Long-term effects of diazepam and phenobarbital treatment during development on GABA receptors, transporters and glutamic acid decarboxylase

Study of phenobarbital removal from the aqueous solutions employing magnetite-functionalized chitosan

Due to its wide use in anticonvulsant pharmacotherapy, phenobarbital (PHEN) is an aquatic contaminant with a high prevalence in the environment. In this adsorption study, chitosan and chitosan-based magnetic adsorbents containing different amounts of incorporated magnetite (CS, CS·Fe₃O₄ 1:1, CS·Fe₃O₄ 1:5, and CS·Fe₃O₄ 1:10) were used for phenobarbital removal. The magnetic adsorbents were synthesized by co-precipitation method and characterized through FTIR, XRD, MEV, and VSM analysis. In PHEN adsorption, the equilibrium and adsorption kinetic were better adjusted by the Sips and pseudo-second-order model, respectively. Among the four nanoadsorbents used, the maximum phenobarbital adsorption capacity was 94.60 mg g^-1 using 25 mg of CS·Fe₃O₄ 1:5, with a concentration of PHEN (50 mg L^-1), pH 7.0 at room temperature. The parameters of pH, adsorbent dosage, ionic strength, and thermodynamic study were tested for the adsorbent with the highest performance (CS·Fe₃O₄ 1:5). The nanoadsorbent demonstrates efficiency in the removal of the contaminant for diverse adsorption cycles. Finally, the protocol employing magnetic adsorbents dispenses the subsequent steps of filtration and centrifugation.

Neuroplastic alterations in cannabinoid receptors type 1 (CB1) in animal models of epileptic seizures

Currently, there is an urgent need to better comprehend neuroplastic alterations in cannabinoid receptors type 1 (CB1) and to understand the biological meaning of these alterations in epileptic disorders. The present study reviewed neuroplastic changes in CB1 distribution, expression, and functionality in animal models of epileptic seizures. Neuroplastic alterations in CB1 were consistently observed in chemical, genetic, electrical, and febrile seizure models. Most studies assessed changes in hippocampal and cortical CB1, while thalamic, hypothalamic, and brainstem nuclei were rarely investigated. Additionally, the relationship between CB1 alteration and the control of brain excitability through modulation of specific neuronal networks, such as striatonigral, nigrotectal and thalamocortical pathways, and inhibitory projections to hippocampal pyramidal neurons, were all presented and discussed in the present review. Neuroplastic alterations in CB1 detected in animal models of epilepsy may reflect two different scenarios: (1) endogenous adaptations aimed to control neuronal hyperexcitability in epilepsy or (2) pathological alterations that facilitate neuronal hyperexcitability. Additionally, a better comprehension of neuroplastic and functional alterations in CB1 can improve pharmacological therapies for epilepsies and their comorbidities.

Reduced GABAergic neuropil and interneuron profiles in schizophrenia: Complementary analysis of disease course-related differences

BACKGROUND

GABAergic interneuron dysfunction has been implicated in the pathophysiology of schizophrenia. Expression of glutamic acid decarboxylase (GAD), a key enzyme in GABA synthesis, may also be altered. Here, we have simultaneously evaluated GAD-immunoreactive (GAD-ir) neuropil and cell profiles in schizophrenia-relevant brain regions, and analysed disease-course related differences.

METHODS

GAD65/67 immunoreactivity was quantified in specific brain regions for profiles of fibres and cell bodies of interneurons by automated digital image analysis in post-mortem brains of 16 schizophrenia patients from paranoid (n = 10) and residual (n = 6) diagnostic subgroups and 16 matched controls. Regions of interest were superior temporal gyrus (STG) layers III and V, mediodorsal (MD) and laterodorsal (LD) thalamus, and hippocampal CA1 and dentate gyrus (DG) regions.

RESULTS

A reduction in GAD-ir neuropil profiles (p < 0.001), particularly in STG layer V (p = 0.012) and MD (p = 0.001), paralleled decreased GAD-ir cell profiles (p = 0.029) in schizophrenia patients compared to controls. Paranoid schizophrenia patients had lower GAD-ir neuron cell profiles in STG layers III (p = 0.007) and V (p = 0.001), MD (p = 0.002), CA1 (p = 0.001) and DG (p = 0.043) than residual patients. There was no difference in GAD-ir neuropil profiles between paranoid and residual subgroups (p = 0.369).

CONCLUSIONS

These results support the hypothesis of GABAergic dysfunction in schizophrenia. They show a more prominent reduction of GAD-ir interneurons in paranoid versus residual patients, suggestive of more pronounced GABAergic dysfunction in the former. Fully automated analyses of histological sections represent a step towards user-independent assessment of brain structure.

Transcranial Magnetic Stimulation and H1-Magnetic Resonance Spectroscopy Measures of Excitation and Inhibition Following Lorazepam Administration

This study aimed at better understanding the neurochemistry underlying transcranial magnetic stimulation (TMS) and magnetic resonance spectroscopy (MRS) measurements as it pertains to GABAergic activity following administration of allosteric GABA_A receptor agonist lorazepam. Seventeen healthy adults (8 females, 26.0 ± 5.4 years old) participated in a double-blind, crossover, placebo-controlled study, where participants underwent TMS and MRS two hours after drug intake (placebo or lorazepam; 2.5 mg). Neuronavigated TMS measures reflecting cortical inhibition and excitation were obtained in the left primary motor cortex. Sensorimotor cortex and occipital cortex MRS data were acquired using a 3T scanner with a MEGA-PRESS sequence, allowing water-referenced [GABA] and [Glx] (glutamate + glutamine) quantification. Lorazepam administration decreased occipital [GABA], decreased motor cortex excitability and increased GABA_A-receptor mediated motor cortex inhibition (short intracortical inhibition (SICI)). Lorazepam intake did not modulate sensorimotor [GABA] and TMS measures of intra-cortical facilitation, long-interval cortical inhibition, cortical silent period, and resting motor threshold. Furthermore, higher sensorimotor [GABA] was associated with higher cortical inhibition (SICI) following lorazepam administration, suggesting that baseline sensorimotor [GABA] may be valuable in predicting pharmacological or neuromodulatory treatment response. Finally, the differential effects of lorazepam on MRS and TMS measures, with respect to GABA, support the idea that TMS measures of cortical inhibition reflect synaptic GABAergic phasic inhibitory activity while MRS reflects extrasynaptic GABA.

