A novel 2,3-benzodiazepine-4-one derivative AMPA antagonist inhibits G2/M transition and induces apoptosis in human leukemia Jurkat T cell line.

It has been shown that the antagonism of glutamate receptors activity was able inhibit proliferation and induce apoptosis in several neuronal and non-neuronal cancer cell lines. In addition, it has been shown that glutamate might facilitate the spread and growth of leukemia T cells through interactions with AMPA receptors. The aim of the present study was to investigate the modulation of cell cycle elicited by a novel 2,3-benzodiazepine-4-one non-competitive AMPA antagonist derivative in the human leukemia Jurkat T cells. Our results indicated that the 1-(4-amino-3,5-dimethylphenyl)-3,5-dihydro-7,8-ethylenedioxy-4h-2,3-benzodiazepin-4-one, named 1g, exerted a significant growth inhibition of leukemia Jurkat T cells in a time and dose dependent manner, arresting the transition of G2/M phase through activation of Myt-1. The molecule also induced apoptosis through the enhanced expression of the pro-apoptotic p53, and the inhibition of Bcl-2, and Bcl-xl, followed by the activation of caspase-3. The results suggested that compound 1g might act mostly as a cytostatic rather than cytotoxic compound. Although further studies are necessary, in order to identify others specific pathways involved in the activity of the present molecule, the presented results identified a novel molecule acting on specific G2/M checkpoint regulation pathway. Finally, our data suggest that compound 1g might be a good molecule for future development in the cancer research.

Sex differences in food choices, adherence to dietary recommendations and plasma lipid profile in type 2 diabetes - The TOSCA.IT study.

BACKGROUND AND AIMS: Diabetic women have a more adverse plasma lipid profile than men. Sex differences in dietary habits may play a role, but are little investigated. The study evaluates the quality of diet, adherence to the nutritional recommendations of the Diabetes and Nutrition Study Group and their relation with plasma lipid in men and women with diabetes. METHODS AND RESULTS: We studied 2573 people, aged 50-75, enrolled in the TOSCA.IT study (clinicaltrials.gov; NCT00700856). Plasma lipids were measured centrally. Diet was assessed with a semi-quantitative food frequency questionnaire. Women had a more adverse plasma lipid profile than men. Women consumed significantly more legumes, vegetables, fruits, eggs, milk, vegetable oils, and added sugar, whereas men consumed more starchy foods, soft drinks and alcoholic beverages. This stands for a higher proportion (%) of energy intake from saturated fat and added sugar (12.0 ± 2.4 vs 11.5 ± 2.5 and 3.4 ± 3.2 vs 2.3 ± 3.2, P < 0.04), and a higher intake of fiber (11.2 ± 2.8 vs 10.4 ± 2.6 g/1000 Kcal/day) in women. Adherence to the recommendations for saturated fat and fiber consumption was associated with significantly lower LDL-cholesterol regardless of sex. Adherence to the recommendations for added sugars was associated with significantly lower triglycerides and higher HDL-cholesterol in men and women. CONCLUSIONS: Men and women with diabetes show significant differences in adherence to nutritional recommendations, but sex differences in plasma lipid profile are unlikely to be explained by nutritional factors. Adherence to the nutritional recommendations is associated with a better plasma lipid profile regardless of sex, thus reinforcing the importance of substituting saturated for unsaturated fat sources, increasing fiber and reducing added sugar intake.

Carcinogenic potential of metal nanoparticles in BALB/3T3 cell transformation assay.

