Effects of the anticonvulsant lacosamide compared to valproate and lamotrigine on cocaine-enhanced reward in rats

The impact of lacosamide on mood disorders in adult patients with epilepsy: A systematic review

Mood disorders such as depression and anxiety have a high prevalence in adult patients with epilepsy, and their evaluation is crucial in choosing the most appropriate antiepileptic drug (AED) with regard to side effects, which can account for long-term discontinuation, poor compliance, and ultimately, failure of seizure control. While more evidence is provided for older AEDs on their effect on mood changes, newer AEDs such as lacosamide have not yet been extensively studied. We performed a systematic review of the literature available on the impact of lacosamide on mood in adult patients with epilepsy. A literature search on MEDLINE, COCHRANE, Scielo, and Clinicaltrials.gov databases was performed, and articles where mood scales where specifically reported as primary or secondary outcome measures were included. Articles differed greatly in terms of inclusion criteria, concomitant AEDs, seizure reduction control, and outcome measures. If lacosamide is used as add-on, two studies point towards a beneficial effect on depressive and anxiety symptoms, two studies claim no effects on mood, and one reports a positive effect only in patients with major depressive symptoms at baseline. Additional evidence from either retrospective or comparative drug studies indicates no effects of lacosamide on mood. Even though presently, a negative effect on mood seems unlikely, whether lacosamide could exert a beneficial impact on mood remains controversial. Multicenter, randomized, controlled, double-blind studies are needed to assess the impact on lacosamide on mood disorders, given the low evidence level (Class III and IV) of currently available studies.

Effect of lacosamide on ethanol induced conditioned place preference and withdrawal associated behavior in mice: Possible contribution of hippocampal CRMP-2

BACKGROUND

Excessive consumption of ethanol is known to activate the mTORC1 pathway and to enhance the Collapsin Response Mediator Protein-2 (CRMP-2) levels in the limbic region of brain. The latter helps in forming microtubule assembly that is linked to drug taking or addiction-like behavior in rodents. Therefore, in this study, we investigated the effect of lacosamide, an antiepileptic drug and a known CRMP-2 inhibitor, which binds to CRMP-2 and inhibits the formation of microtubule assembly, on ethanol-induced conditioned place preference (CPP) in mice.

METHODS

The behavior of mice following ethanol addiction and withdrawal was assessed by performing different behavioral paradigms. Mice underwent ethanol-induced CPP training with alternate dose of ethanol (2 g/kg, po) and saline (10 ml/kg, po). The effect of lacosamide on the expression of ethanol-induced CPP and on ethanol withdrawal associated anxiety and depression-like behavior was evaluated. The effect of drug on locomotor activity was also assessed and hippocampal CRMP-2 levels were measured.

RESULTS

Ethanol-induced CPP was associated with enhanced CRMP-2 levels in the hippocampus. Lacosamide significantly reduced the expression of ethanol-induced CPP and alleviated the levels of hippocampal CRMP-2 but aggravated withdrawal-associated anxiety and depression in mice.

CONCLUSION

The present study demonstrated the beneficial effect of lacosamide in attenuation of expression of ethanol induced conditioned place preference via reduction of hippocampal CRMP-2 level. These findings suggest that lacosamide may be investigated further for ethanol addiction but not for managing withdrawal.

Lamotrigine attenuates the motivation to self-administer ketamine and prevents cue- and prime-induced reinstatement of ketamine-seeking behavior in rats

BACKGROUND

Lamotrigine is an anticonvulsant drug used in the treatment of epilepsy and bipolar disorder. A case report has demonstrated that a ketamine addict experienced a significant reduction in craving and ketamine use after taking lamotrigine. The present study determined whether lamotrigine can reduce the motivation for ketamine and prevent the relapse to ketamine seeking behavior in rats.

METHODS

Male Sprague-Dawley rats were trained to respond for intravenous ketamine (0.5 mg/kg/infusion) self-administration or food pellets. The effects of lamotrigine on the motivation for ketamine or food were assessed using breakpoint test under a progressive ratio (PR) paradigm. Furthermore, the effects of lamotrigine on reinstatement of ketamine-seeking and food-seeking behaviors were examined after extinction.