Effects of a potassium channel opener on brain injury and neurologic outcomes in an animal model of neonatal hypoxic-ischemic injury

BACKGROUND

Hypoxia-ischemia (HI) is the most common cause of brain injury in newborns and the survivors often develop cognitive and sensorimotor disabilities that undermine the quality of life. In the current study, we examined the effectiveness of flupirtine, a potassium channel opener, shown previously in an animal model to have strong anti-neonatal-seizure efficacy, to provide neuroprotection and alleviate later-life disabilities caused by neonatal hypoxic-ischemic injury.

METHODS

The rats were treated with a single dose of flupirtine for 4 days following HI induction in 7-day-old rats. The first dose of flupirtine was given after the induction of HI and during the reperfusion period. The effect of treatment was examined on acute and chronic brain injury, motor functions, and cognitive abilities.

RESULTS

Flupirtine treatment significantly reduced HI-induced hippocampal and cortical tissue loss at acute time point. Furthermore, at chronic time point, flupirtine reduced contralateral hippocampal volume loss and partially reversed learning and memory impairments but failed to improve motor deficits.

CONCLUSION

The flupirtine treatment regimen used in the current study significantly reduced brain injury at acute time point in an animal model of neonatal hypoxic-ischemic encephalopathy. However, these neuroprotective effects were not persistent and only modest improvement in functional outcomes were observed at chronic time points.

Ziziphus spinosa seeds for insomnia: A review of chemistry and psychopharmacology

BACKGROUND

In Chinese medicine, Ziziphus jujuba Mill. var. spinosa (Bunge) Hu ex H. F. Chou is widely used for the treatment of insomnia.

PURPOSE/SECTIONS

This paper summarises the chemistry, psychopharmacology, and compares the pharmaceutical effects of the seeds of Ziziphus jujuba plant, Ziziphus spinosa (ZS) seeds, with benzodiazepines. Whole extracts and constituent compounds have been evaluated in preclinical and clinical studies.

CONCLUSIONS

ZS secondary metabolites modulate GABAergic activity and the serotonergic system. The actual therapeutic agents require further confirmation/identification so that new insomnia phytomedicines can be discovered.

Anticonvulsant effect of flupirtine in an animal model of neonatal hypoxic-ischemic encephalopathy

Research studies suggest that neonatal seizures, which are most commonly associated with hypoxic-ischemic injury, may contribute to brain injury and adverse neurologic outcome. Unfortunately, neonatal seizures are often resistant to treatment with current anticonvulsants. In the present study, we evaluated the efficacy of flupirtine, administered at clinically relevant time-points, for the treatment of neonatal seizures in an animal model of hypoxic-ischemic injury that closely replicates features of the human syndrome. We also compared the efficacy of flupirtine to that of phenobarbital, the current first-line drug for neonatal seizures. Flupirtine is a KCNQ potassium channel opener. KCNQ channels play an important role in controlling brain excitability during early development. In this study, hypoxic-ischemic injury was induced in neonatal rats, and synchronized video-EEG records were acquired at various time-points during the experiment to identify seizures. The results revealed that flupirtine, administered either 5 min after the first electroclinical seizure, or following completion of 2 h of hypoxia, i.e., during the immediate reperfusion period, reduced the number of rats with electroclinical seizures, and also the frequency and total duration of electroclinical seizures. Further, daily dosing of flupirtine decreased the seizure burden over 3 days following HI-induction, and modified the natural evolution of acute seizures. Moreover, compared to a therapeutic dose of phenobarbital, which was modestly effective against electroclinical seizures, flupirtine showed greater efficacy. Our results indicate that flupirtine is an extremely effective treatment for neonatal seizures in rats and provide evidence for a trial of this medication in newborn humans.

Epilepsy, Antiepileptic Drugs, and Aggression: An Evidence-Based Review

Antiepileptic drugs (AEDs) have many benefits but also many side effects, including aggression, agitation, and irritability, in some patients with epilepsy. This article offers a comprehensive summary of current understanding of aggressive behaviors in patients with epilepsy, including an evidence-based review of aggression during AED treatment. Aggression is seen in a minority of people with epilepsy. It is rarely seizure related but is interictal, sometimes occurring as part of complex psychiatric and behavioral comorbidities, and it is sometimes associated with AED treatment. We review the common neurotransmitter systems and brain regions implicated in both epilepsy and aggression, including the GABA, glutamate, serotonin, dopamine, and noradrenaline systems and the hippocampus, amygdala, prefrontal cortex, anterior cingulate cortex, and temporal lobes. Few controlled clinical studies have used behavioral measures to specifically examine aggression with AEDs, and most evidence comes from adverse event reporting from clinical and observational studies. A systematic approach was used to identify relevant publications, and we present a comprehensive, evidence-based summary of available data surrounding aggression-related behaviors with each of the currently available AEDs in both adults and in children/adolescents with epilepsy. A psychiatric history and history of a propensity toward aggression/anger should routinely be sought from patients, family members, and carers; its presence does not preclude the use of any specific AEDs, but those most likely to be implicated in these behaviors should be used with caution in such cases.

