Brain-derived neurotrophic factor scales presynaptic calcium transients to modulate excitatory neurotransmission.

Brain-derived neurotrophic factor (BDNF) plays a critical role in synaptic physiology, as well as mechanisms underlying various neuropsychiatric diseases and their treatment. Despite its clear physiological role and disease relevance, BDNF's function at the presynaptic terminal, a fundamental unit of neurotransmission, remains poorly understood. In this study, we evaluated single synapse dynamics using optical imaging techniques in hippocampal cell cultures. We find that exogenous BDNF selectively increases evoked excitatory neurotransmission without affecting spontaneous neurotransmission. However, acutely blocking endogenous BDNF has no effect on evoked or spontaneous release, demonstrating that different approaches to studying BDNF may yield different results. When we suppressed BDNF-Tropomyosin receptor kinase B (TrkB) activity chronically over a period of days to weeks using a mouse line enabling conditional knockout of TrkB, we found that evoked glutamate release was significantly decreased while spontaneous release remained unchanged. Moreover, chronic blockade of BDNF-TrkB activity selectively downscales evoked calcium transients without affecting spontaneous calcium events. Via pharmacological blockade by voltage-gated calcium channel (VGCC) selective blockers, we found that the changes in evoked calcium transients are mediated by the P/Q subtype of VGCCs. These results suggest that BDNF-TrkB activity increases presynaptic VGCC activity to selectively increase evoked glutamate release.

Novel protocol for multiple-dose oral administration of the L-type Ca2+ channel blocker isradipine in mice: A dose-finding pharmacokinetic study.

Studies in genetically modified animals and human genetics have recently provided new insight into the role of voltage-gated L-type Ca2+ channels in human disease. Therefore, the inhibition of L-type Ca2+ channels in vivo in wildtype and mutant mice by potent dihydropyridine (DHP) Ca2+ channel blockers serves as an important pharmacological tool. These drugs have a short plasma half-life in humans and especially in rodents and show high first-pass metabolism upon oral application. In the vast majority of in vivo studies, they have therefore been delivered through parenteral routes, mostly subcutaneously or intraperitoneally. High peak plasma concentrations of DHPs cause side effects, evident as DHP-induced aversive behaviors confounding the interpretation of behavioral readouts. Nevertheless, pharmacokinetic data measuring the exposure achieved with these applications are sparse. Moreover, parenteral injections require animal handling and can be associated with pain, discomfort and stress which could influence a variety of physiological processes, behavioral and other functional readouts. Here, we describe a noninvasive oral application of the DHP isradipine by training mice to quickly consume small volumes of flavored yogurt that can serve as drug vehicle. This procedure does not require animal handling, allows repeated drug application over several days and reproducibly achieves peak plasma concentrations over a wide range previously shown to be well-tolerated in humans. This protocol should facilitate ongoing nonclinical studies in mice exploring new indications for DHP Ca2+ channel blockers.

T- and L-Type Calcium Channels Maintain Calcium Oscillations in the Murine Zona Glomerulosa.

BACKGROUND: The zona glomerulosa of the adrenal gland is responsible for the synthesis and release of the mineralocorticoid aldosterone. This steroid hormone regulates salt reabsorption in the kidney and blood pressure. The most important stimuli of aldosterone synthesis are the serum concentrations of angiotensin II and potassium. In response to these stimuli, voltage and intracellular calcium levels in the zona glomerulosa oscillate, providing the signal for aldosterone synthesis. It was proposed that the voltage-gated T-type calcium channel CaV3.2 is necessary for the generation of these oscillations. However, Cacna1h knock-out mice have normal plasma aldosterone levels, suggesting additional calcium entry pathways. METHODS: We used a combination of calcium imaging, patch clamp, and RNA sequencing to investigate calcium influx pathways in the murine zona glomerulosa. RESULTS: Cacna1h-/- glomerulosa cells still showed calcium oscillations with similar concentrations as wild-type mice. No calcium channels or transporters were upregulated to compensate for the loss of CaV3.2. The calcium oscillations observed were instead dependent on L-type voltage-gated calcium channels. Furthermore, we found that L-type channels can also partially compensate for an acute inhibition of CaV3.2 in wild-type mice. Only inhibition of both T- and L-type calcium channels abolished the increase of intracellular calcium caused by angiotensin II in wild-type. CONCLUSIONS: Our study demonstrates that T-type calcium channels are not strictly required to maintain glomerulosa calcium oscillations and aldosterone production. Pharmacological inhibition of T-type channels alone will likely not significantly impact aldosterone production in the long term.

