Acetylcholine Receptor Gene Expression Research Articles

Vitamin D and rosuvastatin alleviate type-II diabetes-induced cognitive dysfunction by modulating neuroinflammation and canonical/noncanonical Wnt/β-catenin signaling.

Type-II diabetes mellitus (T2DM) is a major risk factor for cognitive impairment. Protecting the brain environment against inflammation, and neurodegeneration, as well as preservation of the BBB veracity through modulating the crosstalk between insulin/AKT/GSK-3β and Wnt/β-catenin signaling, might introduce novel therapeutic targets. This study aimed at exploring the possible neuroprotective potential of vitamin D3 (VitD) and/or rosuvastatin (RSV) in T2DM-induced cognitive deficits. T2DM was induced by a high-fat sucrose diet and a single streptozotocin (STZ) dose. Diabetic rats were allocated into a diabetic control and three groups treated with RSV (15 mg/kg/day, PO), VitD (500 IU/kg/day, PO), or their combination. Administration of VitD and/or RSV mitigated T2DM-induced metabolic abnormalities and restored the balance between the anti-inflammatory, IL 27 and the proinflammatory, IL 23 levels in the hippocampus. In addition, they markedly activated both the canonical and noncanonical Wnt/β-catenin cassettes with stimulation of their downstream molecular targets. VitD and/or RSV upregulated insulin and α7 nicotinic acetylcholine (α7nACh) receptors gene expression, as well as blood-brain barrier integrity markers including Annexin A1, claudin 3, and VE-cadherin. Also, they obliterated hippocampal ApoE-4 content, Tau hyperphosphorylation, and Aβ deposition. These biochemical changes were reflected as improved behavioral performance in Morris water maze and novel object recognition tests and restored hippocampal histological profile. The current findings have accentuated the neuroprotective potential of VitD and RSV and provide new incentives to expand their use in T2DM-induced cognitive and memory decline. This study also suggests a superior benefit of combining both treatments over either drug alone.

Human skeletal muscle acetylcholine receptor gene expression in elderly males performing heavy resistance exercise.

Muscle fiber denervation is a major contributor to the decline in muscle mass and function during aging. Heavy resistance exercise is an effective tool for increasing muscle mass and strength, but whether it can rescue denervated muscle fibers remains unclear. Therefore, the purpose of this study was to investigate the potential of heavy resistance exercise to modify indices of denervation in healthy elderly individuals. Thirty-eight healthy elderly men (72 ± 5 yr) underwent 16 wk of heavy resistance exercise, whereas 20 healthy elderly men (72 ± 6 yr) served as nonexercising sedentary controls. Muscle biopsies were obtained pre and post training, and midway at 8 wk. Biopsies were analyzed by immunofluorescence for the prevalence of myofibers expressing embryonic myosin [embryonic myosin heavy chain (MyHCe)], neonatal myosin [neonatal myosin heavy chain (MyHCn)], nestin, and neural cell adhesion molecule (NCAM), and by RT-qPCR for gene expression levels of acetylcholine receptor (AChR) subunits, MyHCn, MyHCe, p16, and Ki67. In addition to increases in strength and type II fiber hypertrophy, heavy resistance exercise training led to a decrease in AChR α1 and ε subunit messenger RNA (mRNA; at 8 wk). Changes in gene expression levels of the α1 and ε AChR subunits with 8 wk of heavy resistance exercise supports the role of this type of exercise in targeting stability of the neuromuscular junction. The number of fibers positive for NCAM, nestin, and MyHCn was not affected, suggesting that a longer timeframe is needed for adaptations to manifest at the protein level.

Berberine Ameliorates Glucose Metabolism in Diabetic Rats through the alpha7 Nicotinic Acetylcholine Receptor-Related Cholinergic Anti-Inflammatory Pathway.

