Losartan suppresses the kainate-induced changes of angiotensin AT1 receptor expression in a model of comorbid hypertension and epilepsy

Dissecting the association between blood pressure traits, hypertension, antihypertensive medications and epilepsy: A Mendelian randomization study

BACKGROUND

Observational studies suggest that hypertension and epilepsy have a high co-occurrence, and antihypertensive medications may have impacts on the prevention and treatment of epilepsy. However, the directionality of causation between them is elusive.

METHOD

By leveraging genome-wide association studies (GWAS) summary data of each trait, we firstly performed bidirectional univariate Mendelian randomization (UVMR) to assess the strength and direction of the associations between pairs of traits, then multivariate MR (MVMR) was conducted to adjust for potential confounders in causalities. Cochran's Q statistics, leave-one-out analysis, MR-Egger regression and MR-Pleiotropy Residual Sum and Outlier methods (MR-PRESSO) were employed to evaluate the robustness of the results. Drug target MR was proceeded to assess the association between five classes of first-line antihypertensive medications and epilepsy. Specifically, single nucleotide polymorphisms (SNPs) extracted from GWAS data on systolic blood pressure (SBP)/diastolic blood pressure (DBP), along with expression quantitative trait loci (eQTL) were utilized as proxies for antihypertensive medications, respectively.

RESULTS

Forward UVMR results provided evidence that genetically predicted blood pressure traits and hypertension have causal effects on epilepsy, while reverse UVMR indicated no causal impacts of epilepsy on blood pressure traits or hypertension. The sensitivity analysis results were robust. The causalities between DBP, hypertension and epilepsy remained remarkable after adjustment by MVMR. Inverse-variance-weighted MR (IVW-MR) yielded evidence of positive association only between Beta-Blockers target genes based on DBP GWAS screening and epilepsy. Summary-data-based MR (SMR) identified a positive correlation between Beta-Blockers target gene ADRA1D and epilepsy risk.

CONCLUSIONS

Hypertension has a causal effect on epilepsy and managing DBP in patients with hypertension through Beta-Blockers may help prevent epilepsy.

Use of Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers Is Associated With a Reduced Risk of Poststroke Epilepsy in Patients With Ischemic Stroke

BACKGROUND

Poststroke epilepsy (PSE) is a common complication after ischemic stroke. This study investigates the association between the use of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) and the risk of PSE in patients with ischemic stroke.

METHODS AND RESULTS

A population-based retrospective cohort study was conducted using Taiwan's National Health Insurance Research Database between 2000 and 2015. Patients with hypertension with a history of ischemic stroke were classified into prevalent, new, and nonusers according to their use of ACEIs/ARBs. Prevalent ACEI/ARB users were further classified into continuing or discontinued users, based on their poststroke medication adherence. We used multivariate Cox regression models, adjusted for demographics and comorbidities, to assess the risk of PSE among different ACEI/ARB user groups. There were 182 983 ACEI/ARB users and 38 365 nonusers included. There were 7387 patients diagnosed with PSE, whereas 213 961 were not. Nonusers exhibited a higher risk of PSE (adjusted hazard ratio [aHR], 1.72 [95% CI, 1.63-1.82]). Both prevalent and nonusers had higher risks compared with new ACEI/ARB users, with respective aHRs of 1.33 (95% CI, 1.25-1.41) and 2.00 (95% CI, 1.87-2.14). Discontinued ACEI/ARB users showed the highest risk of PSE (aHR, 2.34 [95% CI, 2.15-2.54]), suggesting the importance of continuing ACEI/ARB use after stroke. Treatment-by-age interaction was significant among patients with or without ACEI/ARB use before stroke (P value for interaction 0.004 and <0.001, respectively), suggesting a stronger beneficial association in younger patients.

CONCLUSIONS

The use of ACEIs/ARBs after ischemic stroke in patients with hypertension is associated with a reduced risk of PSE, especially among younger patients.

The anticonvulsant effect of chronic treatment with topiramate after pilocarpine-induced status epilepticus is accompanied by a suppression of comorbid behavioral impairments and robust neuroprotection in limbic regions in rats