Pharmacokinetic Study of Swertisin by HPLC-MS/MS After Intravenous Administration in Rats

A sensitive and reliable high-performance liquid chromatography with tandem mass spectrometry was developed and validated for the quantification of swertisin in rat plasma. The samples were prepared with methanol by protein precipitation. Swertisin was separated by using an Agilent Poroshell 120 EC-C₁₈ column (4.6 mm × 50 mm, 2.7 μm) with the mobile phase consisted of acetonitrile and water containing 0.1% formic acid running at a flow rate of 0.3 mL/min for 5 min. The analytes were detected with the multiple reaction monitoring in the negative electrospray ionization source for quantitative response of swertisin [M-H]^- (445.1→281.7) and puerarin (internal standard) [M-H]^- (415.1→295.0). Precision (relative standard deviation, RSD%) of the inter-day and the intra-day was <9.89% and 11.34% while accuracy (relative error, RE%) ranged from -6.01% to 4.92% and -3.97% to 4.39%, respectively. Interestingly, the expression of the γ-aminobutyric acid (GABA) receptor subunits (GABA_Aα₁, GABA_Aα₅ and GABA_Aβ₁) mRNAs was enhanced in the rat hippocampal neurons treated with swertisin as analyzed by real-time polymerase chain reaction. Moreover, the method was successfully applied to determine the pharmacokinetic of swertisin in rats after tail vein injection with 4.0 mg/kg of the compound. Our results provide useful pharmacokinetic information for swertisin in vivo and suggest that the sedative function of this compound may be through inducing the expression of the GABA_A receptor subunits.

Phenobarbital Versus Valproate for Generalized Convulsive Status Epilepticus in Adults: A Prospective Randomized Controlled Trial in China

OBJECTIVE

Although generalized convulsive status epilepticus (GCSE) is a life-threatening emergency, evidence-based data to guide initial drug treatment choices are lacking in the Chinese population. We conducted this prospective, randomized, controlled trial to evaluate the relative efficacy and safety of intravenous phenobarbital and valproate in patients with GCSE.

METHODS

After the failure of first-line diazepam treatment, Chinese adult patients with GCSE were randomized to receive either intravenous phenobarbital (standard doses, low rate) or valproate (standard). Successful treatment was considered when clinical and electroencephalographic seizure activity ceased. Adverse events following treatment, as well as the neurological outcomes at discharge and 3 months later, were also evaluated.

RESULTS

Overall, 73 cases were enrolled in the study. Intravenous phenobarbital was successful in 81.1% of patients, and intravenous valproate was successful in 44.4% of patients (p < 0.05). The relapse rate of status epilepticus within 24 h of receiving phenobarbital (6.7%) was significantly lower than that in patients receiving valproate (31.3%), and the total number of adverse events did not differ significantly between the two groups (p > 0.05). In the phenobarbital group, two patients (5.4%) required ventilation and two patients (5.4%) developed serious hypotension. The neurological outcomes of the phenobarbital group were generally better than those of the valproate group; however, no significant differences were observed between phenobarbital and valproate with respect to mortality (8.1 vs. 16.6%) at discharge, or mortality (16.2 vs. 30.5%) and post-symptomatic epilepsy (26.3 vs. 42.8%) at 3-month follow-up.

CONCLUSIONS

Intravenous phenobarbital appears to be more effective than intravenous valproate for Chinese adult patients with GCSE. The occurrence of serious respiratory depression and hypotension caused by phenobarbital was reduced by decreasing the intravenous infusion rate; however, even at a lower infusion rate than typically used in other institutions, intravenous phenobarbital resulted in more serious adverse events than intravenous valproate. The better outcomes in the phenobarbital group compared with the valproate group suggest that phenobarbital should be considered for the early successful treatment of GCSE.

Consequences of early postnatal benzodiazepines exposure in rats. II. Social behavior

Social behavior represents an integral part of behavioral repertoire of rats particularly sensitive to pharmacological and environmental influences. The aim of the present study was to investigate whether early postnatal clonazepam (CZP) exposure can induce age-dependent changes related to expression of social behavior. The drug was administered from postnatal day (P) 7 until P11 at daily doses of 0.1, 0.5 and 1.0 mg/kg i.p. We designed three experiments to assess whether exposure to CZP affects social behavior in respect to the age of rats and the test circumstances, specifically their familiarity with test conditions during adolescence (P32), social behavior in juveniles and adolescents (P18–P42) and social behavior in a resident-intruder paradigm. The frequency and duration of a various patterns of social behavior related to play and social investigation not related to play were evaluated. The results showed that CZP postnatal exposure decreased social play behavior regardless of age and familiarity or unfamiliarity of experimental environment but did not affect the social investigation per se. When rats were confronted with an intruder in their home cages intense wrestling and inhibition of genital investigation were found. In conclusion, these findings show that short-term CZP postnatal exposure inhibits social play behavior and alters specific patterns of social behavior in an age and environment related manner.

Molecular mechanisms of antiseizure drug activity at GABAA receptors

The GABAA receptor (GABAAR) is a major target of antiseizure drugs (ASDs). A variety of agents that act at GABAARs s are used to terminate or prevent seizures. Many act at distinct receptor sites determined by the subunit composition of the holoreceptor. For the benzodiazepines, barbiturates, and loreclezole, actions at the GABAAR are the primary or only known mechanism of antiseizure action. For topiramate, felbamate, retigabine, losigamone and stiripentol, GABAAR modulation is one of several possible antiseizure mechanisms. Allopregnanolone, a progesterone metabolite that enhances GABAAR function, led to the development of ganaxolone. Other agents modulate GABAergic "tone" by regulating the synthesis, transport or breakdown of GABA. GABAAR efficacy is also affected by the transmembrane chloride gradient, which changes during development and in chronic epilepsy. This may provide an additional target for "GABAergic" ASDs. GABAAR subunit changes occur both acutely during status epilepticus and in chronic epilepsy, which alter both intrinsic GABAAR function and the response to GABAAR-acting ASDs. Manipulation of subunit expression patterns or novel ASDs targeting the altered receptors may provide a novel approach for seizure prevention.