Metal-based nanoparticles (NPs), are currently used in many application fields including consumer products, pharmaceuticals, and biomedical treatments. In spite to their wide applications, an in-depth study of their potential toxic effects is still lacking. The aim of the present research was to investigate the potential initiator or promoter-like activity of different metallic NPs such as gold, iron, cobalt, and cerium using the Balb/3T3 two-stage transformation assay. The results indicated that all the selected metallic NPs, except for cobalt, when used as initiators did not induce any transformation in Balb/3T3 cell line. Moreover, Au and Fe3 O4 NPs, when used in place of the tumor promoter treatment TPA, increased significantly the number of Foci/dish as compared to the MCA treatment alone. The number of Foci/dish was 2.6 for Au NPs and 2.13 for Fe3 O4 ones, similar to those obtained by the positive control treatment (MCA + TPA), whereas 1.27 for MCA treatment alone. On the contrary, CeO2 NPs did not show any difference in the number of Foci/dish, as compared to MCA alone, but it decreased the number of foci by 65% in comparison to the positive control (MCA + TPA). As expected, cobalt NPs showed an increased cytotoxicity and only a few surviving cells were found at the time of analysis showing a number of Foci/dish of 0.13. For the first time, our data clearly showed that Au and Fe3 O4 NPs act as promoters in the two stage transformational assay, suggesting the importance to fully investigate the NPs carcinogenic potential with different models.

Influence of dietary fat and carbohydrates proportions on plasma lipids, glucose control and low-grade inflammation in patients with type 2 diabetes-The TOSCA.IT Study.

PURPOSE: The optimal macronutrient composition of the diet for the management of type 2 diabetes is debated, particularly with regard to the ideal proportion of fat and carbohydrates. The aim of the study was to explore the association of different proportions of fat and carbohydrates of the diet-within the ranges recommended by different guidelines-with metabolic risk factors. METHODS: We studied 1785 people with type 2 diabetes, aged 50-75, enrolled in the TOSCA.IT Study. Dietary habits were assessed using a validated food-frequency questionnaire (EPIC). Anthropometry, fasting lipids, HbA1c and C-reactive protein (CRP) were measured. RESULTS: Increasing fat intake from <25 to ≥35 % is associated with a significant increase in LDL-cholesterol, triglycerides, HbA1c and CRP (p < 0.05). Increasing carbohydrates intake from <45 to ≥60 % is associated with significantly lower triglycerides, HbA1c and CRP (p < 0.05). A fiber intake ≥15 g/1000 kcal is associated with a better plasma lipids profile and lower HbA1c and CRP than lower fiber consumption. A consumption of added sugars of ≥10 % of the energy intake is associated with a more adverse plasma lipids profile and higher CRP than lower intake. CONCLUSIONS: In people with type 2 diabetes, variations in the proportion of fat and carbohydrates of the diet, within the relatively narrow ranges recommended by different nutritional guidelines, significantly impact on the metabolic profile and markers of low-grade inflammation. The data support the potential for reducing the intake of fat and added sugars, preferring complex, slowly absorbable, carbohydrates.

Lipid profile and cardiovascular risk factors among first-year Brazilian university students in São Paulo.

BACKGROUND/AIMS: The surveillance of cardiovascular risk factors has been recommended worldwide. The current study is aimed to estimate the prevalence of cardiovascular risk factors among first-year students from a public university in the city of Sao Paulo, Brazil. METHODS: A cross-sectional study of 56 first-year students, of both genders, was performed. Information about demographic characteristics, family history of chronic diseases, smoking, and physical activity was obtained by means of a standardised questionnaire. Anthropometrical parameters (BMI, waist circumference, body fat percentage), metabolic parameters (glycaemia, serum lipid profile), and dietary data (total energy intake, percentage of total energy from macronutrients, cholesterol and dietary fiber) were assessed. RESULTS: The risk of cardiovascular diseases was characterised by family history of cardiovascular diseases (44.6%), smoking (10.7%), physical inactivity (35.7%), borderline high total cholesterol and LDL-c levels (16.1% and 5.4, respectively), decreased HDL-c levels (8.9%), increased triglyceride levels (8.9%), and overweight and obesity (17.8% and 7.1%, respectively). The diet of the students was inadequate: it was high in fat and protein, and low in carbohydrate and dietary fibre. CONCLUSIONS: The prevalence of risk factors for cardiovascular diseases in young adults draws attention to the need to adopt preventive plans in the university setting.