Epilepsy is a widespread neurological disorder frequently associated with a lot of comorbidities. The present study aimed to evaluate the effects of the antiseizure medication topiramate (TPM) on spontaneous motor seizures, the pathogenesis of comorbid mood and cognitive impairments, hippocampal neuronal loss, and oxidative stress and inflammation in a rat model of temporal lobe epilepsy (TLE). Vehicle/TPM treatment (80 mg/kg, p.o.) was administered 3 h after the pilocarpine (pilo)-induced status epilepticus (SE) and continued for up to 12 weeks in Wistar rats. The chronic TPM treatment caused side effects in naïve rats, including memory disturbance, anxiety, and depressive-like responses. However, the anticonvulsant effect of this drug, administered during epileptogenesis, was accompanied by beneficial activity against comorbid behavioral impairments. The drug treatment suppressed the SE-induced neuronal damage in limbic structures, including the dorsal (CA1 and CA2 subfield), the ventral (CA1, CA2 and CA3) hippocampus, the basolateral amygdala, and the piriform cortex, while was ineffective against the surge in the oxidative stress and inflammation. Our results suggest that neuroprotection is an essential mechanism of TPM against spontaneous generalized seizures and concomitant emotional and cognitive impairments.

Recent Advances in the Endogenous Brain Renin-Angiotensin System and Drugs Acting on It

The RAS (renin-angiotensin system) is the part of the endocrine system that plays a prime role in the control of essential hypertension. Since the discovery of brain RAS in the seventies, continuous efforts have been put by the scientific committee to explore it more. The brain has shown the presence of various components of brain RAS such as angiotensinogen (AGT), converting enzymes, angiotensin (Ang), and specific receptors (ATR). AGT acts as the precursor molecule for Ang peptides—I, II, III, and IV—while the enzymes such as prorenin, ACE, and aminopeptidases A and N synthesize it. AT1, AT2, AT4, and mitochondrial assembly receptor (MasR) are found to be plentiful in the brain. The brain RAS system exhibits pleiotropic properties such as neuroprotection and cognition along with regulation of blood pressure, CVS homeostasis, thirst and salt appetite, stress, depression, alcohol addiction, and pain modulation. The molecules acting through RAS predominantly ARBs and ACEI are found to be effective in various ongoing and completed clinical trials related to cognition, memory, Alzheimer's disease (AD), and pain. The review summarizes the recent advances in the brain RAS system highlighting its significance in pathophysiology and treatment of the central nervous system-related disorders.

Impact of drug treatment and drug interactions in post-stroke epilepsy

Stroke is a huge burden on our society and this is expected to grow in the future due to the aging population and the associated co-morbidities. The improvement of acute stroke care has increased the survival rate of stroke patients, and many patients are left with permanent disability, which makes stroke the main cause of adult disability. Unfortunately, many patients face other severe complications such as post-stroke seizures and epilepsy. Acute seizures (ASS) occur within 1 week after the stroke while later occurring unprovoked seizures are diagnosed as post-stroke epilepsy (PSE). Both are associated with a poor prognosis of a functional recovery. The underlying neurobiological mechanisms are complex and poorly understood. There are no universal guidelines on the management of PSE. There is increasing evidence for several risk factors for ASS/PSE, however, the impacts of recanalization, drugs used for secondary prevention of stroke, treatment of stroke co-morbidities and antiseizure medication are currently poorly understood. This review focuses on the common medications that stroke patients are prescribed and potential drug interactions possibly complicating the management of ASS/PSE.

Amygdaloid complex anatomopathological findings in animal models of status epilepticus

Temporal lobe epileptic seizures are one of the most common and well-characterized types of epilepsies. The current knowledge on the pathology of temporal lobe epilepsy relies strongly on studies of epileptogenesis caused by experimentally induced status epilepticus (SE). Although several temporal lobe structures have been implicated in the epileptogenic process, the hippocampal formation is the temporal lobe structure studied in the greatest amount and detail. However, studies in human patients and animal models of temporal lobe epilepsy indicate that the amygdaloid complex can be also an important seizure generator, and several pathological processes have been shown in the amygdala during epileptogenesis. Therefore, in the present review, we systematically selected, organized, described, and analyzed the current knowledge on anatomopathological data associated with the amygdaloid complex during SE-induced epileptogenesis. Amygdaloid complex participation in the epileptogenic process is evidenced, among others, by alterations in energy metabolism, circulatory, and fluid regulation, neurotransmission, immediate early genes expression, tissue damage, cell suffering, inflammation, and neuroprotection. We conclude that major efforts should be made in order to include the amygdaloid complex as an important target area for evaluation in future research on SE-induced epileptogenesis. This article is part of the Special Issue "NEWroscience 2018".