Management of neonatal abstinence syndrome from opioids

Most infants at risk for neonatal abstinence syndrome have opioid plus another drug exposure; polypharmacy is the rule rather than the exception. Scales for evaluation of neonatal abstinence syndrome are primarily based for opioid withdrawal. A standard protocol to treat neonatal abstinence syndrome has not been developed. Institute nonpharmacologic strategies for all neonates at risk. The American Academy of Pediatrics recommends mechanism-directed therapy (treat opioid withdrawal with an opioid) as the first-line therapy. Second-line medications are currently under evaluation.

What is special about the adolescent (JME) brain?

Juvenile myoclonic epilepsy (JME) involves cortico-thalamo-cortical networks. Thalamic, frontal gray matter, connectivity, and neurotransmitter disturbances have been demonstrated by structural/functional imaging studies. Few patients with JME show mutations in genes coding ion channels or GABAA (gamma-aminobutyric acid) receptor subunits. Recent research points to EFHC1 gene mutations leading to microdysgenesis and possible aberrant circuitry. Imaging studies have shown massive structural/functional changes of normally developing adolescent brain structures maturing at strikingly different rates and times. Gray matter (GM) volume diminishes in cortical areas (frontal and parietal) and deep structures (anterior thalamus, putamen, and caudate). Diffusion tensor imaging (DTI) findings support continued microstructural change in WM (white matter) during late adolescence with robust developmental changes in thalamocortical connectivity. The GABAA receptor distribution and specific receptor subunits' expression patterns change with age from neonate to adolescent/adult, contributing to age-related changes in brain excitability. Hormonal influence on brain structure development during adolescence is presented. Possible implications of brain changes during adolescence on the course of JME are discussed.

Searching for new targets for treatment of pediatric epilepsy

The highest incidence of seizures in humans occurs during the first year of life. The high susceptibility to seizures in neonates and infants is paralleled by animal studies showing a high propensity to seizures during early life. The immature brain is highly susceptible to seizures because of an imbalance of excitation and inhibition. While the primary outcome determinant of early-life seizures is etiology, there is evidence that seizures which are frequent or prolonged can result in long-term adverse consequences, and there is a consensus that recurrent early-life seizures should be treated. Unfortunately, seizures in many neonates and children remain refractory to therapy. There is therefore a pressing need for new seizure drugs as well as antiepileptic targets in children. In this review, we focus on mechanisms of early-life seizures, such as hypoxia-ischemia, and novel molecular targets, including the hyperpolarization-activated cyclic nucleotide-gated channels.

Cognitive-impairing effects of medroxyprogesterone acetate in the rat: independent and interactive effects across time

RATIONALE

The synthetic progestin medroxyprogesterone acetate (MPA), widely used in hormone therapy (HT) and as the contraceptive Depo Provera, is implicated in detrimental cognitive effects in women. Recent evidence in aged ovariectomized (Ovx) rodents shows that short-term MPA treatment impairs cognition and alters the GABAergic system.

OBJECTIVES

Using rats, we evaluated the long-lasting cognitive and GABAergic effects of MPA administered in young adulthood (Early-MPA), modeling contraception, and how this early exposure interacts with later MPA treatment (Late-MPA), modeling HT.

METHODS

Early-MPA treatment involved weekly anti-ovulatory MPA injections (3.5 mg) from 4 to 8 months of age in ovary-intact rats. At 10 months old, rats were Ovx and weekly MPA injections were re-initiated and continued throughout testing for Late-MPA treatment.

RESULTS

On the water radial-arm maze, all MPA-treated groups showed working memory impairment compared to Controls (p < 0.05); Early + Late-MPA rats were impaired on multiple dimensions of working memory (p < 0.05). On the Morris maze, Late-MPA rats showed greater overnight forgetting compared to Controls (p < 0.05). At study conclusion, MPA was detected in serum in all MPA-treated groups except Early-MPA, confirming treatment and clearance from serum in Early-MPA rats. In animals with detectable serum MPA, higher MPA levels were associated with less dorsal-hippocampal glutamic acid decarboxylase, the synthesizing enzyme for GABA (p = 0.0059).

CONCLUSIONS

Findings suggest that MPA treatment leads to long-lasting cognitive impairments in the rodent, even in the absence of circulating MPA in animals given prior MPA treatment, which may relate to the GABAergic system. Further research defining the parameters of the negative impact of this widely used progestin on brain and cognition is warranted.

Regulatory interactions of stress and reward on rat forebrain opioidergic and GABAergic circuitry

Palatable food intake reduces stress responses, suggesting that individuals may consume such ?comfort? food as self-medication for stress relief. The mechanism by which palatable foods provide stress relief is not known, but likely lies at the intersection of forebrain reward and stress regulatory circuits. Forebrain opioidergic and gamma-aminobutyric acid ergic signaling is critical for both reward and stress regulation, suggesting that these systems are prime candidates for mediating stress relief by palatable foods. Thus, the present study (1) determines how palatable ?comfort? food alters stress-induced changes in the mRNA expression of inhibitory neurotransmitters in reward and stress neurocircuitry and (2) identifies candidate brain regions that may underlie comfort food-mediated stress reduction. We used a model of palatable ?snacking? in combination with a model of chronic variable stress followed by in situ hybridization to determine forebrain levels of pro-opioid and glutamic acid decarboxylase (GAD) mRNA. The data identify regions within the extended amygdala, striatum, and hypothalamus as potential regions for mediating hypothalamic-pituitary-adrenal axis buffering following palatable snacking. Specifically, palatable snacking alone decreased pro-enkephalin-A (ENK) mRNA expression in the anterior bed nucleus of the stria terminalis (BST) and the nucleus accumbens, and decreased GAD65 mRNA in the posterior BST. Chronic stress alone increased ENK mRNA in the hypothalamus, nucleus accumbens, amygdala, and hippocampus; increased dynorphin mRNA in the nucleus accumbens; increased GAD65 mRNA in the anterior hypothalamus and BST; and decreased GAD65 mRNA in the dorsal hypothalamus. Importantly, palatable food intake prevented stress-induced gene expression changes in subregions of the hypothalamus, BST, and nucleus accumbens. Overall, these data suggest that complex interactions exist between brain reward and stress pathways and that palatable snacking can mitigate many of the neurochemical alterations induced by chronic stress.