Do calcium channel blockers applied to cardiomyocytes cause increased channel expression resulting in reduced efficacy?

In the initial hours following the application of the calcium channel blocker (CCB) nifedipine to microtissues consisting of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), we observe notable variations in the drug's efficacy. Here, we investigate the possibility that these temporal changes in CCB effects are associated with adaptations in the expression of calcium ion channels in cardiomyocyte membranes. To explore this, we employ a recently developed mathematical model that delineates the regulation of calcium ion channel expression by intracellular calcium concentrations. According to the model, a decline in intracellular calcium levels below a certain target level triggers an upregulation of calcium ion channels. Such an upregulation, if instigated by a CCB, would then counteract the drug's inhibitory effect on calcium currents. We assess this hypothesis using time-dependent measurements of hiPSC-CMs dynamics and by refining an existing mathematical model of myocyte action potentials incorporating the dynamic nature of the number of calcium ion channels. The revised model forecasts that the CCB-induced reduction in intracellular calcium concentrations leads to a subsequent increase in calcium ion channel expression, thereby attenuating the drug's overall efficacy. The data and fit models suggest that dynamic changes in cardiac cells in the presence of CCBs may be explainable by induced changes in protein expression, and that this may lead to challenges in understanding calcium based drug effects on the heart unless timings of applications are carefully considered.

Isradipine, an L-type calcium channel blocker, attenuates cocaine effects in mice by reducing central glutamate release.

Substance abuse disorder is a chronic condition for which pharmacological treatment options remain limited. L-type calcium channels (LTCC) have been implicated in drug-related plasticity and behavior. Specifically, dopaminergic neurons in the mesocorticolimbic pathway express Cav1.2 and Cav1.3 channels, which may regulate dopaminergic activity associated with reward behavior. Therefore, this study aimed to investigate the hypothesis that pre-administration of the LTCC blocker, isradipine can mitigate the effects of cocaine by modulating central glutamatergic transmission. For that, we administered isradipine at varying concentrations (1, 7.5, and 15 µg/µL) via intracerebroventricular injection in male Swiss mice. This pretreatment was carried out prior to subjecting animals to behavioral assessments to evaluate cocaine-induced locomotor sensitization and conditioned place preference (CPP). The results revealed that isradipine administered at a concentration of 1 µg/µL effectively attenuated both the sensitization and CPP induced by cocaine (15 mg/kg, via i. p.). Moreover, mice treated with 1 µg/µL of isradipine showed decreased presynaptic levels of glutamate and calcium in the cortex and hippocampus as compared to control mice following cocaine exposure. Notably, the gene expression of ionotropic glutamate receptors, AMPA, and NMDA, remained unchanged, as did the expression of Cav1.2 and Cav1.3 channels. Importantly, these findings suggest that LTCC blockage may inhibit behavioral responses to cocaine, most likely by decreasing glutamatergic input in areas related to addiction.

Discovery of α-Obscurine Derivatives as Novel Cav3.1 Calcium Channel Blockers.

Voltage-gated calcium channels (VGCCs), particularly T-type calcium channels (TTCCs), are crucial for various physiological processes and have been implicated in pain, epilepsy, and cancer. Despite the clinical trials of TTCC blockers like Z944 and MK8998, none are currently available on the market. This study investigates the efficacy of Lycopodium alkaloids, particularly as natural product-based TTCC blockers. We synthesized eighteen derivatives from α-obscurine, a lycodine-type alkaloid, and identified five derivatives with significant Cav3.1 blockade activity. The most potent derivative, compound 7, exhibited an IC50 value of 0.19±0.03 µM and was further analyzed through molecular docking, revealing key interactions with Cav3.1. These findings provide a foundation for the structural optimization of Cav3.1 calcium channel blockers and present compound 7 as a promising lead compound for drug development and a tool for chemical biology research.

