Standardized Centella asiatica extract ECa 233 alleviates pain hypersensitivity by modulating P2X3 in trigeminal neuropathic pain.

OBJECTIVE: During oral surgery and temporomandibular joint repositioning, pain hypersensitivity often occurs due to irritation or inflammation of the nerve endings in the orofacial region. This study aimed to investigate the effects of ECa 233, a Centella asiatica-standardized extract, on the development of mechanical hyperalgesia and allodynia induced by chronic constriction injury of the infraorbital nerve in mice. METHODOLOGY: The right infraorbital nerves of the mice were ligated. Oral carbamazepine (20 mg/kg) or ECa 233 (30, 100, or 300 mg/kg) was administered daily for 21 days. Von Frey and air-puff tests were performed on both sides of the whisker pad on days 0, 7, 14, and 21. Thereafter, the expression of purinergic receptor subtype 3 (P2X3) and voltage-gated sodium channel 1.7 (NaV1.7), a transmembrane protein, in the trigeminal ganglion and c-fos immunoreactivity-positive neurons in the trigeminal nucleus caudalis was assessed. RESULTS: After 21 days of infraorbital nerve ligation, the mice showed allodynia- and hyperalgesia-like behavior, P2X3 and NaV1.7 were upregulated in the trigeminal ganglion, and nociceptive activity increased in the trigeminal nucleus caudalis. However, the oral administration of carbamazepine (20 mg/kg), ECa 233 (100 mg/kg), or ECa 233 (300 mg/kg) mitigated these effects. Nevertheless, ECa 233 failed to affect NaV1.7 protein expression. CONCLUSION: Carbamazepine and ECa 233 can prevent pain hypersensitivity in mice. Considering the side effects of the long-term use of carbamazepine, ECa 233 monotherapy or combined ECa 233 and carbamazepine therapy can be used as an alternative for regulating the development of hypersensitivity in trigeminal pain. However, further detailed clinical studies should be conducted to provide comprehensive information on the use of ECa 233.

Study on the reversal of epileptic drug resistance by tetramethylpyrazine in combination with carbamazepine through modulation of P-Glycoprotein expression in rat brain microvessel endothelial cell.

The purpose of this study was to detect the changes of P-Glycoprotein (P-GP) expression in rat brain microvessel endothelial cell line RBE4 after the action of Tetramethylpyrazine (TMP) on Carbamazepine (CBZ), so as to clarify the potential mechanism of TMP combined with CBZ against intractable epilepsy drug resistance. The RBE4 cell line was utilized for in vitro analysis. Cells were divided into control, CBZ, and CBZ-TMP group. The expression of P-GP was assessed using Western blot and reverse transcription polymerase chain reaction (RT-PCR). Intracellular concentration of CBZ was measured through high-performance liquid chromatography (HPLC). The differential expression of mRNA was evaluated by RNA sequencing. The intracellular concentration of CBZ in the CBZ-TMP group was significantly higher than that in other groups. The expression of P-GP in the CBZ group was significantly higher than that in the control group, while in the CBZ&TMP group, it was significantly lower than that in the other groups. Comparative analysis also revealed some differentially expressed genes. Compared with the CBZ group, FAM106A, SLC3A2, TENM2, etc. were upregulated most significantly in the CBZ&TMP group. ZBTB10, WDR7, STARD13, etc. were downregulated most significantly. Results suggest that TMP increases the intracellular concentration of CBZ, downregulates the expression of P-GP increased by CBZ, and modulates related cellular metabolism and signaling pathways, thus reversing the drug resistance mechanism of intractable epilepsy, providing a theoretical basis for the combination of traditional Chinese medicine and antiepileptic drugs.

Anticonvulsant effects of isopimpinellin and its interactions with classic antiseizure medications and borneol in the mouse tonic-clonic seizure model: an isobolographic transformation.

