± 4.2E‐06 AU). In a primary culture of adventitial fibroblasts obtained from Y adult (6 mo) Sprague‐Dawley rats, 24‐hr treatment with TGF‐β1 increased type I collagen (1.38 ± 0.07 vs. 1.0 ± 0.08, P &lt; 0.05, western blot) and superoxide (O2−) production (4514 ± 317 vs. 2828 ± 185, P &lt; 0.05, electron paramagnetic resonance). These preliminary data are consistent with the working hypothesis that habitual aerobic exercise may reverse large elastic artery stiffening with aging in part by reducing O2− production, which inhibits adventitial TGF‐β1‐induced adventitial collagen accumulation.AG013038 and HL007822

The Effects of Hindlimb Suspension on Proteins Essential to Cholesterol Metabolism in Rat Skeletal Muscle

IntroductionHindlimb suspension (HS) results in significant deleterious effects on numerous physiological systems, including atrophy of weight‐bearing muscles. However, HS and its effects on proteins essential for cholesterol metabolism have not been investigated in unloaded skeletal muscle. Cholesterol serves as a critical constituent of all cell membranes, including skeletal muscle. The purpose of this study was to examine the effects of 28 days of HS on sterol regulatory element‐binding protein 2 (SREBP‐2), which is a transcriptional factor necessary for endogenous cholesterol synthesis. We hypothesized that HS causes a downregulation of this protein in rat skeletal muscle.MethodsTwelve male Sprague‐Dawley rats, 6 months of age, were hindlimb suspended for 28 days (HS; n=5) or served as cage controls (CC; n=7). After 4 weeks, plantarflexor muscles were harvested, weighed and analyzed by Western Blotting for SREBP‐2.ResultsSoleus muscle mass and soleus muscle mass to body mass were significantly different between groups (HS: 97.0 ± 14.2 mg and 0. 22 ± 0. 03 mg/g; CC: 244.3 ± 38.1 mg and 0.49 ± 0. 06 mg/g, P &lt; 0.05). However, mature SREBP‐2 was not significantly different between groups (HS: 0.66 ± 0.31 arbitrary units (AU) and CC: 1.06 ± 0.39 AU, P=0.09).ConclusionAfter 28 days, HS resulted in significant decreases in soleus muscle mass, but not mature SREBP‐2, as compared to cage controls.