Effects of lercanidipine on traumatic spinal cord injury: an experimental study.

BACKGROUND: Spinal cord injury is a devastating trauma that leaves survivors at risk for several medical complications throughout their lives. Lercanidipine, a third-generation calcium channel blocker, possesses anti-apoptotic, anti-inflammatory, and antioxidative properties. This study aimed to evaluate the neuroprotective effects of lercanidipine in an experimental spinal cord trauma model. METHODS: Twenty-one Wistar rats were randomly assigned to three groups. Group 1 (G1) underwent laminectomy. Group 2 (G2) were subjected to trauma following laminectomy. Group 3 (G3) were exposed to trauma following laminectomy and treated with lercanidipine. Lercanidipine was administered intraperitoneally for seven days. Histopathological and immunohistochemical evaluations were conducted. RESULTS: Regarding Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, there was no significant difference among the groups. However, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) levels were significantly different across the groups. G2 had significantly higher NF-κB levels compared to G1 and G3. CONCLUSION: Lercanidipine, a third-generation calcium channel blocker, is effective against inflammatory responses induced in spinal cord injury. Further studies are required to determine its capability in preventing apoptosis or improving functional recovery. To the best of our knowledge, this study is the first in the literature to examine the neuroprotective effects of lercanidipine on spinal cord injury.

A computational model predicts sex-specific responses to calcium channel blockers in mammalian mesenteric vascular smooth muscle.

The function of the smooth muscle cells lining the walls of mammalian systemic arteries and arterioles is to regulate the diameter of the vessels to control blood flow and blood pressure. Here, we describe an in silico model, which we call the 'Hernandez-Hernandez model', of electrical and Ca2+ signaling in arterial myocytes based on new experimental data indicating sex-specific differences in male and female arterial myocytes from murine resistance arteries. The model suggests the fundamental ionic mechanisms underlying membrane potential and intracellular Ca2+ signaling during the development of myogenic tone in arterial blood vessels. Although experimental data suggest that KV1.5 channel currents have similar amplitudes, kinetics, and voltage dependencies in male and female myocytes, simulations suggest that the KV1.5 current is the dominant current regulating membrane potential in male myocytes. In female cells, which have larger KV2.1 channel expression and longer time constants for activation than male myocytes, predictions from simulated female myocytes suggest that KV2.1 plays a primary role in the control of membrane potential. Over the physiological range of membrane potentials, the gating of a small number of voltage-gated K+ channels and L-type Ca2+ channels are predicted to drive sex-specific differences in intracellular Ca2+ and excitability. We also show that in an idealized computational model of a vessel, female arterial smooth muscle exhibits heightened sensitivity to commonly used Ca2+ channel blockers compared to male. In summary, we present a new model framework to investigate the potential sex-specific impact of antihypertensive drugs.