Berberine is an isoquinoline derivative alkaloid extracted from Chinese herbs. Recent studies have demonstrated the therapeutic effect of berberine on glucose metabolic disorders. However, its specific mechanism is still unclear. Our study aimed to research the glucose-lowering effect of berberine in diabetic rats and to reveal the possible role of the cholinergic anti-inflammatory pathway. Diabetic rats induced by administration of a high-calorie diet and streptozocin tail vein injection were assessed by the oral glucose tolerance test. Then, the diabetic rats were divided into two groups, those with or without the alpha7 nicotinic acetylcholine receptor gene downregulated, respectively, followed by treatment including berberine for 6 weeks. Results of this study show that the administration of berberine downregulated levels of fasting blood glucose and fasting insulin, and ameliorated insulin resistance in diabetic rats. Treatment with berberine inhibited acetylcholinesterase activity, and upregulated acetylcholine levels in the serum and alpha7 nicotinic acetylcholine receptor gene expression in the liver tissue. Meanwhile, berberine reversed elevated expression of cytokines interleukin-1β and TNF-α in the serum and downregulated nuclear factor κB expression. However, berberine administration showed no glucose-lowering or anti-inflammatory effect in diabetic rats in which alpha7 nicotinic acetylcholine receptor gene expression was downregulated, and acetylcholinesterase activity was also significantly inhibited. In conclusion, berberine may ameliorate glucose metabolism by activating the alpha7 nicotinic acetylcholine receptor-mediated cholinergic anti-inflammatory pathway.

The Effect of Swimming Endurance Exercise on Cell Death and Nicotinic Acetylcholine Receptor Gene Expression in Brain of Rat: An Experimental Study of Alzheimer's Disease Model

The Effect of Swimming Endurance Exercise on Cell Death and Nicotinic Acetylcholine Receptor Gene Expression in Brain of Rat: An Experimental Study of Alzheimer's Disease Model

Effects of Photobiomodulation with Low-level Laser Therapy on Muscle Repair Following a Peripheral Nerve Injury in Wistar Rats.

Peripheral nerve injury (PNI) can lead to sensory and/or motor impairment. As a treatment photobiomodulation (PBM) has demonstrated positive effects in terms of the maintenance of muscle activation and trophism. Wistar rats were divided into five groups: control, injury, injury+PBMn (irradiation over injured nerve), injury+PBMm (irradiation over affected muscle) and injury+PBMnm (irradiation over nerve and muscle). The left sciatic nerve was submitted to a crushing injury. Treatment was administered with low-level laser (780nm, 0.04cm2 , 1Wcm-2 , 3.2J) over the injured nerve and/or the tibialis anterior muscle. The effects of PBM were favorable on muscle morphology and gene expression of calcineurin, myogenin and acetylcholine receptors. PBM led to an acceleration on muscle repair process, and effects were more evident in 2weeks after PNI. Thus, PBM is indicated for the area over both the injured nerve and the affected muscle.

Effects of curcuminoids on cognitive deficits in young audiovisually overstimulated mice

Constant audiovisual exposure from digital media devices can cause overstimulation (OS) of the infant brain, which negatively impacts cognition. Curcuminoids (Cur, the principal component of turmeric) have shown neuroprotective qualities, however, their effects on overstimulated brain are unknown. This study aimed to determine the effects of audiovisual OS on cognitive functions in young mice, and to investigate if Cur offered neuroprotection. Ten day old mice were exposed to flashing lights and sound 8 h/day for 5 days/wk along with Cur (1 or 20 mg/kg in feed) for 42 days. Cognitive functions were measured using behaviour tests. Cholinergic function was determined using hippocampal and cortical acetylcholine levels and muscarinic acetylcholine receptors (M1, M3 and M5) gene expression. It was observed that OS did not affect spatial learning and memory, but reduced cued and contextual fear learning (p < 0.001) and impaired short-term memory retrieval (p < 0.05) as compared to control. The OS led to elevated anxiety (p < 0.05), but did not alter acetylcholine levels in the cortex and hippocampus. The OS significantly reduced gene expression in the cortex (M1: p < 0.05 and M3: p < 0.001) and hippocampus (M1: p < 0.001, M3: p < 0.05 and M5: p < 0.001), compared to control. The Cur treatment along with OS not only worsened spatial learning, exploratory activity and social behaviour, but also reduced acetylcholine levels in the cortex and hippocampus, as compared to control and OS groups. It was concluded that OS has a negative impact on behaviour and cholinergic function. Further studies on Cur usage in developing children's brain are needed for its cautious use.

