41 research outputs found
The small GTPase RhoA regulates the expression and function of the sodium channel Nav1.5 in breast cancer cells.
Voltage-gated Na+ channels (VGSCs) are highly expressed in several types of carcinomas including breast, prostate and lung cancers as well as in mesothelioma and cervical cancers. Although the VGSCs activity is considered crucial for the potentiation of cancer cell migration and invasion, the mechanisms responsible for their functional expression and regulation in cancer cells remain unclear. In the present study, the role of the small GTPase RhoA in the regulation of expression and function of the Nav1.5 channel in the breast cancer cell lines MDA-MB 231 and MCF-7 was investigated. RhoA silencing significantly reduced both Nav1.5 channel expression and sodium current indicating that RhoA exerts a stimulatory effect on the synthesis of an active form of Nav1.5 channel in cancer cells. The inhibition of Nav1.5 expression dramatically reduced both cell invasion and proliferation. In addition, a decrease of RhoA protein levels induced by Nav1.5 silencing was observed. Altogether, these findings revealed: i) the key role of the small GTPase RhoA in upregulation of Nav1.5 channel expression and tumor aggressiveness, and ii) the existence of a positive feedback of Nav1.5 channels on RhoA protein levels.journal articleresearch support, non-u.s. gov't2014 Feb2013 12 10importe
Dose-effect study of Gelsemium sempervirens in high dilutions on anxiety-related responses in mice
Introduction
This study was designed to investigate the putative anxiolytic-like activity of ultra-low doses of Gelsemium sempervirens (G. sempervirens), produced according to the homeopathic pharmacopeia.
Methods
Five different centesimal (C) dilutions of G. sempervirens (4C, 5C, 7C, 9C and 30C), the drug buspirone (5 mg/kg) and solvent vehicle were delivered intraperitoneally to groups of ICR-CD1 mice over a period of 9 days. The behavioral effects were assessed in the open-field (OF) and light\u2013dark (LD) tests in blind and randomized fashion.
Results
Most G. sempervirens dilutions did not affect the total distance traveled in the OF (only the 5C had an almost significant stimulatory effect on this parameter), indicating that the medicine caused no sedation effects or unspecific changes in locomotor activity. In the same test, buspirone induced a slight but statistically significant decrease in locomotion. G. sempervirens showed little stimulatory activity on the time spent and distance traveled in the central zone of the OF, but this effect was not statistically significant. In the LD test, G. sempervirens increased the % time spent in the light compartment, an indicator of anxiolytic-like activity, with a statistically significant effect using the 5C, 9C and 30C dilutions. These effects were comparable to those of buspirone. The number of transitions between the compartments of the LD test markedly increased with G. sempervirens 5C, 9C and 30C dilutions.
Conclusion
The overall pattern of results provides evidence that G. sempervirens acts on the emotional reactivity of mice, and that its anxiolytic-like effects are apparent, with a non-linear relationship, even at high dilutions
Effect of streptozotocin-induced diabetes on the gene expression and biological activity of 3 beta-hydroxysteroid dehydrogenase in the rat spinal cord
Abnormal secretion of steroids by the adrenals
and gonads is one of the disturbances occurring in diabetics
but the impact of diabetes on steroid formation in the nervous
system has never been studied. However, it is well
known that numerous actions of peripheral steroids on the
nervous system require their conversion into neuroactive
metabolites within the neural tissue. As this in situ steroid
synthesis/metabolism is crucial for the control of several
neurobiological functions, we investigated the effects of
streptozotocin-induced diabetes on the gene expression and
activity of 3 -hydroxysteroid dehydrogenase in the spinal
cord, a pivotal structure involved in sensorimotor and neurovegetative
mechanisms. 3 -Hydroxysteroid dehydrogenase
is a key enzyme which participates to the biosynthesis
of all classes of steroids by converting 5-3 -hydroxysteroids
such as pregnenolone and dehydroepiandrosterone
into 4-3-ketosteroids as progesterone and androstenedione,
respectively. Reverse transcription coupled with quantitative
real-time polymerase chain reaction revealed that 3 -hydroxysteroid
dehydrogenase gene was over-expressed in the spinal
cord of streptozotocin-treated rats compared with controls.