High blood pressure is a major risk factor for heart disease, which is one of the leading causes of death worldwide. While drugs are available to control blood pressure, male and female patients can respond differently to treatment. However, the biological mechanisms behind this sex difference are not fully understood. Blood pressure is controlled by cells lining the artery walls called smooth muscle cells which alter the width of blood vessels. On the surface of smooth muscle cells are potassium and calcium channels which control the cell's electrical activity. When calcium ions enter the cell via calcium channels, this generates an electrical signal that causes the smooth muscle to contract and narrow the blood vessel. Potassium ions then flood out of the cell via potassium channels to dampen the rise in electrical activity, causing the muscle to relax and widen the artery. There are various sub-types of potassium and calcium channels in smooth muscle cells. Here, Hernandez-Hernandez et al. set out to find how these channels differ between male and female mice, and whether these sex differences could alter the response to blood pressure medication. The team developed a computational model of a smooth muscle cell, incorporating data from laboratory experiments measuring differences in cells isolated from the arteries of male and female mice. The model predicted that the sub-types of potassium and calcium channels in smooth muscle cells varied between males and females, and how the channels impacted electrical activity also differed. For instance, the potassium channel Kv2.1 was found to have a greater role in controlling electrical activity in female mice, and this sex difference impacted blood vessel contraction. The model also predicted that female mice were more sensitive than males to calcium channel blockers, a drug commonly prescribed to treat high blood pressure. The findings by Hernandez-Hernandez et al. provide new insights into the biological mechanisms underlying sex differences in response to blood pressure medication. They also demonstrate how computational models can be used to predict the effects of drugs on different individuals. In the future, these predictions may help researchers to identify better, more personalized treatments for blood pressure.

Bloqueadores de los canales de calcio frente a otras clases de fármacos para la hipertensión: una revisión Cochrane / Calcium channel blockers versus other classes of drugs for hypertension: a Cochrane review

¿Cuál es el objetivo de esta revisión? En esta primera actualización de una revisión publicada en 2010. Se pretendía averiguar si los bloqueadores de los canales del calcio (BCC) pueden prevenir eventos cardiovasculares perjudiciales, como el ictus, el infarto de miocardio y la insuficiencia cardiaca, en comparación con otros antihipertensivos (hipotensores) utilizados en personas con presión arterial elevada (hipertensión). Fundamento. La disminución adecuada de la presión arterial elevada en personas con hipertensión puede reducir la cantidad de complicaciones importantes de la hipertensión, como el ictus, el infarto de miocardio, la insuficiencia cardiaca congestiva e incluso la muerte. Los BCC se utilizan como medicación de primera línea para reducir la presión arterial, pero se ha debatido si esta es la mejor forma de reducir los eventos cardiovasculares nocivos. Fecha de búsqueda. La evidencia está actualizada hasta el 1 de septiembre de 2020. Características del estudio. Se encontraron 23 estudios relevantes realizados en Europa, Norteamérica, Oceanía, Israel y Japón. Los estudios compararon el tratamiento con tratamiento con BCC frente al tratamiento con otras clases de fármacos hipotensores en personas con hipertensión e incluyeron 153.849 participantes. El seguimiento de los participantes en los ensayos osciló entre 2 y 5,3 años. Resultados clave. No hubo diferencias en las muertes por todas las causas entre los BCC y otros fármacos hipotensores. Los diuréticos probablemente reducen los eventos cardiovasculares totales y la insuficiencia cardiaca congestiva más que los BCC. Los BCC probablemente reducen los eventos cardiovasculares totales más que los bloqueadores beta... (AU)

Bloqueadores de los canales de calcio frente a otras clases de fármacos para la hipertensión: una revisión Cochrane / Calcium channel blockers versus other classes of drugs for hypertension: a Cochrane review

¿Cuál es el objetivo de esta revisión? En esta primera actualización de una revisión publicada en 2010. Se pretendía averiguar si los bloqueadores de los canales del calcio (BCC) pueden prevenir eventos cardiovasculares perjudiciales, como el ictus, el infarto de miocardio y la insuficiencia cardiaca, en comparación con otros antihipertensivos (hipotensores) utilizados en personas con presión arterial elevada (hipertensión). Fundamento. La disminución adecuada de la presión arterial elevada en personas con hipertensión puede reducir la cantidad de complicaciones importantes de la hipertensión, como el ictus, el infarto de miocardio, la insuficiencia cardiaca congestiva e incluso la muerte. Los BCC se utilizan como medicación de primera línea para reducir la presión arterial, pero se ha debatido si esta es la mejor forma de reducir los eventos cardiovasculares nocivos. Fecha de búsqueda. La evidencia está actualizada hasta el 1 de septiembre de 2020. Características del estudio. Se encontraron 23 estudios relevantes realizados en Europa, Norteamérica, Oceanía, Israel y Japón. Los estudios compararon el tratamiento con tratamiento con BCC frente al tratamiento con otras clases de fármacos hipotensores en personas con hipertensión e incluyeron 153.849 participantes. El seguimiento de los participantes en los ensayos osciló entre 2 y 5,3 años. Resultados clave. No hubo diferencias en las muertes por todas las causas entre los BCC y otros fármacos hipotensores. Los diuréticos probablemente reducen los eventos cardiovasculares totales y la insuficiencia cardiaca congestiva más que los BCC. Los BCC probablemente reducen los eventos cardiovasculares totales más que los bloqueadores beta... (AU)

