Trained Rats Research Articles

Serum calcitonin gene-related peptide facilitates adipose tissue lipolysis during exercise via PIPLC/IP3 pathways.

Calcitonin gene-related peptide (CGRP) is formed by alternative transcription of the calcitonin/α-CGRP gene, which also gives rise to calcitonin (CT). Recently, CGRP has been the focus of research for its metabolic effects in vitro. In the present study, the in vivo effects of CGRP on epididymal fat pads lipolysis at rest and during exercise were investigated in trained male Wistar rats. Male Wistar rats were assigned to control and trained groups, which underwent endurance training for 12 weeks. The control (at rest) and trained (during acute exercise) animals were subjected to an intravenous injection of rat recombinant CGRP (2 µg kg-1) and CGRP-(8-37), a competitive CGRP receptors antagonist, to evaluate if and how CGRP can affect adipose tissue lipolysis at rest and during exercise. Intravenous injection of rat CGRP recombinant at rest upregulated major lipolysis pathways (cyclic AMP (cAMP), AMP-activated protein kinase (AMPK), and phospholipase C (PIPLC/IP3)) in fat pads, causing an elevation in plasma-free fatty acid (FFA) and a decrease in plasma triglyceride (TG). All the effects were eliminated by pretreating the animals with CGRP-(8-37), suggesting that CGRP receptors were necessary for lipolytic effects of CGRP in fat pads. In trained animals, acute exercise augmented CGRP in serum, cerebrospinal fluid (CSF), and the cortex. Pretreating the animals with CGRP-(8-37) attenuated PIPLC/IP3 pathway in fat pads and had no effect on cAMP and AMPK pathways. Epididymal fat pads is a metabolic target for CGRP during exercise and CGRP effects on adipose tissue metabolism during exercise could be related to PIPLC/IP3 pathway.

The role of the hippocampus in object discrimination based on visual features.

The role of rodent hippocampus has been intensively studied in different cognitive tasks. However, its role in discrimination of objects remains controversial due to conflicting findings. We tested whether the number and type of features available for the identification of objects might affect the strategy (hippocampal-independent vs. hippocampal-dependent) that rats adopt to solve object discrimination tasks. We trained rats to discriminate 2D visual objects presented on a computer screen. The objects were defined either by their shape only or by multiple-features (a combination of filling pattern and brightness in addition to the shape). Our data showed that objects displayed as simple geometric shapes are not discriminated by trained rats after their hippocampi had been bilaterally inactivated by the GABAA-agonist muscimol. On the other hand, objects containing a specific combination of non-geometric features in addition to the shape are discriminated even without the hippocampus. Our results suggest that the involvement of the hippocampus in visual object discrimination depends on the abundance of object's features.

Animal Learning in a Multidimensional Discrimination Task as Explained by Dimension-Specific Allocation of Attention.

Reinforcement learning describes the process by which during a series of trial-and-error attempts, actions that culminate in reward are reinforced, becoming more likely to be chosen in similar circumstances. When decisions are based on sensory stimuli, an association is formed between the stimulus, the action and the reward. Computational, behavioral and neurobiological accounts of this process successfully explain simple learning of stimuli that differ in one aspect, or along a single stimulus dimension. However, when stimuli may vary across several dimensions, identifying which features are relevant for the reward is not trivial, and the underlying cognitive process is poorly understood. To study this we adapted an intra-dimensional/ extra-dimensional set-shifting paradigm to train rats on a multi-sensory discrimination task. In our setup, stimuli of different modalities (spatial, olfactory and visual) are combined into complex cues and manipulated independently. In each set, only a single stimulus dimension is relevant for reward. To distinguish between learning and decision-making we suggest a weighted attention model (WAM). Our model learns by assigning a separate learning rule for the values of features of each dimension (e.g., for each color), reinforced after every experience. Decisions are made by comparing weighted averages of the learnt values, factored by dimension specific weights. Based on the observed behavior of the rats we estimated the parameters of the WAM and demonstrated that it outperforms an alternative model, in which a learnt value is assigned to each combination of features. Estimated decision weights of the WAM reveal an experience-based bias in learning. In the first experimental set the weights associated with all dimensions were similar. The extra-dimensional shift rendered this dimension irrelevant. However, its decision weight remained high for the early learning stage in this last set, providing an explanation for the poor performance of the animals. Thus, estimated weights can be viewed as a possible way to quantify the experience-based bias.

