Efficacy and Safety of Repetitive Intravenous Sodium Valproate in Pediatric Patients With Refractory Chronic Headache Disorders: A Retrospective Review.

BACKGROUND: Chronic headache disorders can cause substantial disability and be treatment refractory. Often, these patients are excluded from clinical trials with leaving little evidence to guide treatment. In adults, divalproex sodium is an effective preventive migraine treatment. METHODS: All pediatric patients admitted for first-time sodium valproate infusions to treat refractory, chronic migraine (CM), new daily persistent headache, or persistent headache attributed to head trauma from January 2017 to October 2020 were identified for review. Each patient underwent a standardized, 4-day protocol. A new preventive was started one week after discharge. Data on headache frequency, severity, and acute medication use were collected through preadmission and postadmission clinic notes. Safety and tolerability were evaluated. Results were evaluated using descriptive statistics and compared with paired t-tests. RESULTS: Forty-five patients were identified for review. Patients with CM had a median of 7 previous preventive trials, and 85% had previously received alternative intravenous treatment for headache. Baseline headache pain significant decreased from 6.9/10 to 5.4/10 by 7-week postadmission follow up, (95% confidence interval = -0.7 to -2.4), P < 0.001. Use of medications for acute headache treatment decreased significantly from 2.1 days/week to 1.5 days/week, (95% confidence interval = -0.3 to -1), P < 0.001. Baseline headache frequency did not significantly change. At postadmission follow-up, 26 of 39 (67%) patients saw improvements in headache frequency, headache intensity, and/or acute pain medication usage. There were no serious adverse events. CONCLUSIONS: Repetitive sodium valproate infusions were well tolerated and significantly reduced baseline headache intensity and acute medication usage in pediatric patients with refractory, chronic headache disorders.

Paradoxical anesthesia: Sleep-like EEG during anesthesia induced by mesopontine microinjection of GABAergic agents.

General anesthetic agents are thought to induce loss-of-consciousness (LOC) and enable pain-free surgery by acting on the endogenous brain circuitry responsible for sleep-wake cycling. In clinical use, the entire CNS is exposed to anesthetic molecules with LOC and amnesia usually attributed to synaptic suppression in the cerebral cortex and immobility and analgesia to agent action in the spinal cord and brainstem. This model of patch-wise suppression has been challenged, however, by the observation that all functional components of anesthesia can be induced by focal delivery of minute quantities of GABAergic agonists to the brainstem mesopontine tegmental anesthesia area (MPTA). We compared spectral features of the cortical electroencephalogram (EEG) in rats during systemic anesthesia and anesthesia induced by MPTA microinjection. Systemic administration of (GABAergic) pentobarbital yielded the sustained, δ-band dominant EEG signature familiar in clinical anesthesia. In contrast, anesthesia induced by MPTA microinjection (pentobarbital or muscimol) featured epochs of δ-band EEG alternating with the wake-like EEG, the pattern typical of natural non-rapid-eye-movement (NREM) and REM sleep. The rats were not sleeping, however, as they remained immobile, atonic and unresponsive to noxious pinch. Recalling the paradoxical wake-like quality the EEG during REM sleep, we refer to this state as "paradoxical anesthesia". GABAergic anesthetics appear to co-opt both cortical and spinal components of the sleep network via dedicated axonal pathways driven by MPTA neurons. Direct drug exposure of cortical and spinal neurons is not necessary, and is probably responsible for off-target side-effects of systemic administration including monotonous δ-band EEG, hypothermia and respiratory depression. SIGNIFICANCE STATEMENT: The concept that GABAergic general anesthetic agents induce loss-of-consciousness by substituting for an endogenous neurotransmitter, thereby co-opting neural circuitry responsible for sleep-wake transitions, has gained considerable traction. However, the electroencephalographic (EEG) signatures of sleep and anesthesia differ fundamentally. We show that when the anesthetic state is generated by focal delivery of GABAergics into the mesopontine tegmental anesthesia area (MPTA) the resulting EEG repeatedly transitions between delta-wave-dominant and wake-like patterns much as in REM-NREM sleep. This suggests that systemic (clinical) anesthetic delivery, which indiscriminately floods the entire cerebrum with powerful inhibitory agents, obscures the sleep-like EEG signature associated with the less adulterated form of anesthesia obtained when the drugs are applied selectively to loci where the effective neurotransmitter substitution actually occurs.

