Function In Adult Mice Research Articles

Early Postnatal Hyperoxia in Mice Leads to Severe Persistent Vitreoretinopathy.

To describe a mouse model of hyperoxia-induced vitreoretinopathy that replicated some of the clinical and pathologic features encountered in infants with severe retinopathy of prematurity and congenital ocular conditions such as persistent hyperplastic primary vitreous. Experimental mice (C57BL/6J) were exposed to 65% oxygen between postnatal days (P)0 to P7 and studied at P10, P14, and 3, 5, 8, 20, and 40 weeks. Controls were exposed to normoxic conditions. Fundus imaging and fluorescein angiography were performed at all time points, and spectral-domain optical coherence tomography (SD-OCT) and electroretinography were performed at 8- and 20-week time points. Eyes were processed for resin histology, frozen sections, and retinal whole mounts. Immunostaining was performed to visualize vasculature isolectin B4 (Ib4), collagen type IV, glial fibrillary acidic protein, and α-smooth muscle actin. Early exposure to hyperoxia resulted in bilateral vitreous hemorrhages at 3 weeks. From 5 weeks onward there were extensive zones of retinal degeneration, scarring or gliosis, retinal folding, and detachments caused by traction of α-smooth muscle actin-positive vitreous membranes. Tortuous retinal vessels, together with hyperplastic and persistence of hyaloid vessels are evident into adulthood. In the early stages (P10-3 weeks), branches from the tunica vasculosa lentis (TVL) supplied the marginal retina until retinal vessels were established. The peripheral retina remained poorly vascularized into adulthood. Electroretinography revealed 50% to 60% diminution in retinal function in adult mice that strongly correlated with vitreal changes identified using SD-OCT. This animal model displays a mixture of vitreoretinal pathologic changes that persist into adulthood. The model may prove valuable in experimental investigations of therapeutic approaches to blinding conditions caused by vitreous and retinal abnormalities.

Roles of Cbln1 in Non-Motor Functions of Mice.

Despites its well known role in motor coordination and motor learning, whether and how the cerebellum is involved in cognitive functions remains less clear. Cerebellin 1 (Cbln1) is highly expressed in the cerebellum and serves as an essential synaptic organizer. Although genes encoding Cbln1 and its receptor are associated with many psychiatric disorders, it remains unknown whether such cognitive impairments are caused by cerebellar dysfunction. Here, we show that Cbln1 is also expressed in the forebrain, including the hippocampus and retrosplenial granular cortex. Using forebrain- and cerebellum-predominant conditional Cbln1-null mice, we show that Cbln1 in the forebrain and cerebellum mediates specific aspects of fear conditioning and spatial memory differentially, indicating that Cbln1 signaling regulates both motor and non-motor functions in multiple brain regions.

Effect of ischaemic brain injury on sexual function in adult mice

ObjectivePriapism refers to a condition with persistent abnormal erection of the penis, which is usually caused by disease or injury in the brain or spinal cord, or obstruction to the...

Multi-Vitamin B Supplementation ReversesHypoxia-Induced Tau Hyperphosphorylation and Improves Memory Function in Adult Mice.

Hypobaric hypoxia (HH) leads to reduced oxygen delivery to brain. It could trigger cognitive dysfunction and increase the risk of dementia including Alzheimer's disease (AD). The present study was undertaken in order to examine whether B vitamins (B6, B12, folate, and choline) could exert protective effects on hypoxia-induced memory deficit and AD related molecular events in mice. Adult male Kunming mice were assigned to five groups: normoxic control, hypoxic model (HH), hypoxia+vitamin B6/B12/folate (HB), hypoxia+choline (HC), hypoxia+vitamin B6/B12/folate+choline (HBC). Mice in the hypoxia, HB, HC, and HBC groups were exposed to hypobaric hypoxia for 8 h/day for 28 days in a decompression chamber mimicking 5500 meters of high altitude. Spatial and passive memories were assessed by radial arm and step-through passive test, respectively. Levels of tau and glycogen synthase kinase (GSK)-3β phosphorylation were detected by western blot. Homocysteine (Hcy) concentrations were determined using enzymatic cycling assay. Mice in the HH group exhibited significant spatial working and passive memory impairment, increased tau phosphorylation at Thr181, Ser262, Ser202/Thr205, and Ser396 in the cortex and hippocampus, and elevated Hcy levels compared with controls. Concomitantly, the levels of Ser9-phosphorylated GSK-3β were significantly decreased in brain after hypoxic treatment. Supplementations of vitamin B6/B12/folate+choline could significantly ameliorate the hypoxia-induced memory deficits, observably decreased Hcy concentrations in serum, and markedly attenuated tau hyperphosphorylation at multiple AD-related sites through upregulating inhibitory Ser9-phosphorylated GSK-3β. Our finding give further insight into combined neuroprotective effects of vitamin B6, B12, folate, and choline on brain against hypoxia.