Locus coeruleus activation accelerates perceptual learning

Neural representations of the external world are constructed and updated in a manner that depends on behavioral context. For neocortical networks, this contextual information is relayed by a diverse range of neuromodulatory systems, which govern attention and signal the value of internal state variables such as arousal, motivation, and stress. Neuromodulators enable cortical circuits to differentially process specific stimuli and modify synaptic strengths in order to maintain short- or long-term memory traces of significant perceptual events and behavioral episodes. One of the most important subcortical neuromodulatory systems for attention and arousal is the noradrenergic locus coeruleus. Here we report that the noradrenergic system can enhance behavior in rats performing a self-initiated auditory recognition task, and optogenetic stimulation of noradrenergic locus coeruleus neurons accelerated the rate at which trained rats began correctly responding to a change in reward contingency. Animals successively progressed through distinct behavioral epochs, including periods of perseverance and exploration that occurred much more rapidly when animals received locus coeruleus stimulation. In parallel, we made recordings from primary auditory cortex and found that pairing tones with locus coeruleus stimulation led to a similar set of changes to cortical tuning profiles. Thus both behavioral and neural responses go through phases of adjustment for exploring and exploiting environmental reward contingencies. Furthermore, behavioral engagement does not necessarily recruit optimal locus coeruleus activity.

Rate and Temporal Coding Mechanisms in the Anterior Cingulate Cortex for Pain Anticipation

Pain is a complex sensory and affective experience. Through its anticipation, animals can learn to avoid pain. Much is known about passive avoidance during a painful event; however, less is known about active pain avoidance. The anterior cingulate cortex (ACC) is a critical hub for affective pain processing. However, there is currently no mechanism that links ACC activities at the cellular level with behavioral anticipation or avoidance. Here we asked whether distinct populations of neurons in the ACC can encode information for pain anticipation. We used tetrodes to record from ACC neurons during a conditioning assay to train rats to avoid pain. We found that in rats that successfully avoid acute pain episodes, neurons that responded to pain shifted their firing rates to an earlier time, whereas neurons that responded to the anticipation of pain increased their firing rates prior to noxious stimulation. Furthermore, we found a selected group of neurons that shifted their firing from a pain-tuned response to an anticipatory response. Unsupervised learning analysis of ensemble spike activity indicates that temporal spiking patterns of ACC neurons can indeed predict the onset of pain avoidance. These results suggest rate and temporal coding schemes in the ACC for pain avoidance.

Interleukin-10 and collagen type II immunoexpression are modulated by photobiomodulation associated to aerobic and aquatic exercises in an experimental model of osteoarthritis.

The aim of this study was to compare the effects of photobiomodulation (PBM) associated with an aerobic and an aquatic exercise training on the degenerative process related to osteoarthritis (OA) in the articular cartilage in rats. Fifty male Wistar rats were randomly divided into 5 groups: OA control group (CG), OA plus aerobic training group (AET), OA plus aquatic training group (AQT), OA plus aerobic training associated with PBM group (AETL), OA plus aquatic training associated with PBM group (AQTL). The aerobic training (treadmill; 16m/min; 50min/day) and the aquatic training (water jumping; 50-80% of their body mass) started 4weeks after the surgery and they were performed 3days/week for 8weeks. Moreover, PBM was performed after the physical exercise trainings on the left joint. Morphological characteristics and immunoexpression of IL-10, TGF-β, and collagen type I (Col I) and II (Col II) of the articular cartilage were evaluated. The results showed that all the treated groups (exercise and PBM) presented less intense signs of degradation (measured by histopathological analysis and OARSI grade system). Additionally, aerobic and aquatic exercise training rats (associated or not with PBM) showed increased IL-10 (AET p = 0.0452; AETL p = 0.03; AQTL p = 0.0193) and Col II (AET p = 0.012; AQT p = 0.0437; AETL p = 0.0001; AQTL p = 0.0001) protein expression compared to CG. Furthermore, a statistically higher TGF-β expression was observed in AET (p = 0.0084) and AETL (p = 0.0076) compared to CG. These results suggest that PBM associated with aerobic and aquatic exercise training were effective in mediating chondroprotective effects and maintaining the integrity of the articular tissue in the knees of OA rats.

Aerobic Exercise Training Attenuates Tumor Growth and Reduces Insulin Secretion in Walker 256 Tumor-Bearing Rats.