Valproic acid treated female Long-Evans rats are impaired on attentional set-shifting.

Autism spectrum disorder (ASD), is a neurodevelopmental disorder characterized by social deficits, communication impairments, restrictive behaviors, and cognitive flexibility deficits. The valproic acid (VPA) model of autism has been widely used to examine changes in rodent behavior and neurobiology to better understand ASD. This study examined social and anxiety behavior as well as cognitive flexibility in VPA and control offspring. Results for social behavior were consistent with prior studies showing reduced sociability in VPA rats and increased self-grooming, which may be viewed as a repetitive behavior. VPA rats also had deficits in performing the set-shifting task, with female VPA rats demonstrating greater impairment compared to female control rats and male VPA rats. These results support the hypothesis that females diagnosed with ASD may suffer from different symptoms and present a unique behavioral profile compared to males with ASD. Female VPA rats were also less likely to form an attentional set; offering evidence that the VPA model of autism is encompassing executive function deficits similar to those observed in humans with ASD.

Association of timing of gabapentinoid use with motor recovery after spinal cord injury.

OBJECTIVE: To explore the hypothesis that earlier administration of acute gabapentinoids is beneficial to motor recovery after spinal cord injury in humans. METHODS: This is an observational study using a cohort from the European Multi-Centre Study about Spinal Cord Injury. Patient charts were reviewed to extract information regarding the administration and timing of gabapentinoid anticonvulsants. The primary outcome measure was motor scores, as measured by the International Standards for Neurological Classification of Spinal Cord Injury, collected longitudinally in the first year after injury. Sensory scores (light touch and pinprick) and functional measures (Spinal Cord Independence Measure) were secondary outcomes. Linear mixed effects regression models included a drug-by-time interaction to determine whether exposure to gabapentinoids altered recovery of muscle strength in the first year after injury. RESULTS: A total of 201 participants were included in the study and had a median age of 46 and baseline motor score of 50. Participants were mostly men (85%) with sensory and motor complete injuries (50%). Seventy individuals (35%) were administered gabapentinoids within the first 30 days after injury, and presented with similar demographics. In the longitudinal model, the administration of gabapentinoids within 30 days after injury was associated with improved motor recovery when compared to those who did not receive gabapentinoids during this time (3.69 additional motor points from 4 to 48 weeks after injury; p = 0.03). This effect size increased as administration occurred earlier after injury (i.e., a benefit of 4.68 points when administered within 5 days). CONCLUSIONS: This retrospective, observational study provided evidence of the beneficial effect of gabapentinoid anticonvulsants on motor recovery after spinal cord injury. More critically, it highlighted a potential time dependence, suggesting that earlier intervention is associated with better outcomes. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that gabapentinoids improve motor recovery for individuals with acute spinal cord injury.

Microinjection of valproic acid into the ventrolateral orbital cortex exerts an antinociceptive effect in a rat of neuropathic pain.

RATIONALE: Ventrolateral orbital cortex (VLO) has been found to play an important role in the regulation of neuropathic pain (NPP). As a traditional mood stabilizer, valproic acid (VPA) is currently employed in the treatment of NPP. However, whether VPA plays an analgesic role in VLO is still unknown. OBJECTIVES: To elucidate the underlying analgesic mechanism of microinjection of VPA into the VLO on spared nerve injury (SNI), an animal model of NPP. METHODS: We firstly examined the role of VPA by intraperitoneal and intral-VLO injection. Then, we accessed its role as a histone deacetylase inhibitor by intral-VLO microinjection of sodium butyrate. Finally, the GABAergic mechanism was measured through the intra-VLO microinjection of several agonists and antagonists of various GABAergic receptor subtypes. RESULTS: Both intraperitoneal and intral-VLO injection of VPA attenuated SNI-induced mechanical allodynia. Microinjection of sodium butyrate, one of the histone deacetylase inhibitors, into the VLO attenuated the mechanical allodynia. Besides, microinjection of valpromide, a derivative of VPA which is a GABAergic agonist, into the VLO also attenuated allodynia. Furthermore, microinjection of picrotoxin, a GABAA receptor antagonist, into the VLO attenuated mechanical allodynia; microinjection of picrotoxin before VPA into the VLO increased VPA-induced anti-allodynia. Besides, microinjection of CGP 35348, a GABAB receptor antagonist, into the VLO attenuated allodynia; microinjection of CGP 35348 before VPA into the VLO also increased VPA-induced anti-allodynia. What is more, microinjection of imidazole-4-acetic acid (I4AA), a GABAC receptor antagonist, into the VLO enhanced allodynia; microinjection of I4AA before VPA into the VLO decreased VPA-induced anti-allodynia. CONCLUSIONS: These results suggest that both the histone acetylation mechanism and GABAergic system are involved in mediating VLO-induced anti-hypersensitivity.