89 EFFECT OF VOLUNTARY WHEEL RUNNING ON GROWTH OF PROSTATE CANCER IN IMMUNOCOMPROMISED AND IMMUNOCOMPETENT MOUSE MODELS

You have accessJournal of UrologyProstate Cancer: Basic Research I1 Apr 201089 EFFECT OF VOLUNTARY WHEEL RUNNING ON GROWTH OF PROSTATE CANCER IN IMMUNOCOMPROMISED AND IMMUNOCOMPETENT MOUSE MODELS Jodi Antonelli, Lee Jones, Jean-Alfred Thomas, Elizabeth Masko, Jessica Lloyd, Susan Poulton, Tameika Phillips, Alok Tewari, Phillip Febbo, Michael Pollak, Mark Dewhirst, and Stephen J. Freedland Jodi AntonelliJodi Antonelli Durham, NC More articles by this author , Lee JonesLee Jones Durham, NC More articles by this author , Jean-Alfred ThomasJean-Alfred Thomas Durham, NC More articles by this author , Elizabeth MaskoElizabeth Masko Durham, NC More articles by this author , Jessica LloydJessica Lloyd Durham, NC More articles by this author , Susan PoultonSusan Poulton Durham, NC More articles by this author , Tameika PhillipsTameika Phillips Durham, NC More articles by this author , Alok TewariAlok Tewari Durham, NC More articles by this author , Phillip FebboPhillip Febbo Durham, NC More articles by this author , Michael PollakMichael Pollak Montreal, Canada More articles by this author , Mark DewhirstMark Dewhirst Durham, NC More articles by this author , and Stephen J. FreedlandStephen J. Freedland Durham, NC More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.138AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Little is known about the therapeutic potential of exercise for PC. Therefore, we sought to characterize the effect of exercise on PC in a post-diagnosis setting using both immunocompromised (LAPC-4) and immunocompetent (TRAMP) mouse models. METHODS In the LAPC-4 model, 62 Nude male mice were orthotopically implanted with LAPC-4 cells and at 14 days post-implant, were randomized to exercise (individual housing in cages with a running wheel, n=29) or sedentary control (cage without a wheel, n=33). After sacrificing 24 mice at various time points for analysis, 38 mice (21 control, 17 exercise) remained and underwent necropsy at day 57. Tumor tissue was analyzed for markers of vascularization and gene expression and serum was assayed for PSA and IGF axis markers. In the TRAMP model 59 male C57BL/6 mice were orthotopically implanted with TRAMP cells and at 14 days post-implant were randomized to exercise (n=28) or sedentary control (n=31) groups. Surgical procedure, housing, and early sacrifices were identical to the LAPC-4 model. On days 42-53 a total of 38 mice (20 control, 18 exercise) underwent necropsy where tumors were weighed. RESULTS In the LAPC-4 model there were no significant differences in tumor weight between the exercise and control groups. However, for mice sacrificed on day 57, those exercising more than 1.8km/day (median run distance) had larger tumors than their sedentary counterparts (p=0.06). The control group had greater tumor microvessel density (p=0.03) and the exercise group had greater tumor VEGF concentration (p=0.06). Gene expression analysis showed pathways involved in hypoxia, oxidative stress, VEGF, and insulin sensitivity were enriched in the exercise group. In the TRAMP model there was a trend toward the exercise mice having smaller tumors than control mice (p=0.08) and of mice with measurable metastatic lesions, exercise mice had smaller metastases (p=0.049). CONCLUSIONS Overall, in immunocompromised mice exercise had no effect on PC tumor growth, however, greater running distance was associated with larger tumors. Interestingly, in an immunocompetent host there was a trend for exercise mice having smaller tumors. These results along with serum and tissue analyses implicate alterations in blood flow and immune function as potential biochemical mechanisms through which exercise may alter PC growth. Ultimately further investigation is required to clearly delineate these mechanisms and apply them to our understanding of PC. © 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e37 Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jodi Antonelli Durham, NC More articles by this author Lee Jones Durham, NC More articles by this author Jean-Alfred Thomas Durham, NC More articles by this author Elizabeth Masko Durham, NC More articles by this author Jessica Lloyd Durham, NC More articles by this author Susan Poulton Durham, NC More articles by this author Tameika Phillips Durham, NC More articles by this author Alok Tewari Durham, NC More articles by this author Phillip Febbo Durham, NC More articles by this author Michael Pollak Montreal, Canada More articles by this author Mark Dewhirst Durham, NC More articles by this author Stephen J. Freedland Durham, NC More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Weightbearing In Simulated 1/6th and 1/3rd Gravity Does Not Prevent Cancellous Bone Loss

The effect of partial gravity (G) (as on the Lunar surface) on weight bearing bone remains undefined; a new model (the partial G mouse) provides for graded reductions in weight bearing. We hypothesized that mice exposed to 1/6th G and 1/3rd G will experience significant reductions in cancellous bone mass and altered microarchitecture as compared to ambulatory control animals but that the magnitude of these changes would be less than in 0 G mice.MethodsForty‐three female BALB/cByJ mice were randomly assigned to cage control (1G), “zero‐gravity” hindlimb unloaded (0G), 1/6th gravity (G/6), or 1/3rd gravity (G/3) groups for a 21‐day suspension protocol. In vivo peripheral quantitative computed tomography (pQCT) scans were conducted at the proximal tibia metaphysis on days 0 and 21 to measure volumetric bone mineral density (vBMD). Ex vivo micro‐CT scans were conducted at the distal femur to quantify bone volume (BV/TV), trabecular thickness (Tb.Th), and trabecular number (Tb.N).ResultsBody mass decreased significantly (7.6%) in 0G mice and non‐significantly in the G/3 or G/6 groups (−3.9%). In vivo total vBMD at the proximal tibia decreased significantly in the 0G (20%), G/6 (14%), and G/3 (14%) groups compared to 1G mice (−3%). Relative to the 1G group, distal femur BV/TV, Tb.Th, and Tb.N in the 0G, G/6 and G/3 groups were lower (24%, 12%, 14%, respectively). Mineral density gray scale of distal femur cancellous bone was significantly lower only in 0G (−2.6%) vs. 1G mice.ConclusionThese data suggest that partial weight bearing (as high as 1/3rd G) does not provide enough mechanical loading to prevent the significant deterioration of cancellous bone observed in the 0G non‐weight bearing condition. Funded by NSBRI via NASA Cooperative Agreement NCC 9‐58.