Effects of the novel non-peptidyl low molecular weight radical scavenger IAC in different models of inflammation: a new perspective in anti- inflammatory therapy.

The bis (1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)-decandioate called IAC, is a new non-peptidyl low molecular weight radical scavenger able to give a fast reaction with the majority of radical species involved in the oxidative stress. This intrinsic property might be of particular interest in all the processes where it presents an over production of reactive oxygen/nitrogen species (ROS/RNS) such as inflammation. Indeed, it is well known that systemic inflammatory response is associated with the production of ROS, nitric oxide (NO), which in turn deplete the endogenous GSH, mediating cytotoxicity. It has been shown that IAC through its antioxidant activity, exerted a protective effect in vitro in islets isolated from type-2 diabetic patients, and in vivo in a non-obese diabetic mouse model and in DNBS-induced colitis in rats. The ability of IAC to protect brain from ischemia, suggests a possible use of the compound in broad range of inflammatory- related diseases. It is well known that the use of non steroidal anti-inflammatory drugs (NSAIDs) is associated with a broad spectrum of untoward side-effects such as gastrointestinal ulceration. The major pathogenetic element in the development of these effects is the depletion of prostaglandins (PGs) through inhibition of cyclooxygenase. The evidence that IAC protects gastric mucosa in an animal model of indomethacin-induced ulcer, through local increase of PGE2 levels and antioxidant activity, candidates this compound as a novel, promising, anti-inflammatory compound avoiding the major common untoward side-effects elicited by NSAID's.

Natural endogenous ligands for benzodiazepine receptors in hepatic encephalopathy.

Benzodiazepines of natural origin (NBZDs) have been found in human blood and brains as well as in medicinal plants and foods. In plasma and brain tissue there are i.e. diazepam and nordiazepam equal to commercial drugs but there are also other benzodiazepine-like compounds termed "endozepines", which act as agonists at the benzodiazepine receptors of central type (CBR). A synthetic pathway for the production of NBZDs has not yet been found, but it has been suggested that micro-organisms may synthesize molecules with benzodiazepine-like structures. Hence NBZDs could be of both endogenous and exogenous source and be considered as natural anxyolitic and sedative. Interestingly there are also natural compounds, such as the polypeptide Diazepam Binding Inhibitor (DBI) acting as an "inversive agonist" implicated in fair and panic disorders. It has been suggested that NBZDs may play a role in the pathogenesis of hepatic encephalopathy (HE). Multidirectional studies evaluated NBZDs levels (1) in the blood of normal subjects, of cirrhotic with or without HE and in commercial benzodiazepine consumers; (2) in the blood of cirrhotic treated or not with a non-absorbable antibiotic; (3) in several constituents of our diet. In conclusion, NBZDs increase sometime in cirrhotics with or without HE but they reach concentrations not higher than those found in commercial benzodiazepines consumers. Hence NBZDs must be considered as occasional precipitating factor of HE and benzodiazepine antagonists only symptomatic drugs. The finding that NBZDs may be in part synthesized by intestinal bacterial flora and in part constituent of our diet underlines the importance to feed cirrhotic patients with selected food.

Evaluation of rifaximin, placebo and lactulose in reducing the levels of benzodiazepine-like compounds in patients with liver cirrhosis: a pilot study.