Abstract 411: In Utero Exposure to PM2.5 Causes Adult Cardiovascular Dysfunction and Reduced Exercise Capacity

Objective: Exposure to particulate matter 2.5 μm (PM2.5) during intrauterine development is associated with adverse cardiovascular outcomes at adulthood. Deteriorations in cardiac function are observed with increased myocardial demand in PM2.5-exposed individuals. The goal of this study was to determine the effects of in utero PM2.5exposure on exercise training capacity and cardiac function in adult mice. Methods: Female FVB mice were exposed either to filtered air (FA) or PM2.5at an average concentration of 73.61μg/m 3 for 6h/day, 7days/wk throughout pregnancy. 12wk old male offspring from exposed dams were assigned to in utero FA (n=5) or PM2.5 (n=5) exposed groups which underwent exercise training for 3 weeks (housed with running wheels for 3 weeks). We measured total distance travelled and performed echocardiography at baseline, 1, 2 and 3 weeks. Results: There was a progressive decrease in total distance travelled each week in the in utero PM2.5 exposed mice (Week 1: 12.2±3.46 Km FA, 5.32±2.06 Km PM2.5; Week 2: 41.4±9.62 Km FA, 17.28±6.60 Km PM2.5; Week 3: 61.8±16.59 Km FA, 25.92.±8.62 Km PM2.5) compared to the in utero FA exposed mice. When comparing to their respective sedentary counterparts, the FA exercise group showed increased fractional shortening (%FS), left ventricular end systolic (LVESd) and diastolic (LVEDd) diameters, suggesting eccentric hypertrophy. There was a modest decrease in %FS and marked increase in posterior wall thickness during diastole (PWTd) in the PM2.5 exercise group suggesting concentric hypertrophy. Comparison of in utero FA vs PM2.5 exercise groups after 3 weeks of exercise training showed reduced %FS and marked decrease in LVEDd in the PM2.5 exercise group compared to the FA exercise group. Furthermore, a decrease in PWTs and increased PWTd was also observed in the PM2.5 group compared to FA controls. Conclusions: In utero PM2.5exposure reduced exercise capacity at adulthood and the development of both systolic and diastolic dysfunction. Thus, our study showed that individuals residing in high pollution areas are predisposed to develop cardiac dysfunction under conditions of increased myocardial demand.

TAK1 Is a Key Regulator of Skeletal Muscle Maintenance in Mice

TGFβ-activated kinase 1 (TAK1), a member of the MEK kinase (MAP3K) family, has been demonstrated to be a component of signaling pathways leading to the activation of NF-kB and activator protein-1 (AP-1) in response to cytokines and growth factors. Our previous study has shown that TAK1 is a critical regulator for the proliferation and differentiation of cultured C2C12 myoblasts. However, the role of TAK1 in regulation of skeletal muscle mass has not yet been investigated. PURPOSE: To determine if skeletal muscle-specific deletion of TAK1 alters the skeletal muscle mass and function in adult mice. METHODS: Skeletal muscle-specific TAK1 knockout (TAK1mko, n=5) mice were generated by crossing HSA-cre mice with floxed TAK1 (i.e. TAK1f/f) mice. Tamoxifen was injected intraperitoneally to inactivate TAK1 and the mice were fed with tamoxifen-containing standard chow for the entire duration of the experiment. TAK1f/f mice (n=6) were used as control. All mice were sacrificed at approximately 3 months of age and the tibialis anterior (TA) and soleus (SOL) muscles were excised for further analysis. RESULTS: TAK1mko mice were found to have reduced body weight (14%) and TA muscle weight (10%) compared to TAK1f/f mice. Mean fiber-cross sectional area (CSA) was decreased in TAK1mko mice by 42% and 39% in TA and SOL muscles, respectively. TAK1mko mice showed lower grip strength compared to control mice by 39%. Genetic ablation of TAK1 in skeletal muscle significantly reduced the levels of specific muscle proteins whereas the levels of atrogin-1, poly-ubiquitinated proteins, and proteasome activity were increased. CONCLUSION: These data demonstrate that TAK1 is essential for maintenance of skeletal muscle in adult animals. Supported by NIH Grant AR059810 and AG029623 to AK.

