Number Of Bromodeoxyuridine-positive Cells Research Articles

Study on Effect of Simvastatin on Regeneration of Hippocampal Dentate Gyrus Nerve after Cerebral Ischemia in Rats

This study is to explore the effect of simvastatin on regeneration of hippocampal dentate gyrus nerve after cerebral ischemia in rats. Morris water maze test is an important experimental method which has been established to judge the learning and memory of animals in the last twenty years. Except for the sham operation group, animals in the other two groups show neurologic impairment of varying degrees after waking, characterized by turning to the affected side, toppling, being unable to stand, and being unable to walk. The number of bromodeoxyuridine positive cells in simvastatin group is significantly larger than that in middle cerebral artery occlusion group, indicating that statins may play a role in promoting nerve regeneration, alleviating brain tissue damage and improving prognosis after cerebral ischemia. We haven’t made the mechanism of simvastatin for promoting nerve regeneration clear-cut, and some scholars believe that simvastatin may regulate neural cell apoptosis by influencing cell signaling pathway.

C1q/TNF-related protein 1 prevents neointimal formation after arterial injury

Background and aimsObesity contributes to the progression of vascular disorders. C1q/TNF-related protein (CTRP) 1 is a circulating adipokine, which is upregulated in obese complications including coronary artery disease. Here, we investigated the role of CTRP1 in regulation of vascular remodeling after mechanical injury and evaluated its potential mechanism. MethodsMice were subjected to wire-induced injury of left femoral arteries. An adenoviral vector encoding CTRP1 (Ad-CTRP1) or β-galactosidase as a control was injected into the jugular vein of mice 3 days prior to surgery. ResultsSystemic administration of Ad-CTRP1 to wild-type mice led to reduction of the neointimal thickening after wire-induced arterial injury and the number of bromodeoxyuridine-positive cells in injured vessels as compared with treatment with control vectors. Treatment of vascular smooth muscle cells (VSMCs) with CTRP1 protein attenuated proliferative activity and ERK phosphorylation in response to PDGF-BB. CTRP1 treatment increased cyclic AMP (cAMP) levels in VSMCs, and inhibition of adenylyl cyclase reversed the inhibitory effect of CTRP1 on VSMC growth and ERK phosphorylation. Antagonization of sphingosine-1-phosphaterote (S1P) receptor 2 blocked the effects of CTRP1 on cAMP production and VSMC growth. Furthermore, CTRP1-knockout mice had enhanced neointimal thickening following injury and increased numbers of proliferating cells in neointima compared to control WT mice. ConclusionsThese findings indicate that CTRP1 functions to prevent the development of pathological vascular remodeling by reducing VSMC growth through the cAMP-dependent pathway.

Pentylenetetrazol-induced seizures are exacerbated by sleep deprivation through orexin receptor-mediated hippocampal cell proliferation

Sleep deprivation has been shown to be an activator of seizures in clinical and animal studies. Orexin-A was speculated to be involved in the aggravation of seizures by sleep deprivation through the activation of its receptors: orexin-1 and orexin-2 receptor (OX1R and OX2R, respectively). Therefore, we aimed to investigate the effects of pre-treating sleep-deprived Wistar rats with the OX1R or OX2R antagonists, SB334867 (30 nM/kg) or TCS OX2 29 (30 nM/kg), respectively, followed by a convulsive dose of 50 mg/kg pentylenetetrazol administration (seizure induction), on seizure behavior, and hippocampal neurodegeneration and cellular proliferation. Our results revealed that treatment with SB334867 or TCS OX2 29 significantly prolonged the latency and reduced the duration of seizures, while also lowering the mortality rate in sleep-deprived rats exposed to pentylenetetrazol. In addition, SB334867 or TCS OX2 29 reduced the damage to hippocampal CA3 neurons and the number of bromodeoxyuridine-positive cells in the dentate gyrus (particularly in the hilus). Overall, the effect of TCS OX2 29 was greater than that of SB334867. Taken together, these data suggest that OX1R and OX2R antagonists may alleviate the damage of pentylenetetrazol-induced seizures that are exacerbated by sleep deprivation, and furthermore could be associated with a reduction of neuronal damage in the hippocampus and the inhibition of cellular proliferation in the dentate gyrus.