Cav3.1 T-type calcium channel blocker NNC 55-0396 reduces atherosclerosis by increasing cholesterol efflux.

Calcium channel blockers (CCBs) are commonly used as antihypertensive agents. While certain L-type CCBs exhibit antiatherogenic effects, the impact of Cav3.1 T-type CCBs on antiatherogenesis and lipid metabolism remains unexplored. NNC 55-0396 (NNC) is a highly selective blocker of T-type calcium channels (Cav3.1 channels). We investigated the effects of NNC on relevant molecules and molecular mechanisms in human THP-1 macrophages. Cholesterol efflux, an indicator of reverse cholesterol transport (RCT) efficiency, was assessed using [3H]-labeled cholesterol. In vivo, high cholesterol diet (HCD)-fed LDL receptor knockout (Ldlr-/-) mice, an atherosclerosis-prone model, underwent histochemical staining to analyze plaque burden. Treatment of THP-1 macrophages with NNC facilitated cholesterol efflux and reduced intracellular cholesterol accumulation. Pharmacological and genetic interventions demonstrated that NNC treatment or Cav3.1 knockdown significantly enhanced the protein expression of scavenger receptor B1 (SR-B1), ATP-binding cassette transporter A1 (ABCA1), ATP-binding cassette transporter G1 (ABCG1), and liver X receptor alpha (LXRα) transcription factor. Mechanistic analysis revealed that NNC activates p38 and c-Jun N-terminal kinase (JNK) phosphorylation, leading to increased expression of ABCA1, ABCG1, and LXRα-without involving the microRNA pathway. LXRα isrequired for NNC-induced ABCA1 and ABCG1 expression. Administering NNC diminished atherosclerotic lesion area and lipid deposition in HCD-fed Ldlr-/- mice. NNC's anti-atherosclerotic effects, achieved through enhanced cholesterol efflux and inhibition of lipid accumulation, suggest a promising therapeutic approach for hypertensive patients with atherosclerosis. This research highlights the potential of Cav3.1 T-type CCBs in addressing cardiovascular complications associated with hypertension.

Effects of allisartan-isoproxil-based combination antihypertensive regimen in hypertensive patients with microalbuminuria or hyperuricemia.

Microalbuminuria and hyperuricemia management are crucial for the integrated management of hypertensive patients. This retrospective post hoc analysis aims to evaluate the optimal allisartan-isoproxil-based combination regimen for hypertensive patients with microalbuminuria or hyperuricemia. A total of 460 hypertensive patients with microalbuminuria and 486 hypertensive patients with hyperuricemia were included in this study. All patients were initially treated with allisartan-isoproxil for 4 weeks. Thereafter, patients with blood pressure (BP) < 140/90 mmHg continued the monotherapy for 8 weeks; patients with BP ≥140/90 mmHg were randomly assigned in a 1:1 ratio to receive allisartan-isoproxil + amlodipine (Group A + C) or allisartan-isoproxil + indapamide (Group A + D) for 8 weeks. The changes of BP, urinary albumin and serum uric acid (UA) were measured. In patients with microalbuminuria, the urinary albumin/creatinine ratio (UACR) significantly decreased by 10.4 mg/g in Group A + C (vs. baseline p = .0035) and 24.2 mg/g in Group A + D (vs baseline p < .0001), intergroup p = NS. In patients with hyperuricemia, serum UA level decreased by 44.5 µmol/L in Group A + C (vs. baseline p = .0003), but increased by 27.2 µmol/L in Group A + D (vs. baseline p = .0167), intergroup p < .0001. The results suggest that for hypertensive patients with microalbuminuria, angiotensin receptor blocker (ARB) + calcium channel blocker (CCB) or ARB+ diuretic both are good choices based on their improvement of microalbuminuria and BP. But for patients with hyperuricemia, ARB + diuretic may further increase the level of UA.