BACKGROUND: Overwhelming evidence indicates that some naturally occurring coumarins and terpenes are widely used in folk medicine due to their various therapeutic effects affecting the brain. Antiseizure medications (ASMs) are the principal treatment option for epilepsy patients, although some novel strategies based on naturally occurring substances are intensively investigated. This study was aimed at determining the influence of isopimpinellin (ISOP-a coumarin) when administered either separately or in combination with borneol (BOR-a monoterpenoid), on the antiseizure potencies of four classic ASMs (carbamazepine (CBZ), phenytoin (PHT), phenobarbital (PB), and valproate (VPA)) in the mouse model of maximal electroshock-induced (MES) tonic-clonic seizures. MATERIALS: Tonic-clonic seizures were evoked experimentally in mice after systemic (ip) administration of the respective doses of ISOP, BOR, and classic ASMs. Interactions for two-drug (ISOP + a classic ASM) and three-drug (ISOP + BOR + a classic ASM) mixtures were assessed isobolographically in the mouse MES model. RESULTS: ISOP (administered alone) had no impact on the anticonvulsant potencies of four classic ASMs. Due to the isobolographic transformation of data, the combination of ISOP + VPA exerted an antagonistic interaction, whereas the two-drug mixtures of ISOP + CBZ, ISOP + PHT, and ISOP + PB produced additive interactions in the mouse MES model. The three-drug combinations of ISOP + BOR with CBZ and PHT produced additive interactions, while the three-drug combinations of ISOP + BOR with PB and VPA exerted synergistic interactions in the mouse MES model. CONCLUSIONS: The most intriguing interaction was that for ISOP + VPA, for which the addition of BOR evoked a transition from antagonism to synergy in the mouse MES model.

Fabrication of Carbamazepine Cocrystals: Characterization, In Vitro and Comparative In Vivo Evaluation.

Carbamazepine (CBZ) is an antiepileptic drug having low bioavailability due to its hydrophobic nature. In the current study, efforts are made to investigate the effect of dicarboxylic acid coformer spacer groups (aliphatic chain length) on physicochemical properties, relative humidity (RH) stability, and oral bioavailability of CBZ cocrystals. Slurry crystallization technique was employed for the preparation of CBZ cocrystals with the following coformers: adipic (AA), glutaric (GA), succinic (SA), and malonic acid (MA). Powder X-ray diffractometry and Fourier-transform infrared spectroscopy confirmed cocrystal preparation. Physicochemical properties, RH stability, and oral bioavailability of cocrystals were investigated. Among the prepared cocrystals, CBZ-GA showed maximum solubility as well as improved dissolution profile (CBZ-GA > CBZ-MA > CBZ-AA > pure CBZ > CBZ-SA) in ethanol. Maximum RH stability was shown by CBZ-AA, CBZ-SA, and CBZ-MA. In vivo studies confirmed boosted oral bioavailability of cocrystals compared to pure CBZ. Furthermore, in vivo studies depicted the oral bioavailability order of cocrystals as CBZ-GA > CBZ-MA > Tegral® > CBZ-AA > CBZ-SA > pure CBZ. Thus, pharmaceutical scientists can effectively employ cocrystallization technique for tuning physicochemical properties of hydrophobic drugs to achieve the desired oral bioavailability. Overall, results reflect no consistent effect of spacer group on physicochemical properties, RH stability, and oral bioavailability of cocrystals.

Effects of antiepileptic drugs' administration during pregnancy on the nerve cell proliferation and axonal outgrowth of human neuroblastoma SH-SY5Y nerve cells.

It has been suggested that the intelligence quotient of children born to pregnant women taking 1000 mg or more of valproic acid per day is lower than that of children born to pregnant women taking other antiepileptic drugs. However, the mechanism whereby intelligence quotient is decreased in children exposed to valproic acid during the fetal period has not yet been elucidated. Therefore, we used the human neuroblastoma cell line SH-SY5Y to evaluate the effects of antiepileptic drugs containing valproic acid on nerve cells. We assessed the anti-proliferative effects of drugs in these cells via WST-8 colorimetric assay, using the Cell Counting Kit-8. We also quantified drug effects on axonal elongation from images using ImageJ software. We also evaluated drug effects on mRNA expression levels on molecules implicated in nervous system development and folic acid uptake using real-time PCR. We observed that carbamazepine and lamotrigen were toxic to SH-SY5Y cells at concentrations >500 µM. In contrast, phenytoin and valproic acid were not toxic to these cells. Carbamazepine, lamotrigen, phenytoin, and valproic acid did not affect axonal outgrowth in SH-SY5Y cells. Sodium channel neuronal type 1a (SCN1A) mRNA expression-level ratios increased when valproic acid was supplemented to cells. The overexpression of SCN1A mRNA due to high valproic acid concentrations during the fetal period may affect neurodevelopment. However, since detailed mechanisms have not yet been elucidated, it is necessary to evaluate it by comparing cell axon elongation and SCN1A protein expression due to high-concentration valproic acid exposure.