Pulse-chase experiments combined with high performance
liquid chromatography and continuous flow detection
of newly-synthesized steroids showed an increase of 3 -
hydroxysteroid dehydrogenase activity responsible for a hyper-
production of progesterone in the spinal cord of diabetic
rats. This up-regulation of progesterone biosynthesis was
concomitant with a decrease of its transformation into tetrahydroprogesterone,
a process which facilitated progesterone
accumulation in the spinal cord of streptozotocin-treated
rats. Since progesterone is a potent neuroprotective steroid,
increase of its production appeared as an endogenous molecular
and biochemical mechanism triggered by spinal nerve
cells to cope with degenerative effects of streptozotocininduced
diabetes. Our results constitute the first direct evidence
showing an impact of diabetes on steroid biosynthetic
and metabolic pathways in the nervous system. The data
open new perspectives for the modulation of deleterious
effects of diabetes by neuroprotective steroids
Selective regulation of neurosteroid biosynthesis in human neuroblastoma cells under hydrogen peroxide-induced oxidative stress condition
Neurosteroid biosynthesis is demonstrated in many species but key factors interacting with neurosteroidogenesis under pathophysiological conditions are unknown. Hydrogen peroxide (H(2)O(2))-induced oxidative stress is an etiological factor involved in several disorders. We hypothesized that, if neurosteroidogenesis is a pivotal mechanism for nerve cell protection or viability, it might be selectively regulated under oxidative stress condition. To check our hypothesis, we investigated H(2)O(2) effects on neurosteroidogenesis in human neuroblastoma SH-SY5Y cells. Pulse-chase, high performance liquid chromatography and flow-scintillation analyses showed that, along neurosteroidogenic pathways converting pregnenolone into various neurosteroids, only estradiol synthesis selectively decreased in SH-SY5Y cells after H(2)O(2)-treatment. Testosterone conversion into estradiol was also inhibited by H(2)O(2). Real-time reverse transcription-polymerase chain reaction revealed aromatase gene repression in SH-SY5Y cells 12 h after the oxidative stress onset. Consistently, viability assays showed that chronic inhibition of aromatase activity by letrozole killed neuroblastoma cells. A 12-h pretreatment of SH-SY5Y cells with estradiol was protective against H(2)O(2)-induced death. In addition, estradiol was also capable of rescuing markedly neuroblastoma cells from letrozole-evoked death. Altogether, these results suggest that endogenous estradiol formation is pivotal for SH-SY5Y cell viability. Serum deprivation-evoked stress, which also killed SH-SY5Y cells, unaffected neurosteroidogenesis, indicating that inhibitory effect on neuroprotective-neurosteroid estradiol biosynthesis is specific for H(2)O(2)-induced stress. Selective targeting of neurosteroidogenic pathways may therefore constitute an interesting strategy against H(2)O(2)-evoked neurodegenerative processes
Assessment of neuroactive steroid formation in diabetic rat spinal cord using high-performance liquid chromatography and continuous flow scintillation detection
The combination of pulse-chase experiments with high-performance liquid chromatography and continuous flow scintillation detection was
used successfully to determine the effects of chronic diabetes on neurosteroid production in the adult rat spinal cord. The long-term diabetes was
induced by treatment of adult rats with streptozotocin. In the first part, the review provides an extensive description of the HPLC combined with
continuous flow scintillation detection method, its advantages and appropriateness for the question investigated. Afterwards, the paper shows that
progesterone formation is up-regulated in the spinal cord of diabetic rats while the biosynthesis of tetrahydroprogesterone decreased. The downregulation
of tetrahydroprogesterone appeared as a mechanism facilitating progesterone accumulation in the spinal cord of streptozotocin-treated
rats. Progesterone is well known to be a potent neuroprotective steroid. Enhancement of its biosynthesis may be an endogenous mechanism
triggered by neural cells in the spinal tissue to cope with degenerative effects provoked by chronic diabetes. Since steroid metabolism in the spinal
cord is pivotal for the modulation of several neurobiological processes including sensorimotor activities, the data analyzed herein may constitute
useful information for the development of efficient strategies against deleterious effects of diabetes on the nervous system
Evidence for effective structure-based neuromodulatory effects of new analogues of neurosteroid allopregnanolone