Altered GABA(A) receptor subunit expression and pharmacology in human Angelman syndrome cortex

The neurodevelopmental disorder Angelman syndrome is most frequently caused by deletion of the maternally derived chromosome 15q11-q13 region, which includes not only the causative UBE3A gene, but also the beta(3)-alpha(5)-gamma(3) GABA(A) receptor subunit gene cluster. GABAergic dysfunction has been hypothesized to contribute to the occurrence of epilepsy and cognitive and behavioral impairments in this condition. In the present study, analysis of GABA(A) receptor subunit expression and pharmacology was performed in cerebral cortex from four subjects with Angelman syndrome and compared to that from control tissue. The membrane fraction of frozen postmortem neocortical tissue was isolated and subjected to quantitative Western blot analysis. The ratios of beta(3)/beta(2) and alpha(5)/alpha(1) subunit protein expression in Angelman syndrome cortex were significantly decreased when compared with controls. An additional membrane fraction was injected into Xenopus oocytes, resulting in incorporation of the brain membrane vesicles with their associated receptors into the oocyte cellular membrane. Two-electrode voltage-clamp analysis of GABA(A) receptor currents was then performed. Studies of GABA(A) receptor pharmacology in Angelman syndrome cortex revealed increased current enhancement by the alpha(1)-selective benzodiazepine-site agonist zolpidem and by the barbiturate phenobarbital, while sensitivity to current inhibition by zinc was decreased. GABA(A) receptor affinity and modulation by neurosteroids were unchanged. This shift in GABA(A) receptor subunit expression and pharmacology in Angelman syndrome is consistent with impaired extrasynaptic but intact to augmented synaptic cortical GABAergic inhibition, which could contribute to the epileptic, behavioral, and cognitive phenotypes of the disorder.

Pretreatment of Guinea pigs with galantamine prevents immediate and delayed effects of soman on inhibitory synaptic transmission in the hippocampus

Galantamine has emerged as a potential antidote to prevent the acute toxicity of organophosphorus (OP) compounds. Changes in inhibitory GABAergic activity in different brain regions can contribute to both induction and maintenance of seizures in subjects exposed to the OP nerve agent soman. Here, we tested the hypothesis that galantamine can prevent immediate and delayed effects of soman on hippocampal inhibitory synaptic transmission. Spontaneous inhibitory postsynaptic currents (IPSCs) were recorded from CA1 pyramidal neurons in hippocampal slices obtained at 1 h, 24 h, or 6 to 9 days after the injection of guinea pigs with saline (0.5 ml/kg i.m.), 1xLD(50) soman (26.3 microg/kg s.c.), galantamine (8 mg/kg i.m.), or galantamine at 30 min before soman. Soman-challenged animals that were not pretreated showed mild, moderate, or severe signs of acute intoxication. At 1 h after the soman injection, the mean IPSC amplitude recorded from slices of mildly intoxicated animals and the mean IPSC frequency recorded from slices of severely intoxicated animals were larger and lower, respectively, than those recorded from slices of control animals. Regardless of the severity of the acute toxicity, at 24 h after the soman challenge the mean IPSC frequency was lower than that recorded from slices of control animals. At 6 to 9 days after the challenge, the IPSC frequency had returned to control levels, whereas the mean IPSC amplitude became larger than control. Pretreatment with galantamine prevented soman-induced changes in IPSCs. Counteracting the effects of soman on inhibitory transmission can be an important determinant of the antidotal effectiveness of galantamine.

Genetic disruption of the autism spectrum disorder risk gene PLAUR induces GABAA receptor subunit changes

Disruption of the GABAergic system has been implicated in multiple developmental disorders, including epilepsy, autism spectrum disorder and schizophrenia. The human gene encoding uPAR (PLAUR) has been shown recently to be associated with the risk of autism. The uPAR(-/-) mouse exhibits a regionally-selective reduction in GABAergic interneurons in frontal and parietal regions of the cerebral cortex as well as in the CA1 and dentate gyrus subfields of the hippocampus. Behaviorally, these mice exhibit increased sensitivity to pharmacologically-induced seizures, heightened anxiety, and atypical social behavior. Here, we explore potential alterations in GABAergic circuitry that may occur in the context of altered interneuron development. Analysis of gene expression for 13 GABA(A) receptor subunits using quantitative real-time polymerase chain reaction (PCR) indicates seven subunit mRNAs (alpha(1), alpha(2), alpha(3), beta(2), beta(3), gamma(2S) and gamma(2L)) of interest. Semi-quantitative in situ hybridization analysis focusing on these subunit mRNAs reveals a complex pattern of potential gene regulatory adaptations. The levels of alpha(2) subunit mRNAs increase in frontal cortex, CA1 and CA3, while those of alpha3 decrease in frontal cortex and CA1. In contrast, alpha(1) subunit mRNAs are unaltered in any region examined. beta(2) subunit mRNAs are increased in frontal cortex whereas beta(3) subunit mRNAs are decreased in parietal cortex. Finally, gamma(2S) subunit mRNAs are increased in parietal cortex while gamma(2L) subunit mRNAs are increased in the dentate gyrus, potentially altering the gamma(2S):gamma(2L) ratio in these two regions. For all subunits, no changes were observed in forebrain regions where GABAergic interneuron numbers are normal. We propose that disrupted differentiation of GABAergic neurons specifically in frontal and parietal cortices leads to regionally-selective alterations in local circuitry and subsequent adaptive changes in receptor subunit composition. Future electrophysiological studies will be useful in determining how alterations in network activity in the cortex and hippocampus relate to the observed behavioral phenotype.

