4-Chloropropofol enhances chloride currents in human hyperekplexic and artificial mutated glycine receptors.

BACKGROUND: The mammalian neurological disorder hereditary hyperekplexia can be attributed to various mutations of strychnine sensitive glycine receptors. The clinical symptoms of "startle disease" predominantly occur in the newborn leading to convulsive hypertonia and an exaggerated startle response to unexpected mild stimuli. Amongst others, point mutations R271Q and R271L in the α1-subunit of strychnine sensitive glycine receptors show reduced glycine sensitivity and cause the clinical symptoms of hyperekplexia.Halogenation has been shown to be a crucial structural determinant for the potency of a phenolic compound to positively modulate glycine receptor function.The aim of this in vitro study was to characterize the effects of 4-chloropropofol (4-chloro-2,6-dimethylphenol) at four glycine receptor mutations. METHODS: Glycine receptor subunits were expressed in HEK 293 cells and experiments were performed using the whole-cell patch-clamp technique. RESULTS: 4-chloropropofol exerted a positive allosteric modulatory effect in a low sub-nanomolar concentration range at the wild type receptor (EC50 value of 0.08 ± 0.02 nM) and in a micromolar concentration range at the mutations (1.3 ± 0.6 µM, 0.1 ± 0.2 µM, 6.0 ± 2.3 µM and 55 ± 28 µM for R271Q, L, K and S267I, respectively). CONCLUSIONS: 4-chloropropofol might be an effective compound for the activation of mutated glycine receptors in experimental models of startle disease.

Canine muscle cell culture and consecutive patch-clamp measurements - a new approach to characterize muscular diseases in dogs.

BACKGROUND: The recognition of functional muscular disorders, (e.g. channelopathies like Myotonia) is rising in veterinary neurology. Morphologic (e.g. histology) and even genetic based studies in these diseases are not able to elucidate the functional pathomechanism. As there is a deficit of knowledge and skills considering this special task, the aim of the current pilot study was to develop a canine muscle cell culture system derived from muscle biopsies of healthy client-owned dogs, which allows sampling of the biopsies under working conditions in the daily veterinary practise. RESULTS: Muscular biopsies from 16 dogs of different age and breed were taken during standard surgical procedures and were stored for one to three days at 4°C in a transport medium in order to simulate shipping conditions. Afterwards biopsies were professionally processed, including harvesting of satellite cells, inducing their proliferation, differentiating them into myotubes and recultivating myotubes after long-term storage in liquid nitrogen. Myogenic origin of cultured cells was determined by immunofluorescence, immunohistology and by their typical morphology after inducing differentiation. Subsequent to the differentiation into myotubes feasibility of patch-clamp recordings of voltage gated ion channels was successfully. CONCLUSION: We have developed a canine muscle cell culture system, which allows sampling of biopsies from young and old dogs of different breeds under practical conditions. Patch clamp measurements can be carried out with the cultured myotubes demonstrating potential of these cells as source for functional research.

Onset and spreading patterns of upper and lower motor neuron symptoms in amyotrophic lateral sclerosis.

INTRODUCTION: The potential linkage between upper (UMN) and lower motor neuron (LMN) involvement in amyotrophic lateral sclerosis (ALS) has not yet been fully elucidated. There is ongoing discussion as to whether ALS is primarily a disease of UMNs or LMNs. METHODS: We performed a retrospective analysis of 189 ALS patients from our ALS outpatient database to investigate the different spreading patterns of UMN and LMN affection in disease progression in relation to the onset region. RESULTS: The body region with the highest UMN involvement at onset in general also had the highest frequency of LMN signs and vice versa. This is in line with the hypothesis of a focal onset of disease, which then spreads to adjacent areas. However, there was a great variation between ALS phenotypes. DISCUSSION: These observations support the hypothesis of focal damage of a localized group of motor neurons, which then spreads to adjacent motor neurons.

Nerve compression syndromes in ALS: a retrospective analysis in 554 patients.