Benzodiazepine-like compounds (BZDs), either taken with the diet or synthesized by intestinal bacterial flora, may represent a precipitating factor for hepatic encephalopathy (HE) in cirrhotic patients. We evaluated whether a diet and/or treatment with rifaximin or lactulose can reduce serum concentrations of BZDs in 18 cirrhotic patients without HE. Patients were given a standard diet for 7 days to keep the dietary intake of BZDs constant and were then randomized to a 7-day treatment with rifaximin 1,200 mg/day, lactulose 10-20 g three times daily, or placebo. Blood samples were collected at enrollment, at the end of the diet and drug treatment periods, and 7 days after the drug was stopped (follow-up). Serum concentrations of BZDs were measured by a radioligand binding technique after high-performance liquid chromatography extraction and purification and were expressed as diazepam equivalents (DE). No change in serum BZD concentrations was observed during the diet, while a statistically significant decrease from 105.6 +/- 66.5 to 63.5 +/- 49.5 pmol DE/ml was achieved in rifaximin-treated patients (p < 0.05) but not in patients treated with lactulose or placebo. During the followup, serum BZD concentrations returned to 104.5 +/- 74.0 pmol DE/ml in rifaximin-treated patients (p < 0.05 vs. end-treatment values), while no significant change was observed in the lactulose- and placebo-treated patients. These data indicate that control of bacterial flora with cyclic administration of rifaximin plays a pivotal role in avoiding increased plasma concentrations of BZDs, which represent a precipitating factor for HE inpatients with severe liver disease.

Clinical evaluation of piroxicam-FDDF and azithromycin in the prevention of complications associated with impacted lower third molar extraction.

Combined treatments with non-steroidal anti-inflammatory drugs and antibiotics may offer significant benefits in the prevention of pain and infections associated with oral surgery. In this study, piroxicam and azithromycin were administered to patients undergoing dental extraction to examine the efficacy of piroxicam in the prevention of post-operative pain and inflammatory complications, either in the absence or in the presence of a concomitant antibiotic treatment. Thirty patients were randomly assigned to three groups and treated for 3 days, before impacted lower third molar removal, as follows: (1) sublingual piroxicam-FDDF (fast dissolving dosage formulation) 20 mg/day; (2) oral azithromycin 500 mg/day; (3) piroxicam-FDDF 20 mg/day plus azithromycin 500 mg/day. Oral acetaminophen (500 mg tablets) was allowed as rescue analgesic medication. Pain intensity was evaluated on a 100-mm visual-analogue scale after dental extraction (day 1), and at days 2, 3, 7 after surgery. Edema and trismus were estimated at days 2 and 7. At days 1 and 2, pain intensity was significantly lower in patients treated with piroxicam-FDDF, either alone (p < 0.05) or in combination with azithromycin (p < 0.05), than in patients administered with azithromycin alone. A higher acetaminophen consumption was also recorded in the latter group (p < 0.01). Pain intensity values did not differ among treatment groups at days 3 and 7. At day 2, the facial edema was significantly less intense in patients exposed to piroxicam-FDDF alone, as compared to patients treated with azithromycin, either alone (p < 0.05) or in combination with piroxicam-FDDF (p < 0.05). No significant differences were detected when comparing groups for trismus at days 2 and 7. The present results indicate that, when given alone in the pre-operative period, piroxicam-FDDF effectively counteracts post-surgical pain and inflammatory reactions in oral tissues. Upon combined treatment with piroxicam-FDDF and azithromycin, the macrolide antibiotic may reduce the influence of piroxicam on post-operative inflammation, without affecting its beneficial effect on surgical pain.

Nuclear location-dependent role of peripheral benzodiazepine receptor (PBR) in hepatic tumoral cell lines proliferation.

PBR is involved in numerous biological functions, including steroid biosynthesis, mitochondrial oxidative phosphorylation and cell proliferation. The presence of PBR at the perinuclear/nuclear subcellular level has been demonstrated in aggressive breast cancer cell lines and human glioma cells where it seems to be involved in cell proliferation. In our study we investigated the presence of perinuclear/nuclear PBR in different hepatic tumor cell lines with regard to binding to [3H] PK 11195 and protein analysis. The results obtained by saturation binding experiments and scatchard analysis of perinuclear/nuclear PBR density in parallel with the results on the growth curves of the cell lines tested, indicate that the perinuclear/nuclear PBR density correlates inversely with cell doubling time. Moreover, the cell line with high perinuclear/nuclear PBR proliferated in response to PBR ligand, whereas that with low perinuclear/nuclear PBR did not. Our results reinforce the idea that the subcellular localisation of PBR defines its function and that this receptor could be a possible target for new strategies against cancer.