Prevention of muscle fibers atrophy during gravitational unloading: The effect of l-arginine administration

Gravitational unloading results in pronounced atrophy of m.soleus. Probably, the output of NO is controlled by the muscle activity. We hypothesized that NO may be involved in the protein metabolism and increase of its concentration in muscle can prevent atrophic changes induced by gravitational unloading. In order to test the hypothesis we applied NO donor l-arginine during gravitational unloading. 2.5-month-old male Wistar rats weighing 220–230g were divided into sedentary control group (CTR, n=7), 14-day hindlimb suspension (HS, n=7), 14 days of hindlimb suspension+ l-arginine (HSL, n=7) (with a daily supplementation of 500 mg/kg wt l-arginine) and 14 days of hindlimb suspension+ l-NAME (HSN, n=7) (90 mg/kg wt during 14 days). Cross sectional area (CSA) of slow twitch (ST) and fast twitch (FT) soleus muscle fibers decreased by 45% and 28% in the HS group ( p<0.05) and 40% and 25% in the HSN group, as compared to the CTR group ( p<0.05), respectively. CSA of ST and FT muscle fibers were 25% and 16% larger in the HSL group in comparison with the HS group ( p<0.05), respectively. The atrophy of FT muscle fibers in the HSL group was completely prevented since FT fiber CSA had no significant differences from the CTR group. In HS group, the percentage of fibers revealing either gaps/disruption of the dystrophin layer of the myofiber surface membrane increased by 27% and 17%, respectively, as compared to the controls (CTR group, p<0.05). The destructions in dystrophin layer integrity and reductions of desmin content were significantly prevented in HSL group. NO concentration decreased by 60% in the HS group (as well as HSN group) and at the same time no changes were detectable in the HSL group. This fact indicates the compensation of NO content in the unloaded muscle under l-arginine administration. The levels of atrogin-1 mRNA were considerably altered in suspended animals (HS group: plus 27%, HSL group: minus 13%) as compared to the control level. Conclusion: l-arginine administration allows maintaining NO concentration in m.soleus at the level of cage control group, prevents from dystrophin layer destruction, decreases the atrogin mRNA concentration in the muscle and atrophy level under gravitational unloading.

Psychotropic drugs have contrasting skeletal effects that are independent of their effects on physical activity levels

Popular psychotropic drugs, like the antidepressant selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs), and the mood stabilizer lithium, may have skeletal effects. In particular, preclinical observations suggest a direct negative effect of SSRIs on the skeleton. A potential caveat in studies of the skeletal effects of psychotropic drugs is the hypoactive (skeletal unloading) phenotype they induce. The aim of this study was to investigate the contribution of physical inactivity to the skeletal effects of psychotropic drugs by studying bone changes in cage control and tail suspended mice treated with either vehicle, SSRI, TCA or lithium. Tail suspension was used to control for drug differences on physical activity levels by normalizing skeletal loading between groups. The psychotropic drugs were found to have contrasting skeletal effects which were independent of drug effects on animal physical activity levels. The latter was evident by an absence of statistical interactions between the activity and drug groups. Pharmacological inhibition of the 5-hydroxytryptamine (5-HT) transporter (5-HTT) using a SSRI reduced in vivo gains in lower extremity BMD, and negatively altered ex vivo measures of femoral and spinal bone density, architecture and mechanical properties. These effects were mediated by a decrease in bone formation without a change in bone resorption suggesting that the SSRI had anti-anabolic skeletal effects. In contrast, glycogen synthase kinase-3[beta] (GSK-3[beta]) inhibition using lithium had anabolic effects improving in vivo gains in BMD via an increase in bone formation, while TCA-mediated inhibition of the norepinephrine transporter had minimal skeletal effect. The observed negative skeletal effect of 5-HTT inhibition, combined with recent findings of direct and indirect effects of 5-HT on bone formation, are of interest given the frequent prescription of SSRIs for the treatment of depression and other affective disorders. Likewise, the anabolic effect of GSK-3[beta] inhibition using lithium reconfirms the importance of Wnt/beta-catenin signaling in the skeleton and it's targeting by recent drug discovery efforts. In conclusion, the current study demonstrates that different psychotropic drugs with differing underlying mechanisms of action have contrasting skeletal effects and that these effects do not result indirectly via the generation of animal physical inactivity.

