Interaction between exercise, dietary restriction and age-related bone loss in a rodent model of male senile osteoporosis.

BACKGROUND: The pathophysiology of age-related bone loss and whether age-related bone loss can be prevented by exercise are still a matter of debate. OBJECTIVE: It was the aim of this study to investigate the long-term effects of exercise and mild food restriction on bone mineral density (BMD) and bone geometry in the appendicular skeleton of aging male rats. METHODS: Male Sprague-Dawley rats were studied from 5 to 23 months of age. The rats were divided into 4 groups: baseline, free access to food and running wheels (RW), fed to pair weight with the RW group (PW) and sedentary control animals with free access to food (SED). All rats were housed individually. Volumetric BMD and geometry of femurs and tibiae were assessed by peripheral quantitative computed tomography (pQCT). In addition, the tibial shafts were analyzed by cortical bone histomorphometry. RESULTS: At the end of the experiment, RW and PW rats had similar body weight. The body weight of SED rats was 31% greater than that of RW rats. pQCT analysis of femurs and tibiae as well as histomorphometric analysis of the tibial shafts showed that dietary restriction resulted in an enlargement of the marrow cavity and cortical thinning at the femoral and tibial shafts relative to the RW and SED groups. Voluntary running exercise provided no additional protection against age-related bone loss when compared with the 31% heavier SED control rats. Neither exercise nor increased body weight in SED animals could completely prevent age-related bone loss between 19 and 23 months of age. CONCLUSION: We conclude that dietary restriction had clear negative effects on BMD and bone geometry and that running wheel exercise provided partial protection but could not prevent age-related bone loss.

Right intercostal insertion of a Veress needle for laparoscopy in dogs.

OBJECTIVE: To evaluate right intercostal Veress needle (VN) insertion for laparoscopy in dogs. STUDY DESIGN: Longitudinal cohort study. ANIMALS: Female dogs (n = 56). METHODS: The VN was inserted in the last palpable right intercostal space, either 1/3 (Group T; 28 dogs) or mid distance (Group H; 28 dogs) from the xiphoid cartilage to the most caudal extent of the costal arch. Problems encountered during VN insertion and injuries were recorded, graded, and compared between groups, and also between the first and last 20 insertions. RESULTS: Pneumoperitoneum was successfully achieved by VN insertion in 49 (88%) dogs after a single (45 dogs) or 2nd attempt (4 dogs). Frequency of complications was as follows: 20 grade 1 (subcutaneous emphysema, omentum, or falciform injuries); 6 grade 2 (liver or spleen injury), and 1 grade 3 complication (pneumothorax occurred). No significant difference was found between the 2 groups or between the first and last 20 dogs. CONCLUSIONS: Right intercostal VN insertion facilitates pneumoperitoneum in dogs with few consequential complications. No significant difference was found between entry sites; however, the mid distance insertion site in the last palpable intercostal space with dog positioned in dorsal recumbency is likely to result in less complications.

Decline of bone marrow-derived hematopoietic progenitor cell quality during aging in the rat.

Several studies have shown that aging is associated with quantitative and qualitative alterations of the stem and progenitor cell compartment. The current results indicate that there is a significant age-associated decline in the proliferative capacity of rat myeloid progenitor cells. In contrast, no difference was found in the frequency of myeloid progenitor cells in the bone marrow of young versus old rats. Furthermore, a significant shift towards higher proliferative capacity of myeloid progenitors was observed after lifelong voluntary exercise. These data emphasize that aging is accompanied by a loss of proliferative capacity and that voluntary exercise could retard this process.

Evaluation of healthy equine eyes by use of retinoscopy, keratometry, and ultrasonographic biometry.