Antiproliferative effects of Ceratonia siliqua L. on mouse hepatocellular carcinoma cell line.

Extracts from pods and leaves of carob (Ceratonia siliqua L.) were tested for their ability to inhibit cell proliferation of mouse hepatocellular carcinoma cell line (T1). The two extracts showed a marked alteration of T1 cell proliferation in a dose-related fashion reaching the maximal effect at 1 mg/ml. Moreover, we demonstrated that leaf and pod extracts were able to induce apoptosis in T1 cell lines after 24-h treatment mediating a direct activation of the caspase 3 pathway. HPLC analysis revealed the presence of gallic acid, (-) epigallocatechin-3-gallate and (-) epicatechin-3-gallate in pod and leaf extracts, compounds well known to exert antiproliferative effects. Their concentration reached 6.28 mg/g in carob leaves and 1.36 mg/g in carob pods extract. The discovery that carob pod and leaf extracts contained antiproliferative agents could be of practical importance in the development of functional foods and/or chemopreventive drugs.

Ribozyme-mediated reduction of the GABA(A) receptor alpha1 subunit.

As an approach to understanding the role of the alpha1 subunit of the GABA(A) receptor, ribozymes were designed to reduce expression of this subunit protein by hydrolysis of alpha1 subunit message and antisense inactivation. The ribozyme cleavage sites were selected through homology comparison of all known murine GABA(A) receptor subunits at the amino acid and nucleotide sequence level. Two ribozymes were designed and synthesized: one against the extracellular domain and the other against the cytoplasmic domain. These ribozymes were cloned in a mammalian expression plasmid, pZeoSV2 (+). Cleavage of both extracellular and cytoplasmic domain transcripts by the respective ribozymes was observed when each ribozyme was tested against in vitro transcribed mRNA. The stable cell line, 122, expressing recombinant human GABA(A) alpha1, beta2 and gamma2S subunits of receptor was stably transfected with the cytoplasmic domain ribozyme (cy) alone and with both the cytoplasmic (cy) and extracellular domain (ex) ribozyme expression plasmids. Northern analysis showed a 55-60% reduction of alpha1 mRNA in clones of cells transfected with either the single ribozyme (Cy) or with both ribozymes (EC). The alpha1 protein level was reduced 75% in a stable Cy clone and more than 90% in a stable EC clone when compared with alpha1 expression in 122 cells and the vector transfected (Zeo) cells. Electrophysiological analysis revealed that the GABA(A) receptor properties were very similar in 122 cells and in stable clones in which the subunit protein expression had been greatly reduced. No significant difference was detected in the potentiation of the receptor response by either bretazenil or zolpidem. These data demonstrate the efficacy of the ribozyme approach in dramatically reducing GABA(A) subunit protein levels in transfected cells and identify those elements that will be important to the application of similar ribozymes to knock-down transmitter receptor subunit proteins under inducible promoters in transgenic mice.

Ammonia and endogenous benzodiazepine-like compounds in the pathogenesis of hepatic encephalopathy.

BACKGROUND: Ammonia and endogenous benzodiazepines (BDZs) are two of the most important agents among those taken into consideration in the pathogenesis of hepatic encephalopathy (HE). METHODS: Venous ammonia and endogenous BDZs sera levels were assayed in 58 liver cirrhosis patients (34 male, 24 female) free of commercial BDZs. Endogenous BDZs were measured by binding assay after high-performance liquid chromatography purification. Ammonia was assessed by colorimetric test. RESULTS: Endogenous BDZs and ammonia were significantly higher in Child-Pugh class C than in class B and class A (P < 0.05), correlating to the severity of the liver dysfunction but not with the degree of HE. A significant difference, in fact, was noted between degree 0 (no HE) versus III-IV of HE (P < 0.05), but not between degrees I-II versus III-IV. Regression analysis performed to find a correlation between the ammonia and BDZ levels in HE resulted negative. CONCLUSION: Clinical evidence is provided in cirrhotic patients that ammonia and endogenous BDZ levels do not correlate with each other in the outcome of HE.