Effect of ABT-639 on Cav3.2 channel activity and its analgesic actions in mouse models of inflammatory and neuropathic pain.

Cav3.2 T-type calcium channels are important targets for pain relief in rodent models of inflammatory and neuropathic pain. Even though many T-type channel blockers have been tested in mice, only one molecule, ABT-639, has been tested in phase II clinical studies and did not produce analgesic effects over placebo. Here we examined the effects of ABT-639 on Cav3.2 channel activity in tsA-201 cells and dorsal root ganglion (DRG) neurons, in comparison with another established Cav3.2 inhibitor Z944. These experiments revealed that Z944 mediated ∼100-fold more potent inhibition of Cav3.2 currents than ABT-639, with the latter blocking channel activity by less than 15 percent when applied at a concentration of 30 µM. A slight increase in ABT-639 potency was observed at more depolarized holding potentials, suggesting that this compound may act preferentially on inactivated channels. We tested the effects of both compounds in the Complete Freund's Adjuvant (CFA) model of chronic inflammatory pain, and in partial sciatic nerve injury model of neuropathic pain in mice. In the neuropathic pain model, both Z944 and ABT-639 reversed mechanical hypersensitivity to similar degrees when delivered systemically, but remarkably, when delivered intrathecally, only Z944 was effective. In the CFA model, both compounds reversed thermal hyperalgesia upon systemic delivery, but only Z944 mediated pain relief upon intrathecal delivery, indicating that ABT-639 acts primarily at peripheral sites. ABT-639 lost its analgesic effects in CFA treated Cav3.2 null mice, indicating that these channels are essential for ABT-639-mediated pain relief despite its poor inhibition of Cav3.2 currents.

Resistant Hypertension in Dialysis: Epidemiology, Diagnosis, and Management.

Apparent treatment-resistant hypertension is defined as an elevated BP despite the use of ≥3 antihypertensive medications from different classes or the use of ≥4 antihypertensives regardless of BP levels. Among patients receiving maintenance hemodialysis or peritoneal dialysis, using this definition, the prevalence of apparent treatment-resistant hypertension is estimated to be between 18% and 42%. Owing to the lack of a rigorous assessment of some common causes of pseudoresistance, the burden of true resistant hypertension in the dialysis population remains unknown. What distinguishes apparent treatment-resistance from true resistance is white-coat hypertension and adherence to medications. Accordingly, the diagnostic workup of a dialysis patient with apparent treatment-resistant hypertension on dialysis includes the accurate determination of BP control status with the use of home or ambulatory BP monitoring and exclusion of nonadherence to the prescribed antihypertensive regimen. In a patient on dialysis with inadequately controlled BP, despite adherence to therapy with maximally tolerated doses of a ß -blocker, a long-acting dihydropyridine calcium channel blocker, and a renin-angiotensin system inhibitor, volume-mediated hypertension is the most important treatable cause of resistance. In daily clinical practice, such patients are often managed with intensification of antihypertensive therapy. However, this therapeutic strategy is likely to fail if volume overload is not adequately recognized or treated. Instead of increasing the number of prescribed BP-lowering medications, we recommend diet and dialysate restricted in sodium to facilitate achievement of dry weight. The achievement of dry weight is facilitated by an adequate time on dialysis of at least 4 hours for delivering an adequate dialysis dose. In this article, we review the epidemiology, diagnosis, and management of resistant hypertension among patients on dialysis.

Effects of 1,4-dihydropyridine derivatives on cell injury and mTOR of HepG2 and 3D-QSAR study.