Bioactive nanoparticle embedded microcapsules for improving the efficacy of type I diabetes therapy.

In order to overcome the side effects of pancreatic transplantation and insulin injection treatment for type I diabetes, we established a drug delivery system employing nanoparticle embedded microcapsules (NEMs). The system co-encapsulated chitosan nanoparticles with γ-aminobutyric acid and ß-TC-6 cells for combined drug and cell therapy in diabetes mellitus (DM). The NEMs, which were formed via high-voltage electrostatic method, had an excellent sphericity with a smooth surface. The average size NEM was 245.52 ± 22.00 µm, which indicated a good size for cell encapsulation. Haemolysis rate of NEMs at concentrations of 100, 200 or 300 mg/mL were all below 5%. Relative viability rates of L929 cells with the same concentrations at 24, 48 or 72 h were all above 80%. We implanted bioactive NEMs into type 1 DM mice to evaluate the effect of the combined therapy. The level of blood glucose in the group receiving the combined therapy decreased during the first 2 weeks of treatment. During the next week, the level of blood glucose stayed in a safe range. Body weight continuously increased during the postoperative period after combined therapy group. Oral glucose tolerance test (OGTT) performed after 24 d showed that the level of blood glucose combined therapy reached the maximum peak of 13.04 mmol/L, lower than 16.56 mmol/L for the cell therapy group. This primary study indicated that microencapsulation technology and combined therapy are promising for the treatment of type I diabetes mellitus.

The pro-algesic effect of γ-aminobutyric acid (GABA) injection into the masseter muscle of healthy men and women.

Background and aims Preclinical studies have reported that activation of peripheral γ-aminobutyric acid A (GABAA) receptors may result in analgesia. The current study was conducted in young healthy men (n = 30) and women (n = 28) to determine whether injections of GABA into the masseter muscle reduce pain in a sex-related manner. Methods The effect of injection of GABA alone, or in combination with the non-inflammatory algogen glutamate, was assessed in two separate studies. Lorazepam, a positive allosteric modulator of the GABAA-receptor, was co-injected with GABA in both studies to explore the role of this receptor in muscle pain responses of healthy human volunteers. Masticatory muscle mechanical pain intensity was recorded on an electronic visual analogue scale (VAS) while muscle pain sensitivity was assessed by determining the pressure pain threshold (PPT), tolerance and maximal jaw opening (MJO) of the subjects prior to, and again after the various intramuscular injections. Results Intramuscular injection of GABA alone was reported to be significantly more painful, in a concentration related manner, than saline control injections, and this pain was further increased by co-injection of lorazepam with GABA. Co-injection of GABA with glutamate was found to significantly increase glutamate-evoked masseter muscle pain in men, but not in women. There was no effect of injections of either GABA alone, or GABA with glutamate, on PPT, tolerance or maximum jaw opening. Conclusions Injection of GABA into the human masseter muscle appears to excite nociceptors to produce muscle pain without a longer term effect on mechanical pain sensitivity in the muscle. The findings suggest that GABA-mediated pain in humans is produced through peripheral GABAA receptor activation. The mechanism underlying the sex-related difference in the effect of GABA on glutamate-evoked muscle pain was speculated to be due to a methodological artifact. Implications This study was designed to detect analgesic rather than algesic effects of peripherally administered GABA, and as a result, the concentration of glutamate chosen for injection was close to the maximal pain response for healthy women, based on previously determined pain-concentration response relationships for glutamate. This may explain the finding of greater pain in men than women, when GABA and glutamate were co-injected. Overall, the findings suggest that activation of peripheral GABAA receptors in human masticatory muscle produces pain, possibly due to depolarization of the masticatory muscle afferent fibers.

Sodium Divalproate in Low Alternating Daily Doses for Migraine Prevention: A Retrospective Study.