CSM 2010 Orthopaedic Section Platform Presentations (Abstracts OPL1-OPL67)

CSM 2010 Orthopaedic Section Platform Presentations (Abstracts OPL1-OPL67)

Chronic Sleep Disturbance Impairs Glucose Homeostasis in Rats

Epidemiological studies have shown an association between short or disrupted sleep and an increased risk for metabolic disorders. To assess a possible causal relationship, we examined the effects of experimental sleep disturbance on glucose regulation in Wistar rats under controlled laboratory conditions. Three groups of animals were used: a sleep restriction group (RS), a group subjected to moderate sleep disturbance without restriction of sleep time (DS), and a home cage control group. To establish changes in glucose regulation, animals were subjected to intravenous glucose tolerance tests (IVGTTs) before and after 1 or 8 days of sleep restriction or disturbance. Data show that both RS and DS reduce body weight without affecting food intake and also lead to hyperglycemia and decreased insulin levels during an IVGTT. Acute sleep disturbance also caused hyperglycemia during an IVGTT, yet, without affecting the insulin response. In conclusion, both moderate and severe disturbances of sleep markedly affect glucose homeostasis and body weight control.

Roles of Hypothalamic Subgroup Histamine and Orexin Neurons on Behavioral Responses to Sleep Deprivation Induced by the Treadmill Method in Adolescent Rats

Sleep deprivation induces several negative effects on behavior, emotion, attention, and learning ability. Sleep appears to be particularly important during adolescent brain development. In the present study, we examined the effects of sleep deprivation on behavior and hypothalamic neurotransmission including histamine and orexin neurons in adolescent rats using the treadmill method. Adolescent male rats were divided into three groups: treadmill sleep-deprived, treadmill control, and cage control groups. Energy expenditure, anxiety-like behavior, and locomotor activity were examined among the three groups. Histamine concentration in the cortex and diencephalon and the number of c-Fos-positive neurons in the hypothalamus were also examined. In addition, histamine and orexin neurons in the hypothalamus were simultaneously identified using rat histidine decarboxylase and orexin-A immunohistochemistry, respectively. Both energy expenditure and anxiety-related behavior significantly increased by the experimental 3-day sleep deprivation, while exploratory locomotor activity significantly decreased. Histamine contents did not change in the cortex, but significantly decreased in the diencephalon of sleep-deprived rats. Increased expression of c-Fos-positive neurons, including subgroup histamine and orexin neurons, was observed in the hypothalamus. These findings indicate that sleep deprivation increases energy expenditure and anxiety in adolescent rats and provide evidence for the pivotal role of hypothalamus subgroup histamine and orexin neurons in the behavioral response to sleep deprivation.

The medial amygdala modulates body weight but not neuroendocrine responses to chronic stress.

Stress pathologies such as depression and eating disorders (i.e. anorexia nervosa) are associated with amygdalar dysfunction, which are linked with hypothalamic-pituitary-adrenal axis (HPA) axis hyperactivity. The medial amygdaloid nucleus (MeA), a key output nucleus of the amygdaloid complex, promotes HPA axis activation to acute psychogenic stress and is in a prime position to mediate the deleterious effects of chronic stress on physiology and behaviour. The present study tests the hypothesis that the MeA is necessary for the development of maladaptive physiological changes caused by prolonged stress exposure. Male rats received bilateral ibotenate or sham lesions targeting the MeA and one half underwent 2 weeks of chronic variable stress (CVS) or served as home cage controls. Sixteen hours post CVS, all animals were exposed to an acute restraint challenge. CVS induced thymic involution, adrenal hypertrophy, and attenuated body weight gain and up-regulation of hypothalamic corticotrophin-releasing hormone mRNA expression. Consistent with previous literature, lesions of the MeA dampened stress-induced increases in corticosterone after 30 min of exposure to acute restraint stress. However, this effect was independent of CVS exposure, suggesting that the MeA may not be critical for modulating neuroendocrine responses after chronic HPA axis drive. Interestingly, lesion of the MeA modestly exaggerated the stress-induced attenuation of weight gain. Overall, the data obtained suggest that the MeA modulates the neuroendocrine responses to acute but not chronic stress. In addition, the data suggest that the MeA may be an important neural component for the control of body weight in the face of chronic stress.