Aerobic exercise training can improve insulin sensitivity in many tissues; however, the relationship among exercise, insulin, and cancer cell growth is unclear. We tested the hypothesis that aerobic exercise training begun during adolescence can attenuate Walker 256 tumor growth in adult rats and alter insulin secretion. Thirty-day-old male Wistar rats engaged in treadmill running for 8 weeks, 3 days/week, 44 min/day, at 55–65% VO2max until they were 90 days old (TC, Trained Control). An equivalently aged group was kept inactive during the same period (SC, Sedentary Control). Then, half the animals of the SC and TC groups were reserved as the control condition and the other half were inoculated with Walker 256 cancer cells, yielding two additional groups (Sedentary Walker and Trained Walker). Zero mortalities were observed in tumor-bearing rats. Body weight (BW), food intake, plasma glucose, insulin levels, and peripheral insulin sensitivity were analyzed before and after tumor cell inoculation. We also evaluated tumor growth, metastasis and cachexia. Isolated pancreatic islets secretory activity was analyzed. In addition, we evaluated mechanic sensibility. Our results showed improved physical performance according to the final workload and VO2max and reduced BW in trained rats at the end of the running protocol. Chronic adaptation to the aerobic exercise training decreased tumor weight, cachexia and metastasis and were associated with low glucose and insulin levels and high insulin sensitivity before and after tumor cell inoculation. Aerobic exercise started at young age also reduced pancreatic islet insulin content and insulin secretion in response to a glucose stimulus, without impairing islet morphology in trained rats. Walker 256 tumor-bearing sedentary rats also presented reduced pancreatic islet insulin content, without changing insulin secretion through isolated pancreatic islets. The mechanical sensitivity test indicated that aerobic exercise training did not cause injury or trigger inflammatory processes prior to tumor cell inoculation. Taken together, the current study suggests that aerobic exercise training applied during adolescence may mitigate tumor growth and related disorders in Walker 256 tumor-bearing adult rats. Improved insulin sensibility, lower glucose and insulin levels and/or reduced insulin secretion stimulated by glucose may be implicated in this tumor attenuation.

Contractile Activity Is Necessary to Trigger Intermittent Hypobaric Hypoxia-Induced Fiber Size and Vascular Adaptations in Skeletal Muscle.

Altitude training has become increasingly popular in recent decades. Its central and peripheral effects are well-described; however, few studies have analyzed the effects of intermittent hypobaric hypoxia (IHH) alone on skeletal muscle morphofunctionality. Here, we studied the effects of IHH on different myofiber morphofunctional parameters, investigating whether contractile activity is required to elicit hypoxia-induced adaptations in trained rats. Eighteen male Sprague-Dawley rats were trained 1 month and then divided into three groups: (1) rats in normobaria (trained normobaric inactive, TNI); (2) rats subjected daily to a 4-h exposure to hypobaric hypoxia equivalent to 4,000 m (trained hypobaric inactive, THI); and (3) rats subjected daily to a 4-h exposure to hypobaric hypoxia just before performing light exercise (trained hypobaric active, THA). After 2 weeks, the tibialis anterior muscle (TA) was excised. Muscle cross-sections were stained for: (1) succinate dehydrogenase to identify oxidative metabolism; (2) myosin-ATPase to identify slow- and fast-twitch fibers; and (3) endothelial-ATPase to stain capillaries. Fibers were classified as slow oxidative (SO), fast oxidative glycolytic (FOG), fast intermediate glycolytic (FIG) or fast glycolytic (FG) and the following parameters were measured: fiber cross-sectional area (FCSA), number of capillaries per fiber (NCF), NCF per 1,000 μm2 of FCSA (CCA), fiber and capillary density (FD and CD), and the ratio between CD and FD (C/F). THI rats did not exhibit significant changes in most of the parameters, while THA animals showed reduced fiber size. Compared to TNI rats, FOG fibers from the lateral/medial fields, as well as FIG and FG fibers from the lateral region, had smaller FCSA in THA rats. Moreover, THA rats had increased NCF in FG fibers from all fields, in medial and posterior FIG fibers and in posterior FOG fibers. All fiber types from the three analyzed regions (except the posterior FG fibers) displayed a significantly increased CCA ratio compared to TNI rats. Global capillarisation was also increased in lateral and medial fields. Our results show that IHH alone does not induce alterations in the TA muscle. The inclusion of exercise immediately after the tested hypoxic conditions is enough to trigger a morphofunctional response that improves muscle capillarisation.

Training Rats Using Water Rewards Without Water Restriction.

High-throughput behavioral training of rodents has been a transformative development for systems neuroscience. Water or food restriction is typically required to motivate task engagement. We hypothesized a gap between physiological water need and hedonic water satiety that could be leveraged to train rats for water rewards without water restriction. We show that when Citric Acid (CA) is added to water, female rats drink less, yet consume enough to maintain long term health. With 24 h/day access to a visual task with water rewards, rats with ad lib CA water performed 84% ± 18% as many trials as in the same task under water restriction. In 2-h daily sessions, rats with ad lib CA water performed 68% ± 13% as many trials as under water restriction. Using reward sizes <25 μl, rats with ad lib CA performed 804 ± 285 trials/day in live-in sessions or 364 ± 82 trials/day in limited duration daily sessions. The safety of CA water amendment was previously shown for male rats, and the gap between water need and satiety was similar to what we observed in females. Therefore, it is likely that this method will generalize to male rats, though this remains to be shown. We conclude that at least in some contexts rats can be trained using water rewards without water restriction, benefitting both animal welfare and scientific productivity.