Effects of Lacosamide Treatment on Epileptogenesis, Neuronal Damage and Behavioral Comorbidities in a Rat Model of Temporal Lobe Epilepsy

Clinically, temporal lobe epilepsy (TLE) is the most prevalent type of partial epilepsy and often accompanied by various comorbidities. The present study aimed to evaluate the effects of chronic treatment with the antiepileptic drug (AED) lacosamide (LCM) on spontaneous motor seizures (SMS), behavioral comorbidities, oxidative stress, neuroinflammation, and neuronal damage in a model of TLE. Vehicle/LCM treatment (30 mg/kg, p.o.) was administered 3 h after the pilocarpine-induced status epilepticus (SE) and continued for up to 12 weeks in Wistar rats. Our study showed that LCM attenuated the number of SMS and corrected comorbid to epilepsy impaired motor activity, anxiety, memory, and alleviated depressive-like responses measured in the elevated plus maze, object recognition test, radial arm maze test, and sucrose preference test, respectively. This AED suppressed oxidative stress through increased superoxide dismutase activity and glutathione levels, and alleviated catalase activity and lipid peroxidation in the hippocampus. Lacosamide treatment after SE mitigated the increased levels of IL-1β and TNF-α in the hippocampus and exerted strong neuroprotection both in the dorsal and ventral hippocampus, basolateral amygdala, and partially in the piriform cortex. Our results suggest that the antioxidant, anti-inflammatory, and neuroprotective activity of LCM is an important prerequisite for its anticonvulsant and beneficial effects on SE-induced behavioral comorbidities.

Brain angiotensin system: a new promise in the management of epilepsy?

Epilepsy is a highly prevalent neurological disease and anti-epileptic drugs (AED) are almost the unique clinical treatment option. A disbalanced brain renin-angiotensin system (RAS) has been proposed in epilepsy and several reports have shown that angiotensin II (Ang II) receptor-1 (ATR1) activation is pro-inflammatory and pro-epileptogenic. In agreement, ATR1 blockage with the repurposed drug losartan has shown benefits in animal models of epilepsy. Processing of Ang II by ACE2 enzyme renders Ang-(1-7), a metabolite that activates the mitochondrial assembly (Mas) receptor (MasR) pathway. MasR activation presents beneficial effects, facilitating vasodilatation, increasing anti-inflammatory and antioxidative responses. In a recent paper published in Clinical Science, Gomes and colleagues (Clin. Sci. (Lond.) (2020) 134, 2263-2277) performed intracerebroventricular (icv) infusion of Ang-(1-7) in animals subjected to the pilocarpine model of epilepsy, starting after the first spontaneous motor seizure (SMS). They showed that this approach reduced the frequency of SMS, restored animal anxiety, increased exploration, and augmented the hippocampal expression of protective catalase enzyme and antiapoptotic protein B-cell lymphoma 2 (Bcl-2). Interestingly, but surprisingly, Gomes and colleagues showed that MasR expression and mTor activity were reduced in the hippocampus of the epileptic Ang-(1-7) treated animals. These results show that Ang-(1-7) administration could represent a new avenue for developing strategies for the management of epilepsy in clinical settings. However, future work is necessary to evaluate the levels of RAS metabolites and the activity of key enzymes in these experimental interventions to completely understand the therapeutic potential of the brain RAS manipulation in epilepsy.

Epilepsy Seizures in Spontaneously Hypertensive Rats After Acoustic Stimulation: Role of Renin-Angiotensin System

Hypertension is a common comorbidity observed in individuals with epilepsy. Growing evidence suggests that lower blood pressure is associated with reduced frequency and severity of seizures. In this study, we sought to investigate whether the renin–angiotensin system (RAS), which is a critical regulator of blood pressure, is involved in the pathogenesis of audiogenic epilepsy-related seizures in a hypertensive rat model. Spontaneously hypertensive rats (SHRs) were given RAS inhibitors, angiotensin-converting enzyme (ACE) inhibitor or angiotensin II type I receptor (AT1R) antagonist, for 7 days prior to inducing epileptic seizures by acoustic stimulation. After the pretreatment phase, blood pressure (BP) of SHRs normalized as expected, and there was no difference in systolic and diastolic BP between the pretreated SHRs and normotensive rat group (Wistar). Next, treated and untreated SHRs (a high BP control) were individually subjected to acoustic stimuli twice a day for 2 weeks. The severity of tonic–clonic seizures and the severity of temporal lobe epilepsy seizures (product of forebrain recruitment) were evaluated by the mesencephalic severity index (Rossetti et al. scale) and the limbic index (Racine’s scale), respectively. Seizures were observed in both untreated (a high BP control) SHRs and in SHRs treated with AT1R antagonist and ACE inhibitor. There was no statistical difference in the mesencephalic severity and limbic index between these groups. Our results demonstrate that SHRs present seizure susceptibility with acoustic stimulation. Moreover, although RAS inhibitors effectively reduce blood pressure in SHR, they do not prevent developing epileptic seizures upon acoustic stimulation in SHR. In conclusion, our study shows that RAS is an unlikely link between hypertension and susceptibility to epileptic seizures induced by acoustic stimulation in SHRs, which is in contrast with the anticonvulsant effect of losartan in other animal models of epilepsy.