Oral exposure to aluminum leads to reduced nicotinic acetylcholine receptor gene expression, severe neurodegeneration and impaired hippocampus dependent learning in mice

Aluminum (Al) is known for its neurotoxicity for over a century and is reported to have specifically high toxicity for cholinergic system. The effect of Al on muscarinic acetylcholine receptors is widely reported, but its effect on nicotinic acetylcholine receptors (nAChRs) is less well known. The aim of this study was to determine the effects of Al on hippocampus dependent learning and memory, function and expression of nAChRs in the hippocampus. Al concentration and neurodegeneration were also measured in the hippocampus following Al treatment. The mice were treated with 250 mg/kg AlCl3.6H2O in drinking water for a period of 42 days. Results show that Al treated animals have significantly reduced spatial reference memory as compared to control animals in Morris water maze test. Similarly, Al treated animals showed reduced contextual memory for Pavlovian fear compared to control animals. Al treated animals show higher anxiety in elevated plus maze as compared to control animals. The analysis of nAChR expression via RT-PCR showed reduced expression of α7, α4 and β2 nAChR gene expression in the hippocampus of Al treated animals. High Al accumulation was observed in Al-treated animals (688.14 ± 242.82 μg/g) compared to the control group (115.14 ± 18.18 μg/g) that resulted in severe neurodegeneration in the hippocampus. These results demonstrated that Al exposure caused neurotoxicity in mice hippocampus which is manifested by reduced memory and elevated anxiety. The results were further validated by high Al accumulation in the hippocampus, severe neurodegeneration and reduced expression of nAChRs.

Increased Active OMI/HTRA2 Serine Protease Displays a Positive Correlation with Cholinergic Alterations in the Alzheimer\u2019s Disease Brain

OMI/HTRA2 (high-temperature requirement serine protease A2) is a mitochondrial serine protease involved in several cellular processes, including autophagy, chaperone activity, and apoptosis. Few studies on the role of OMI/HTRA2 in Alzheimer’s disease (AD) are available, but none on its relationship with the cholinergic system and neurotrophic factors as well as other AD-related proteins. In this study, immunohistochemical analyses revealed that AD patients had a higher cytosolic distribution of OMI/HTRA2 protein compared to controls. Quantitative analyses on brain extracts indicated a significant increase in the active form of OMI/HTRA2 in the AD brain. Activated OMI/HTRA2 protein positively correlated with stress-associated read-through acetylcholinesterase activity. In addition, α7 nicotinic acetylcholine receptor gene expression, a receptor also known to be localized on the outer membrane of mitochondria, showed a strong correlation with OMI/HTRA2 gene expression in three different brain regions. Interestingly, the activated OMI/HTRA2 levels also correlated with the activity of the acetylcholine-biosynthesizing enzyme, choline acetyltransferase (ChAT); with levels of the neurotrophic factors, NGF and BDNF; with levels of the soluble fragments of amyloid precursor protein (APP); and with gene expression of the microtubule-associated protein tau in the examined brain regions. Overall, the results demonstrate increased levels of the mitochondrial serine protease OMI/HTRA2, and a coherent pattern of association between the activated form of OMI/HTRA2 and several key proteins involved in AD pathology. In this paper, we propose a new hypothetical model to highlight the importance and needs of further investigation on the role of OMI/HTRA2 in the mitochondrial function and AD.

Retinal changes in the Tg-SwDI mouse model of Alzheimer’s disease

Alzheimer’s disease (AD), a debilitating neurodegenerative illness, is characterized by neuronal cell loss, mental deficits, and abnormalities in several neurotransmitter and protein systems. AD is also associated with visual disturbances, but their causes remain unidentified. We hypothesize that the visual disturbances stem from retinal changes, particularly changes in the retinal cholinergic system, and that the etiology in the retina parallels the etiology in the rest of the brain. To test our hypothesis, quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC) were employed to assess changes in acetylcholine receptor (AChR) gene expression, number of retinal cells, and astrocytic gliosis in the Transgenic Swedish, Dutch and Iowa (Tg-SwDI) mouse model as compared to age-matched wild-type (WT). We observed that Tg-SwDI mice showed an initial upregulation of AChR gene expression early on (young adults and middle-aged adults), but a downregulation later on (old adults). Furthermore, transgenic animals displayed significant cell loss in the photoreceptor layer and inner retina of the young adult animals, as well as specific cholinergic cell loss, and increased astrocytic gliosis in the middle-aged adult and old adult groups. Our results suggest that the changes observed in AD cerebrum are also present in the retina and may be, at least in part, responsible for the visual deficits associated with the disease.