0069 The Different Effect of Tongue Motor Task Training (TTT) and Strength Training (ST) on the Modulation of Genioglossus Corticomotor Excitability in Rats

The neuromuscular activation of upper airway stabilizing muscles, their propensity to fatigue and mechanical efficiency are pivotal in maintaining UA stability. Since training rats in a skilled reaching condition will induce task-related changes in the associated motor cortex, we aimed to investigate if different tongue training paradigms using fixed-training-intensity could differently induce neuroplastic changes in the corticomotor pathways, and to detect the time course of such changes. 18 water-restricted adult male Sprague-Dawley rats were trained to lick an isometric force-sensing disc at targeting forces for water reinforcement with sound feedback. In TTT group, 30–50% of maximal protrusion force (MPF) was used as a target window, while the ST paradigm used a progressive resistance training program with targeting force set above 50%, 60% and 70% of MPF, progressively. The rats in two groups were trained daily for two month with the same training intensity (1000 g·s per day). Corticomotor excitability was assessed via motor evoked potentials (MEPs) in genioglossus evoked by transcranial magnetic stimulation (TMS) at four sessions: at baseline before training, at different times after the 4th and 8th weeks of training. Overall, after 4 weeks in both groups, MEPs latencies of genioglossus evoked by TMS decreased immediately after training and dropped to the nadir 20 minutes after training compared to baseline (3.5 ± 0.5 ms vs. 4.8 ± 0.2 ms). This decreased latency lasted up to 80 minutes in TTT-treated rats; but in ST group, it rebound above the baseline value after 20 minutes and reached apex at 80 minutes (5.3 ± 0.4 ms). After 8 weeks in both groups, MEPs latencies consistently decreased within the 2 hours after training, and the precision of task performance (percent of peak force inside target window) significantly increased in TTT-treated rats. Tongue-task-training is associated with stable increment of genioglossus corticomotor excitability in a shorter time of training, while the tongue-strength-training rats might suffer fatigue at early stages of training. supported by the 2016 China National Nature Fund, number 81670085.

Effect of Resistance Training on Extracellular Matrix Adaptations in Skeletal Muscle of Older Rats.

Accumulation of connective tissue, particularly extracellular matrix (ECM) proteins, has been observed in skeletal muscles with advancing age. Resistance training (RT) has been widely recommended to attenuate age-induced sarcopenia, even though its effects on the components that control ECM turnover in skeletal muscles remain to be elucidated. Thus, the aim of this study was to determine the effects of RT on connective tissue content and gene expression of key components of ECM in the skeletal muscles of aged rats. Young (3 mo.) and older (21 mo.) adult male Wistar rats were submitted to a RT protocol (ladder climbing with 65, 85, 95, and 100% load), 3 times a week for 12 weeks. Forty-eight hours post-training, the soleus (SOL) and gastrocnemius (GAS) muscles were dissected for histological and mRNA analysis. RT mitigated the age-associated increase of connective tissue content in both muscles, even though mRNA levels of COL-1 and−3 were elevated in older trained rats. Overall, RT significantly elevated the gene expression of key components of connective tissue deposition (TGFβ and CTGF; MMP-2 and-9; TIMP-1 and−2) in the GAS and SOL muscles of older rats. In conclusion, RT blunted the age-induced accumulation of connective tissue concomitant to the upregulation of genes related to synthesis and degradation of the ECM network in the SOL and GAS muscles of older rats. Although our findings indicate that RT plays a crucial role reducing connective tissue accumulation in aged hindlimb muscles, key components of ECM turnover were paradoxically elevated. The phenotypic responses induced by RT were not accompanied by the gene expression of those components related to ECM turnover.

Effects of exercise training on adipose tissue apelin expression in streptozotocin-nicotinamide induced diabetic rats

Apelin is an adipocyte-derived peptide that plays an important role in regulation of energy homoeostasis and decrease of insulin resistance. We investigated the effects of exercise training on adipose tissue apelin expression in streptozotocin-nicotinamide induced diabetic rats. In this experimental study, 38 male Wistar rats were assigned to 4 groups: sedentary non-diabetic, trained non-diabetic, sedentary diabetic and trained diabetic. Type 2 diabetes mellitus (T2DM) was induced by intraperitoneal injection of streptozotocin and nicotinamide in adult rats. The trained groups ran 8-week on treadmill progressively for 45 min at a speed of 24 m/min and a 5% grade. After the training period, an intraperitoneal glucose tolerance test was performed in addition to the measurement of blood lipids and plasma apelin levels. Apelin mRNA levels in visceral adipose tissue were also analyzed. Two-way repeated measures analysis of variance (ANOVA) and Pearson correlation coefficient was used for analyzing data. P < 0.05 was considered to be statistically significant. Results indicated a significant decrease of insulin resistance followed by a significant increase of plasma levels and mRNA expression of apelin in trained diabetic compared with sedentary diabetic rats. Furthermore, apelin levels did not correlate significantly with body weight and epididymal fat weight in trained diabetic rats. In conclusion, the findings revealed that chronic exercise training, independently of body weight and fat pad weight by decrease of insulin resistance can increase apelin levels in visceral adipose tissue, thereby attenuating the progression of diabetes and decreasing insulin resistance in T2DM rats.