BACKGROUND AND OBJECTIVE: Sodium divalproate is an effective neuromodulator for migraine prevention. Recommended doses vary from 1,000 to 1,500 mg/day, which may provoke unpleasant side effects as weight gain, tremor, and hair loss. Some patients do respond to lower doses even used once daily in ER presentations, but alternating low daily doses was never studied so far. The aim of this study was to evaluate the adherence, the tolerability, and the efficacy of sodium divalproate (SD) in low alternating daily doses for migraine prevention in patients of a tertiary center. METHODS: Consecutive migraineurs from a tertiary center to whom SD was prescribed as monotherapy from January 2017 until September 2018 were studied retrospectively. The doses were 250 mg alternated with 500 mg and were used based on the treating physician expertise and previous experience with tolerability issues when using higher doses. Headache frequency compared to baseline, adherence expressed by returning to a visit after 2 and 4 months and side effects reported by the patients, were evaluated. RESULTS: Sixty-eight patients (53 women and 15 men, aged 18-58) were included. The average headache frequency (HF) during baseline was decreased from 8.2 to 5.1 headache days/month among the 50 out of 68 patients returning at 2 months (adherence rate 73.5%). Weight gain was reported by 15 patients (30%, mean 2.1 kg). At 4 months, HF was reduced to 4.2 days/month (adherence rate 61.8%, n = 42) and weight gain reported by 18 patients (42.8%, mean 2.3 kg). CONCLUSIONS: Despite the retrospective open design, which cannot allow definitive conclusions, SD in low alternating daily doses seems to be effective as with higher doses, but still induce modest weight gain. Controlled studies are necessary to confirm these observations.

Retrospective analysis of a gabapentin high dose taper compared to lorazepam in acute inpatient alcohol withdrawal.

Background: Benzodiazepines have remained the standard of care for alcohol withdrawal syndrome; however, they have numerous unfavorable physiologic effects. Gabapentin has limited data to support a benefit in reducing benzodiazepine usage in alcohol withdrawal syndrome.Objectives: Evaluate the association of an institutional guideline and order set for alcohol withdrawal that incorporates high dose gabapentin tapers in acutely withdrawing patients. Methods: This retrospective study evaluated patients experiencing acute alcohol withdrawal. Two time periods were evaluated: a pre-protocol group assessed outcomes prior to implementation of a gabapentin backbone taper-based guideline (PRE-implementation), and a post-protocol group assessed post-guideline and order set introduction (POST-implementation). A total of 100 patients (50 PRE-implementation and 50 POST-implementation; 84% male, 16% female) were included in the analysis. Results: There was a significant difference in the median daily lorazepam usage in the PRE-implementation versus POST-implementation groups (9.48 [5.58-28.46] vs 6.52 [3.84-11.65] mg, P = 0.024) with a reduction observed in the POST-implementation group. There was also a significant difference in the mean hospital length of stay (LOS) in the PRE-implementation versus POST-implementation groups (9.92 ± 7.33 vs 7.04 ± 4.59 days, P = 0.021) in favor of the POST-implementation group. There was no difference in the number of rapid responses called, median intensive care unit (ICU) LOS, median number of days the patient was confusion assessment method for the ICU (CAM-ICU) positive or number of transfers to a higher level of care. Conclusions: Implementation of an institutional guideline and order set for alcohol withdrawal incorporating high dose gabapentin tapers was associated with a decreased median daily lorazepam use as well as hospital LOS; however, retrospective design and inherent limitations require larger prospective trials to validate results.

Electrophoretic drug delivery for seizure control.

The persistence of intractable neurological disorders necessitates novel therapeutic solutions. We demonstrate the utility of direct in situ electrophoretic drug delivery to treat neurological disorders. We present a neural probe incorporating a microfluidic ion pump (µFIP) for on-demand drug delivery and electrodes for recording local neural activity. The µFIP works by electrophoretically pumping ions across an ion exchange membrane and thereby delivers only the drug of interest and not the solvent. This "dry" delivery enables precise drug release into the brain region with negligible local pressure increase. The therapeutic potential of the µFIP probe is tested in a rodent model of epilepsy. The µFIP probe can detect pathological activity and then intervene to stop seizures by delivering inhibitory neurotransmitters directly to the seizure source. We anticipate that further tailored engineering of the µFIP platform will enable additional applications in neural interfacing and the treatment of neurological disorders.

Therapeutic potential of valproic acid in advanced glaucoma: A pilot study.