OBJECTIVE: To assess natural variations in degree of refraction, corneal curvature, corneal astigmatism, corneal radius, and intraocular distance of healthy equine eyes. ANIMALS: 159 horses with healthy eyes that were admitted to a veterinary teaching hospital for nonophthalmic surgeries. PROCEDURES: Eyes of horses were examined with a retinoscope prior to anesthesia and with a keratograph and A- and B-scan ultrasonographic biometers during surgery. In addition, manual caliper measurements of horizontal and vertical corneal radii were obtained. RESULTS: Mean +/- SD degree of refraction in the horizontal meridian of eyes was -0.06 +/- 0.68 diopters (D). Vitreous body length and horse age correlated negatively with refraction values. The horizontal corneal radius (15.96 +/- 1.28 mm) was larger than the vertical corneal radius (15.02 +/- 1.09 mm). Accordingly, the vertical corneal curvature (21.56 +/- 1.68 D) was greater than the horizontal corneal curvature (22.89 +/- 1.65 D). Axial globe length (40.52 +/- 2.67 mm), anterior chamber depth (6.35 +/- 0.59 mm), lens thickness (12.30 +/- 0.83 mm), and vitreous body length (21.87 +/- 1.85 mm) were positively correlated with body weight, height, and age. Results of keratograph and caliper measurements correlated well for horizontal corneal diameter but poorly for vertical corneal diameter. Results of A- and B-scan ultrasonography differed by < or = 1 mm in 64% of measured eyes. CONCLUSIONS AND CLINICAL RELEVANCE: Results of keratometry and ultrasonographic biometry varied widely. Additional research is needed to validate the keratograph used in our study for measurements in equine eyes.

Modulation of the hippocampal protein machinery in voluntary and treadmill exercising rats.

Information about protein expression studies in the brain of exercising and sedentary animals is limited. Cognitive functions change during exercise and the aim of this study was to investigate rat protein levels of the protein machinery in the hippocampus, the main cognitive brain area for spatial learning and memory, in exercising rats. Protein fluctuations may reflect functional variation during exercise. Male Sprague-Dawley rats, 23 months old, were used for the study: the first group consisted of sedentary rats, the second of rats undertaking voluntary exercise from 5 months to 23 months and the third undertaking involuntary exercise on a treadmill from 5 months to 23 months. Two-dimensional gel electrophoresis with subsequent mass spectrometrical identification assigning spots to proteins and determination of coomassie-densities was carried out. Heterogeneous nuclear ribonucleoprotein K, one protein variant of heat shock cognate 71 kDa protein and BAG family molecular chaperone regulator 5 showed differential protein levels in the three groups when a p-value of <0.005 was considered as statistically significant thus respecting multiple testing. The biological meaning of changed protein levels in hippocampus under different conditions of exercise is not known but warrants further investigation.

Long-term marginal zinc supply is not detrimental to the skeleton of aged female rats.

In this experiment, we investigated the long-term effects of a marginal zinc (Zn) supply on bone metabolism in aged rats. Nine-mo-old female Fischer-344 rats were divided into 8 weight-matched groups of 8 rats each. All rats were adapted for 1 mo to restrictive feeding (7.5 g/d) of a purified diet containing 8 g/kg sodium phytate and 64 mg/kg Zn. Control rats were pair-fed throughout the experiment. During the 1-mo depletion phase, controls received the Zn-replete diet with 64 mg/kg Zn, whereas Zn-deficient rats were fed the same diet with 2.2 mg/kg Zn. The depletion phase was followed by a 3-mo marginal phase in which the rats fed the diet with 2.2 mg/kg Zn received an additional daily Zn supplement of 75 microg Zn/rat by gavage. In the following 2-mo repletion phase, a marginal group was switched to the Zn-replete diet, while the other groups were maintained on marginal Zn supply or on the Zn-replete diet. Zn depletion and marginal Zn reduced serum and bone Zn and serum alkaline phosphatase activity. Zn repletion normalized serum Zn. However, apart from subtle changes in bone mineralization density distribution, Zn deficiency was not associated with detrimental effects on bone mineral density, turnover, architecture, or biomechanics relative to control rats at any time point. Our data suggest that Zn does not play an essential role in bone metabolism in aged rats and cast doubt on the hypthosis that Zn deficiency is a risk factor for osteoporosis.