We retrospectively screened a large cohort of 554 ALS patients with regard to documented nerve compression syndromes and identified 23 patients, mostly with carpal tunnel syndrome. Patients could be subdivided into three groups. Group A comprised 13 patients in whom nerve compression was apparently confused with early ALS signs. Group B consisted of six patients diagnosed with carpal tunnel syndrome who had experienced improvement after surgery years before they eventually developed ALS. Group C consisted of four patients who, after diagnosis of ALS, additionally developed a nerve compression syndrome. Altogether, the frequency of true nerve compression syndromes in our ALS cohort (1.8%) was no higher than in the general population (0.3-10.8%). In group A, the initial confusion with a nerve compression syndrome led to a slight though not significant delay (15.2 vs. 12.9 months; p = 0.32) of the diagnosis of ALS. Survival was no different between group A and the cohort. It can also be concluded that the misdiagnoses could have been avoided by thorough electrophysiological examination using a standardized protocol.

Characterization and differentiation potential of rat ventral mesencephalic neuronal progenitor cells immortalized with SV40 large T antigen.

Neuronal progenitor cells (NPCs) possess high potential for use in regenerative medicine. To overcome their limited mitotic competence, various immortalization strategies have been applied that allow their prolonged maintenance and expansion in vitro. Such immortalized cells can be used for the design and discovery of new cell-based therapies for neurodegenerative diseases, such as Parkinson's disease. We immortalized rat ventral mesencephalic NPCs by using SV40 large T antigen (SV40Tag). All cell clones displayed a two- to three-fold higher proliferation rate compared with the primary cells. In order to induce dopaminergic differentiation of generated cell clones, both glial-derived neurotrophic factor and di-butyryl cyclic adenosine monophosphate were applied. Treated cells were then characterized regarding the expression of dopaminergic lineage markers, differentiation of various cell populations, calcium imaging in the presence of kainate, and immunohistochemistry after intrastriatal transplantation. Treated cells displayed morphological maturation, and calcium imaging revealed neuronal properties in the presence of kainate. These cells also expressed low mRNA levels of the dopamine transporter and tyrosine hydroxylase (TH), although no TH-immunopositive neurons were found. Intrastriatal transplantation into the neurotoxin-lesioned rats did not induce further differentiation. As an alternative approach, we silenced SV40Tag with short interfering RNA, but this was not sufficient to trigger differentiation into dopaminergic neurons. Nevertheless, neuronal and glial cells were detected as shown by beta-tubulin type III and glial fibrillary acidic protein staining, respectively. SV40Tag cells are suitable for carrying out controlled genetic modifications as shown by overexpression of enhanced green fluorescence protein after efficient non-viral transfection.

The interaction of the neuroprotective compounds riluzole and phenobarbital with AMPA-type glutamate receptors: a patch-clamp study.

BACKGROUND: Blockade of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type glutamate receptors is a promising pharmacological strategy in the treatment of neurodegenerative diseases. The aim of the study is to elucidate if there are direct interactions of riluzole and phenobarbital with AMPA-type receptor channels and to determinethe molecular pharmacological mechanisms. METHODS: The patch-clamp technique was used combining an ultrafast solution exchange system to investigate the interaction of riluzole and phenobarbital with recombinant AMPA-type glutamate receptor channels (homomeric GluR2flipGQ or nondesensitizing GluR2L504Y). RESULTS: A dose-dependent decrease in the relative peak current amplitude (rAmp) and the relative area-under-the-current curve (rAUC) were found after preincubation with 0.1 mmol/l or higher concentrations of riluzole. Furthermore, in coapplication experiments with GluR2L504Y, the application of 1 or 3 mmol/l riluzole showed a decrease in the current decay time constant, and a reopening current was observed at 3 mmol/l riluzole. Phenobarbital blocks AMPA receptor channels dose-dependently in the coapplication experiments, and reopening currents after removing glutamate and blocker were observed. A slight block effect after preincubation should indicate an additional competitive block effect. CONCLUSION: Riluzole and phenobarbital modulate AMPA-type receptor channels separately, which could be both characterized as a combination of open-channel block and competitive-block mechanism.

Preserved expression of fibroblast growth factor (FGF)-2 and FGF receptor 1 in brain and spinal cord of amyotrophic lateral sclerosis patients.