Discovery of novel small molecule inhibitors of cardiac hypertrophy using high throughput, high content imaging

Chronic cardiac hypertrophy is maladaptive and contributes to the pathogenesis of heart failure. The objective of this study was to identify small molecule inhibitors of pathological cardiomyocyte hypertrophy. High content screening was performed with primary neonatal rat ventricular myocytes (NRVMs) cultured on 96-well plates and treated with a library of 3241 distinct small molecules. Non-toxic hit compounds that blocked hypertrophy in response to phenylephrine (PE) and phorbol myristate acetate (PMA) were identified based on their ability to reduce cell size and inhibit expression of atrial natriuretic factor (ANF), which is a biomarker of pathological cardiac hypertrophy. Many of the hit compounds are existing drugs that have not previously been evaluated for benefit in the setting of cardiovascular disease. One such compound, the anti-malarial drug artesunate, blocked left ventricular hypertrophy (LVH) and improved cardiac function in adult mice subjected to transverse aortic constriction (TAC). These findings demonstrate that phenotypic screening with primary cardiomyocytes can be used to discover anti-hypertrophic lead compounds for heart failure drug discovery. Using annotated libraries of compounds with known selectivity profiles, this screening methodology also facilitates chemical biological dissection of signaling networks that control pathological growth of the heart.

Exposure to environmentally persistent free radicals during gestation lowers energy expenditure and impairs skeletal muscle mitochondrial function in adult mice.

We have investigated the effects of in utero exposure to environmentally persistent free radicals (EPFRs) on growth, metabolism, energy utilization, and skeletal muscle mitochondria in a mouse model of diet-induced obesity. Pregnant mice were treated with laboratory-generated, combustion-derived particular matter (MCP230). The adult offspring were placed on a high-fat diet for 12 wk, after which we observed a 9.8% increase in their body weight. The increase in body size observed in the MCP230-exposed mice was not associated with increases in food intake but was associated with a reduction in physical activity and lower energy expenditure. The reduced energy expenditure in mice indirectly exposed to MCP230 was associated with reductions in skeletal muscle mitochondrial DNA copy number, lower mRNA levels of electron transport genes, and reduced citrate synthase activity. Upregulation of key genes involved in ameliorating oxidative stress was also observed in the muscle of MCP230-exposed mice. These findings suggest that gestational exposure to MCP230 leads to a reduction in energy expenditure at least in part through alterations to mitochondrial metabolism in the skeletal muscle.

Neonatal pneumococcal colonisation caused by Influenza A infection alters lung function in adult mice.

There is emerging epidemiological data to suggest that upper respiratory tract bacterial colonisation in infancy may increase the risk of developing respiratory dysfunction later in life, and respiratory viruses are known to precipitate persistent colonisation. This study utilized a neonatal mouse model of Streptococcus pneumonia (SP) and influenza A virus (IAV) co-infection, where bronchoalveolar leukocyte infiltration had resolved by adulthood. Only co-infection resulted in persistent nasopharyngeal colonisation over 40 days and a significant increase in airway resistance in response to in vivo methacholine challenge. A significant increase in hysteresivity was also observed in IAV and co-infected mice, consistent with ventilatory heterogeneity and structural changes in the adult lung. Airway hyper-responsiveness was not associated with a detectable increase in goblet cell transdifferentiation, peribronchial smooth muscle bulk or collagen deposition in regions surrounding the airways. Increased reactivity was not observed in precision cut lung slices challenged with methacholine in vitro. Histologically, the airway epithelium appeared normal and expression of epithelial integrity markers (ZO-1, occludin-1 and E-cadherin) were not altered. In summary, neonatal co-infection led to persistent nasopharyngeal colonisation and increased airway responsiveness that was not associated with detectable smooth muscle or mucosal epithelial abnormalities, however increased hysteresivity may reflect ventilation heterogeneity.

Progesterone to improve neurocognitive outcomes following cranial irradiation.