Cortex- and Amygdala-Dependent Learning and Nicotinic Acetylcholine Receptor Gene Expression is Severely Impaired in Mice Orally Treated with AlCl3.

Recent industrialization has increased human exposure to bio-available aluminum (Al). If more Al enters the brain than leaves, Al concentration will rise in the brain leading to neurodegenerative disorders. The aim of the present study was to determine Al concentration, neurodegeneration, and nicotinic acetylcholine receptor (nAChR) gene expression in the cortex and amygdala after oral ingestion of Al salt. The effect of Al on cortex- and amygdala-dependent learning and memory functions was also assessed. Mice were given AlCl3 (250mg/kg) in drinking water for 42days. nAChR gene expression was determined in the cortex and amygdala. The mice were subjected to behavior tests (fear conditioning, fear extinction, and open field), to assess memory deficits. The acquisition of fear memory in the fear conditioning test remained unaffected due to the Al administration. However, fear extinction (which is a new learning) was severely impaired. The behavioral analysis in the open field test showed greater anxiety and less adaptability to the new environment in Al-treated animals. High Al concentration and severe neurodegeneration in the cortex were observed following Al treatment while a slight, non-significant elevation in Al concentration was observed in the amygdala of Al-treated animals. The analysis of nAChR gene expression via RT-PCR showed a significant reduction in expression of α7, α4, and β2 nAChR genes in the cortex of Al-treated animals, while in the amygdala, the level of the α4 nAChR gene remained unaltered. Oral Al ingestion causes neuropathological changes and suppresses expression of nAChR genes that lead to deficits in learning and higher anxiety in Al-treated animals.

Sodium nitrate decreases agrin-induced acetylcholine receptor clustering.

BackgroundHumans are exposed to nitrate predominantly through diet with peak plasma concentrations within an hour after ingestion, but additional exposure is obtained from the environment, and minimally through de novo synthesis. Higher nitrate consumption has been associated with methemoglobinemia, spontaneous abortions, atherosclerosis, myocardial ischemia, septic and distressed lung, inflammatory bowel disease, amyotrophic lateral sclerosis, and neural tube defects. However, skeletal muscle development has not been examined.MethodsC2C12 skeletal muscle cell cultures were maintained, myoblasts were fused into myotubes, and then cultures were exposed to motor neuron derived agrin to enhance acetylcholine receptor (AChR) clustering. Untreated cultures were compared with cultures exposed to sodium nitrate at concentrations ranging from 10 ng/mL–100 μg/mL.ResultsThe results reported here demonstrate that 1 μg/mL sodium nitrate was sufficient to decrease the frequency of agrin-induced AChR clustering without affecting myotube formation. In addition, concentrations of sodium nitrate of 1 μg/mL or 100 μg/mL decreased gene expression of the myogenic transcription factor myogenin and AChR in correlation with the agrin-induced AChR clustering data.ConclusionsThese results reveal that sodium nitrate decreases the frequency of agrin-induced AChR clustering by a mechanism that includes myogenin and AChR gene expression. As a consequence sodium nitrate may pose a risk for skeletal muscle development and subsequent neuromuscular synapse formation in humans.