The neurosteroid allopregnanolone (AP) modulates neuroendocrine/neurobiological processes, including hypothalamic-Âpituitary-Âadrenocortical activities, pain, anxiety, neurogenesis and neuroprotection. These observations raised the hope of developing AP-Âbased therapies against neuroendocrine and/or neurodegenerative disorders. However, the pleiotropic actions of AP, particularly its cell-Âproliferation-Âpromoting effects, hamper the development of selective/targeted therapies. For example, although AP-Âinduced neurogenesis may serve to compensate neuronal loss in degenerative brains, AP-Âevoked cell-Âproliferation is contraindicated for steroid-Âsensitive cancer patients. To foster progress, we synthesised 4 novel AP analogues of neurosteroids (ANS) designated BR053 (12-o xo-e pi-ÂAP), BR297 (O-Âallyl-Âepi-ÂAP), BR351 (O-Âallyl-ÂAP) and BR338 (12-Âoxo-ÂAP). First, because AP is well-Âknown as allosteric modulator of GABAA receptors (GABAA-ÂR), we used the electrophysiological patch-Âclamp technique to determine the structure-Âactivity relationship of our ANS on GABAA-Âactivated current in NCB20 cells expressing functional GABAA-ÂR. We found that the addition of 12-o xo-g roup did not significantly change the respective positive or negative allosteric effects of 3α-ÂAP or 3β-(Âepi)-ÂAP analogues. Importantly, substitution of the 3α-h ydroxyl- group by 3α-O -Âallyl highly modified the ANS activities. Unlike AP, BR351 induced a long-lÂasting desensitisation/inhibition of GABAA-ÂR. Interestingly, replacement of the 3β-Âhydroxyl by 3β-O -Âallyl (BR297) completely reversed the activity from negative to positive allosteric action. In a second step, we compared the actions of AP and ANS on SH-ÂSY5Y neuronal cell viability/proliferation using MTT-Âreduction assays. Different dose-r esponse curves were demonstrated for AP and the ANS. By contrast to AP, BR297 was totally devoid of cell-Âproliferative effect. Finally, we compared AP and ANS abilities to protect against oxidative stress-Âinduced neuronal death pivotally involved in neurodegenerative diseases. Both BR351 and BR297 had notable advantages over AP in protecting SH-ÂSY5Y cells against oxidative stress-Âinduced death. Thus, BR297 appears to be a potent neuroprotective compound devoid of cell-Âproliferative activity. Altogether, our results suggest promising perspectives for the development of neurosteroid-Âbased selective and effective strategies against neuroendocrine and/or neurodegenerative disorders
Translocator Protein Ligand PIGA1138 Reduces Disease Symptoms and Severity in Experimental Autoimmune Encephalomyelitis Model of Primary Progressive Multiple Sclerosis
Multiple sclerosis (MS) is an autoimmune and demyelinating disease of the central nervous system (CNS) caused by CNS infiltration of peripheral immune cells, immune-mediated attack of the myelin sheath, neuroinflammation, and/or axonal/neuronal dysfunctions. Some drugs are available to cope with relapsing–remitting MS (RRMS) but there is no therapy for the primary progressive MS (PPMS). Because growing evidence supports a regulatory role of the translocator protein (TSPO) in neuroinflammatory, demyelinating, and neurodegenerative processes, we investigated the therapeutic potential of phenylindolyilglyoxylamydes (PIGAs) TSPO ligands in myelin oligodendrocyte glycoprotein (MOG)–induced experimental autoimmune encephalomyelitis (EAE) mice mimicking the human PPMS. MOG-EAE C57Bl/6-mice were treated by TSPO ligands PIGA839, PIGA1138, or the vehicle. Several methods were combined to evaluate PIGAs-TSPO ligand effects on MOG-EAE symptoms, CNS infiltration by immune cells, demyelination, and axonal damages. PIGA1138 (15 mg/kg) drastically reduced MOG-EAE mice clinical scores, ameliorated motor dysfunctions assessed with the Catwalk device, and counteracted MOG-EAE-induced demyelination by preserving Myelin basic protein (MBP) expression in the CNS. Furthermore, PIGA1138-treatment prevented EAE-evoked decreased neurofilament-200 expression in spinal and cerebellar axons. Moreover, PIGA1138 inhibited peripheral immune-CD45 + cell infiltration in the CNS, suggesting that it may control inflammatory mechanisms involved in PPMS. Concordantly, PIGA1138 enhanced anti-inflammatory interleukin-10 serum level in MOG-EAE mice. PIGA1138-treatment, which increased neurosteroid allopregnanolone production, ameliorated all pathological biomarkers, while PIGA839, unable to activate neurosteroidogenesis in vivo, exerted only moderate/partial effects in MOG-EAE mice. Altogether, our results suggest that PIGA1138-based treatment may represent an interesting possibility to be explored for the innovation of effective therapies against PPMS