ROCK inhibitor Y‐27632 maintains the proliferation of confluent human mesenchymal stem cells

The transplantation of cell sheets of mesenchymal stem cells (MSCs) is expected to be the next generation of periodontal regenerative therapy. An adequate method of multilayering MSCs has yet to be established. When cell sheets proliferate, they usually contract and detach from culture dishes and then the proliferation of cells in the contracted areas is arrested. ROCK-mediated contractile force causes cell contraction. Although multilayer formation medium (MFM) stimulated the proliferation of growth-arrested confluent MSCs, MSCs detached from the culture dish. Therefore, we investigated the effects of ROCK inhibitor Y-27632 on the proliferation and detachment of confluent MSCs, and examined the ability of cells to differentiate within the cell sheets. Confluent MSCs were cultured in MFM containing transforming growth factor-β1, ascorbic acid and fetal bovine serum either with or without Y-27632. Cell proliferation was examined by bromodeoxyuridine incorporation assays and total DNA measurement. Sheet contractions were examined by light microscopy and stereomicroscopy. Multilayer formations and focal adhesion assembly were observed with confocal microscopy. Characteristic of cells were examined by flow cytometric analysis. Osteoblast lineage differentiation was observed with alkaline phosphatase and alizarin red S staining. Adipocyte lineage differentiation was observed with oil red O staining. The addition of Y-27632 to MFM prevented the cell sheets from detaching and did not inhibit MSC growth. The cell numbers cultured with MFM/Y-27632 were significantly higher than that obtained with MFM-only on day 4. Cell sheets detached from the culture dish on day 4, and the number of bromodeoxyuridine-positive cells in the detached area decreased. Cells in the cell sheets had similar characteristics to primary MSCs, and differentiated into osteoblast and adipocyte lineages. Y-27632 both prevented the MSC sheets from detaching and maintained the multilayered proliferation of confluent MSCs by MFM, and then cells in the sheets had differentiation potency.

Protection by DHA of Early Hippocampal Changes in Diabetes: Possible Role of CREB and NF-κB

The mechanisms underlying diabetic encephalopathy, are only partially understood. In this study, we try to address the mechanisms of diabetes induced damage and whether docosahexaenoic acid (DHA) could attenuate the degenerative changes in diabetic hippocampus in a rodent model of diabetes. Diabetes was induced in rats by an intraperitoneal injection of streptozotocin. Animals were divided into the following experimental groups: control rats; control animals treated with DHA; untreated diabetic rats; diabetic rats treated with insulin; diabetic rats treated with DHA; diabetic rats treated with insulin and DHA. At the end of week 12, rats were killed and one of the hemispheres was cryosectioned and the other was dissected and hippocampi homogenized. The number of bromodeoxyuridine positive cells in the hippocampus of diabetic rats was decreased, and the latency time to find the platform in the Morris Water maze was significantly increased in the diabetic rats when compared to controls. No changes where observed in the expression of p21 in the hippocampus of control and diabetic rats. Biochemical markers of oxidative stress were altered in hippocampus of diabetic rats, and NFκB-positive cells were increased in the hippocampus of diabetic rats when compared to controls. Treatment with DHA, or the combination of DHA with insulin, significantly restored to control levels all the values mentioned above. Our findings confirm a pivotal role for oxidative stress as well as NF-κB, but not p21, in diabetes-induced hippocampal impairments. Administration of DHA as well as insulin prevented the changes induced by diabetes in hippocampus.

Minor neuronal damage and recovered cellular proliferation in the hippocampus after continuous unilateral forelimb restraint in normal rats

Constraint-induced movement therapy (CIMT) involves the restraint of an intact limb to force the dominant use of an affected limb, in an attempt to enhance use-dependent plasticity and reduce dysfunction. To investigate whether forced disuse of an intact forelimb with CIMT causes a loss of limb function and degenerative damage in the brain, a staircase test and a horizontal ladder test were carried out in control rats and forelimb-restrained rats, and then Argyrophil III silver staining, which is capable of detecting subtle neuronal damage, was used to examine histological alterations associated with restraint. No significant changes in forelimb function were observed in restrained rats. However, atypical weak argyrophilic neurons, an indicator of minor neural damage, were found in the bilateral hippocampus of restrained rats. This damage was not found in the cortex, striatum, or spinal cord. Investigation of neurogenesis in the subventricular zone (SVZ) and subgranular zone (SGZ) revealed a clear reduction in the number of bromodeoxyuridine-positive cells in bilateral SGZ, but not in the SVZ, in restrained rats compared with controls. This reduction was accompanied by reduced mRNA expression of vascular endothelial growth factor and glial-derived neurotrophic factor. However, reduced cellular proliferation and decreased gene expression were recovered after the removal of the restraint. Our results suggest that forced disuse of the intact forelimb has no significant effect on skilled forelimb function but has a minor effect on neurogenesis in SGZ, suggesting that mild stress may be caused by the restraint.