Sex-related differences in long-term pulmonary outcomes of neonatal hyperoxia in mice

ABSTRACTAim: Premature infants are often exposed to hyperoxia to maintain adequate oxygenation, which may lead to the development of bronchopulmonary dysplasia (BPD). Sex-specific differences exist in the development and severity of BPD. Only a few studies have examined the mechanisms underlying these sex-related differences. The aim of the present study is to examine the sex-related long-term effects of neonatal hyperoxia on the lungs of adult mice. Materials and Methods: Newborn mice were exposed to 95% oxygen (hyperoxia) for 96 hours and were allowed to recover in room air to adulthood (8 weeks of age). Lung tissues were excised at 4 days, 14 days, or 8 weeks of age. Short-term effects of neonatal hyperoxia on the mouse lung and sex-related differences in pulmonary function, airway hyper-responsiveness, and lung structure in adult mice were assessed. Results: Neonatal hyperoxia was found to have no differential effect on body weight, muscarinic acetylcholine receptor gene expression, or bronchiolar epithelial thickness in adult mice. Respiratory resistance was increased and sensitivity to methacholine was decreased in male adult mice following exposure to neonatal hyperoxia, whereas delayed alveolarization was observed in female adult mice following exposure to neonatal hyperoxia. Conclusions: The findings of the present study demonstrate that neonatal hyperoxia differentially affects pulmonary outcome in female and male adult mice.

Regulation of acetylcholine receptors during differentiation of bone mesenchymal stem cells harvested from human reaming debris

Acetylcholine (ACh) is an important signaling molecule in non-neuronal systems where it is involved in regulation of viability, proliferation, differentiation and migration of mesenchymal stem cells (MSC) that are capable to differentiate into osteoblasts, chondrocytes and adipocytes. Patients with the systemic disease osteoporosis show altered MSC properties, reduced bone formation and mineral density followed by increased bone fragility and high fracture incidence. Here we asked whether nicotinic and muscarinic acetylcholine receptors (AChR) are expressed in osteoblasts, adipocytes and chondrocytes differentiated from bone MSC extracted from human reaming debris (RDMSC) that was harvested during surgery of long bone diaphyseal fractures.Using RT-PCR, AChR were detected in RDMSC, osteoblasts, chondrocytes and adipocytes of male and female bone-healthy and of female osteoporotic donors. An up-regulation in multiplicity and occurrence of AChR subtypes was found in female compared to male donors and in osteoblast of male donors compared to adipocytes. Real-time RT-PCR analysis resulted in a significant increase in relative expression of nAChR α9 in chondrocytes compared to adipocytes of healthy female donors. The nAChR subunit α10 was significantly up-regulated in osteoblasts of healthy compared to osteoporotic donors as well as the mAChR M5 that is additionally decreased in osteoporotic osteoblasts compared to MSC and chondrocytes of osteoporotic donors.In summary, the gene expression of AChR during differentiation of RDMSC and its regulation in cells of osteoporotic donors lead to the assumption that AChR signaling is involved in bone formation and might be utilized to stimulate bone remodeling processes.

Effects of ovarian hormone treatment on the gene expression of muscarinic acetylcholine receptors in the ovariectomized rat myometrium

We investigate the effects of ovarian hormone on the gene expression of muscarinic acetylcholine receptors (M1–M5) in the myometrium using real-time PCR and evaluate the relationships between their expression and that of ovarian hormone receptors (ERα, ERβ, and PgR). Wistar rats were sham operated (SO) or ovariectomized (OVX) and treated with vehicle, estradiol (E2), progesterone (P4), or both E2 and P4 for 2 days beginning on postoperative day 33.M1 and M4 mRNA expressions were not detected in the myometrium. M2 mRNA expression did not change significantly in the OVX and OVX+P4 groups compared to the SO group, but increased significantly in the OVX+E2 group and was normalized in the OVX+E2P4 group. M3 mRNA expression increased significantly in the OVX and OVX+P4 groups compared to the SO group, but was normalized in the OVX+E2 and OVX+E2P4 groups. M5 mRNA expression did not change significantly in all experimental groups. ERα mRNA expression increased significantly in the OVX, OVX+E2, and OVX+P4 groups compared to the SO group, but was normalized in the OVX+E2P4 group. The changes in ERβ mRNA expression were similar to those of M3 mRNA expression in all experimental groups. In contrast, the changes in PgR mRNA expression did not correspond with that of M2, M3, or M5 mRNA expression in any of the experimental groups.Additionally, we evaluated the relationship between the expression of muscarinic acetylcholine receptors and ovarian hormone receptors in estrus cycle. M2 mRNA expression increased significantly in diestus and metaestrus compared in proestrus and estrus. M3 mRNA expression increased significantly in only diestrus compared in the other stages. In contrast, M5 mRNA expression did not change in estrus cycle. The changes in ERα mRNA expression appeared to be similar to those of M2 in estrus cycle, but no significant difference was found. The changes in ERβ mRNA expression were similar to those of M3 mRNA expression. The change in PgR mRNA expression increased significantly in diestrus compared in metaestrus, but did not correspond with that of M2, M3, or M5 mRNA expression in estrus cycle. When acetylcholine sensitivity in the myometrium was compared between diestrus and estrus, the sensitivity is significantly lower in estrus than in diestrus.These results suggest that ovarian hormones influence the expression of M2 and M3 in the myometrium by regulating the expression of hormone receptors. E2 may upregulate M2 via ERα, but P4 may downregulate M2 by inhibiting ERα via PgR. E2 may downregulate M3 by inhibiting ERβ, but P4 may not regulate the expression of M3 and ERβ. M5 may be a constitutive muscarinic receptor in the myometrium because neither E2 nor P4 influence the expression of M5. The combination of E2 and P4 may contribute the reproduction by quieting down the acetylcholine-induced myometrial contraction.