1,4-dihydropyridine derivatives (1,4-DHPs) are a class of drugs used to treat cardiovascular diseases, but these drugs can cause liver injury. To reveal the toxicity characteristics of these compounds, we used a series of assays, including cell viability, enzyme activity detection, and western blotting, to investigate the toxicity of seven kinds of 1,4-DHPs (0-100 µM) on HepG2 cells and establish 3D-QSAR model based on relevant toxicity data. After HepG2 cells were treated with 1,4-DHPs for 24 h, high-dose (100 µM) 1,4-DHPs decreased cell viability to varying degrees, while ROS and MDA contents were significantly increased, and ATP content was reduced. Moreover, with the concentration of 100 µM 1,4-DHPs (Nimodipine, Nitrendipine, Cilnidipine, and Manidipine) were markedly inhibited the phosphorylation levels of mTOR protein. The results of the 3D-QSAR model showed that the non-cross validation coefficient (R2) and cross validation coefficient (Q2) of the model were 0.982 and 0.652, respectively. Combined with external validation and the Williams diagram, the model showed good predictability and application domain. Based on the CoMSIA 3D contour map, the introduction of large volume and hydrogen bond receptor groups on the carbonyl oxygen side chains of the 1,4-DHPs ring 3- and 5- was beneficial for reducing the toxicity of 1,4-DHPs. The results of this study could supplement information on the cytotoxicity of 1,4-DHPs, and could provide theoretical support for predicting the toxicity of 1,4-DHPs.

Pharmacological Prevention of Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Causes of morbidity and mortality following aneurysmal subarachnoid hemorrhage (aSAH) include early brain injury and delayed neurologic deterioration, which may result from delayed cerebral ischemia (DCI). Complex pathophysiological mechanisms underlie DCI, which often includes angiographic vasospasm (aVSP) of cerebral arteries. METHODS: Despite the study of many pharmacological therapies for the prevention of DCI in aSAH, nimodipine-a dihydropyridine calcium channel blocker-remains the only drug recommended universally in this patient population. A common theme in the research of preventative therapies is the use of promising drugs that have been shown to reduce the occurrence of aVSP but ultimately did not improve functional outcomes in large, randomized studies. An example of this is the endothelin antagonist clazosentan, although this agent was recently approved in Japan. RESULTS: The use of the only approved drug, nimodipine, is limited in practice by hypotension. The administration of nimodipine and its counterpart nicardipine by alternative routes, such as intrathecally or formulated as prolonged release implants, continues to be a rational area of study. Additional agents approved in other parts of the world include fasudil and tirilazad. CONCLUSIONS: We provide a brief overview of agents currently being studied for prevention of aVSP and DCI after aSAH. Future studies may need to identify subpopulations of patients who can benefit from these drugs and perhaps redefine acceptable outcomes to demonstrate impact.

Calcium channel blockers' contribution to overcoming Current drug discovery challenges in Alzheimer's disease.

INTRODUCTION: Alzheimer's disease (AD) is a progressive, irreversible, and multifactorial brain disorder that gradually and insidiously destroys individual's memory, thinking, and other cognitive abilities. AREAS COVERED: In this perspective, the authors examine the complex and multifactorial nature of Alzheimer's disease and believe that the best approach to develop new drugs is the MTDL strategy, which obviously faces several challenges. These challenges include identifying the key combination of targets and their suitability for coordinated actions, as well as developing an acceptable pharmacokinetic and toxicological profile to deliver a drug candidate. EXPERT OPINION: Since calcium plays a crucial role in the pathology of AD, a polypharmacological approach with calcium channel blockers reinforced by activities targeting other factors involved in AD is a serious option in our opinion. This is exemplified by a phase III clinical trial using a drug combination approach with Losartan, Amlodipine (a calcium channel blocker), and Atorvastatin, as well as several MTDL-based calcium channel blockade approaches with a promising in vitro and in vivo profile.

Zonisamide attenuates pressure overload-induced myocardial hypertrophy in mice through proteasome inhibition.