Comparison of conventional and digital measurements of tibial plateau angle in dogs.

OBJECTIVE: To compare values for tibial plateau angle (TPA) obtained in dogs by conventional and digital methods. DESIGN: Evaluation study. ANIMALS: 37 dogs with stifle joint abnormalities. PROCEDURES: In all dogs, radiographs of both stifle joints were obtained by conventional and digital means. On conventionally acquired radiographs, TPA was measured with a protractor and fine-point pencil in accordance with standard guidelines. A software program was used to measure TPA on digitally acquired radiographs. Two viewers with different levels of experience performed all measurements 3 times. RESULTS: For both viewers and both limbs, conventional TPA measurements were significantly correlated with digital measurements all 3 times. Conventional and digital measurements obtained by viewer 1 were significantly different from values obtained by viewer 2. However, inter-viewer and intertechnique differences in TPA measurements resulted in rotational differences of < 1 mm. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that TPA measurements obtained with the digital method were comparable to those obtained by use of the conventional method. Subjectively, the digital method was easier to perform and faster and produced better-quality images.

Laparoscopic ovariectomy in dogs: comparison between single portal and two-portal access.

OBJECTIVE: To compare surgical times and perioperative complication rates of single portal access and 2-portal laparoscopic ovariectomy (LapOVE) in dogs using a bipolar vessel sealer/divider device, and to evaluate the performance of novice laparoscopists for right ovariectomy. STUDY DESIGN: Controlled clinical trial. ANIMALS: Female dogs (n=42). METHODS: Dogs were divided into groups: 1=single portal and 2=2 portal. LapOVE was performed using a 5 mm vessel sealer/divider device and a 10 mm operating laparoscope (Group 1) or a 5 mm laparoscope (Group 2). Dog characteristics (weight, body condition score, ovarian ligament fat score), operative time, and perioperative complication rate were compared between groups. Right ovariectomy duration was evaluated for 2 novice laparoscopists. RESULTS: No significant difference was found in mean total surgical time between group 1 (21.07 min/s) and group 2 (19.06 min/s). Factors significantly affecting times included body condition scores, ovarian ligament fat score, ovarian bleeding, and surgeon expertise. Minor complications (bleeding from ovaries or after splenic trauma) occurred and were similar in both groups. Bleeding was correlated to body condition score and ovarian ligament fat score. Interindividual differences were found among surgeons for right ovariectomy time. CONCLUSIONS: Single portal access LapOVE using vessel sealer/divider device is feasible, safe, and does not significantly increase total surgical time in comparison with 2-portal approach. Laparoscopic skills may play a role in ability to perform single portal LapOVE. CLINICAL RELEVANCE: LapOVE can be performed using single portal access.

Running has a negative effect on bone metabolism and proinflammatory status in male aged rats.

Animal models for male osteoporosis are scarce. This study aimed at identifying the impact of different living conditions on bone structure and metabolism as well as the inflammatory status in a rat model of age-related male osteoporosis. Bone mineral density, bone histomorphometric data, ex vivo osteoclast generation, and bone metabolism serum marker as well as intracellular cytokine expressions were evaluated in 23-month-old male Sprague-Dawley rats subjected to different housing conditions from the age of 5 months. Running rats were housed individually and were exercised voluntarily in running wheels attached to their cages. Dieting rats were housed individually, too, but were fed to pair weight with the running rats. Walking rats were exercised mildly by use of a treadmill (800m/day, 5 days a week) and social rats were kept as four in a cage and fed ad libitum. Whereas no marked differences could be found for bone mineral density, trabecular bone volume as well as trabecular bone surface were diminished in walking rats. The ex vivo osteoclast generation assay revealed no significant differences between groups. Osteoblasts of running rats were not only decreased in number, but displayed also a lower activity as indicated by decreased serum osteocalcin levels. Osteoclast activity was increased in the same group as indicated by elevated CTX (c-terminal telopeptide of type I collagen) levels. Additionally, production of tumor necrosis factor (TNF)-alpha and interferone (IFN)-gamma by CD8(+) T cells was elevated in running rats. In conclusion, running has a negative effect on bone metabolism and proinflammatory status in male aged rats.