Influence of inhibited α7 nicotinic acetylcholine receptor gene expression on the production of β-amyloid peptide in SH-SY5Y cells

To investigate the influence of inhibited α7 neuronal nicotinic acetylcholine receptor (nAChR) by small interference RNA (siRNA) in SH-SY5Y cells and to explore the connection of these changes with the β-amyloid precursor protein (APP) metabolism and the pathogenesis of Alzheimer's disease (AD). The siRNA of α7 nAChR was transfected into SH-SY5Y cells, and the expression of α7 nAChR and two subtypes of β-secretases (BACE1 and BACE2) at mRNA and protein levels was studied by real-time PCR and Western blot, respectively. The variation of Aβ(1-42) content was detected by ELISA. As compared with controls, the expression of α7 nAChR at mRNA and protein levels in the SH-SY5Y cells transfected with the α7 nAChR siRNA were decreased by 84% and 79% (P < 0.01), respectively. The expressions of BACE1 mRNA and protein levels was increased by 527% and 71% (P < 0.01), respectively, while the expression of BACE2 decreased by 58% and 75% (P < 0.01), respectively. The Aβ(1-42) content increased by 208% (P < 0.01). An inhibited α7 nAChR mRNA induced by siRNA may markedly stimulate the production of Aβ through the mechanism of increased expression of BACE1 and inhibited expression of BACE2, which may be related to the pathogenesis of AD.

Effects of sevoflurane exposure on muscarinic acetylcholine receptor gene expression, protein amount and cellular localization

Wiklund, A.; Gustavsson, D.; Ebberyd, A.; Jonsson Fagerlund, M.; Eriksson, L. I.; Schulte, G. Author Information

Behavioral decay in aging male C. elegans correlates with increased cell excitability

Deteriorative changes in behavioral functions are natural processes that accompany aging. In advanced aged C. elegans nematodes, gross decline in general behaviors, such as locomotion and feeding, is correlated with degeneration of muscle structure and contractile function. In this study, we characterized the age-related changes in C. elegans male mating behavior to determine possible causes that ultimately lead to age-related muscle frailty. Unlike the kinetics of general behavioral decline, we found that mating behavior deteriorates early in adulthood, with no obvious muscle fiber disorganization or sperm dysfunction. Through direct mating behavior observations, Ca2+ imaging, and pharmacological tests, we found that the muscular components used for mating become more excitable as the males age. Interestingly, manipulating either the expression of acetylcholine receptor (AChR) genes or dietary-mediated ether-a-go-go family K+ channel function can reduce the muscle excitability of older males and concurrently improve mating behavior, suggesting a correlation between these biological processes.