Pediatric tuberculosis detection using trained African giant pouched rats

BackgroundTuberculosis (TB) diagnosis in children is a challenge with up to 94% of children with TB treated empirically in TB high-burden countries. Therefore, new diagnostic tests are needed for TB diagnosis. We determined the performance of trained rats in the diagnosis of pediatric TB and whether they can improve detection rate compared to the standard of care.MethodsPresumptive TB patients in 24 TB clinics in Tanzania were tested. Samples indicated as TB-positive by rats underwent confirmation by concentrated smear microscopy. TB yield of bacteriologically confirmed pediatric TB patients (≤5 years) was compared with yield of standard of care.ResultsSputum samples from 55,148 presumptive TB patients were tested. Nine hundred eighty-two (1.8%) were the children between 1 and 5 years. Clinics detected 34 bacteriologically positive children, whereas rats detected additional 23 children yielding 57 bacteriologically TB-positive children. Rats increased pediatric TB detection by 67.6%. Among 1–14-year-old children, clinics detected 331 bacteriologically positive TB whereas rats found the additional 208 children with TB that were missed by clinics. Relative increase in TB case detection by rats decreased with the increase in age (P<0.0001).ConclusionTrained rats increase pediatric TB detection significantly and could help address the pediatric TB diagnosis challenges. Further determination of accuracy of rats involving other sample types is still needed.

Inhibition of Medial Preoptic Area Improves Physical Performance in Trained Rats

The medial preoptic area (MPO) plays a key role in the regulation of autonomic thermoeffectors and this area seems to be more activated after physical training, as evidenced by greater number of exercise‐induced c‐Fos immunoreactive neurons in trained rats. This observation raised the question as to whether inhibition of MPO can affect physical performance and thermoregulatory responses in trained rats. Following 2 weeks of high‐intensity interval training (HIIT), Wistar rats were submitted to an incremental‐speed exercise on a motor‐driven treadmill until fatigue after bilateral microinjection of muscimol (80 pmol/100 nl) to evaluate their aerobic capacity and thermoregulatory responses. The core body temperature (Tc) and the maximal oxygen uptake (VO2 max) were recorded continuously during exercise. Physical training increased the time to fatigue (43 ± 2 min vs. 64 ± 2 min; p=0.0009; n=6); the maximum speed attained during the incremental exercise (24 ± 1 m/min vs. 31 ± 1 m/min; p=0.0013), the distance traveled (675 ± 36 m vs. 1261 ± 68 m; p=0.0008); and resulted in a higher oxygen uptake (38 ± 1 ml/min/kg vs. 42 ± 1 ml/min/kg; p=0.01). Interestingly, at fatigue, no difference in the absolute Tc was found between the groups (38.28 ± 0.2 °C vs. 38.78 ± 0.1 °C; p=0.1). Bilateral blockade of MPO using muscimol improved physical performance, as observed by the increased time to fatigue (71 ± 6 min muscimol vs. 58 ± 2 min ‐ control, p=0.004; n=3); distance traveled (1528 ± 188 m muscimol vs. 1094 ± 84 m control; p=0.05); and maximum oxygen uptake (49 ± 1 ml/min/kg muscimol vs. 44 ± 2 ml/min/kg control; p=0.04). Regarding the thermoregulatory adjustments, MPO inhibition tended to increase Tc at fatigue (40.37 ± 0.5 °C muscimol vs. 39.35 ± 0.2 °C ‐ control; p=0.08). There was an increase in the Tc of the control animals during exercise but this temperature remained lower than that of the muscimol group (p&lt;0.001). Our findings show that neurons in the MPO are involved in the control of the aerobic capacity of trained rats, however, the improved physical performance of these animals caused by MPO inhibition did not result from changes in thermoregulatory adjustments.Support or Funding InformationConselho Nacional de Desenvolvimento Científico e Tecnlógico ‐ CNPq; grant 434646/2016‐4This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Intensive physical training reduces intermittent hypoxia‐related vascular dysfunction by affecting the mechanisms of smooth muscle from molecular to physiological scales