Influence of physical exercise and food restriction on the biomechanical properties of the femur of ageing male rats.

BACKGROUND: Voluntary running in wheels as well as food reduction increase the life spans of rats. Disparate parameters such as the collagen biomarker of ageing and the development of kidney pathologies are decreased by voluntary exercise. There are few reports on the influence of physical exercise and food restriction on the skeleton of male rats. Most investigations initiated rather short-term interventions in 4- to 5-week-old animals and thus studied more the influence of growth than the influence of ageing on the skeleton. OBJECTIVE: To compare the effects of physical exercise and food restriction on the biomechanical properties of bone tissue of ageing male rats with the interventions starting at the age of 5 months with the end point at 23 months. This enables the study of the influence of these interventions on the ageing of the skeleton. METHODS: Five groups of male Sprague-Dawley rats were used: baseline (BL), voluntarily running in wheels (RW), food restriction to attain pair weight with RW animals (PW), forced running in treadmills (TM), and sedentary controls (SE). The biomechanical properties of femoral neck, diaphysis, and distal metaphysis were measured. RESULTS: While the body weights and fat-free mass increased from BL to SE group, the occiput-sacrum length did not increase and the length of the femur increased marginally. These lengths were slightly retarded in RW and PW groups compared to the SE group. The strength of the distal femoral metaphysis decreased from BL to SE group. This decrease was counteracted by physical exercise (RW and TM groups) as well as by food restriction (PW group). In contrast, the strength of the femoral mid-diaphysis did not differ between BL and SE groups. CONCLUSIONS: The distal metaphysis in the male rat femur is more prone to decreasing biomechanical strength than the diaphysis during ageing. Physical exercise, when started at the age of 5 months, when the skeleton has reached its adult size, is somewhat effective in counteracting these changes. There is also some retarding effect of food restriction.

Microvessel density in normal lymph nodes and lymphomas of dogs and their correlation with vascular endothelial growth factor expression.

Microvessel density is a frequently used parameter of angiogenesis, which is a complex multistep process necessary for tumor progression. The aim of this study was to compare the microvessel density of normal lymph node biopsies with those diagnosed with lymphoma in dogs. Furthermore, we sought to determine if there was any correlation between microvessel density and vascular endothelial growth factor expression in canine lymphoma, representing a potential target for anti-angiogenic therapy. Combined immunohistochemistry (von Willebrand factor) and lectin histochemistry was used to highlight microvessels in 40 untreated canine lymphomas and 14 normal lymph nodes. To evaluate microvessel density, the number of profiles of blood vessels per unit area was calculated. Fifty image fields (a total area of 5.68 mm(2)) were sampled for each specimen in a systematic random, way. We found a significant difference between the microvessel densities (MVD) of normal and neoplastic lymph nodes (177+/-35 versus 241+/-72 microvessel profiles/mm(2)). Classifying lymphoma samples according to the working formulation and the Kiel classification system revealed no significant differences in MVD between different grade malignancies. Immunohistochemical demonstration of the proangiogenic protein vascular endothelial growth factor showed expression in 60% of canine lymphomas, although there was no correlation between microvessel density and vascular endothelial growth factor expression. As an increase in tumor angiogenesis was observed in lymphoma samples compared to normal canine lymph node tissue, additional anti-angiogenic therapy, besides conventional chemotherapy as a lymphoma treatment may be effective. The optimal target among many pro-angiogenic factors has yet to be elucidated.

Norepinephrine treatment and aging lead to systemic and intracellular oxidative stress in rats.