128 Background: Neurocognitive functional decline is a common sequalae of cranial irradiation (CI) that significantly impacts quality of life. Preclinical studies and randomized clinical trials show that following traumatic brain injury and cerebrovascular accidents, premenopausal women demonstrate decreased mortality and improved neurocognitive function, with these benefits presumed to be derived from progesterone. We hypothesized that progesterone may serve similar role in neuroprotection following cranial irradiation. Methods: Adult non-tumor bearing wild type C57BL/6 male mice were treated with two separate fractionated radiation therapy regimen (9 Gy and 15 Gy) to the brain. Cohorts of these mice were administered progesterone (16mg/kg daily) as a pretreatment for 3 days and concurrent with the radiotherapy for a total of 14 days with tapering during the last two days. The animals were then tested using different behavioral measures for cognitive function including morris water maze (MWM) for assessing spatial and related forms of learning and memory, elevated plus maze (EPM), , and spontaneous locomotor activity (SLA) tests. Mice were tested for cognitive function on day 10 and after 30 days of treatment for short and long-term effects of (CI) on memory function. Results: All irradiated mice showed statistically significant decline in MWM, EPM, and SLA measures. There were no significant differences in the 9 Gy versus 15 Gy cohorts. Progesterone administration produced a statistically significant group effect (F (4, 25) = 8.553; P<0.001) in the improvement of long-term memory function over 5 days of learning process. Progesterone administration also demonstrated a significant group effect (F (4, 25) = 8.613; P<0.001) in the probe trial, and a significant beneficial effect (F (4, 25)= 7.993; P<0.001) in short-term memory functional latency to reach the platform. Conclusions: The preclinical data show that progesterone improves radiation-induced deficits in short-and long-term memory functions in adult mice. Further work is required to show if progesterone may show similar clinical benefit in neuroprotection for adults undergoing prophylactic CI or definitive CI for brain metastases or benign intracranial processes such as AVM.

The role of particulate guanylyl cyclase B (GC-B) in auditory function in adult mice

Background cGMP signaling triggered by the binding of C-type natriuretic peptide (CNP) to its receptor guanylyl cyclase B (GC-B; NPR2; NPRB) has been linked by genetic evidence to a remarkable variety of physiological functions like skeletal bone growth, female fertility, cardiac growth, fat metabolism and gastrointestinal function. For the nervous system it has been recently demonstrated that the CNP/GC-B/cGMP/cGMP-dependent protein kinase type I (cGKI) signaling pathway is essential for sensory axon branching at the dorsal root entry zone of the spinal cord and at the rhombomeres of the hindbrain during embryonic development [1]. Also in the auditory system, distinct auditory nerve fiber (ANF) types that differ in their discharge rate and sound sensitivity bifurcate in the cochlear nucleus (CN), sending collaterals to the anteroventral, posteroventral, and dorsal subdivisions. The lack of GC-B has been shown to lead to a central phenotype [2].

Crosstalk between Bone and Muscle: Deletion of Mbtps1 in Bone Leads to Age‐Dependent Increase in Muscle Size and Contractile Function

Proprotein convertase Mbtps1 is required for transcription of bone matrix proteins including fibronectin, collagen XI, and PHEX by osteoblastic/osteocytic cells. Since complete loss of Mbtps1 is lethal at E4, we asked if conditional deletion of Mbtps1 using early osteocyte DMP1 cre would disrupt bone structure. Mbtps1 cKO male mice were slightly larger than controls (43.6 g vs. 40.2 g, p=0.057) but displayed no significant changes in bone dimensions, BMD, mineral content, or cortical/trabecular bone parameters at 12 and 40 weeks of age. However, 40 week old soleus muscles from cKO mice weighed 20% more and contracted with 50% more force ex vivo even when normalized for size despite the fact that Mptps1 expression was unchanged (0.94 cKO/control +/‐ 0.42 STD). Immunostaining revealed cKO soleus muscles contained about 35% type I and 60% type 2 myosin heavy chain positive cells, were devoid of myosin 2b fiber+ cells which comprised 5% of control cells, and displayed a higher percentage of central nuclei than controls. Central nuclei, which can reflect muscle repair or regeneration, were restricted to type I myosin heavy chain positive cells. The osteocyte specific deletion of Mbtps1 along with genome arrays that demonstrate increased expression of muscle performance markers such as α‐actinin3 support a cross‐talk signaling mechanism by which Mbtps1‐deficient bone cells increase muscle contractile function in adult mice. Revealing the molecular mechanism responsible could lead to new therapies for a host of muscle disorders.