Purpose: Oral valproic acid (VPA) used as an anticonvulsant has been shown to improve contrast threshold sensitivities in patients receiving it on long-term. This study aimed to evaluate the efficacy of oral VPA in improving visual function in eyes with advanced stage glaucoma. Methods: In this prospective randomized study, 31 patients (n = 31 eyes) with advanced stage glaucoma (with an intraocular pressure <16 mmHg) in at least one eye received oral VPA 500 mg once a day for 3 months and 33 patients (n = 33 eyes) continued on glaucoma therapy. Patients were followed up at 3 and 12 months (to evaluate the legacy effect of the drug). Blood VPA concentrations were measured at 3 months. Following parameters were assessed at baseline, 3 months and 12 months: log of the minimum angle of resolution (LogMAR) visual acuity, mean deviation on visual fields, and multifocal electroretinogram (ERG). Results: Median LogMar visual acuity in the VPA group improved from 0.3 at baseline to 0.18 and 0.18 at 3 and 12 months, respectively (P < 0.01). In comparison, the median visual acuity in control group at baseline was 0.18 and showed neither worsening nor improvement over 3 and 12 months (P = 0.56). The improvement in VPA group was significant compared to the control group (P < 0.01; Wilcoxon Signed-rank test). An improvement in one line was experienced in 11 out of 31 eyes in the VPA group compared to 1 out of 33 eyes among controls (P = 0.003). No significant improvement was noted in the mean deviation, and the multifocal ERG (Latency and amplitudes) in the VPA-treated patients. The average blood VPA concentration measured at 3 months of therapy was 26 ± 8.9 µg/ml (range 8-55 µg/ml) which is much lower than that achieved during anticonvulsant therapy. None of the patients complained of any adverse effects that required stopping VPA therapy. Conclusion: A 3 months oral VPA therapy results in some improvement in visual acuity in a subgroup of eyes with advanced glaucoma and the effect was seen to persist 9 months after the drug was stopped.

Intervention effect of gamma aminobutyric acid on anxiety behavior induced by phthalate (2-ethylhexyl ester) in rats.

BACKGROUND: Di(2-ethylhexyl) phthalate (DEHP) is one of the most widely used phthalate esters. The application of DEHP has caused serious environmental pollution and posed a threat to human health. METHODS: A total of 30 male Sprague-Dawley rats were randomly divided into control group, DEHP group (500 mg/kg DEHP), low GABA (Gama-aminobutyric acid) group (500 mg/kg DEHP and 1 mg/kg GABA), medium GABA group (500 mg/kg DEHP and 2 mg/kg GABA) and high GABA group (500 mg/kg DEHP and 4 mg/kg GABA). The interventions continued for 30 consecutive days. Open-field test and elevated plus-maze test were used to detect behavioral changes of rats before and after interventions. RESULTS: The levels of nitric oxide and nitric oxide synthase in prefrontal cortex of rats were measured using enzyme-linked immunosorbent assay. DEHP and GABA treatment had no significant effects on the body weight of rats. GABA restored food utilization rate of rats impaired by DEHP to the level of healthy rats. According to open-field test and elevated plus-maze test, GABA alleviated the effects of DEHP on rat behaviors. Enzyme-linked immunosorbent assay showed that GABA was effective in reducing the levels of nitric oxide and nitric oxide synthase in rats treated with DEHP. CONCLUSION: DEHP exposure induced anxiety in rats, which may be achieved through elevating nitric oxide and nitric oxide synthase levels in prefrontal cortex of rats. However, the effects caused by DEHP could be alleviated by GABA.

Brief activation of GABAergic interneurons initiates the transition to ictal events through post-inhibitory rebound excitation.

Activation of γ-aminobutyric acid (GABAA) receptors have been associated with the onset of epileptiform events. To investigate if a causal relationship exists between GABAA receptor activation and ictal event onset, we activated inhibitory GABAergic networks in the superficial layer (2/3) of the somatosensory cortex during hyperexcitable conditions using optogenetic techniques in mice expressing channelrhodopsin-2 in all GABAergic interneurons. We found that a brief 30ms light pulse reliably triggered either an interictal-like event (IIE) or ictal-like ("ictal") event in the in vitro cortical 4-Aminopyridine (4-AP) slice model. The link between light pulse and epileptiform event onset was lost following blockade of GABAA receptors with bicuculline methiodide. Additionally, recording the chronological sequence of events following a light pulse in a variety of configurations (whole-cell, gramicidin-perforated patch, and multi-electrode array) demonstrated an initial hyperpolarization followed by post-inhibitory rebound spiking and a subsequent slow depolarization at the transition to epileptiform activity. Furthermore, the light-triggered ictal events were independent of the duration or intensity of the initiating light pulse, suggesting an underlying regenerative mechanism. Moreover, we demonstrated that brief GABAA receptor activation can initiate ictal events in the in vivo 4-AP mouse model, in another common in vitro model of epileptiform activity, and in neocortical tissue resected from epilepsy patients. Our findings reveal that the synchronous activation of GABAergic interneurons is a robust trigger for ictal event onset in hyperexcitable cortical networks.