Reactive oxygen species (ROS) play important roles in cellular senescence and organismic aging. Furthermore, they have been implicated in some of the adverse effects of chronic stress due to elevated peripheral levels of catecholamines. Here, we applied three different techniques to individually compare the systemic and intracellular oxidative stress in aged (23 months) and young (5 months) Sprague-Dawley rats, and in young rats treated for 12 or 24 h with norepinephrine (NE). Thiol groups of blood serum proteins (RSH) were determined by means of Ellman's reaction. Intracellular ROS were assessed in spleen cells and peripheral blood lymphocytes (PBL) by carbonylation of cellular (spleen) proteins as determined by immunoblotting (Oxyblot) and/or by means of 2',7'-dichlorofluorescein (DCF) fluorescence. As compared to the young, untreated controls, both old rats and NE treated young rats showed similarly lowered RSH values paralleled by elevated intracellular ROS levels or enhanced Oxyblot signals. Individual RSH values were highly significantly, negatively correlated with respective Oxyblot data as well as with DCF fluorescence. The results confirm the roles of ROS in aging and adrenergic stress in the rat model, and suggest that the decrease in RSH of blood serum may be taken as a valid indicator for the enhanced oxidative stress in lymphocytes.

Bone structure and metabolism in a rodent model of male senile osteoporosis.

Osteoporosis is a common and severe condition in elderly men, which is poorly characterized. In order to identify the hallmarks of age-related bone loss in the male mammalian skeleton, we studied several aspects of bone structure and metabolism in 23-month-old male Sprague-Dawley rats and compared them to 5-month-old animals. Cancellous bone mineral density, bone volume and trabecular number were markedly reduced in the proximal tibia of aged rats when compared to the young rats. An increase in bone matrix material density indicating a reduced deposition of new bone matrix was seen. Also, serum levels of osteocalcin, a marker of bone formation, were reduced in old males. The decreased bone formation could in part be linked to the decreased serum insulin-like growth factor 1 (IGF-1) levels which were observed in these animals. Serum levels of RatLaps (c-terminal telopeptide of type I collagen) were increased. Interestingly, an ex vivo osteoclast generation assay revealed that bone marrow from aged rats formed fewer osteoclasts than that from young rats. Consistent with this observation, serum levels of soluble RANKL, a critical osteoblast derived factor for osteoclastogenesis, were decreased in aged rats and RANKL mRNA expression was slightly reduced in bone marrow cells. Elevated leptin and adiponectin levels present in these animals could have contributed further to impaired osteoclastogenesis. We conclude that aged male rodents are characterized by a severely diminished cancellous bone network and a bone turnover situation in which bone formation is decreased to such an extent that it is outweighed by bone resorption, despite a blunted osteoclast generation potential of the bone marrow.

Reliability of ground reaction forces measured on a treadmill system in healthy dogs.

The reliability of repeated measurements of vertical ground reaction force (GRF) variables was determined using 10 clinically sound adult dogs walking on a treadmill three times daily on three different days. Peak vertical force, vertical impulse and duration of stance phase of each limb were determined and analysed for significant differences within and between days and between dogs. Contributions to the variance of GRF were determined using a random effect model including dogs, different days, trials and extremities. ANOVA did not show any significant differences in variables within and between days, but did reveal differences between dogs. Variance was mainly seen in different dogs, whereas different days and trials were less important factors. It was concluded that the ground reaction forces determined by a treadmill system are suitable and provide reproducible parameters in canine gait analysis. Such treadmill/force plate systems allow the simultaneous measurement of all four legs of dogs at a constant velocity walk.

Impairment of water maze behaviour with ageing is counteracted by maze learning earlier in life but not by physical exercise, food restriction or housing conditions.