Obstructive sleep apnea syndrome (OSA) is a common clinical condition produced by episodes of repeated upper airways obstruction resulting in airflow blockade (apnea) during sleep. OSA is defined as a frequent chronic disease, which is highly prevalent in the population (affecting 9% of women and 24% of men) and which increases linearly with age. Chronic intermittent hypoxia (IH), the main pathogenic consequence related to OSA, is responsible for cardiovascular morbidity, including systemic arterial hypertension, cardiac infarct, atherosclerosis, and muscular remodeling in OSA patients.Systemic hypertension is the first cardiovascular disease related to OSA, thus 50% to 90% of patients with OSA develop hypertension. The mechanisms by which intermittent hypoxia induces the hypertension are not fully explained; we still don't know exactly the cause of hypertension, which make it a difficult medical condition to control, and make standard pharmacological interventions ineffective. Thus in order to found an effective treatment for hypertension induced by IH, we have to seek a non‐pharmacological intervention.While IH is known to contribute to hypertension, physical intensive training (IT) wields beneficial effects on the cardiovascular system and is known to reduce the hypertension risk in adults. Since physical exercise decreases the risk of cardiovascular events, the magnitude of this benefit can be also used as an anti‐hypertensive intervention.We choses a high‐intensity exercise protocol (exercise sessions during 21 days, 5 times/week on rats as a double fast 24 min‐walk with a speed progressively rising from 16 to 30 m/min), to prevent the IH‐impact and examine if IT can reverse or reduce the deleterious effects of IH (alternating normoxia (21%O2) and hypoxia (5%O2) every 30 sec in the cages for 8 h/day during 3 weeks) on the vascular reactivity, muscular remodeling and prevents the occurrence of hypertension.As expected, we found beneficial effects of training on physiological parameters (heart rate, arterial pressure), but also on vascular remodeling of several vessels (thoracic, abdominal, carotidal and pulmonary arteries); in addition we were able to observe opposite effects between IH and IT on gene transcription (Q‐PCR) and protein production (western blot) of several channels associated to calcium signaling (e.g. RyR, IP3R, SERCA, TRP) in cardiovascular system. We also compared calcium transient (ΔF/F0) from sarcoplasmic reticulum between normoxic and hypoxic smooth muscle cells and the significant difference (respectively 0,69±0,15 vs 1,01±0,21, p&lt;0,05) was abolished in cells from trained rats. Taken together, these results suggest that IT could decrease the adverse effects of IH on the cardiovascular system by acting from molecular to physiological organizations of muscular tissue. These data support the hypothesis that intensive exercise training may represent a promising non‐invasive, non‐pharmacological and complementary approach for the treatment of systemic hypertension.Support or Funding InformationINSERM, University of Grenoble Alps, University of Lebanon, AUF (PCSI)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Moderate exercise training under constant light condition amplifies inflammatory signals through disruption of splenic clock mechanism in osteoarthritic animals

Physical exercise has been recommended for osteoarthritic(OA) patients, the effects of which depends on exercise protocol. Here, we determined whether the benefits of exercise are influenced by lighting condition in the OA rats. Moderate treadmill exercise(Ex) was performed for 4 weeks at ZT14 under 12:12hr light‐dark(L/D) as well as constant light(LL). Intervention was applied for 30 min on 5 days/week. Splenic Cry1 expression was suppressed in the trained rats under constant light condition, leading to upregulation of proinflammatory cytokines mRNA. Moreover, TNFα level in serum was higher in the LL+Ex group than the L/D+Ex group. Constant light combined with exercise exacerbated primary cartilage lesion through an increase of catabolic molecules as well as a transcriptional suppression of anabolic factors. The level of synovial RANKL protein was elevated in the LL+Ex group, leading to loss of tibial trabeculae. And increased joint diameter was not recovered in the exercise‐trained rats under LL condition. Exercise training under constant lighting condition enhanced activation of catabolic machinery in soleus as well as gastrocnemius muscle. Treatment of proinflammatory cytokines disrupted rhythmic expression of catabolic enzymes in C2C12‐derived myotubes. Taken together, lighting condition might be a considerable environmental factor to obtain exercise‐induced benefits.Support or Funding InformationFunding: NRF‐2015R1C1A2A01055691, NRF‐2017R1A2A2A01067169, KGM4611714This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The Effect of Exercise Training on Sympathetic Vasoconstrictor Responsiveness and Sympatholysis in Female Rats