Efficiency of airborne pollen released by honeybee foraging on pollination in oilseed rape: a wind insect-assisted pollination

Oilseed rape (Brassica napus L.) is an entomophilous crop. Its pollen is covered with sticky pollenkitt and not readily released from the anthers. We investigated the role of foraging honeybees in making this pollen airborne. To assess this, six cages were laid over male-fertile (MF) and male-sterile (MS) plants; at flowering, three cages received a honeybee colony while the others served as controls. On average, approximately 25% more pollen grains were deposited on sticky slides (covered with gauze) in cages with honeybees, compared to control cages. The fruit and seed set per not-empty pod of 5 MS plants bagged under gauze to avoid bee visits were 7 times and 3.4 times higher, respectively, in the cages with honeybees than in control cages without honeybees. These results demonstrate the role of bees in releasing airborne pollen, as well as the effectiveness of this insect-assisted wind pollination: at close range, honeybees participate to pollination without touching the female flowers.

Sleep fragmentation reduces hippocampal CA1 pyramidal cell excitability and response to adenosine

Sleep fragmentation (SF) impairs the restorative/cognitive benefits of sleep via as yet unidentified alterations in neural physiology. Previously, we found that hippocampal synaptic plasticity and spatial learning are impaired in a rat model of SF which utilizes a treadmill to awaken the animals every 2min, mimicking the frequency of awakenings observed in human sleep apnea patients. Here, we investigated the cellular mechanisms responsible for these effects, using whole-cell patch-clamp recordings. 24h of SF decreased the excitability of hippocampal CA1 pyramidal neurons via decreased input resistance, without alterations in other intrinsic membrane or action potential properties (when compared to cage controls, or to exercise controls that experienced the same total amount of treadmill movement as SF rats). Contrary to our initial prediction, the hyperpolarizing response to bath applied adenosine (30μM) was reduced in the CA1 neurons of SF treated rats. Our initial prediction was based on the evidence that sleep loss upregulates cortical adenosine A1 receptors; however, the present findings are consistent with a very recent report that hippocampal A1 receptors are not elevated by sleep loss. Thus, increased adenosinergic inhibition is unlikely to be responsible for reduced hippocampal long-term potentiation in SF rats. Instead, the reduced excitability of CA1 pyramidal neurons observed here may contribute to the loss of hippocampal long-term potentiation and hippocampus-dependent cognitive impairments associated with sleep disruption.

Increased corticosterone levels in mice subjected to the rat exposure test

In recent years, there has been a notable interest in studying prey–predator relationships to develop rodent-based models for the neurobehavioral aspects of stress and emotion. However, despite the growing use of transgenic mice and results showing important differences in the behavioral responses of rats and mice, little research has been conducted regarding the responses of mice to predators. The rat exposure test (RET), a recently developed and behaviorally validated prey–predator (mouse-rat)-based model, has proven to be a useful tool in evaluating the defensive responses of mice facing rats. To further validate the RET, we investigated the endocrine and behavioral responses of mice exposed to this apparatus. We first constructed a plasma corticosterone secretion curve in mice exposed to a rat or to an empty cage (control). Rat-exposed mice showed a pronounced rise in corticosterone levels that peaked 15 min from the beginning of the predator exposure. The corticosterone levels and behavioral responses of mice exposed to a rat or to a toy in the RET apparatus were then measured. We observed high plasma corticosterone levels along with clear avoidance behaviors represented by decreases in tunnel and surface area exploration and increases in risk assessment behaviors and freezing. This strongly suggests that the test elicits a repertoire of behavioral responses compatible with an aversion state and indicates that it is a promising model for the evaluation of prey-predator interactions. However, more physiological, neurochemical, and pharmacological studies are needed to further validate the test.