Antiseizure drug efficacy and tolerability in established and novel drug discovery seizure models in outbred vs inbred mice.

OBJECTIVE: Initial identification of new investigational drugs for the treatment of epilepsy is commonly conducted in well-established mouse acute and chronic seizure models: for example, maximal electroshock (MES), 6 Hz, and corneal kindling. Comparison of the median effective dose (ED50) of approved antiseizure drugs (ASDs) vs investigational agents in these models provides evidence of their potential for clinical efficacy. Inbred and outbred mouse strains exhibit differential seizure susceptibility. However, few comparisons exist of the ED50 or median behaviorally impairing dose (TD50) of prototype ASDs in these models in inbred C57Bl/6 vs outbred CF-1 mice, both of which are often used for ASD discovery. METHODS: We defined the strain-related ED50s and TD50s of several mechanistically distinct ASDs across established acute seizure models (MES, 6 Hz, and corneal-kindled mouse). We further quantified the strain-related effect of the MES ED50 of each ASD on gross behavior in a locomotor activity assay. Finally, we describe a novel pharmacoresistant corneal-kindling protocol that is suitable for moderate-throughput ASD screening and demonstrates highly differentiated ASD sensitivity. RESULTS: We report significant strain-related differences in the MES ED50 of valproic acid (CF-1 ED50: 90 mg/kg [95% confidence interval (CI) 165-214] vs C57Bl/6: 276 mg/kg [226-366]), as well as significant differences in the ED50 of levetiracetam in the pharmacoresistant 6 Hz test (CF-1: 22.5 mg/kg [14.7-30.2] vs C57Bl/6: >500 mg/kg [CI not defined]). There were no differences in the calculated TD50 of these ASDs between strains. Furthermore, the MES ED50 of phenobarbital significantly enhanced locomotor activity of outbred CF-1, but not C57Bl/6, mice. SIGNIFICANCE: Altogether, this study provides strain-related information to differentiate investigational agents from ASD standards-of-care in commonly employed preclinical discovery models and describes a novel kindled seizure model to further explore the mechanisms of drug-resistant epilepsy.

Herb-drug interaction of gastrodiae rhizoma on carbamazepine: A pharmacokinetic study in rats.

OBJECTIVE: Gastrodiae Rhizoma (GR), is a traditional Chinese Medicine that has been used for neurological disorders, including epilepsy. Epilepsy patients may be treated with adjunctive therapy of GR with antiepileptic drugs (AEDs). In particular, carbamazepine (CBZ) is of high potential to interact with concurrent treatment of Chinese Medicine. This study was to investigate the herb-drug interactions of GR and CBZ, an AED, through pharmacokinetic approach in rats. METHODS: We adopted a high-performance liquid chromatography (HPLC) system to quantify the plasma level of CBZ and its metabolite (carbamazepine-10, 11-epoxide, CBZE). The method was validated as per instructions under United States Food and Drug Administration (USFDA) guidance. For the herb-drug interaction study, rats were randomly divided into four different treatment groups: single-dose CBZ treatment, single-dose CBZ/GR treatment, 2-week course of CBZ treatment and 2-week course of CBZ/GR treatment. RESULTS: Our results demonstrated the auto-induction of CBZ metabolization when comparing single-dose with 2-week course of CBZ treatment. Pharmacokinetic interactions were noted in concomitant use of GR with CBZ by comparing two single-dose treatments (CBZ versus CBZ/GR). Our data showed that GR increased the mean residence time (MRT0-t) and the time taken to reach the maximum concentration (Tmax) of CBZ in single-dose of CBZ/GR treatment. The maximum drug concentration (Cmax) of CBZ was reduced in single-dose CBZ/GR treatment. When comparing the 2-week course of CBZ treatment with the 2-week course of CBZ/GR treatment, the MRT0-t and half-life of CBZ were increased. The AUC0-t, the Cmax and the half-life of CBZE were increased. CONCLUSION: CBZ/GR treatment may reduce the auto-induction of CBZ over 2 weeks. While the reduction of auto-induction could enhance the therapeutic effects of CBZ, it could also lead to an increase in neurological side effects and non-neurological adverse effects. Our results provided preclinical evidence of herb-drug interaction, which may have implications for epilepsy patients treated with GR.