Our laboratory has previously reported that aerobic exercise training enhances contraction‐mediated inhibition of sympathetic vasoconstriction (sympatholysis) in male rats. Whether aerobic exercise training has a similar effect in female rats has not been established. Therefore, the purpose of the present study was to investigate the hypothesis that aerobic exercise training would blunt sympathetic vasoconstrictor responsiveness and enhance sympatholysis in female rats. Female Sprague‐Dawley rats were randomly assigned to sedentary (n=10) or treadmill exercise training (n=8) groups (15 min at 40 m/min, 5% gradient; 5 d/week) for 10 weeks. Following the completion of the sedentary behavior or exercise training intervention, rats were anaesthetized and instrumented for stimulation of the lumbar sympathetic chain and the measurement of arterial blood pressure and femoral vascular conductance (FVC). The triceps surae muscle group was stimulated to contract rhythmically at 60% of maximal contractile force. The percentage change of FVC (Δ%FVC) in response to sympathetic stimulation delivered at 2 and 5 Hz was determined at rest and during contraction. At rest, sympathetic vasoconstrictor responsiveness (Δ%FVC) was not different (p&gt;0.05) between sedentary and exercise trained rats in response to sympathetic stimulation delivered at 2Hz (Sedentary: −39 ± 12 %; Exercise Trained: −45 ± 9 %) and 5Hz (Sedentary: −57 ± 8 %; Exercise Trained: −61 ± 9 %). Muscle contraction blunted (p&lt;0.05) sympathetic vasoconstrictor responsiveness in both sedentary and exercise trained rats and the magnitude of sympatholysis was not different (p&gt;0.05) between sedentary (2Hz: 24 ± 8 %; 5Hz: 29 ± 10 %) and exercise‐trained (2Hz: 30 ± 10 %; 5Hz: 29 ± 13 %) rats. These data demonstrate that aerobic exercise training does not alter sympathetic vasoconstrictor responsiveness or contraction mediated inhibition of sympathetic vasoconstriction (sympatholysis) in female rats. Further investigation is required to determine why female rats respond differently to exercise training than male rats.Support or Funding InformationNatural Sciences and Engineering Research Council of Canada, Canadian Foundation for Innovation, and Alberta Advanced Education and Technology.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Early Exercise Training Postpones Hypertension Progression via Activation of Central ACE2‐Ang(1–7)‐Mas Axis in Prehypertensive Rats

ObjectivesTo investigate the effects of exercise training on the development of hypertension in spontaneously hypertensive rats (SHR) and explore the underlying mechanisms by focusing on the central ACE2‐Ang (1–7)‐MAS axis.MethodsThe male SHR (n=20, 5 weeks old) and 20 normotensive Wistar Kyoto rats (WKY) were randomly assigned to sedentary (Sed) group or exercise training (ExT) group. The trained rats run on a treadmill in 20 m/min, 30 min/day, 5 day/week for 20 weeks. Systolic blood pressure (SBP) were measured by a tail‐cuff method. The baroreflex sensitivity (BRS) was assessed by intravenous injection of phenylephrine under anesthesia. The expression of ACE2 and MAS receptors mRNA and protein in the cardiovascular centers was determined by real‐time PCR and Western blot. Alterations in the BRS were evaluated before and after intracerebroventricular injection of MAS receptor agonist Ang (1–7) and its antagonist A779, respectively.Results(1) Exercise training significantly postponed the development of hypertension in SHR and decreased SBP in both SHR and WKY as compared with Sed groups (P&lt;0.01 and P&lt;0.05). (2) Exercise training enhanced blood pressure regulation and improved the BRS in the SHR (P&lt;0.01). (3) The expression of ACE2 and MAS receptor mRNA and protein in rostral ventrolateral medulla (RVLM), nucleus tract solitarius (NTS), and paraventricular nucleus (PVN) was up‐regulated in SHR+ExT group (P&lt;0.05, P&lt;0.01). (4) Central administration of A779 abolished the benefits of exercise‐induced improvement of BRS in the SHR+ExT rats (P&lt;0.01). In contrast, Ang (1–7) improved the BRS in both SHR+Sed group and SHR +ExT group (P&lt;0.05).ConclusionExercise training postpones hypertension progression and improves blood pressure regulation, which is associated with the enhancement of central ACE2‐Ang(1–7)‐Mas axis.Support or Funding InformationNational Natural Science Foundation of China (No. 81372111) and Natural Science Foundation of Fujian Province of China (No. 2014J01339)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Prostate Cancer Cell Viability and Migration in Serum and Prostate Conditioned Media from Moderate‐Intensity Exercise Trained Rats