RESULTS

Lamotrigine significantly decreased the breakpoint for ketamine and prevented cue- and ketamine priming-induced reinstatement of ketamine seeking behavior. However, lamotrigine did not affect the breakpoint for food reinforcement, cue-induced reinstatement of food-seeking behavior, or spontaneous locomotor activity.

CONCLUSIONS

Our data reveal that lamotrigine is capable of attenuating the reinforcing efficacy of ketamine and reducing ketamine craving and relapse risk, which lays the foundation for conducting clinical trials in patients with ketamine use disorder.

Lacosamide in bipolar disorder: A 30-day comparison to a retrospective control group treated with other antiepileptics

AIM

Bipolar disorder (BD) is often treated with anticonvulsants. Lacosamide has not been tested in BD. We assessed its effects in a hospital setting in patients with BD without epilepsy.

METHODS

We treated 102 consecutive hospitalized patients with acute BD with lacosamide 50-300 mg/day. We compared this sample with a retrospective sample treated with other antiepileptics (OAE). We rated patients after 3, 7, 15, and 30 days of treatment with the Brief Psychiatric Rating Scale, Young Mania Rating Scale, Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale, Clinical Global Impressions - Severity, and Global Assessment of Functioning.

RESULTS

Patients receiving lacosamide were significantly younger and had fewer mixed episodes at intake, and less substance use disorder comorbidity than those receiving OAE. Both groups showed positive effects on all measures. The two groups did not differ on any clinical measure at baseline, but from the 3rd day on, lacosamide patients fared better than OAE patients on the Young Mania Rating Scale and Clinical Global Impressions - Severity and worse on the Hamilton Anxiety Rating Scale. From the 15th day, OAE patients scored better on the Brief Psychiatric Rating Scale. Global Assessment of Functioning scores were significantly more improved in the lacosamide patients. Age, substance use disorder comorbidity, episode type, and educational level significantly affected results. No interactions were found amongst these parameters.

CONCLUSION

Lacosamide was effective in reducing psychopathology, mania, depression, and anxiety and in improving global functioning in patients with BD-I/II disorder in the short term, with few side-effects. Lacosamide improved mania, clinical severity, and global functioning better than OAE at doses lower than those used in epilepsy.

Valproate reduces neuroinflammation and neuronal death in a rat chronic constriction injury model

Valproate (VPA) is a well-known drug for treating epilepsy and mania, but its action in neuropathic pain is unclear. We used a chronic constriction injury (CCI) model to explore whether VPA prevents neuropathic pain-mediated inflammation and neuronal death. Rats were treated with or without VPA. CCI + VPA rats were intraperitoneally injected with VPA (300 mg/kg/day) from postoperative day (POD) 1 to 14. We measured paw withdrawal latency (PWL) and paw withdrawal threshold (PWT) 1 day before surgery and 1, 3, 7, 14 days after CCI and harvested the sciatic nerves (SN), spinal cord (SC) and dorsal root ganglia (DRG) on POD 3, 7, and 14. PWL and PWT were reduced in CCI rats, but increased in CCI + VPA rats on POD 7 and POD 14. VPA lowered CCI-induced inflammatory proteins (pNFκB, iNOS and COX-2), pro-apoptotic proteins (pAKT/AKT and pGSK-3β/GSK-3β), proinflammatory cytokines (TNF-α and IL-1β) and nuclear pNFκB activation in the SN, DRG and SC in CCI rats. COX-2 and pGSK-3 proteins were decreased by VPA on immunofluorescence analysis. VPA attenuated CCI-induced thermal and mechanical pain behaviors in rats in correlation with anti-neuroinflammation action involving reduction of pNFκB/iNOS/COX-2 activation and inhibition of pAKT/pGSK-3β-mediated neuronal death from injury to peripheral nerves.