Trio gene is required for mouse learning ability

Trio is a guanine nucleotide exchange factor with multiple guanine nucleotide exchange factor domains. Trio regulates cytoskeleton dynamics and actin remodeling and is involved in cell migration and axonal guidance in neuronal development. The null allele of the Trio gene led to embryonic lethality, and Trio null embryos displayed aberrant organization in several regions of the brain at E18.5, including hippocampus. Nestin-Trio−/− mice, in which the Trio gene was deleted specifically in the neuronal system by the Nestin-Cre system, displayed severe phenotypes, including low survival rate, ataxia and multiple developmental defects of the cerebellum. All Nestin-Trio−/− mice died before reaching adulthood, which hinders research on Trio gene function in adult mice. Thus, we generated EMX1-Trio−/− mice by crossing Trio-floxed mice with EMX1-Cre mice in which Cre is expressed in the brain cortex and hippocampus. EMX1-Trio−/− mice can survive to adulthood. Trio gene deletion results in smaller brains, an abnormal hippocampus and disordered granule cells in the dentate gyrus (DG) and cornu ammonis (CA). Behavior tests showed that Trio deletion interfered with the hippocampal-dependent spatial learning in the mice, suggesting that Trio plays critical roles in the learning ability of adult mice. We conclude that the Trio gene regulates the neuronal development of the hippocampus and that it affects the intelligence of adult mice.

TRPV2 is critical for the cardiac function in adult mice

TRPV2 is critical for the cardiac function in adult mice

Effects of postnatal alcohol exposure on hippocampal gene expression and learning in adult mice.

Fetal alcohol syndrome (FAS) is a condition resulting from excessive drinking by pregnant women. Symptoms of FAS include abnormal facial features, stunted growth, intellectual deficits and attentional dysfunction. Many studies have investigated FAS, but its underlying mechanisms remain unknown. This study evaluated the relationship between alcohol exposure during the synaptogenesis period in postnatal mice and subsequent cognitive function in adult mice. We delivered two injections, separated by 2 h, of ethanol (3 g/kg, ethanol/saline, 20% v/v) to ICR mice on postnatal day 7. After 10 weeks, we conducted a behavioral test, sacrificed the animals, harvested brain tissue and analyzed hippocampal gene expression using a microarray. In ethanol-treated mice, there was a reduction in brain size and decreased neuronal cell number in the cortex, and also cognitive impairment. cDNA microarray results indicated that 1,548 genes showed a > 2-fold decrease in expression relative to control, whereas 974 genes showed a > 2-fold increase in expression relative to control. Many of these genes were related to signal transduction, synaptogenesis and cell membrane formation, which are highlighted in our findings.

Caffeine exposure alters cardiac gene expression in embryonic cardiomyocytes.

Previous studies demonstrated that in utero caffeine treatment at embryonic day (E) 8.5 alters DNA methylation patterns, gene expression, and cardiac function in adult mice. To provide insight into the mechanisms, we examined cardiac gene and microRNA (miRNA) expression in cardiomyocytes shortly after exposure to physiologically relevant doses of caffeine. In HL-1 and primary embryonic cardiomyocytes, caffeine treatment for 48 h significantly altered the expression of cardiac structural genes (Myh6, Myh7, Myh7b, Tnni3), hormonal genes (Anp and BnP), cardiac transcription factors (Gata4, Mef2c, Mef2d, Nfatc1), and microRNAs (miRNAs; miR208a, miR208b, miR499). In addition, expressions of these genes were significantly altered in embryonic hearts exposed to in utero caffeine. For in utero experiments, pregnant CD-1 dams were treated with 20-60 mg/kg of caffeine, which resulted in maternal circulation levels of 37.3-65.3 μM 2 h after treatment. RNA sequencing was performed on embryonic ventricles treated with vehicle or 20 mg/kg of caffeine daily from E6.5-9.5. Differential expression (DE) analysis revealed that 124 genes and 849 transcripts were significantly altered, and differential exon usage (DEU) analysis identified 597 exons that were changed in response to prenatal caffeine exposure. Among the DE genes identified by RNA sequencing were several cardiac structural genes and genes that control DNA methylation and histone modification. Pathway analysis revealed that pathways related to cardiovascular development and diseases were significantly affected by caffeine. In addition, global cardiac DNA methylation was reduced in caffeine-treated cardiomyocytes. Collectively, these data demonstrate that caffeine exposure alters gene expression and DNA methylation in embryonic cardiomyocytes.