Spatial learning and memory decline with ageing in humans as well as rats. We examined the influence of different interventions on male Sprague Dawley rats with respect to learning ability and memory at the age of 5, 10 and 18 months. The intervention and control groups were: (RW) voluntary exercise in running wheels, (PW) sedentary, food restricted (by about 25%) to keep them at pair weight with RW, (S1) sedentary, fed ad libitum, (TM) forced training in a treadmill, and, (S4) sedentary, fed ad libitum. The animals in all groups were housed individually except those in group S4, which were housed four in each cage. The ability of learning and memory was determined in the Morris water maze. The results showed a significantly better learning ability when young in comparison with their ability when having grown older. At the age of 18 months, the performance was significantly better in the subgroups which had received training also at the age of 10 months compared to the subgroups receiving their first training. None of the various interventions had any significant effect on these functions. Repeated training seems to be the best intervention with respect to retaining learning ability and memory.

Effects of life-long exercise on circulating free fatty acids and muscle triglyceride content in ageing rats.

Regular physical exercise has emerged, together with dietary restriction, as an effective intervention in delaying degenerative diseases and augmenting life span in rodents. The mechanisms involved remain largely unknown, although a beneficial influence on the age-related alteration of insulin sensitivity has been hypothesized. As muscle triglyceride (TG) accumulation is considered a reliable index of muscle insulin resistance, in this study we explored muscle TG content in 23-month-old male Sprague-Dawley rats subjected to life-long training. Plasma glucose, insulin, free fatty acid (FFA) and leptin levels were also measured. Both voluntary running in wheels (RW) and forced training in treadmill (TM) were studied. As RW rats weighed less than controls, a cohort of untrained animals, fed to pair weight (PW) with RW, was added to discriminate the effect of exercise from that of food restriction. Sedentary ad libitum fed rats served as controls. In 23-month-old RW rats, muscle TG content was reduced by 50% with respect to age-matched sedentary controls, while in TM group this reduction was smaller but still highly significant, and occurred independently on the changes in body fat mass. In both the trained rat groups, there was a significant decrease in circulating FFA levels and a trend to reduced insulin levels. In PW rats, muscle TG levels decreased similarly to RW rats, while plasma parameters were less modified. In particular, RW training was more effective than PW in preventing the age-related increase in circulating leptin levels. Our results suggest that voluntary exercise effectively counteracts the development of insulin resistance in the muscles of ageing rats as well as other related changes such as hyperlipacidaemia and compensatory hyperleptinaemia. Forced training or moderate food restriction appear slightly less effective than voluntary exercise in preventing age-dependent alterations in nutrient distribution and/or utilization.

Prevention of glucocorticoid-induced bone loss in mice by inhibition of RANKL.

OBJECTIVE: RANKL has been implicated in the pathogenesis of glucocorticoid-induced osteoporosis. This study was undertaken to evaluate the efficacy of denosumab, a neutralizing monoclonal antibody against human RANKL (hRANKL), in a murine model of glucocorticoid-induced osteoporosis. METHODS: Eight-month-old male homozygous hRANKL-knockin mice expressing a chimeric RANKL protein with a humanized exon 5 received 2.1 mg/kg of prednisolone or placebo daily over 4 weeks via subcutaneous slow-release pellets and were additionally treated with phosphate buffered saline or denosumab (10 mg/kg subcutaneously twice weekly). Two groups of wild-type mice were also treated with either prednisolone or vehicle. RESULTS: The 4-week prednisolone treatment induced loss of vertebral and femoral volumetric bone mineral density in the hRANKL-knockin mice. Glucocorticoid-induced bone loss was associated with suppressed vertebral bone formation and increased bone resorption, as evidenced by increases in the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts, TRAP-5b protein in bone extracts, serum levels of TRAP-5b, and urinary excretion of deoxypyridinoline. Denosumab prevented prednisolone-induced bone loss by a pronounced antiresorptive effect. Biomechanical compression tests of lumbar vertebrae revealed a detrimental effect of prednisolone on bone strength that was prevented by denosumab. CONCLUSION: Our findings indicate that RANKL inhibition by denosumab prevents glucocorticoid-induced loss of bone mass and strength in hRANKL-knockin mice.