Effect of feeding Rumen-protected capsule containing niacin, K2SO4, vitamin C, and gamma-aminobutyric acid on heat stress and performance of dairy cows.

This study was conducted to evaluate the effects of supplemental rumen-protected capsule (RPC) on animal performance, serological indicators, and serum heat shock protein 70 (HSP70) of lactating Holstein cows under heat stress (HS). During summer months, 30 healthy multiparous lactating Holstein cows with a parity number of 3.1 ± 0.44, 70 ± 15 d in milk, an average body weight of 622 ± 62kg, and an average milk yield of 32.28 ± 0.96kg/d, were used. The cows were randomly allocated to two groups: a control group and an RPC-supplemented group (0.13373kg K2SO4, 0.02488kg vitamin C, 0.021148kg niacin, and 0.044784kggamma-aminobutyric acid per cow). During the 42-d experiment, ambient air temperature and relative humidity inside and outside the barn were recorded hourly every day for the determination of temperature-humidity index (THI). Milk and blood samples were collected every week, and body weight and body condition scoring were measured on day 0. Based on the THI values, the animals had moderate HS. On day 42, the RPC group had lower HSP70, adrenocorticotropic hormone (P = 0.0001), lactate dehydrogenase (P = 0.0338), and IL-6 (P = 0.0724) levels than the control group, with no significant differences in creatine kinase, glucocorticoid, or IL-2 levels. Milk yield, energy-corrected milk, and dry matter intake were higher in RPC than in the control group (P = 0.0196). There were no significant differences in milk fat or daily protein levels between the two groups; however, daily protein and milk fat levels were higher in the RPC group than in the control group (P = 0.0114 and P = 0.0665, respectively). Somatic cell counts were no different between the two groups. In conclusion, RPC may alleviate HS and improve dairy cow performance.

Terminalia arjuna bark extract attenuates picrotoxin-induced behavioral changes by activation of serotonergic, dopaminergic, GABAergic and antioxidant systems.

Stress and emotion are associated with several illnesses from headaches to heart diseases and immune deficiencies to central nervous system. Terminalia arjuna has been referred as traditional Indian medicine for several ailments. The present study aimed to elucidate the effect of T. arjuna bark extract (TA) against picrotoxin-induced anxiety. Forty two male Balb/c mice were randomly divided into six experimental groups (n = 7): control, diazepam (1.5 mg·kg-1), picrotoxin (1 mg·kg-1) and three TA treatemt groups (25, 50, and 100 mg/kg). Behavioral paradigms and PCR studies were performed to determine the effect of TA against picrotoxin-induced anxiety. The results showed that TA supplementation increased locomotion towards open arm (EPM) and illuminated area (light-dark box test), and increased rearing frequency (open field test) in a dose dependent manner, compared to picrotoxin (P < 0.05). Furthermore, TA increased number of licks and shocks in Vogel's conflict. PCR studies showed an up-regulation of several genes, such as BDNF, IP3, D2L, CREB, GABAA, SOD, GPx, and GR in TA administered groups. In conclusion, alcoholic extract of TA bark showed protective activity against picrotoxin in mice by modulation of genes related to synaptic plasticity, neurotransmitters, and antioxidant enzymes.

Flow characterization and patch clamp dose responses using jet microfluidics in a tubeless microfluidic device.