Telmisartan, an Antagonist of Angiotensin II Receptors, Accentuates Voltage-Gated Na+ Currents and Hippocampal Neuronal Excitability

Telmisartan (TEL), a non-peptide blocker of the angiotensin II type 1 receptor, is a widely used antihypertensive agent. Nevertheless, its neuronal ionic effects and how they potentially affect neuronal network excitability remain largely unclear. With the aid of patch-clamp technology, the effects of TEL on membrane ion currents present in hippocampal neurons (mHippoE-14 cells) were investigated. For additional characterization of the effects of TEL on hippocampal neuronal excitability, we undertook in vivo studies on Sprague Dawley (SD) rats using pilocarpine-induced seizure modeling, a hippocampal histopathological analysis, and inhibitory avoidance testing. In these hippocampal neurons, TEL increased the peak amplitude of I_Na, with a concomitant decline in the current inactivation rate. The TEL concentration dependently enhanced the peak amplitude of depolarization-elicited I_Na and lessened the inactivation rate of I_Na. By comparison, TEL was more efficacious in stimulating the peak I_Na and in prolonging the inactivation time course of this current than tefluthrin or (-)-epicatechin-3-gallate. In the continued presence of pioglitazone, the TEL-perturbed stimulation of I_Na remained effective. In addition, cell exposure to TEL shifted the steady-state inactivation I_Na curve to fewer negative potentials with no perturbations of the slope factor. Unlike chlorotoxin, either ranolazine, eugenol, or KMUP-1 reversed TEL-mediated increases in the strength of non-inactivating I_Na. In the cell-attached voltage-clamp recordings, TEL shortened the latency in the generation of action currents. Meanwhile, TEL increased the peak I_Na, with a concurrent decrease in current inactivation in HEKT293T cells expressing SCN5A. Furthermore, although TEL did not aggravate pilocarpine-induced chronic seizures and tended to preserve cognitive performance, it significantly accentuated hippocampal mossy fiber sprouting. Collectively, TEL stimulation of peak I_Na in combination with an apparent retardation in current inactivation could be an important mechanism through which hippocampal neuronal excitability is increased, and hippocampal network excitability is accentuated following status epilepticus, suggesting further attention to this finding.

A review of clinically significant drug-drug interactions involving angiotensin II receptor antagonists and antiepileptic drugs

INTRODUCTION

Angiotensin II receptor blockers are widely used for the treatment of arterial hypertension and heart failure. However, recent studies on animal models of seizures showed that in the brain, the renin-angiotensin-aldosterone system might be involved in neuroinflammation; therefore, the administration of angiotensin II receptor blockers that cross the blood/brain barrier, reduces not only blood pressure but reduces neuroinflammation-induced neuronal injury. Apart from this neuroprotective effect, these drugs exhibit anticonvulsant activity in animal models of seizures, and losartan is associated with a probable anti-epileptogenic activity.

AREAS COVERED

In this review, we intended to highlight the role of drug-drug interactions involving angiotensin II receptor antagonists with antiepileptic drugs accompanied by a brief characteristic of the role of RAS in neuroinflammation.

EXPERT OPINION

Some combinations of antiepileptic drugs (lamotrigine or valproate) with sartans are particularly effective in terms of enhanced seizure control. Considering a possible anti-epileptogenic activity of losartan, its combinations with antiepileptic drugs may prove especially beneficial in epileptogenesis inhibition.

The Potential Therapeutic Capacity of Inhibiting the Brain Renin-Angiotensin System in the Treatment of Co-Morbid Conditions in Epilepsy

Epilepsy is one of the most prevalent neurological diseases and although numerous novel anticonvulsants have been approved, the proportion of patients who are refractory to medical treatment of seizures and have progressive co-morbidities such as cognitive impairment and depression remains at about 20-30%. In the last decade, extensive research has identified a therapeutic capacity of the components of the brain renin-angiotensin system (RAS) in seizure- and epilepsy-related phenomena. Alleviating the activity of RAS in the central nervous system is considered to be a potential adjuvant strategy for the treatment of numerous detrimental consequences of epileptogenesis. One of the main advantages of RAS is associated with its modulatory influence on different neurotransmitter systems, thereby exerting a fine-tuning control mechanism for brain excitability. The most recent scientific findings regarding the involvement of the components of brain RAS show that angiotensin II (Ang II), angiotensin-converting enzyme (ACE), Ang II type 1 (AT₁) and type 2 (AT₂) receptors are involved in the control of epilepsy and its accompanying complications, and therefore they are currently of therapeutic interest in the treatment of this disease. However, data on the role of different components of brain RAS on co-morbid conditions in epilepsy, including hypertension, are insufficient. Experimental and clinical findings related to the involvement of Ang II, ACE, AT₁, and AT₂ receptors in the control of epilepsy and accompanying complications may point to new therapeutic opportunities and adjuvants for the treatment of common co-morbid conditions of epilepsy.