Hippocampal metabolic proteins are modulated in voluntary and treadmill exercise rats.

Systematic protein expression studies in the brain of exercising and sedentary animals have not been carried out so far and it was therefore decided to determine differences in metabolic protein levels in rat hippocampus of sedentary, voluntary and involuntary exercising rats by a proteomic approach. Aged, male Sprague-Dawley rats, 23 months old, were used for the study: the first group consisted of sedentary rats, the second of rats with voluntary exercise from five to 23 months and the third group was performing involuntary exercise on a treadmill from five to 23 months. Two-dimensional gel electrophoresis with subsequent mass spectrometrical identification of spots followed by quantification of spots was carried out. Identification of significantly differential proteins was validated by the determination of the corresponding enzyme activity. Five individual metabolic proteins showed differential protein levels in the three groups: mitochondrial precursors of ornithine aminotransferase, isocitrate dehydrogenase [NAD] subunit alpha, malate dehydrogenase, ubiquinol-cytochrome-c reductase complex core protein 1, and ubiquitin carboxyl-terminal hydrolase isozyme L1. The unambiguously identified metabolic proteins were mainly of mitochondrial localization and fit the expectations of altered mitochondrial activity in exercise. Reduced ubiquitin carboxyl-terminal hydrolase isoenzyme L1 levels in treadmill (forced) exercise show the involvement of the proteasomal pathway as a novel finding. These results not only form the basis for functional studies elucidating mechanisms and differences between voluntary and forced exercise in hippocampal metabolism but also highlight the most intriguing aspect that exercise is affecting the brain at the protein level.

Effect of different claw trimming methods on the pressure distribution under the bovine claw--an in vitro study.

This survey focusses on the effects of various claw trimming methods as well as the effect of the different resulting claw shapes on the pressure distribution under the sole. 64 bovine claws were trimmed according to 3 different trimming methods, the functional claw trimming method by Toussaint Raven and two other specially modified methods. The alternative methods resulted on the one hand in long and acute-angled claws, on the other hand in a very steep claw profile. The limb samples were attached to the hydraulic plunger of a material testing machine and pressed onto a pressure distribution plate with a predefined load. The pressure distribution pattern was recorded before and after trimming. An obvious stress concentration could be observed in the bulbar region of the outer claws. All of the applied claw trimming methods induced a redistribution of load onto the inner claws while relieving the bulbar area of the outer claws. The inner claws were the main reason for the enlarged floor contact area caused by the trimming techniques. The results show that all techniques led to an improvement of stress conditions. In some cases, methods 2 and 3 were slightly superior in reducing maximum pressure and enlarging floor contact area.

Hippocampal signaling cascades are modulated in voluntary and treadmill exercise rats.

Systematic protein expression studies in the brain of exercising and sedentary animals have not been carried out for far. Signaling proteins are main structures regulating hippocampal function and we decided to determine differences in signaling protein levels in rat hippocampus by a proteomic approach. Aged, male Sprague-Dawley rats, 23 months old, were used for the study: the first group consisted of sedentary rats, the second of rats with voluntary exercise from 5 to 23 months and the third was performing involuntary exercise on a treadmill from 5 to 23 months. 2-DE with subsequent mass spectrometrical identification of spots followed by quantification of spots was carried out. Annexin A5, A3, phosphatidylethanolamine-binding protein, guanine nucleotide-binding protein G(I)/G(S)/G(T), 14-3-3 protein gamma, 14-3-3 protein zeta/delta, prohibitin, visinin-like 1, protein phosphatase 1, septin 8, phosphoprotein enriched in astrocytes 15, transcription factor Pur-beta, EEA1 protein, SH3 domain-binding glutamic acid-rich-like protein 2, and cell division cycle 42 showed differential protein levels in the three groups. These results form the basis for functional studies elucidating mechanisms and links between exercise and hippocampal signaling and function.