BACKGROUND: Surface tension passive pumping is a way to actuate flow without the need for pumps, tubing or valves by using the pressure inside small drop to move liquid via a microfluidic channel. These types of tubeless devices have typically been used in cell biology. Herein we present the use of tubeless devices as a fluid exchange platform for patch clamp electrophysiology. NEW METHOD: Inertia from high-speed droplets and jets is used to create flow and perform on-the-fly mixing of solutions. These are then flowed over GABA transfected HEK cells under patch in order to perform a dose response analysis. RESULTS: TIRF imaging and electrical recordings are used to study the fluid exchange properties of the microfluidic device, resulting in 0-90% fluid exchange times of hundreds of milliseconds. COMSOL is used to model flow and fluid exchange within the device. Patch-clamping experiments show the ability to use high-speed passive pumping and its derivatives for studying peak dose responses, but not for studying ion channel kinetics. COMPARISON WITH EXISTING METHOD(S): Our system results in fluid exchange times slower than when using a standard 12-barrel application system and is not as stable as traditional methods, but it offers a new platform with added functionality. CONCLUSIONS: Surface tension passive pumping and tubeless devices can be used in a limited fashion for electrophysiology. Users may obtain peak dose responses but the system, in its current form, is not capable of fluid exchange fast enough to study the kinetics of most ion channels.

[Pharmacological treatment of chronic non-cancer pain].

19% of the grown-up Danish population suffer from a chronic pain condition. Most patients are treated by general practi-tioners (GPs), and only a smaller group need specialist treatment. This article goes through the pharmacological possibilities available with a special focus on treatment by GPs. For chronic pain as fibromyalgia and low back pain non-steroidal anti-inflammatory drugs and paracetamol are not recommended on a regular basis. The main pharmacological treatment is tricyclic antidepressants and gabapentinoids. If opioids are needed, long acting drugs are preferred.

Bioequivalence of two formulations of pregabalin 150-mg capsules under fasting conditions in healthy male subjects
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BACKGROUND: Pregabalin binds to the α2δ auxiliary subunit of voltage-gated calcium channels, which are widely distributed throughout the central and peripheral nervous systems and modulate calcium-dependent neurotransmitter release. Pregabalin is indicated for the treatment of peripheral and central neuropathic pain, partial seizures with or without secondary generalization, and treatment of generalized anxiety disorder (GAD). OBJECTIVE: The purpose of this study was to assess the bioequivalence of two different formulations of pregabalin 150-mg capsules in healthy Korean male subjects under fasting conditions. METHODS: This bioequivalence study was based on an open-label, single-dose, randomized, 2-period, 2-sequence crossover design with a washout period of 7 days. Blood samples for pharmacokinetic (PK) evaluation were collected up to 24 hours postdose. Plasma concentrations of pregabalin were determined using a validated LC-MS/MS method. PK parameters were determined using noncompartmental analysis. Bioequivalence was assumed if the 90% confidence intervals (CIs) for the test/reference ratios of log-transformed Cmax and AUClast values met the bioequivalence criteria specified by Korean regulatory guidelines (90% CI 0.8 - 1.25). RESULTS: The extent of exposure in terms of AUClast amounted to 26,018.3 - 3,580.8 µg×h/L for the test formulation and 25,680.2 ± 3,083.6 µg×h/L for the reference formulation. Cmax reached values of 4,782.7 ± 1,124.2 µg/L and 4,654.0 ± 911.4 µg/L for the test product and reference product, respectively. The geometric mean ratio and 90% CIs of the test product to the reference product were 1.0132 (0.9862 - 1.0351) for AUClast and 1.0153 (0.9351 - 1.1044) for Cmax, which were well within the range necessary to establish bioequivalence (90% CI 0.8 - 1.25). CONCLUSIONS: The bioequivalence between test and reference formulations under fasting conditions was confirmed both in terms of the rate and extent of absorption.
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Increased GABAA receptor binding in amygdala after prenatal administration of valproic acid to rats.

OBJECTIVE: Prenatal exposure to valproic acid (VPA) enhances the risk for later development of autism spectrum disorders (ASD). An altered gamma-aminobutyric acid (GABA) system may be a key factor in ASD. Here we investigated possible changes in the GABA system in rats exposed to a low dose of prenatal VPA. METHOD: We performed autoradiography with [3H]muscimol, (a GABAA receptor agonist), and [11C]Ro15-4513 (a partial agonist of the GABAA α1+5 receptor subtypes), in brain sections containing amygdala, thalamus and hippocampus of rats treated prenatally with 20 mg/kg VPA or saline from the 12th day of gestation. Result Prenatal VPA significantly increased [11C]Ro15-4513 binding in the left amygdala compared with controls (p<0.05). This difference was not observed in the hippocampus, thalamus or right amygdala. No differences were observed in [3H]muscimol binding. CONCLUSION: We observed an asymmetric increase in GABAA receptor binding. Disturbances in the GABAA receptor system have also been detected in human autism with [11C]Ro15-4513.