Longterm Antiepileptic Therapy and Bone Health: Implications for Patients with Brain Tumors.

OBJECTIVE: The objective of our study was to investigate the effects of carbamazepine (CBZ) and lamotrigine (LTG) treatment on bone metabolism in epileptic patients. PATIENTS AND METHODS: A cross-sectional study was performed on normal controls (N=30) and 100 patients with symptomatic epilepsy caused by a primary brain tumor, divided into two groups according to the treatment: LTG monotherapy group (N=50) and CBZ monotherapy group (N=50). For each participant serum levels of 25-OHD and osteocalcin (OCLN) were measured, and bone mineral density (BMD) was evaluated by the dual-energy X-ray absorptiometry method. RESULTS: There was no statistically significant difference in the average values of vitamin D in serum between the CBZ and LTG groups (Vitamin D CBZ 17.03±12.86 vs. Vitamin D LTG 17.97±9.15; F=0.171, P=0.680). There was no statistically significant difference in the average values of OCLN between the CBZ and LTG groups (OCLN CBZ 26.06±10.87 vs. OCLN LTG 27.87±28.45; F=0.171, P=0.674). The BMD value was lower in both groups using antiepileptic agents compared to the controls, but when comparing the CBZ group to the LTG group, a statistically significant difference was only observed for the Z score (T-score CBZ: 0.08± 1.38 vs. T-score LTG: 0.37± 1.02; F=1.495, P=0.224; Z score CBZ: -0.05±1.17 vs. Z. score CBZ: 0.38±0.96; F=4.069, P=0.046) (Table 3). CONCLUSION: The choice of antiepileptic agents for treating seizures in patients with brain tumors should be carefully evaluated in relation to their impact on bone health. These patients could benefit from supplementation and regular measurement of biochemical markers of bone turnover and BMD.

Polygala tenuifolia-Acori tatarinowii herbal pair as an inspiration for substituted cinnamic α-asaronol esters: Design, synthesis, anticonvulsant activity, and inhibition of lactate dehydrogenase study.

Inspired by the traditional Chinese herbal pair of Polygala tenuifolia-Acori Tatarinowii for treating epilepsy, 33 novel substituted cinnamic α-asaronol esters and analogues were designed by Combination of Traditional Chinese Medicine Molecular Chemistry (CTCMMC) strategy, synthesized and tested systematically not only for anticonvulsant activity in three mouse models but also for LDH inhibitory activity. Thereinto, 68-70 and 75 displayed excellent and broad spectra of anticonvulsant activities with modest ability in preventing neuropathic pain, as well as low neurotoxicity. The protective indices of these four compounds compared favorably with stiripentol, lacosamide, carbamazepine and valproic acid. 68-70 exhibited good LDH1 and LDH5 inhibitory activities with noncompetitive inhibition type, and were more potent than stiripentol. Notably, 70, as a representative agent, was also shown as a moderately positive allosteric modulator at human α1ß2γ2 GABAA receptors (EC50 46.3 ±â€¯7.3 µM). Thus, 68-70 were promising candidates for developing into anti-epileptic drugs, especially for treatment of refractory epilepsies such as Dravet syndrome.

Anticonvulsive activity of duloxetine: A new choice for the epileptic patients with depression.