Exercise-induced expression of VEGF and salvation of myocardium in the early stage of myocardial infarction

The mechanism of exercise-induced benefit and angiogenesis in ischemic heart disease remains poorly defined. This study was designed to investigate the effects of exercise training on the expression of angiogenic factors and angiogenesis in the infarcted myocardium [myocarial infaction (MI)]. Sixty-three male FVB mice were used for study and were divided into subgroups to test the response to exercise: the time-dependent expression of angiogenic factors to exercise training in normal (group 1; n = 12) and infarcted myocardium (group 2; n = 15) and the exercise-induced angiogenic response in normal and infarcted myocardium (group 3; n = 20) as well as the impact of exercise preconditioning on infarcted myocardium (group 4; n = 26). Exercise training consisted of daily treadmill exercise for 1 h for 3 days. Expression of VEGF and its receptors Flt-1 and Flk-1 was upregulated by exercise training in mice with MI. Exercise-induced VEGF expression in the MI group was higher than that in the sham (control) group. Cell proliferation assessment showed a significantly higher (P < 0.05) number of bromodeoxyuridine-positive cells in post-MI mice in the exercise group as opposed to post-MI mice in the sedentary group. 2,3,5-Triphenyltetrazolium chloride staining revealed a profound difference in the size of MI (18.25 +/- 2.93%) in the exercise group versus the sedentary group (29.26 +/- 7.64%, P = 0.02). Moreover, exercise preconditioning before MI promoted VEGF expression at both mRNA and protein levels. In conclusion, activation of VEGF and its receptors occurs in the infarcted mice heart in response to exercise, which results in decreased infarct size and improved angiogenesis.

Differential regulation of neurogenesis in two neurogenic regions of APPswe/PS1dE9 transgenic mice

Neurogenesis occurs in two neurogenic regions of the adult mammalian brain: the subgranular zone and the subventricular zone. We have recently demonstrated that the number of bromodeoxyuridine-positive and doublecortin-positive cells is decreased in the subgranular zone of amyloid precursor protein with a Swedish mutation and presenilin-1 with a deletion of exon 9 transgenic mice, an animal model of Alzheimer's disease. In this study, we characterized neurogenesis in the subventricular zone of amyloid precursor protein with a Swedish mutation and presenilin-1 with a deletion of exon 9 transgenic mice at 9 months of age and compared it with neurogenesis in the subgranular zone. In the subventricular zone, the number of proliferating cell nuclear antigen-positive and bromodeoxyuridine-positive cells were normal. In the subgranular zone, the number of proliferating cell nuclear antigen-positive cells was normal; however, the number of bromodeoxyuridine-positive cells was significantly decreased. These results suggest that neurogenesis, probably reflecting the survival of neural progenitor cells, differs between the subgranular zone and the subventricular zone.

Peptide hormone exendin‐4 stimulates subventricular zone neurogenesis in the adult rodent brain and induces recovery in an animal model of parkinson's disease

We investigated the effects of exendin-4 on neural stem/progenitor cells in the subventricular zone of the adult rodent brain and its functional effects in an animal model of Parkinson's disease. Our results showed expression of GLP-1 receptor mRNA or protein in the subventricular zone and cultured neural stem/progenitor cells isolated from this region. In vitro, exendin-4 increased the number of neural stem/progenitor cells, and the number of cells expressing the neuronal markers microtubule-associated protein 2, beta-III-tubulin, and neuron-specific enolase. When exendin-4 was given intraperitoneally to naïve rodents together with bromodeoxyuridine, a marker for DNA synthesis, both the number of bromodeoxyuridine-positive cells and the number of neuronal precursor cells expressing doublecortin were increased. Exendin-4 was tested in the 6-hydroxydopamine model of Parkinson's disease to investigate its possible functional effects in an animal model with neuronal loss. After unilateral lesion and a 5-week stabilization period, the rats were treated for 3 weeks with exendin-4. We found a reduction of amphetamine-induced rotations in animals receiving exendin-4 that persisted for several weeks after drug administration had been terminated. Histological analysis showed that exendin-4 significantly increased the number of both tyrosine hydroxylase- and vesicular monoamine transporter 2-positive neurons in the substantia nigra. In conclusion, our results show that exendin-4 is able to promote adult neurogenesis in vitro and in vivo, normalize dopamine imbalance, and increase the number of cells positive for markers of dopaminergic neurons in the substantia nigra in a model of Parkinson's disease.