Physical activity is associated with diminished risk of several cancers and preclinical studies suggest exercise training may alter tumor cell growth in certain tissues (e.g., adipose). We hypothesized that serum and prostate conditioned media (PCM) from moderate‐intensity exercise trained rats will decrease prostate cancer cell growth, while prostate 5α‐reductase 2 expression will decrease. We evaluated the effects of serum and PCM from moderate‐intensity exercise trained rats on prostate cancer cell viability and migration. In addition, we determined whether moderate‐intensity exercise training would modulate 5α‐reductase 2 protein expression, an essential component of androgen metabolism in prostate cancer. Male Copenhagen rats (~2–3 mo old) were randomly assigned to an exercise‐trained group (n = 10) and a sedentary control group (n = 10). The exercise‐trained rats ran on a motorized treadmill for 5 days/week at 15 m/min, 15° incline for 60 min/day for a 10‐ to 11‐week training period. Serum was collected from both rat groups, and used to supplement media at 5% concentration with and without 5% fetal bovine serum (FBS). Rat prostates were harvested, cut into two approximately equal sections with one section incubated with media for 24 hours to prepare PCM, and immunohistochemistry performed on the other section to quantify 5α‐reductase 2 expression. Dunning R‐3327 AT‐1 prostate cancer cells were grown in PCM, or media supplemented with either 5% serum from the exercise‐trained or sedentary groups with and without 5% FBS for 24–96 hours. Tumor cell viability and migration were determined using MTT and transwell migration assays, respectively. Serum or PCM from exercise‐trained rats did not significantly decrease cell viability compared to serum (e.g. 0.41 ± 0.04 vs. 0.50 ± 0.05 viable cell number, p = 0.14) or PCM (e.g. 0.40 ± 0.07 vs. 0.50 ± 0.08 viable cell number, p = 0.50; all at 48 hour incubation) from sedentary rats, respectively. However, the addition of FBS to serum from exercise‐trained rats significantly decreased cell viability compared to FBS and serum from sedentary rats (e.g. 0.49 ± 0.05 vs. 0.69 ± 0.06 viable cell number, p = 0.02; 48 hour incubation). Serum alone, serum and FBS, or PCM from exercise‐trained rats did not significantly impact cell migration compared to sedentary control (54.7 ± 3.3 vs. 64.2 ± 9.2 cells/field, p = 0.27; 29.3 ± 2.6 vs. 29.3 ± 2.5 cells/field, p &gt; 0.99; 55.9 ± 10.5 vs. 52.8 ± 8.1 cells/field, p = 0.82), respectively. 5α‐reductase 2 in the prostate was not significantly changed with exercise compared to sedentary group (0.87 ± 0.21 vs. 0.78 ± 0.18 positive cells/tissue area (μm2), p = 0.76). In conclusion, prior exercise status did not modify several key characteristics of prostate tumor cell growth and viability from conditioned media from host‐tissue (prostate) or serum in vitro. Whether exercise training alters similar prostate tumor cell growth characteristics in vivo is unknown.Support or Funding InformationAmerican Cancer Society RSG 14‐150‐1‐CCE (BJB)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The effect of cocaine cue re‐exposure after prolonged cocaine self‐administration and forced abstinence on DNA methylation and mRNA expression in the rat dmPFC

Cocaine addiction is a chronic relapsing disorder whereby cocaine craving in response to drug related cues persists, and even intensifies through protracted drug‐free abstinence periods. Studies employing animal models observe cocaine‐seeking patterns that are similar to human addicts. Additionally, there are long term changes in neuron structure, receptor function, and neurotransmission associated with abstinence from cocaine in humans and animals. DNA methylation is an epigenetic modification to the DNA structure that mediates mRNA expression to confer different cell types, but has recently been implicated in learning and memory mechanisms. The long‐term control that DNA methylation has over gene expression in animals makes it a prime candidate for controlling gene expression over the course of abstinence in animals with previous drug experience. To test this, I trained rats to self‐administer either saline (1 h per day) or cocaine (6 h per day) for 15 days, then exposed them to 60 days of forced abstinence. After abstinence half of the rats were put back in self‐administration chambers and re‐exposed to cues for 2 h, while the other half were left in their home cages. After the cue manipulation, all rats were sacrificed, the dmPFC was dissected out, and DNA and mRNA were extracted. Methylated DNA was purified using methylated DNA immuno‐precipitation, and mRNA was reverse‐transcribed into cDNA; levels of each were then quantified via digital PCR procedures. Interestingly, I observed cue‐induced changes in DNA methylation within Homer2, Dlg4, Npas4, and Grin1 promoter regions. These context‐specific changes indicate that DNA methylation is much more dynamic than previously shown. Additionally, I saw changes in mRNA expression for Homer2, Dlg4, and Npas4 that appear to be highly reflective of the changes in DNA methylation. These results indicate re‐exposure to cocaine cues induce gene‐specific mRNA expression via rapid changes in DNA methylation.Support or Funding InformationThis research was supported by NIH grants DA‐027115 and DA‐027525 (TEK) and DA024038 (KKS), as well as funding from and the W.M. Keck Foundation (TEK).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.