The aim of this study was to investigate the antiepileptic effects of duloxetine in the maximal electroshock test and convulsions induced by four compounds: Pentylenetetrazole, 3-mercaptopropionic acid, thiosemicarbazide, and bicuculline. Duloxetine exhibited moderate anticonvulsive activity with an ED50 (median effective dose) of 48.21 mg/kg in the maximal electroshock test in mice. The anticonvulsive action of duloxetine was also confirmed in chemical-induced seizure tests, where this drug decreased tonic convulsions. Single administration of duloxetine (6.25-25 mg/kg) significantly increased the anticonvulsant effects of valproate, carbamazepine, and oxcarbazepine in the maximal electroshock test. Furthermore, pretreatment with thiosemicarbazide (an inhibitor of GABA synthesis enzyme) significantly increased the ED50 of duloxetine, suggesting the GABAergic system may contribute to the anticonvulsive action of duloxetine. These results support the use of duloxetine in the treatment of coexisting depression and epilepsy.

Neuronal protective effect of Songling Xuemaikang capsules alone and in combination with carbamazepine on epilepsy in kainic acid-kindled rats.

CONTEXT: Epilepsy is a common life-threatening neurological disorder that is often drug-resistant and associated with cognitive impairment. The traditional Chinese patent medicine Songling Xuemaikang capsules (SXC) is clinically used for epilepsy therapy and alleviation of cognitive impairment. OBJECTIVE: This study investigates the neuronal protective effect of SXC combined with carbamazepine (CBZ) on epilepsy and cognitive impairment in kainic acid-kindled SD rats. MATERIALS AND METHODS: Kainic acid-kindled rats were established by injection of 0.45 µg kainic acid and randomly divided into 5 groups (n = 14): saline (sham-operated), control, CBZ, SXC and CBZ + SXC combined group. Rats in the treatment groups received CBZ (50 mg/kg/d), SXC (600 mg/kg/d) or combined CBZ (50 mg/kg/d) + SXC (600 mg/kg/d) via intragastric injection for 60 days. Epileptic behaviours, cognitive impairment, neuronal apoptosis and expression of p-Akt, Akt and caspase-9 were measured, and the alleviation of cognitive damage and neuronal apoptosis was analyzed. RESULTS: The combined administration of SXC and CBZ significantly decreased the frequency of seizures (1.2 ± 0.3) and the number of episodes (1.3 ± 0.5) above stage III (p < 0.05). Neuronal apoptosis was improved (p < 0.01), and cognitive damage was ameliorated (p < 0.05).The level of p-Akt was enhanced (p < 0.01) whereas the expression of caspase-9 was evidently inhibited (p < 0.01) in the combined group. CONCLUSIONS: The present findings confirm that the combined use of SXC with CBZ can effectively control epileptic seizures, alleviate damage to hippocampal neurons and protect against cognitive impairment. The mechanism of action might be related to the upregulation of p-Akt and inhibition of caspase-9 expression.

Sodium Channels in Human Pain Disorders: Genetics and Pharmacogenomics.

Acute pain is adaptive, but chronic pain is a global challenge. Many chronic pain syndromes are peripheral in origin and reflect hyperactivity of peripheral pain-signaling neurons. Current treatments are ineffective or only partially effective and in some cases can be addictive, underscoring the need for better therapies. Molecular genetic studies have now linked multiple human pain disorders to voltage-gated sodium channels, including disorders characterized by insensitivity or reduced sensitivity to pain and others characterized by exaggerated pain in response to normally innocuous stimuli. Here, we review recent developments that have enhanced our understanding of pathophysiological mechanisms in human pain and advances in targeting sodium channels in peripheral neurons for the treatment of pain using novel and existing sodium channel blockers.

Protective effect of compound Danshen (Salvia miltiorrhiza) dripping pills alone and in combination with carbamazepine on kainic acid-induced temporal lobe epilepsy and cognitive impairment in rats.