Impaired trophic support of motor neurons appears to be an important pathogenic factor in amyotrophic lateral sclerosis (ALS). We investigated the mRNA expression of the pluripotent fibroblast growth factor 2 (FGF-2) and its receptors in post mortem spinal cord of ALS and control patients. FGF-2 and FGF receptor (FGFR) 1 and 2 transcripts were first studied in the spinal cord using RT-PCR. The cellular distribution of FGF-2 and FGFR mRNA in the spinal cord, motor cortex and brain stem was then assessed by in situ hybridization histochemistry. RT-PCR revealed the presence of FGF-2 and FGF receptor 1 and 2 transcripts with no obvious differences between ALS and control spinal cord. Comparing mRNA expression in the motoneuron-containing ventral horn with the clinically and neuropathologically spared dorsal horn of ALS spinal cord displayed similar expression levels. At the cellular level, we found a prominent neuronal expression of FGF-2 and FGFR1. Interestingly, both morphologically intact and damaged motoneurons showed positive staining for FGF-2 and FGFR1 transcripts. The distribution of cells expressing FGF-2 and FGFR1 transcripts showed no differences between ALS and controls. Our data suggest that FGF-2 and FGFR1 expression is preserved in the motor system in end stage ALS.

Treatment of phantom limb pain with botulinum toxin type A.

INTRODUCTION: Phantom limb pain and sensations are common in amputees. The pathophysiology remains unclear and the treatment difficult and often unsuccessful. Opioids are frequently used when non-narcotics have failed, but are not effective in many cases. We report on three phantom and stump pain patients, refractive to previous treatments, who were successfully treated with botulinum toxin A (BoNT-A). METHODS: Three patients who had previously undergone amputation of their leg due to accident (N = 2) or injury by a landmine (N = 1) were treated with BoNT-A (Dysport). We injected a total dose of up to 500 units (U) BoNT-A under EMG-control. Global clinical improvement was based on a 0-3 scale (0 = no effect; 3 = marked improvement) and on a questionnaire rating pain intensity (based on the visual analog scale), intake of pain medication and phantom limb sensations. RESULTS: All three patients evaluated the clinical global improvement with 3 (marked improvement). The pain intensity and pain medication was reduced significantly in all three cases. No side effects were reported. The duration of response lasted up to 11 weeks. DISCUSSION: These three successfully treated phantom and stump pain patients show that therapy with BoNT-A may be worth studying as an effective and safe treatment option for this kind of pain.

The non-anaesthetic propofol analogue 2,6-di-tert-butylphenol fails to modulate GABA(A) receptor function.

Modulation of inhibitory synaptic transmission within the central nervous system contributes considerably to the anaesthetic effects of propofol and its analogues in vivo. We have studied the effects of the non-anaesthetic propofol analogue 2,6-di-tert-butylphenol on rat alpha(1)beta(2)gamma(2) GABA(A) receptors expressed in a mammalian expression system (HEK 293 cells) using the whole-cell patch clamp technique. Our experiments showed that 2,6-di-tert-butylphenol completely lacks co-activation and direct activation of the inhibitory GABA(A) receptor. Our results support the assumption that modulation of inhibitory GABA(A) receptor function is responsible for the anaesthetic effects of propofol in vivo.

The nonpsychotropic cannabinoid cannabidiol modulates and directly activates alpha-1 and alpha-1-Beta glycine receptor function.

Loss of inhibitory synaptic transmission within the dorsal horn of the spinal cord plays a key role in the development of chronic pain following inflammation or nerve injury. Inhibitory postsynaptic transmission in the adult spinal cord involves mainly glycine. Cannabidiol is a nonpsychotropic plant constituent of Cannabis sativa. As we hypothesized that non-CB receptor mechanisms of cannabidiol might contribute to its anti-inflammatory and neuroprotective effects, we investigated the interaction of cannabidiol with strychnine-sensitive alpha(1 )and alpha(1)beta glycine receptors by using the whole-cell patch clamp technique. Cannabidiol showed a positive allosteric modulating effect in a low micromolar concentration range (EC(50) values: alpha(1) = 12.3 +/- 3.8 micromol/l and alpha(1)beta = 18.1 +/- 6.2 micromol/l). Direct activation of glycine receptors was observed at higher concentrations above 100 micromol/l (EC(50) values: alpha(1) = 132.4 +/- 12.3 micromol/l and alpha(1)beta = 144.3 +/- 22.7 micromol/l). These in vitro results suggest that strychnine-sensitive glycine receptors may be a target for cannabidiol mediating some of its anti-inflammatory and neuroprotective properties.

Modulation of glycine receptor function by the synthetic cannabinoid HU210.