Myotubular myopathy and the neuromuscular junction: a novel therapeutic approach from mouse models

SUMMARYMyotubular myopathy (MTM) is a severe congenital muscle disease characterized by profound weakness, early respiratory failure and premature lethality. MTM is defined by muscle biopsy findings that include centralized nuclei and disorganization of perinuclear organelles. No treatments currently exist for MTM. We hypothesized that aberrant neuromuscular junction (NMJ) transmission is an important and potentially treatable aspect of the disease pathogenesis. We tested this hypothesis in two murine models of MTM. In both models we uncovered evidence of a disorder of NMJ transmission: fatigable weakness, improved strength with neostigmine, and electrodecrement with repetitive nerve stimulation. Histopathological analysis revealed abnormalities in the organization, appearance and size of individual NMJs, abnormalities that correlated with changes in acetylcholine receptor gene expression and subcellular localization. We additionally determined the ability of pyridostigmine, an acetylcholinesterase inhibitor, to ameliorate aspects of the behavioral phenotype related to NMJ dysfunction. Pyridostigmine treatment resulted in significant improvement in fatigable weakness and treadmill endurance. In all, these results describe a newly identified pathological abnormality in MTM, and uncover a potential disease-modifying therapy for this devastating disorder.

Morphological aspects of neuromuscular junctions and gene expression of nicotinic acetylcholine receptors (nAChRs) in skeletal muscle of rats with heart failure

HF is syndrome initiated by a reduction in cardiac function and it is characterized by the activation of compensatory mechanisms. Muscular fatigue and dyspnoea are the more common symptoms in HF; these may be due in part to specific skeletal muscle myopathy characterized by reduced oxidative capacity, a shift from slow fatigue resistant type I to fast less fatigue resistant type II fibers and downregulation of myogenic regulatory factors (MRFs) gene expression that can regulate gene expression of nicotinic acetylcholine receptors (nAChRs). In chronic heart failure, skeletal muscle phenotypic changes could influence the maintenance of the neuromuscular junction morphology and nAChRs gene expression during this syndrome. Two groups of rats were studied: control (CT) and Heart Failure (HF), induced by a single intraperitoneal injection of monocrotaline (MCT). At the end of the experiment, HF was evaluated by clinical signs and animals were sacrificed. Soleus (SOL) muscles were removed and processed for morphological, morphometric and molecular NMJ analyses. Our major finding was an up-regulation in the gene expression of the alpha1 and epsilon subunits of nAChR and a spot pattern of nAChR in SOL skeletal muscle in this acute monocrotaline induced HF. Our results suggest a remodeling of nAChR alpha1 and epsilon subunit during heart failure and may provide valuable information for understanding the skeletal muscle myopathy that occurs during this syndrome.

Role of ghrelin in food reward: impact of ghrelin on sucrose self‐administration and mesolimbic dopamine and acetylcholine receptor gene expression

The decision to eat is strongly influenced by non-homeostatic factors such as food palatability. Indeed, the rewarding and motivational value of food can override homeostatic signals, leading to increased consumption and hence, obesity. Ghrelin, a gut-derived orexigenic hormone, has a prominent role in homeostatic feeding. Recently, however, it has emerged as a potent modulator of the mesolimbic dopaminergic reward pathway, suggesting a role for ghrelin in food reward. Here, we sought to determine whether ghrelin and its receptors are important for reinforcing motivation for natural sugar reward by examining the role of ghrelin receptor (GHS-R1A) stimulation and blockade for sucrose progressive ratio operant conditioning, a procedure used to measure motivational drive to obtain a reward. Peripherally and centrally administered ghrelin significantly increased operant responding and therefore, incentive motivation for sucrose. Utilizing the GHS-R1A antagonist JMV2959, we demonstrated that blockade of GHS-R1A signaling significantly decreased operant responding for sucrose. We further investigated ghrelin's effects on key mesolimbic reward nodes, the ventral tegmental area (VTA) and nucleus accumbens (NAcc), by evaluating the effects of chronic central ghrelin treatment on the expression of genes encoding major reward neurotransmitter receptors, namely dopamine and acetylcholine. Ghrelin treatment was associated with an increased dopamine receptor D5 and acetylcholine receptor nAChRβ2 gene expression in the VTA and decreased expression of D1, D3, D5 and nAChRα3 in the NAcc. Our data indicate that ghrelin plays an important role in motivation and reinforcement for sucrose and impacts on the expression of dopamine and acetylcholine encoding genes in the mesolimbic reward circuitry. These findings suggest that ghrelin antagonists have therapeutic potential for the treatment of obesity and to suppress the overconsumption of sweet food.