Myocardial hypertrophy is a pathological thickening of the myocardium which ultimately results in heart failure. We previously reported that zonisamide, an antiepileptic drug, attenuated pressure overload-caused myocardial hypertrophy and diabetic cardiomyopathy in murine models. In addition, we have found that the inhibition of proteasome activates glycogen synthesis kinase 3 (GSK-3) thus alleviates myocardial hypertrophy, which is an important anti-hypertrophic strategy. In this study, we investigated whether zonisamide prevented pressure overload-caused myocardial hypertrophy through suppressing proteasome. Pressure overload-caused myocardial hypertrophy was induced in mice by trans-aortic constriction (TAC) surgery. Two days after the surgery, the mice were administered zonisamide (10, 20, 40 mg·kg-1·d-1, i.g.) for four weeks. We showed that zonisamide administration significantly mitigated impaired cardiac function. Furthermore, zonisamide administration significantly inhibited proteasome activity as well as the expression levels of proteasome subunit beta types (PSMB) of the 20 S proteasome (PSMB1, PSMB2 and PSMB5) and proteasome-regulated particles (RPT) of the 19 S proteasome (RPT1, RPT4) in heart tissues of TAC mice. In primary neonatal rat cardiomyocytes (NRCMs), zonisamide (0.3 µM) prevented myocardial hypertrophy triggered by angiotensin II (Ang II), and significantly inhibited proteasome activity, proteasome subunits and proteasome-regulated particles. In Ang II-treated NRCMs, we found that 18α-glycyrrhetinic acid (18α-GA, 2 mg/ml), a proteasome inducer, eliminated the protective effects of zonisamide against myocardial hypertrophy and proteasome. Moreover, zonisamide treatment activated GSK-3 through inhibiting the phosphorylated AKT (protein kinase B, PKB) and phosphorylated liver kinase B1/AMP-activated protein kinase (LKB1/AMPKα), the upstream of GSK-3. Zonisamide treatment also inhibited GSK-3's downstream signaling proteins, including extracellular signal-regulated kinase (ERK) and GATA binding protein 4 (GATA4), both being the hypertrophic factors. Collectively, this study highlights the potential of zonisamide as a new therapeutic agent for myocardial hypertrophy, as it shows potent anti-hypertrophic potential through the suppression of proteasome.

The role of HCN channels on the effects of T-type calcium channels and GABAA receptors in the absence epilepsy model of WAG/Rij rats.

In this study we used ivabradine (IVA), a hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker, to identify its effect on spike-wave discharges (SWDs); and aimed to determine the role of IVA on the effects of T-type calcium channel blocker NNC 55-0396, GABAA receptor agonist muscimol and antagonist bicuculline in male WAG/Rij rats. After tripolar electrodes for electrocorticogram (ECoG) recordings were placed on the WAG/Rij rats' skulls, 5, 10, and 20 mg/kg IVA were intraperitoneally administered for 7 consecutive days and ECoG recordings were obtained on days 0th, 3rd, 6th, and 7th for three hours before and after injections. While acute injection of 5, 10, and 20 mg/kg IVA did not affect the total number and the mean duration of SWDs, subacute administration (7 days) of IVA decreased the SWDs parameters 24 hours after the 7th injection. Interestingly, when IVA was administered again 24 hours after the 6th IVA injection, it increased the SWDs parameters. Western-blot analyses showed that HCN1 and HCN2 expressions decreased and HCN4 increased in the 5-month-old WAG/Rij rats compared to the 1-month-old WAG/Rij and 5-month-old native Wistar rats, while subacute IVA administration increased the levels of HCN1 and HCN2 channels, except HCN4. Subacute administration of IVA reduced the antiepileptic activity of NNC, while the proepileptic activity of muscimol and the antiepileptic activity of bicuculline were abolished. It might be suggested that subacute IVA administration reduces absence seizures by changing the HCN channel expressions in WAG/Rij rats, and this affects the T-type calcium channels and GABAA receptors.