Loss of inhibitory synaptic transmission within the dorsal horn of the spinal cord plays a key role in the development of chronic pain following inflammation or nerve injury. Inhibitory postsynaptic transmission in the adult spinal cord involves mainly glycine. HU210 is a non-psychotropic, synthetic cannabinoid. As we hypothesized that non-CB receptor mechanisms of HU210 might contribute to its anti-inflammatory and anti-nociceptive effects we investigated the interaction of HU210 with strychnine-sensitive alpha(1 )glycine receptors by using the whole-cell patch clamp technique. HU210 showed a positive allosteric modulating effect in a low micromolar concentration range (EC(50): 5.1 +/- 2.6 micromol/l). Direct activation of glycine receptors was observed at higher concentrations above 100 micromol/l (EC(50): 188.7 +/- 46.2 micromol/l). These in vitro results suggest that strychnine-sensitive glycine receptors may be a target for HU210 mediating some of its anti-inflammatory and anti-nociceptive properties.

Nuclear erythroid 2-related factor 2-antioxidative response element signaling pathway in motor cortex and spinal cord in amyotrophic lateral sclerosis.

Oxidative stress and inflammation are important pathogenetic mechanisms in amyotrophic lateral sclerosis (ALS). Nuclear erythroid 2-related factor 2 (Nrf2) is a basic region leucine-zipper transcription factor that binds to the antioxidant response element, thereby regulating the expression of many genes that are involved in cellular antioxidant and anti-inflammatory defense. Under normal conditions, Nrf2 activation is inhibited by Kelch-like ECH-associated protein 1 (Keap1). We investigated the potential involvement of the Nrf2/antioxidant response element signaling pathway in the selective degeneration of motor neurons in ALS. Nrf2 and Keap1 expression was analyzed in primary motor cortex and spinal cord postmortem tissue samples from ALS patients and controls by in situ hybridization histochemistry, quantitative real-time polymerase chain reaction, immunohistochemistry, and Western blot analysis. In ALS samples, there was a reduction of Nrf2 mRNA and protein expression in neurons, whereas Keap1 mRNA expression was increased in the motor cortex. These results suggest that alterations in this signaling cascade occur in motor neurons in ALS and that they may contribute to chronic motor neuron degeneration.

Endotoxin reduces availability of voltage-gated human skeletal muscle sodium channels at depolarized membrane potentials.

OBJECTIVE: Critical illness myopathy is a common cause for difficulties in weaning from the respirator and prolonged rehabilitation of patients recovering from sepsis. Several studies have shown that the primary cause of acute generalized muscle weakness is loss of muscle membrane excitability. This study was designed to investigate a potential direct interaction of lipopolysaccharides from Escherichia coli with voltage-gated human skeletal muscle sodium channels (NaV1.4) in vitro. DESIGN: In vitro laboratory investigation. SETTING: University laboratory. SUBJECTS: NaV1.4 sodium channel alpha-subunits stably expressed in human embryonic kidney (HEK293) cells. INTERVENTIONS: We investigated the effect of lipopolysaccharide on voltage-dependent sodium channel gating by using two distinct modes of application: 1) acute perfusion (pharmacologic lipopolysaccharide concentrations between 5 ng/mL and 50 microg/mL) in order to establish a concentration-effect relationship; and 2) incubation with a clinically relevant concentration of lipopolysaccharide (300 pg/mL). MEASUREMENTS AND MAIN RESULTS: Lipopolysaccharide did not alter the kinetics of sodium current activation or inactivation when depolarizations were started from hyperpolarized holding potentials. However, when either fast or slow inactivation was induced by membrane depolarization before the test pulse, lipopolysaccharide reversibly reduced channel availability during the test pulse at concentrations of > or = 50 ng/mL revealed by a maximum hyperpolarizing shift of -25 mV in the voltage dependence of fast and slow inactivation, respectively. Incubation with a lipopolysaccharide concentration of 300 pg/mL for 1 hr reproduced the effects on slow but not on fast inactivation. After 20 hrs of low-dose lipopolysaccharide, the peak sodium current was significantly reduced. CONCLUSIONS: Our results show that lipopolysaccharide interacts with voltage-gated sodium channels, reducing channel availability at depolarized membrane potentials during acute application, independent of the membrane potential after chronic exposure. These effects may contribute to reduced muscle membrane excitability in sepsis.