Adverse early life experience and social stress during adulthood interact to increase serotonin transporter mRNA expression

Anxiety disorders, depression and animal models of vulnerability to a depression-like syndrome have been associated with dysregulation of serotonergic systems in the brain. To evaluate the effects of early life experience, adverse experiences during adulthood, and potential interactions between these factors on serotonin transporter ( slc6a4) mRNA expression, we investigated in rats the effects of maternal separation (180 min/day from days 2 to 14 of life; MS180), neonatal handing (15 min/day from days 2 to 14 of life; MS15), or normal animal facility rearing (AFR) control conditions with or without subsequent exposure to adult social defeat on slc6a4 mRNA expression in the dorsal raphe nucleus (DR) and caudal linear nucleus. At the level of specific subdivisions of the DR, there were no differences in slc6a4 mRNA expression between MS15 and AFR rats. Among rats exposed to a novel cage control condition, increased slc6a4 mRNA expression was observed in the dorsal part of the DR in MS180 rats, relative to AFR control rats. In contrast, MS180 rats exposed to social defeat as adults had increased slc6a4 mRNA expression throughout the DR compared to both MS15 and AFR controls. Social defeat increased slc6a4 mRNA expression, but only in MS180 rats and only in the “lateral wings” of the DR. Overall these data demonstrate that early life experience and stressful experience during adulthood interact to determine slc6a4 mRNA expression. These data support the hypothesis that early life experience and major stressful life events contribute to dysregulation of serotonergic systems in stress-related neuropsychiatric disorders.

Effects of Head-Only Exposure of Rats to GSM-900 on Blood-Brain Barrier Permeability and Neuronal Degeneration

Salford et al. reported in 2003 that a single 2-h exposure to GSM-900 mobile telephony signals induced brain damage (increased permeability of the blood-brain barrier and presence of dark neurons) 50 days after exposure. In our study, 16 Fischer 344 rats (14 weeks old) were exposed head-only to the GSM-900 signal for 2 h at various brain-averaged SARs (0, 0.14 and 2.0 W/kg) or were used as cage or positive controls. Albumin leakage and neuron degeneration were evaluated 14 and 50 days after exposure. No apoptotic neurons were found 14 days after the last exposure using the TUNEL method. No statistically significant albumin leakage was observed. Neuronal degeneration, assessed using cresyl violet or the more specific marker Fluoro-Jade B, was not significantly different among the tested groups. No apoptotic neurons were detected. The findings of our study did not confirm the previous results of Salford et al.

Production of PGE2 increases in tendons subjected to repetitive mechanical loading and induces differentiation of tendon stem cells into non‐tenocytes

Whether tendon inflammation is involved in the development of tendinopathy or degenerative changes of the tendon remains a matter of debate. We explored this question by performing animal and cell culture experiments to determine the production and effects of PGE(2), a major inflammatory mediator in tendons. Mouse tendons were subjected to repetitive mechanical loading via treadmill running, and the effect of PGE(2) on proliferation and differentiation of tendon stem cells (TSCs) was assessed in vitro. Compared to levels in cage control mice, PGE(2) levels in mouse patellar and Achilles tendons were markedly increased in response to a bout of rigorous treadmill running. PGE(2) treatment of TSCs in culture decreased cell proliferation and induced both adipogenesis and osteogenesis of TSCs, as evidenced by accumulation of lipid droplets and calcium deposits, respectively. Effects of PGE(2) on both TSC proliferation and differentiation were apparently PGE(2)-dose-dependent. These findings suggest that high levels of PGE(2), which are present in tendons subjected to repetitive mechanical loading conditions in vivo as shown in this study, may result in degenerative changes of the tendon by decreasing proliferation of TSCs in tendons and also inducing differentiation of TSCs into adipocytes and osteocytes. The consequences of this PGE(2) effect on TSCs is the reduction of the pool of tenocytes for repair of tendons injured by mechanical loading, and production of fatty and calcified tissues within the tendon, often seen at the later stages of tendinopathy.