Clinical stabilisation with lacosamide of mood disorder comorbid with PTSD and fronto-temporal epilepsy

Background and aim of the work:

Mood disorders are often complicated by comorbidity with epilepsy. Anxiety and personality disorders may worsen prognosis and treatment outcome. Lacosamide has been recently introduced as adjunctive treatment for partial epilepsy. Its mechanism consists of selective slow inactivation of voltage-gated sodium channels, thus promoting an extended stabilisation of cell membranes. Antiepileptic drugs have been largely used since the 1950s in psychiatry as mood stabilisers due to their membrane stabilising and anti-kindling effects. Like lithium, antiepileptic drugs are first choice treatment for Bipolar and Cyclothymic Disorders.

Methods:

We tested the efficacy of the most recent antiepileptic medication, lacosamide, in a patient with simultaneously occurring cyclothymic disorder, severe post-traumatic stress disorder, and fronto-temporal epilepsy. Lacosamide was titrated up to 200 mg/day, added to ongoing 750 mg/day lithium, 15 mg/day oral aripiprazole then switched to 400 mg/month long-acting aripiprazole, and 2 mg/day A-desmethyldiazepam.

Results:

We observed EEG normalisation one month later, along with reduced anxiety and an additive effect to lithium-induced stabilisation of mood fluctuations since the second week of lacosamide addition.

Conclusions:

Further studies with this drug in the bipolar spectrum are warranted. (www.actabiomedica.it)

Considerations on nonclinical approaches to modeling risk factors of suicidal ideation and behavior

Given the serious nature of suicidal ideation and behavior (SIB) and the possibility of treatment-emergent SIB, pharmaceutical companies are now applying more proactive approaches in clinical trials and are considering the value of nonclinical models to predict SIB. The current review summarizes nonclinical approaches to modeling three common risk factors associated with SIB: aggression, impulsivity, and anhedonia. For each risk factor, a general description, advantages and disadvantages, species considerations, nonclinical to clinical translation, and pharmacological validation with respect to treatments associated with SIB are summarized. From this review, several gaps were identified that need to be addressed before use of these nonclinical models can be considered a viable option to predict the relative risk for SIB. Other future directions that may compliment these nonclinical approaches, including the use of selectively-bred or genetically-modified rodent models, transgenic models, gene expression profiling, and biomarker analysis, are discussed. This article was developed with the support of the DruSafe Leadership Group of the International Consortium for Innovation and Quality in Pharmaceutical Development (IQ, www.iqconsortium.org).

mTORC1-dependent translation of collapsin response mediator protein-2 drives neuroadaptations underlying excessive alcohol-drinking behaviors

Mammalian target of rapamycin complex 1 (mTORC1) has an essential role in dendritic mRNA translation and participates in mechanisms underlying alcohol-drinking and reconsolidation of alcohol-related memories. Here, we report that excessive alcohol consumption increases the translation of downstream targets of mTORC1, including collapsin response mediator protein-2 (CRMP-2), in the nucleus accumbens (NAc) of rodents. We show that alcohol-mediated induction of CRMP-2 translation is mTORC1-dependent, leading to increased CRMP-2 protein levels. Furthermore, we demonstrate that alcohol intake also blocks glycogen synthase kinase-3β (GSK-3β)-phosphorylation of CRMP-2, which results in elevated binding of CRMP-2 to microtubules and a concomitant increase in microtubule content. Finally, we show that systemic administration of the CRMP-2 inhibitor lacosamide, or knockdown of CRMP-2 in the NAc decreases excessive alcohol intake. These results suggest that CRMP-2 in the NAc is a convergent point that receives inputs from two signaling pathways, mTORC1 and GSK-3β, that in turn drives excessive alcohol-drinking behaviors.