ALSFRS-R score and its ratio: a useful predictor for ALS-progression.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder. To determine predictors of survival, we studied different parameters in our ALS Database including 479 patients. The effects of individual prognostic factors of survival were studied using Kaplan-Meier life table. The prognostic value of each factor of interest was expressed in terms of a hazard ratio. Survival from symptom-onset ranged from 4 months up to 11.9 years. Gender had no effect on survival in our cohort. However, age, site of onset, forced vital capacity, symptom duration and ALSFRS-R score at the first visit were independent prognostic factors in our population (log-rank p<0.01). The ratio of ALSFRS-R score between first symptom and first examination, during whole disease or within 100 days, correlates with survival time. We conclude that the ratio of ALSFRS-R score within 100 days is a useful parameter for clinical trials and daily clinical work in a tertiary ALS-clinic.

A transmembrane residue influences the interaction of propofol with the strychnine-sensitive glycine alpha1 and alpha1beta receptor.

BACKGROUND: Propofol, well known for its anesthetic effects, acts as a positive allosteric modulator of the alpha-aminobutyric acid type A (GABA(A)) receptor but also enhances the function of the glycine receptor. The GABA modulatory effects of propofol are influenced by an amino acid residue located within the second transmembrane domain (TM2) of the GABA(A) receptor beta subunit. In glycine alpha(1) subunits, the homologous residue (serine 267) affects the glycine modulatory actions of alcohols and alkane anesthetics. In the present study we investigated the role of this residue on the interaction of propofol with the glycine alpha(1) and alpha(1)beta receptor. METHODS: The influence of propofol on wild type and mutant (alpha(1)S267M, alpha(1)S267I, alpha(1)S267Mbeta, alpha(1)S267Ibeta) glycine receptors expressed in human embryonic kidney 293 cells was investigated by using the whole-cell clamp technique. RESULTS: Mutation of the alpha(1) subunit TM2 serine residue to either isoleucine or methionine decreased the sensitivity of the receptor to glycine, and abolished the direct activation of the glycine receptor by propofol. Additionally, the methionine and particularly the isoleucine mutation decreased the glycine-enhancing actions of propofol. CONCLUSIONS: The nature of the TM2 residue (267) of the glycine alpha(1) subunit influences the glycine modulatory effect of propofol and direct activation of the receptor by this anesthetic. A comparison of the impact of such complementary mutations on the interaction of propofol with glycine and GABA(A) receptors should permit a better understanding of the molecular determinants of action of propofol on these structurally related receptors and may aid in the development of selective glycine receptor modulators.

The anaesthetic steroid alphaxalone positively modulates alpha1-glycine receptor function.

Inhibitory synaptic transmission within the dorsal horn of the spinal cord plays a key role in the processing of nociceptive signals, and mainly involves glycine. We have studied the effects of alphaxalone on alpha(1) homomeric glycine receptors expressed in a mammalian expression system (HEK 293 cells) using the whole-cell patch-clamp technique. Our experiments showed a coactivating effect of alphaxalone with a concentration for half-maximum activation (EC(50)) of the effect of a low glycine concentration (EC(20)) of 70.9 +/- 21.5 micromol/l. Taking into account the results of other groups, our study suggests that neuroactive steroids might be an interesting class of compounds to probe subunit-specific effects of glycine receptors.

Reduced delayed rectifier K+ current, altered electrophysiology, and increased ventricular vulnerability in MLP-deficient mice.

BACKGROUND: Mice with a knockout (KO) of muscle LIM protein (MLP) exhibit many morphologic and clinical features of human cardiomyopathy. In humans, MLP-expression is downregulated both in ischemic and dilative cardiomyopathy. In this study, we investigated the effects of MLP on the electrophysiologic phenotype in vivo and on outward potassium currents. METHODS AND RESULTS: MLP-deficient (MLPKO) and wild-type (MLPWT) mice were subjected to long-term electrocardiogram (ECG) recording and in vivo electrophysiologic study. The whole-cell, patch-clamp technique was applied to measure voltage dependent outward K+ currents in isolated cardiomyocytes. Long-term ECG revealed a significant prolongation of RR mean (108 +/- 9 versus 99 +/- 5 ms), P (16 +/- 3 versus 14 +/- 1 ms), QRS (17 +/- 3 versus 13 +/- 1 ms), QT (68 +/- 8 versus 46 +/- 7 ms), QTc (66 +/- 6 versus 46 +/- 7 ms), JT (51 +/- 7 versus 34 +/- 7 ms), and JTc (49 +/- 5 versus 33 +/- 7 ms) in MLPKO versus MLPWT mice (P < .05). During EP study, QT (80 +/- 8 versus 58 +/- 7 ms), QTc (61 +/- 6 versus 45 +/- 5 ms), JT (62 +/- 9 versus 43 +/- 6 ms), and JTc (47 +/- 5 versus 34 +/- 5 ms) were also significantly prolonged in MLPKO mice (P < .05). Nonsustained VT was inducible in 9/16 MLPKO versus 2/15 MLPWT mice (P < .05). Analysis of outward K+ currents in revealed a significantly reduced density of the slowly inactivating outward K+ current IK, slow in MLPKO mice (11 +/- 5 pA/pF versus 18 +/- 7 pA/pF; P < .05). CONCLUSION: Mice with KO of MLP exhibit significant prolongation of atrial and ventricular conduction and an increased ventricular vulnerability. A reduction in repolarizing outward K+ currents may be responsible for these alterations.