Dopamine D2 receptor stimulation promotes the proliferation of neural progenitor cells in adult mouse hippocampus

We initially examined the effects of apomorphine in vitro using mouse embryonic and adult neural progenitor cells. The effects of apomorphine treatment led to dose-dependent increases in the number of embryonic and adult neural progenitor cells, and dopamine D2 receptor antagonist treatment significantly reduced the increases induced by apomorphine. Next, we investigated the effects of apomorphine in vivo in the adult mouse hippocampus. The effects of single-dose apomorphine administration led to an increase of approximately 30% in the number of bromodeoxyuridine-positive cells in the dentate gyrus. Moreover, the chronic apomorphine administration induced an increase in the number of bromodeoxyuridine-positive cells by about 30%. Thus, we suggest that the stimulation of dopamine D2 receptors increases the proliferation of neural progenitor cells both in vivo and in vitro.

Transforming growth factor‐β and its effect on reepithelialization of partial‐thickness ear wounds in transgenic mice

Transforming growth factor-beta (TGF-beta) is known to affect nearly every aspect of wound repair. Many of the effects have been extensively investigated; however, the primary effect of endogenously derived TGF-beta on wound reepithelialization is still not completely understood. To examine this, two types of wounds were made on a transgenic mouse over-expressing TGF-beta1. Full-thickness back wounds were made to compare the wound healing process in the presence of compensatory healing mechanisms. Superficial partial-thickness ear wounds involving only the epidermis were made to determine the effect of TGF-beta on reepithelialization. In the partial-thickness ear wounds, at later time points, the transgenic group had smaller epithelial gaps than the wild-type mice. A greater number of actively proliferating cells, as determined by bromodeoxyuridine incorporation, was also found in the transgenic mice at post-injury day 8. These results show that TGF-beta1 stimulates the rate of reepithelialization at later time points in partial-thickness wounds. However, in the full-thickness back wounds, the transgenic animals exhibited a slower reepithelialization rate at all time points and the number of bromodeoxyuridine-positive cells was fewer. Our findings would suggest that the overexpression of TGF-beta1 speeds the rate of wound closure in partial-thickness wounds by promoting keratinocyte migration. In full-thickness wounds, however, the overexpression of TGF-beta1 slows the rate of wound reepithelialization.

Effects of long-term lithium infusion on normal parathyroid tissue

Approximately 10% of patients taking lithium for manic-depressive disorders become hypercalcemic. It remains unclear whether lithium initiates disease or promotes underlying hyperparathyroidism. We have previously demonstrated that at therapeutic concentrations lithium stimulates in vitro incorporation of both tritiated thymidine and bromodeoxyuridine into abnormal human parathyroid tissue, reflecting growth-promoting properties. Whether lithium has similar growth-promoting properties in normal parathyroid tissue remains unresolved. We infused lithium (0 mmol/L, 3 mmol/L, or 10 mmol/L) through implantable subcutaneous pumps into normal rats for 3 months and measured levels of serum lithium, serum calcium, and serum parathyroid hormone (PTH) (with a radioimmunoassay specific for rat PTH 1-34.) On completion of the infusion, bromodeoxyuridine (30 mg/kg) was administered intraperitoneally. The parathyroid glands were removed and measured in two dimensions to calculate gland volume [V = (pi/6) x (d1) x (d2)2.] Parathyroid incorporation of bromodeoxyuridine was assessed by using immunocytochemistry. Serum lithium level was significantly (p < 0.05) different between groups and constant within groups. Levels of serum calcium and PTH were inversely related to each other; however, no significant differences were noted between groups with respect to level of serum calcium or serum PTH at any measurement. Similarly, no significant differences were noted between groups with respect to gland size or number of bromodeoxyuridine-positive cells. Long-term lithium infusion in rats for a period representing approximately 15% of their life span failed to evoke changes in parathyroid gland size or function. These data are consistent with (1) lithium as a promoter of hyperparathyroidism and (2) resection of abnormal parathyroid tissue and resumption of lithium for patients requiring long-term therapy.