CONTEXT: Temporal lobe epilepsy (TLE) is resistant to antiepileptic drugs (AEDs) and is associated with cognitive impairment. The modern Chinese medicine, compound Danshen dripping pills (CDDP), is clinically effective in treating epilepsy and improving cognitive impairment. OBJECTIVE: This study evaluated the protective effects of CDDP alone and in combination with carbamazepine (CBZ) on kainic acid-induced TLE and cognitive impairment in rats. MATERIALS AND METHODS: Sprague-Dawley rats were randomly divided into five groups: control (sham operated), model, CDDP, CBZ and combined. A TLE model was then created via bilateral intrahippocampal injection of 0.35 µg kainic acid (KA). Rats received CDDP (85 mg/kg), CBZ (100 mg/kg) or combined (85 mg/kg CDDP +100 mg/kg CBZ) via intragastric administration for 90 d, respectively. Seizure intensity, apoptosis and glial cell line-derived neurotrophic factor (GDNF) were measured. Furthermore, the improvement in cognitive impairment and hippocampal neuronal damage was evaluated. RESULTS: CDDP combined with CBZ significantly decreased seizure severity and frequency (p < 0.05) and ameliorated cognitive impairment (p < 0.05). The model group showed a significant reduction of neurons and Bcl-2/Bax expression in the hippocampus CA3 area (p < 0.01), the combined groups significantly reversed these change (p < 0.01). GDNF expression in the combined groups showed a clear increase over the model group (p < 0.05). CONCLUSION: These findings support the use of CDDP as an adjuvant drug for the treatment of TLE and cognitive deficit. Its mechanism might be related to an anti-apoptosis effect and up-regulation of GDNF.

Effect of coenzyme Q10 on mitochondrial respiratory proteins in trigeminal neuralgia.

Trigeminal neuralgia (TN) is the neuropathic pain. Mitochondrial dysfunction, increased oxidative stress, and inflammation demonstrated in chronic pain. Carbamazepine (CBZ) is the first-line drug for TN, however, it is still insufficient. Coenzyme Q10 (CoQ10) has been used as the additional supplement for pain therapy. Nonetheless, mitochondrial respiratory proteins, oxidative stress, and inflammation in TN, and the add-on effects of CoQ10 on those defects have never been investigated. CBZ-treated TN-patients, naïve TN-patients, and control subjects were included. CBZ-treated TN-patients were randomised into two subgroups, received either CoQ10 or placebo for 2 months. Pain levels were evaluated, and peripheral blood mononuclear cells were isolated to determine the oxidative stress, mitochondrial oxidative phosphorylation (OXPHOS), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), and cytokines including TNF-α, IL-1ß and IL-18 mRNA expression. Pain scales, oxidative stress, and OXPHOS levels were greater in naïve TN-patients than control, whereas the cytokine profiles were unchanged. Although pain scales were lower in CBZ-treated TN-patients than in naïve TN-patients, oxidative stress, OXPHOS, and cytokine expression profiles were not different. PGC-1α levels found to be increased in CBZ-treated TN patients when compared with the naïve group. CoQ10 supplement in CBZ-treated TN patients reduced pain scale and oxidative stress and increased antioxidants levels when compared with placebo group. However, OXPHOS, PGC-1α, and cytokines were not different between groups. These findings suggest that increased oxidative stress could be potentially involved in the pathogenesis of TN. CoQ10 supplements can reduce oxidative stress, leading to more effective pain reduction in TN patients being treated with CBZ.

L-Arginine Co-Administration with Carbamazepine Improves Cognition in Male Sprague-Dawley Rats.

Cognitive impairment is a common adverse effect associated with carbamazepine use. One of the proposedmechanisms for cognitive impairment may be attributed to the pro-oxidant properties of carbamazepine. This studyinvestigated the effects of L-Arginine supplementation with carbamazepine on cognition in adult male non-epileptic rats.Adult male Sprague-Dawley rats with average weight 200g to 220g were divided into 4 groups; (1) Control group treatedwith distilled water, (2) L-Arginine group treated with L-Arginine (100mg/kg BW) in distilled water, (3) Carbamazepinegroup treated with carbamazepine (25mg/kg BW twice daily) in distilled water, and (4) Carbamazepine + L-Arginine grouptreated with Carbamazepine and L-Arginine as above for two weeks to assess the acute changes in cognition and oxidativestress markers. Following two weeks of treatment, cognition was assessed using the Y-maze, after which the rats werehumanely sacrificed with the hippocampus and frontal lobes isolated from the brain and subsequently homogenized forassessment of oxidative stress markers [(Catalase, superoxide dismutase (SOD), malondialdehyde (MDA), and reducedGlutathione (GSH)]. Arm entry and correct alternation were significantly higher (p < 0.05) in the L-Arginine and L-Arginine+ Carbamazepine groups compared to carbamazepine group. In the frontal lobe, L-Arginine significantly increased (p < 0.05)catalase and GSH levels compared to other groups while in the hippocampus, it significantly (p < 0.05) reduced MDA withno change in other parameters. Likewise, SOD and MDA levels were significantly lower (p < 0.05) in the L-Arginine +Carbamazepine group compared to other groups. Oral L-Arginine supplementation with carbamazepine improved cognitiveperformance on Y maze.