Hypertension, seizures, and epilepsy: a review on pathophysiology and management

BACKGROUND

Epilepsy and hypertension are common chronic conditions, both showing high prevalence in older age groups. This review outlines current experimental and clinical evidence on both direct and indirect role of hypertension in epileptogenesis and discusses the principles of drug treatment in patients with hypertension and epilepsy.

METHODS

We selected English-written articles on epilepsy, hypertension, stroke, and cerebrovascular disease until December, 2018.

RESULTS

Renin-angiotensin system might play a central role in the direct interaction between hypertension and epilepsy, but other mechanisms may be contemplated. Large-artery stroke, small vessel disease and posterior reversible leukoencephalopathy syndrome are hypertension-related brain lesions able to determine epilepsy by indirect mechanisms. The role of hypertension as an independent risk factor for post-stroke epilepsy has not been demonstrated. The role of hypertension-related small vessel disease in adult-onset epilepsy has been demonstrated. Posterior reversible encephalopathy syndrome is an acute condition, often caused by a hypertensive crisis, associated with the occurrence of acute symptomatic seizures. Chronic antiepileptic treatment should consider the risk of drug-drug interactions with antihypertensives.

CONCLUSIONS

Current evidence from preclinical and clinical studies supports the vision that hypertension may be a cause of seizures and epilepsy through direct or indirect mechanisms. In both post-stroke epilepsy and small vessel disease-associated epilepsy, chronic antiepileptic treatment is recommended. In posterior reversible encephalopathy syndrome blood pressure must be rapidly lowered and prompt antiepileptic treatment should be initiated.

Role of the Angiotensin Pathway and its Target Therapy in Epilepsy Management

Despite extensive research on epileptogenesis, there is still a need to investigate new pathways and targeted therapeutic approaches in this complex process. Inflammation, oxidative stress, neurotoxicity, neural cell death, gliosis, and blood–brain barrier (BBB) dysfunction are the most common causes of epileptogenesis. Moreover, the renin–angiotensin system (RAS) affects the brain’s physiological and pathological conditions, including epilepsy and its consequences. While there are a variety of available pharmacotherapeutic approaches, information on new pathways is in high demand and the achievement of treatment goals is greatly desired. Therefore, targeting the RAS presents an interesting opportunity to better understand this process. This has been supported by preclinical studies, primarily based on RAS enzyme, receptor-inhibition, and selective agonists, which are characterized by pleiotropic properties. Although there are some antiepileptic drugs (AEDs) that interfere with RAS, the main targeted therapy of this pathway contributes in synergy with AEDs. However, the RAS-targeted treatment alone, or in combination with AEDs, requires clinical studies to contribute to, and clarify, the evidence on epilepsy management. There is also a genetic association between RAS and epilepsy, and an involvement of pharmacogenetics in RAS, so there are possibilities for the development of new diagnostic and personalized treatments for epilepsy.

Immunohistochemical localization of angiotensin AT1 receptors in the rat carotid body

The carotid body (CB) is a major peripheral arterial chemoreceptor that initiates respiratory and cardiovascular adjustments to maintain homeostasis. Recent evidence suggests that circulating or locally produced hormones like angiotensin II acting via AT₁ receptors modulate its activity in a paracrine-autocrine manner. The aim of this study was to examine the immunohistochemical localization of AT₁ receptor in the CB of adult rats and to compare its expression in vehicle-treated animals, and after the long-term application of its selective blocker losartan. Immunohistochemistry revealed that a subset of CB glomeruli and the vast majority of neurons in the adjacent superior cervical ganglion (SCG) were strongly AT₁ receptor-immunoreactive. In the CB immunostaining was observed in the chemosensory glomus cells typically aggregated in cell clusters while the nerve fibers in-between and large capillaries around them were immunonegative. Exogenous administration of losartan for a prolonged time significantly reduces the intensity of AT₁ receptor immunostaining in the CB glomus cells and SCG neurons. Our results show that AT₁ receptors are largely expressed in the rat CB under physiological conditions, and their expression is down-regulated by losartan treatment.