Effects on the expression of GABAA receptor subunits by jujuboside A treatment in rat hippocampal neurons

AIM OF STUDY

To determine the effect of jujuboside A (JuA) in modulating the gamma-aminobutyric acid (GABA(A)) receptor subunits gene expression of hippocampal neurons at different terms in vitro.

MATERIALS AND METHODS

Hippocampal neurons of rat were cultured in vitro, treated with JuA or diazepam (DZP). Then GABA(A) receptor mRNAs were evaluated by semi-quantitative RT-PCR.

RESULTS

JuA at the low dose of 41 microM (about 0.05 g/l) induced significant increase of GABA(A) receptor alpha1, alpha5, beta2 subunit mRNAs in both 24 and 72h treatments. JuA at the high dose of 82 microM (about 0.1g/l) significantly increased GABA(A) receptor alpha1, alpha5 subunit mRNA levels and decreased beta2 subunit mRNA level at 24h treatment, and decreased GABA(A) receptor subunit alpha1, beta2 mRNAs expression at 72h treatment. DZP of 10 microM significantly increased expression of GABA(A) receptor subunit alpha1, alpha5 and decreased expression of beta2 at 24h treatment, and decreased alpha1, alpha5, beta2 subunits gene expression at 72h treatment.

CONCLUSION

Differences in alterations in GABA(A) receptor subunit mRNAs expression following JuA and DZP treatments could help to explain the differences in the pharmacological action of the two drugs.

Impaired maturation of cortical GABA(A) receptor expression in pediatric epilepsy

PURPOSE

Expression of the protein subunits that make up the γ-aminobutyric acid (GABA)(A) receptor pentamer is known to change during postnatal brain development in animal models. In the present study, analysis of cortical GABA(A) subunit expression was performed in control human tissue obtained from infancy through adolescence, and was compared to that from similarly aged children with intractable focal epilepsy.

METHODS

Twenty frozen pediatric control and 25 epileptic neocortical specimens were collected. The membrane fractions were isolated and subjected to quantitative western blot analysis. Subunit expression was correlated with clinical factors including age, pathology, and medication exposure.

RESULTS

In control cortical samples, α₁ and γ₂ GABA(A) receptor subunits exhibited low expression in infancy, which increased over the first several years of life and then stabilized through adolescence. In contrast, α₄ subunit expression was higher in infants than in older children. The level of the chloride transporter KCC2 increased markedly with age, whereas that of NKCC1 decreased. These patterns were absent in the children with epilepsy, both in those with focal cortical dysplasia and in those with cortical gliosis. Although there was marked variability in GABA(A) receptor subunit expression among the children with epilepsy, identifiable patterns of subunit expression were found in each individual child.

DISCUSSION

Maturation of cortical GABA(A) receptor subunit expression continues over the first several years of postnatal human development. Intractable focal epilepsy in children is associated with disruption of this normal developmental pattern. These findings have significant implications for the treatment of children with medications that modulate GABA(A) receptor function.

Use of analgesic and sedative drugs in the NICU: integrating clinical trials and laboratory data

Recent advances in neonatal intensive care include and are partly attributable to growing attention for comfort and pain control in the term and preterm infant requiring intensive care.Limitation of painful procedures is certainly possible, but most critically ill infants require unavoidable painful or stressful procedures such as intubation, mechanical ventilation, or catheterization.Many analgesics (opioids and nonsteroidal anti-inflammatory drugs)and sedatives (benzodiazepines and other anesthetic agents) are available but their use varies considerably among units. This review summarizes current experimental knowledge on the effects of sedative and analgesic drugs on brain development and reviews clinical evidence that speaks for or against the use of common analgesic and sedative drugs in the NICU but avoids any discussion of anesthesia during surgery. Risk/benefit ratios of intermittent boluses or continuous infusions for the commonly used sedative and analgesic agents are discussed in the light of clinical and experimental studies. The limitations of extrapolating experimental results from animals to humans must be considered while making practical recommendations based on the currently available evidence.

Medroxyprogesterone acetate impairs memory and alters the GABAergic system in aged surgically menopausal rats

In women, medroxyprogesterone acetate (MPA) is the most commonly used progestin component of hormone therapy (HT). In vitro, MPA negatively impacts markers of neuronal health and exacerbates experimentally-induced neurotoxicity. There is in vitro evidence that these factors are driven by GABAergic and neurotrophic systems. Whether these effects translate to a negative impact on brain function has not been tested in vivo, clinically or preclinically. Here we evaluate the mnemonic and neurobiological effects of MPA in the surgically menopausal rat. Aged ovariectomized (OVX) rats were given subcutaneous vehicle, natural progesterone, low-dose MPA or high-dose MPA. Multiple cognitive domains were analyzed via the water radial-arm maze (WRAM) and Morris maze (MM). Cognitive brain regions were assayed for changes in the GABAergic system by evaluating GAD protein, the synthesizing enzyme for GABA, and neurotrophins. On the WRAM, both progestin types impaired learning. Further, high-dose MPA impaired delayed memory retention on the WRAM, and exacerbated overnight forgetting on the MM. While neurotrophins were not affected by progesterone or MPA treatment, both progestin types altered GAD levels. MPA significantly and progesterone marginally decreased GAD levels in the hippocampus, and both MPA and progesterone significantly increased GAD levels in the entorhinal cortex. These findings suggest that MPA, the most commonly used progestin in HT, is detrimental to learning and two types of memory, and modulates the GABAergic system in cognitive brain regions, in aged surgically menopausal rats. These findings, combined with in vitro evidence that MPA is detrimental to neuronal health, indicates that MPA has negative effects for brain health and function.