Correlation between distal motor latency and compound muscle action potential in amyotrophic lateral sclerosis.

OBJECTIVES: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder, characterized by a selective progressive degeneration of the motor system. Electromyography is essential for the diagnosis of ALS. The measurement of motor conduction of peripheral nerves is of major importance to recognize other possible causes of progressive muscle wasting. However, there are also pathologic changes in nerve conduction studies in ALS patients. METHODS: In this study we analysed the values of distal motor latency (DML), compound muscle action potential (CMAP) and motor nerve conduction velocity (MNCV) in 95 patients with definite ALS. RESULTS: We found slight slowing of MNCV and moderate to strong reduction of CMAP and a prolongation of DML. We found no significant correlation between MNCV and CMAP. DISCUSSION: The main finding of the present work was the negative correlation between DML and CMAP. It is interpreted as a very distal axonal damage as the main reason for prolongation of DML in ALS patients.

Molecular analysis of the interaction of the pyrazine derivatives RPR119990 and RPR117824 with human AMPA-type glutamate receptor channels.

Antagonizing glutamatergic neurotransmission by blockade of AMPA-type glutamate receptors is a promising pharmacological strategy in the treatment of neurodegenerative diseases. We investigated the interaction of two new pyrazine derivatives (RPR119990 and RPR117824) with recombinant AMPA-type glutamate receptors. Recombinant homooligomeric GluR1flop, GluR2flip, GluR2flop, GluR6, non-desensitizing GluR2 L504Y channels and heterooligomeric GluR1/2 channels were expressed in HEK293 cells. AMPA-type channels were competitively inhibited by RPR119990 or RPR117824 with an IC(50) around 10 nM, at GluR6 channels the dose-response relation of the inhibition was shifted to higher concentrations. Non-desensitizing GluR2 L504Y channels were used to further characterize the inhibition. After equilibration with the agonist a marked dose-dependent current decay upon coapplication of glutamate and RPR119990 and a dose-independent time course of recovery from block was observed. The extents of current inhibition as well as the time constant of current decay upon addition of the blocker to the test solution were dependent on agonist concentration, pointing to a competitive inhibition. Quantitative analysis of the experimental data using computerized simulations are compatible with a competitive block mechanism and provides hints to binding sites at unliganded and liganded closed states of the receptor.

GABA(A)-receptor mRNA expression in the prefrontal and temporal cortex of ALS patients.

There is evidence that excitotoxic cell death is involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). Electrophysiological and histological studies support the pathophysiological concept of an impaired inhibitory, namely GABAergic, control of the motoneurons in the cerebral cortex of ALS patients. Recently, pathological, neuropsychological and functional imaging data have challenged the view that ALS is a disorder restricted to the motor system. The aim of our study was to investigate the expression of the most abundant GABA(A)-receptor subunit mRNAs and the GABA synthesizing enzyme glutamic acid decarboxylase (GAD) in the prefrontal, temporal, occipital and cerebellar cortex of ALS patients compared to tissue of control persons. We performed in situ hybridization histochemistry (ISH) on human post-mortem cortex sections of ALS patients (n=5) and age-matched controls with no history of neurological disease (n=5). In the prefrontal and temporal cortex of ALS patients, we detected significantly reduced mRNA expression of the alpha1-subunit, while the GABA synthesizing enzyme glutamic acid decarboxylase (GAD) was significantly upregulated in these regions. In the occipital and cerebellar cortex, we did not see disease-specific differences of the mRNA expression of the investigated subunits.