Using the affective bias test to predict drug-induced negative affect: implications for drug safety.

BACKGROUND AND PURPOSE: Predicting the risk of drug-induced adverse psychiatric effects is important but currently not possible in non-human species. We investigated whether the affective bias test (ABT) could provide a preclinical method with translational and predictive validity. EXPERIMENTAL APPROACH: The ABT is a bowl-digging task, which quantifies biases associated with learning and memory. Rats encounter independent learning experiences, on separate days, under either acute manipulations (e.g. pro-depressant vs. control) or different absolute reward values (e.g. high vs. low). A bias is observed during a preference test when an animal's choices reflect their prior experience. We investigated the effects of putative pro-depressant drug treatments following acute or chronic administration on the formation of an affective bias or reward-induced positive bias respectively. KEY RESULTS: The immunomodulators LPS (10 µg·kg-1 ), corticosterone (10 and 30 mg·kg-1 ) and IFN-α (100 U·kg-1 ) induced a negative affective bias following acute treatment. Tetrabenazine (1 mg·kg-1 ) also induced a negative bias, but no effects were observed with varenicline, carbamazepine or montelukast. Chronic treatment with IFN-α (100 U·kg-1 ) and retinoic acid (10 mg·kg-1 ) impaired the formation of a reward-induced positive bias but did not alter sucrose preference test (SPT). CONCLUSIONS AND IMPLICATIONS: The ABT has the potential to provide a novel approach to predict pro-depressant risk in a non-human species. Negative biases induced by acute treatment in the standard version of the task may also predict longer-term effects on reward processing as shown by the deficit in reward-induced positive bias following chronic treatment, an effect distinct from anhedonia in the SPT. LINKED ARTICLES: This article is part of a themed section on Pharmacology of Cognition: a Panacea for Neuropsychiatric Disease? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.19/issuetoc.

Anticonvulsant effects of antiaris toxicaria aqueous extract: investigation using animal models of temporal lobe epilepsy.

BACKGROUND: Antiaris toxicaria has previously shown anticonvulsant activity in acute animal models of epilepsy. The aqueous extract (AAE) was further investigated for activity in kindling with pentylenetetrazole and administration of pilocarpine and kainic acid which mimic temporal lobe epilepsy in various animal species. RESULTS: ICR mice and Sprague-Dawley rats were pre-treated with AAE (200-800 mg kg-1) and convulsive episodes induced using pentylenetetrazole, pilocarpine and kainic acid. The potential of AAE to prevent or delay onset and alter duration of seizures were measured. In addition, damage to hippocampal cells was assessed in kainic acid-induced status epilepticus test. 800 mg kg-1 of the extract suppressed the kindled seizure significantly (P < 0.05) as did diazepam. AAE also produced significant effect (P < 0.01) on latency to first myoclonic jerks and on total duration of seizures. The latency to onset of wet dog shakes was increased significantly (P < 0.05) by AAE on kainic acid administration. Carbamazepine and Nifedipine (30 mg kg-1) also delayed the onset. Histopathological examination of brain sections showed no protective effect on hippocampal cells by AAE and nifedipine. Carbamazepine offered better preservation of hippocampal cells in the CA1, CA2 and CA3 regions. CONCLUSION: Antiaris toxicaria may be effective in controlling temporal lobe seizures in rodents.