Long-term antiepileptic drug administration during early life inhibits hippocampal neurogenesis in the developing brain

Certain antiepileptic drugs (AEDs) that are commonly used to treat seizures in children also affect cognition, and these effects can persist into adulthood, long after drug withdrawal. Widespread enhancement of apoptosis may be one mechanism underlying these lasting cognitive changes. Whether AEDs affect other processes in brain development during early postnatal life has not, however, been systematically analyzed. Here we determined whether chronic administration of common AEDs during early life alters cell proliferation and neurogenesis in the hippocampus. Postnatal day 7 (P7) rats received phenobarbital, clonazepam, carbamazepine, valproate, topiramate, or vehicle for 28 days. Bromodeoxyuridine was administered on P34 to label dividing cells. Cell proliferation was assessed 24 hr later, and cell survival and differentiation were assessed 28 days later. Phenobarbital and clonazepam significantly inhibited cell proliferation by 63% and 59%, respectively, and doublecortin immunoreactivity (indicator of neurogenesis) in the dorsal hippocampus was also significantly decreased by 26% and 24%, respectively. Survival of new cells steadily decreased in phenobarbital and clonazepam groups over 28 days. Reduced cell proliferation and survival resulted in fewer new neurons in the dentate gyrus, as confirmed by neuronal counting on P62. There were, however, no differences in cell distribution pattern or differentiation toward neuron and glial cells when phenobarbital and clonazepam groups were compared with controls. There were no changes in rats exposed to carbamazepine, valproate, or topiramate. Thus, inhibiting cell proliferation, survival, and neurogenesis in the developing hippocampus may be another potential mechanism underlying brain impairment associated with certain AED therapies in early life.

Metabolite changes and gender differences in schizophrenia using 3-Tesla proton magnetic resonance spectroscopy (1H-MRS)

A change in the glutamatergic system is thought to play an important role in the pathophysiology of schizophrenia. The aim of this study was to investigate the changes in metabolites, including glutamate (Glu), in the anterior cingulate cortex (ACC) and the left basal ganglia (ltBG) of patients with chronic schizophrenia using proton magnetic resonance spectroscopy ((1)H-MRS). In addition, since gender differences in this illness were known, we examined the effects of gender on these metabolites. The (1)H-MRS was performed on the ACC and ltBG of 30 patients with schizophrenia and 25 healthy individuals who acted as the control group. The levels of Glu, glutamine (Gln), creatine plus phosphocreatine (Cre), myo-inositol (mI), N-acetylaspartate (NAA), and choline-containing compounds (Cho) were measured. Two-way analysis of variance revealed that the illness significantly affected the levels of Glu and mI in the ACC; both metabolites were lower in the patients with schizophrenia as compared to the control subjects. The results also revealed that gender significantly affected the level of Gln in the ACC and the levels of Cre and NAA in the ltBG; the level of Gln in the ACC were higher in male subjects versus female subjects, whereas Cre and NAA levels in the ltBG were lower in male subjects as compared to female subjects. These results confirmed a change in the glutamatergic system and suggested an involvement of mI in the pathophysiology of schizophrenia.

Phenobarbital withdrawal seizures may occur over several weeks before remitting: human data and hypothetical mechanism

This case is the first report of a patient who had phenobarbital (PB) withdrawal seizures after having been seizure-free for 3 years following temporal lobe surgery. The patient had been taking PB for 14 years when a gradual taper of PB was started. When PB was at 60 mg/d, a titration of lamotrigine (LTG) was started. However, typical complex seizures occurred when the patient was on PB 60 mg/d, along with LTG 25mg/d. PB was increased back to 90 mg/d and levetiracetam (LEV) was titrated. Seizures appeared when the patient was on PB 30 mg/d and LEV 750 mg BID and continued for 3 weeks after PB was stopped and the patient was on LEV 1,000 mg BID. For the following 6 months, her aura frequency remained elevated in comparison to her baseline aura of two auras per month for the previous year before the start of the PB taper. She was followed for 24 months after her last PB withdrawal seizure. During the last 8 months, her aura frequency returned to her baseline. As suggested by animal studies, the PB withdrawal seizures and increase in aura frequency in this patient may be explained by changes in her levels of GABA(A) receptor subunits.

GABA(A) receptor properties in catastrophic infantile epilepsy

Catastrophic epilepsy due to cortical dysplasia is often intractable to anticonvulsant treatment. Many of the medications used unsuccessfully in treating this disorder are thought to exert at least a portion of their action through enhancement of inhibitory GABA(A) neurotransmission. In the present study, GABA(A) receptor properties in resected brain tissue from four infants with infantile spasms and intractable epilepsy due to cortical dysplasia were measured to determine if this clinical resistance to pharmacologic treatment correlates with alterations in receptor function. Results from epileptic cortex were compared with those from autopsy control samples. To perform these studies, we utilized the technique of injection of brain cellular membrane preparations into the Xenopus oocyte, which results in the incorporation of human GABA(A) receptors in their native configuration into the oocyte plasma membrane. Two-electrode voltage-clamp electrophysiology analysis was then performed to assess GABA(A) receptor pharmacologic properties. The intrinsic properties of affinity, reversal potential, current decay, and current rundown were unchanged in the epileptic infants. Current enhancement by benzodiazepines was also unaltered, as was the response to barbiturates. However, a significant decrease was found in the degree of GABA(A) current enhancement by neurosteroids in the epileptic infants, along with an increase in current inhibition by zinc. These findings may contribute to the mechanisms of intractability in catastrophic infantile epilepsy due to cortical dysplasia, and suggest alternative therapeutic approaches.