Effect of Sertoli cell ablation on testicular function in adult mouse

Effect of Sertoli cell ablation on testicular function in adult mouse

Prenatal Infection Affects the Neuronal Architecture and Cognitive Function in Adult Mice

Environmental factors such as prenatal infection are involved in the pathogenic processes of neurodevelopmental psychiatric disorders. In the present study, we administered a viral mimic, polyriboinosinic-polyribocytidylic acid (poly I:C, 20 mg/kg, i.p.), to pregnant B6 mice at gestational day 9.5. Neonates born to these poly I:C-treated dams showed an increase of microglia in the hippocampus, indicating an activation of the immune system in the brains. Moreover, a significant increase in the number of dopamine-producing neurons in the ventral tegmental area was observed in adult male poly I:C offspring compared with age-matched saline offspring. Poly I:C offspring also exhibited hypolocomotor activity in a novel open-field arena but did not display signs of anxiety or depression in the elevated plus maze or the forced swim test, respectively. However, the short-term memory of the poly I:C offspring was impaired in a novel object recognition task. Therefore, the dendritic architecture of granule cells in the dentate gyrus (DG) and pyramidal neurons in the medial prefrontal cortex (mPFC) were examined. The dendritic complexity was reduced in the DG granule cells of the poly I:C offspring and exhibited shorter dendritic length compared with the saline offspring. The density of dendritic spines in the DG granule cells was also decreased in the poly I:C offspring. Furthermore, the dendritic complexity and spine density were reduced in layer II/III mPFC pyramidal neurons of the poly I:C offspring. Together, these data demonstrate impaired short-term memory and altered dendritic architecture in adult poly I:C offspring, which validates the prenatal infection paradigm as a model for neurodevelopmental psychiatric disorders.

Retinoblastoma protein (RB) interacts with E2F3 to control terminal differentiation of Sertoli cells.

The retinoblastoma protein (RB) is essential for normal cell cycle control. RB function depends, at least in part, on interactions with the E2F family of DNA-binding transcription factors (E2Fs). To study the role of RB in the adult testis, a Sertoli cell (SC)-specific Rb knockout mouse line (SC-RbKO) was generated using the Cre/loxP recombination system. SC-RbKO mice exhibited an age-dependent testicular atrophy, impaired fertility, severe SC dysfunction, and spermatogenic defects. Removal of Rb in SC induced aberrant SC cycling, dedifferentiation, and apoptosis. Here we show that E2F3 is the only E2F expressed in mouse SCs and that RB interacts with E2F3 during mouse testicular development. In the absence of RB, the other retinoblastoma family members p107 and p130 began interacting with E2F3 in the adult testes. In vivo silencing of E2F3 partially restored the SC maturation and survival as well as spermatogenesis in the SC-RbKO mice. These results point to RB as a key regulator of SC function in adult mice and that the RB/E2F3 pathway directs SC maturation, cell cycle quiescence, and RB protects SC from apoptosis.

Long-term exposure to decabrominated diphenyl ether impairs CD8 T-cell function in adult mice

Polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental pollutants that accumulate to high levels in human populations that are subject to occupational or regional industry exposure. PBDEs have been shown to affect human neuronal, endocrine and reproductive systems, but their effect on the immune system is not well understood. In this study, experimental adult mice were intragastrically administered 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE-209) at doses of 8, 80 or 800 mg/kg of body weight (bw) at 2-day intervals. Our results showed that continuous exposure to BDE-209 resulted in high levels of BDE-209 in the plasma that approached the levels found in people who work in professions with high risks of PDBE exposure. Reduced leukocytes, decreased cytokine (IFN-γ, IL-2 and TNF-α) production and lower CD8 T-cell proliferation were observed in the mice exposed to BDE-209. Additionally, mice with long-term BDE-209 exposure had lower numbers of antigen-specific CD8 T cells after immunization with recombinant Listeria monocytogenes expressing ovalbumin (rLm-OVA) and the OVA-specific CD8 T cells had reduced functionality. Taken together, our study demonstrates that continuous BDE-209 exposure causes adverse effects on the number and functionality of immune cells in adult mice.