Pharmaceutical Metabolism in Fish: Using a 3-D Hepatic In Vitro Model to Assess Clearance.

At high internal doses, pharmaceuticals have the potential for inducing biological/pharmacological effects in fish. One particular concern for the environment is their potential to bioaccumulate and reach pharmacological levels; the study of these implications for environmental risk assessment has therefore gained increasing attention. To avoid unnecessary testing on animals, in vitro methods for assessment of xenobiotic metabolism could aid in the ecotoxicological evaluation. Here we report the use of a 3-D in vitro liver organoid culture system (spheroids) derived from rainbow trout to measure the metabolism of seven pharmaceuticals using a substrate depletion assay. Of the pharmaceuticals tested, propranolol, diclofenac and phenylbutazone were metabolised by trout liver spheroids; atenolol, metoprolol, diazepam and carbamazepine were not. Substrate depletion kinetics data was used to estimate intrinsic hepatic clearance by this spheroid model, which was similar for diclofenac and approximately 5 fold higher for propranolol when compared to trout liver microsomal fraction (S9) data. These results suggest that liver spheroids could be used as a relevant and metabolically competent in vitro model with which to measure the biotransformation of pharmaceuticals in fish; and propranolol acts as a reproducible positive control.

Adenosine A1 receptor-mediated suppression of carbamazepine-resistant seizure-like events in human neocortical slices.

OBJECTIVE: The need for alternative pharmacologic strategies in treatment of epilepsies is pressing for about 30% of patients with epilepsy who do not experience satisfactory seizure control with present treatments. In temporal lobe epilepsy (TLE) even up to 80% of patients are pharmacoresistant, and surgical resection of the ictogenic tissue is only possible for a minority of TLE patients. In this study we investigate purinergic modulation of drug-resistant seizure-like events (SLEs) in human temporal cortex slices. METHODS: Layer V/VI field potentials from a total of 77 neocortical slices from 17 pharmacoresistant patients were recorded to monitor SLEs induced by application of 8 mM [K(+) ] and 50 µm bicuculline. RESULTS: Activating A1 receptors with a specific agonist completely suppressed SLEs in 73% of human temporal cortex slices. In the remaining slices, incidence of SLEs was markedly reduced. Because a subportion of slices can be pharmacosensitive, we tested effects of an A1 agonist, in slices insensitive to a high dose of carbamazepine (50 µm). Also in these cases the A1 agonist was equally efficient. Moreover, ATP and adenosine blocked or modulated SLEs, an effect mediated not by P2 receptors but rather by adenosine A1 receptors. SIGNIFICANCE: Selective activation of A1 receptors mediates a strong anticonvulsant action in human neocortical slices from pharmacoresistant patients. We propose that our human slice model of seizure-like activity is a feasible option for future studies investigating new antiepileptic drug (AED) candidates.

Influence of MPEP (a selective mGluR5 antagonist) on the anticonvulsant action of novel antiepileptic drugs against maximal electroshock-induced seizures in mice.

The aim of this study was to determine the effects of 2-methyl-6-(phenylethynyl)pyridine (MPEP - a selective antagonist for the glutamate metabotropic receptor subtype mGluR5) on the protective action of some novel antiepileptic drugs (lamotrigine, oxcarbazepine, pregabalin and topiramate) against maximal electroshock-induced seizures in mice. Brain concentrations of antiepileptic drugs were measured to determine whether MPEP altered pharmacokinetics of antiepileptic drugs. Intraperitoneal injection of 1.5 and 2mg/kg of MPEP significantly elevated the threshold for electroconvulsions in mice, whereas MPEP at a dose of 1mg/kg considerably enhanced the anticonvulsant activity of pregabalin and topiramate, but not that of lamotrigine or oxcarbazepine in the maximal electroshock-induced seizures in mice. Pharmacokinetic results revealed that MPEP (1mg/kg) did not alter total brain concentrations of pregabalin and topiramate, and the observed effect in the mouse maximal electroshock seizure model was pharmacodynamic in nature. Collectively, our preclinical data suggest that MPEP may be a safe and beneficial adjunct to the therapeutic effects of antiepileptic drugs in human patients.