Status epilepticus alters zolpidem sensitivity of [3H]flunitrazepam binding in the developing rat brain

GABA, the main inhibitory neurotransmitter in the adult brain, exerts its effects through multiple GABA(A) receptor subtypes with different pharmacological profiles, the alpha subunit variant mainly determining the binding properties of benzodiazepine site on the receptor protein. In adult experimental epileptic animals and in humans with epilepsy, increased excitation, i.e. seizures, alters GABA(A) receptor subunit expression leading to changes in the receptor structure, function, and pharmacology. Whether this also occurs in the developing brain, in which GABA has a trophic, excitatory effect, is not known. We have now applied autoradiography to study properties of GABA(A)/benzodiazepine receptors in 9-day-old rats acutely (6 h) and sub-acutely (7 days) after kainic acid-induced status epilepticus by analyzing displacement of [(3)H]flunitrazepam binding by zolpidem, a ligand selective for the alpha1beta2gamma2 receptor subtype. Regional changes in the binding properties were further corroborated at the cellular level by immunocytochemistry. The results revealed that status epilepticus significantly decreased displacement of [(3)H]flunitrazepam binding by zolpidem 6 h after the kainic acid-treatment in the dentate gyrus of the hippocampus, parietal cortex, and thalamus, and in the hippocampal CA3 and CA1 cell layers 1 week after the treatment. Our results suggest that status epilepticus modifies region-specifically the pharmacological properties of GABA(A) receptors, and may thus disturb the normal, strictly developmentally-regulated maturation of zolpidem-sensitive GABA(A) receptors in the immature rat brain. A part of these changes could be due to alterations in the cell surface expression of receptor subtypes.

Management of the newborn infant affected by maternal opiates and other drugs of dependency

Illicit drug use during pregnancy is common and probably underestimated in the majority of published studies. The infant exposed to opiates or other drugs of dependency during intrauterine development is at risk for post-natal withdrawal as well as to long-term problems that are associated with drug-effects and often, adverse social circumstances. This article examines the early management of the infant and mother for detection and monitoring of drug-exposure, pharmacological intervention for withdrawal and the management of associated, particularly infective and psychosocial, problems. Practical concerns surrounding these issues are discussed and further research on psychosocial intervention to improve long-term outcome are much needed.

Seizures and Antiepileptic Drugs: Does Exposure Alter Normal Brain Development?

Seizures and antiepileptic drugs (AEDs) affect brain development and have long-term neurological consequences. The specific molecular and cellular changes, the precise timing of their influence during brain development, and the full extent of the long-term consequences of seizures and AEDs exposure have not been established. This review critically assesses both the basic and clinical science literature on the effects of seizures and AEDs on the developing brain and finds that evidence exists to support the hypothesis that both seizures and antiepileptic drugs influence a variety of biological process, at specific times during development, which alter long-term cognition and epilepsy susceptibility. More research, both clinical and experimental, is needed before changes in current clinical practice, based on the scientific data, can be recommended.

The interaction of neuroactive steroids and GABA in the development of neuropsychiatric disorders in women

A growing literature suggests that hormonal fluctuations occurring across the menstrual cycle, during and after pregnancy, and during the menopausal transition are associated with onset of affective disorders or exacerbation of existing disorders. This influence of the neuroendocrine system on psychiatric disorders is thought to be mediated by an abnormality in central nervous system response to neuroactive steroids such as estradiol, progesterone, and the progesterone derivative allopregnanolone (ALLO). This interplay is considerably complex as neuroactive steroids modulate the function of multiple neurotransmitter systems throughout various stages of development. While one could choose to study any number of steroid-neurotransmitter interactions, our group in addition to others has focused our investigative efforts on unraveling the contribution of neuroactive steroids to psychiatric syndromes and disorders via their modulation of gamma aminobutyric acid (GABA), the brain's major inhibitory neurotransmitter. The goal of this article is two-fold: to synthesize the clinical and preclinical research focusing on the interplay between neuroactive steroids and GABA as they relate to neuropsychiatric and substance use disorders in women and to integrate data from our laboratory using proton magnetic resonance spectroscopy into this context.

Identification of structures within GABAA receptor alpha subunits that regulate the agonist action of pentobarbital

Barbiturates act on GABA(A) receptors (GABARs) through three distinct mechanisms, resulting in positive allosteric modulation, direct activation, and inhibition. These effects are observed at different concentrations and are differentially affected by some mutations and by the receptor's subunit composition. Mammalian GABARs can be formed from a combination of 16 different subunit subtypes. Although the effect of barbiturates depends largely on the beta subunit, their agonist activity is substantially influenced by the alpha subunit subtype. Pentobarbital is a more effective agonist than GABA only when receptors contain an alpha6 subunit. Results from chimeric alpha1/alpha6 subunits suggested that structural differences within the extracellular N-terminal domain were responsible for this characteristic. Within this domain, we examined 15 amino acid residues unique to the alpha6 subtype. Each of these sites was individually mutated in the alpha6 subunit to the corresponding residue of the alpha1 subunit. The effect of the mutation on direct activation by pentobarbital was determined with whole-cell electrophysiological recordings. Our results indicate that only one of these mutations, alpha6(T69K), altered pentobarbital efficacy. This single mutation reduced the response to pentobarbital to a level intermediate to the wild-type alpha1beta1gamma2L and alpha6beta1gamma2L isoforms. The mutation did not affect the sensitivity of the receptor to GABA but did reduce the efficacy of etomidate, another i.v. anesthetic with activity similar to pentobarbital. The reverse mutation in the alpha1 subunit (K70T) did not alter the response to pentobarbital. This is the first identification of a structural difference in GABAR alpha subtypes that regulates direct activation by barbiturates.