Glutamatergic transmission in drug reward: implications for drug addiction

Individuals addicted to drugs of abuse such as alcohol, nicotine, cocaine, and heroin are a significant burden on healthcare systems all over the world. The positive reinforcing (rewarding) effects of the above mentioned drugs play a major role in the initiation and maintenance of the drug-taking habit. Thus, understanding the neurochemical mechanisms underlying the reinforcing effects of drugs of abuse is critical to reducing the burden of drug addiction in society. Over the last two decades, there has been an increasing focus on the role of the excitatory neurotransmitter glutamate in drug addiction. In this review, pharmacological and genetic evidence supporting the role of glutamate in mediating the rewarding effects of the above described drugs of abuse will be discussed. Further, the review will discuss the role of glutamate transmission in two complex heterogeneous brain regions, namely the nucleus accumbens (NAcc) and the ventral tegmental area (VTA), which mediate the rewarding effects of drugs of abuse. In addition, several medications approved by the Food and Drug Administration that act by blocking glutamate transmission will be discussed in the context of drug reward. Finally, this review will discuss future studies needed to address currently unanswered gaps in knowledge, which will further elucidate the role of glutamate in the rewarding effects of drugs of abuse.

It's MORe exciting than mu: crosstalk between mu opioid receptors and glutamatergic transmission in the mesolimbic dopamine system

Opioids selective for the G protein-coupled mu opioid receptor (MOR) produce potent analgesia and euphoria. Heroin, a synthetic opioid, is considered one of the most addictive substances, and the recent exponential rise in opioid addiction and overdose deaths has made treatment development a national public health priority. Existing medications (methadone, buprenorphine, and naltrexone), when combined with psychosocial therapies, have proven efficacy in reducing aspects of opioid addiction. Unfortunately, these medications have critical limitations including those associated with opioid agonist therapies (e.g., sustained physiological dependence and opioid withdrawal leading to high relapse rates upon discontinuation), non-adherence to daily dosing, and non-renewal of monthly injection with extended-release naltrexone. Furthermore, current medications fail to ameliorate key aspects of addiction such as powerful conditioned associations that trigger relapse (e.g., cues, stress, the drug itself). Thus, there is a need for developing novel treatments that target neural processes corrupted with chronic opioid use. This requires a basic understanding of molecular and cellular mechanisms underlying effects of opioids on synaptic transmission and plasticity within reward-related neural circuits. The focus of this review is to discuss how crosstalk between MOR-associated G protein signaling and glutamatergic neurotransmission leads to immediate and long-term effects on emotional states (e.g., euphoria, depression) and motivated behavior (e.g., drug-seeking, relapse). Our goal is to integrate findings on how opioids modulate synaptic release of glutamate and postsynaptic transmission via α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and N-methyl-D-aspartate receptors in the nucleus accumbens and ventral tegmental area with the clinical (neurobehavioral) progression of opioid dependence, as well as to identify gaps in knowledge that can be addressed in future studies.

Effects of lithium and aripiprazole on brain stimulation reward and neuroplasticity markers in the limbic forebrain

Bipolar disorder (BD) is a severe pathological condition with impaired reward-related processing. The present study was designed to assess the effects of two commonly used BD medications, the mood stabilizer lithium chloride (LiCl) and the atypical antipsychotic and antimanic agent aripiprazole, in an animal model of reward and motivation and on markers of neuroplasticity in the limbic forebrain in rats. We utilized intracranial self-simulation (ICSS) to assess the effects of acute and chronic administration of LiCl and aripiprazole on brain stimulation reward, and phosphorylation studies to determine their effects on specific cellular neuroplasticity markers, i.e., the phosphorylation of CREB and crucial phosphorylation sites on the GluA1 subunit of AMPA receptors and the NA1 and NA2B subunits of NMDA receptors, in the limbic forebrain. Chronic LiCl induced tolerance to the anhedonic effect of the drug observed after acute administration, while chronic aripiprazole induced a sustained anhedonic effect. These distinct behavioral responses might be related to differences in molecular markers of neuroplasticity. Accordingly, we demonstrated that chronic LiCl, but not aripiprazole, decreased phosphorylation of CREB at the Ser133 site and NA1 at the Ser896 site in the prefrontal cortex and GluA1 at the Ser831 site and NA2B at the Ser1303 site in the ventral striatum. The present study provides evidence for BD medication-evoked changes in reward and motivation processes and in specific markers of neuronal plasticity in the limbic forebrain, promoting the notion that these drugs may blunt dysregulated reward processes in BD by counteracting neuronal plasticity deficits.