Endogenous benzodiazepines.

The existence of endogenous benzodiazepines such as diazepam and nordiazepam has been provided in human blood and brains as well as in medicinal plants and foods. It must be stressed, however, that in plasma and brain tissue there are also other benzodiazepine-like compounds termed 'endozepines' which are not halogenated. A synthetic pathway for the production of benzodiazepine-like compounds and endozepines has not yet been found, hence it may be surmised that these compounds could be of exogenous source. Changes in the level of endogenous circulating benzodiazepines due to food or drug ingestion could be responsible for pathological conditions. Clinical experiments were designed in order to study the levels of the endogenous benzodiazepines in vegetables and in the blood of control subjects and of cirrhotic patients. These patients accumulate benzodiazepines because of decreased liver metabolization capacity and impaired renal secretion, reaching plasma concentrations similar to those recorded in commercial benzodiazepine consumers.

Increased expression of peripheral benzodiazepine receptors and diazepam binding inhibitor in human tumors sited in the liver.

The peripheral benzodiazepine receptor system triggers intracellular metabolic events and has been associated with cell proliferation. Its endogenous ligand, the diazepam binding inhibitor, contributes to steroidogenesis by promoting cholesterol delivery to the inner mitochondrial membrane. The present study was undertaken to verify whether this system is altered in tumors sited in the liver. Peripheral benzodiazepine receptors and diazepam binding inhibitor were studied using immunocytochemistry and in situ hybridization in 9 human tumors sited in the liver, in liver hyperplasia, cirrhotic nodular regeneration, intestinal adenocarcinoma and in surrounding non-tumoral tissue. Immunocytochemical staining and in situ hybridization demonstrated that peripheral benzodiazepine receptors and diazepam binding inhibitor were more prominently expressed in neoplastic cells than in non-tumoral tissue. They were present in the same cells, suggesting that diazepam binding inhibitor may act in an intracrine manner in these cells. Higher peripheral benzodiazepine receptors and diazepam binding inhibitor expression in tumor cells suggest an implication of this system in the metabolism of neoplastic cells. Furthermore the evaluation of peripheral benzodiazepine receptor and diazepam binding inhibitor expression might be useful in evaluating malignancy and in diagnostic approaches of tumors in liver tissue.

Up-regulation of peripheral benzodiazepine receptor system in hepatocellular carcinoma.

Increased number of peripheral benzodiazepine receptors (PBRs) have been found in some tumors outside the liver. The present study was to verify whether the PBR system is altered in hepatocellular carcinoma (HCC). The levels of endogenous benzodiazepine-like compounds (BZDs), measured by radioreceptor binding technique after HPLC purification and the endogenous ligand for PBRs, termed diazepam binding inhibitor (DBI), measured by radioimmunoassay utilizing a specific antibody for human DBI, were studied in the blood of 15 normal subjects, 12 liver cirrhosis and 10 patients with HCC. The levels of BZDs in serum were increased hundred fold in liver cirrhosis patients and slightly elevated in HCC patients. DBI was found to be increased in HCC patients. The binding recognition sites for PBRs (Bmax) were increased 4 to 7 fold in HCC tissue in comparison with that found in non-tumoral liver tissue (NTLT). On the contrary the concentrations of DBI were found to be significantly decreased in HCC tissue in comparison with the respective NTLT. These results seem to suggest an implication of PBRs and of their putative endogenous ligands in the metabolism of these neoplastic cells and possibly in their proliferation. The up-regulation of PBRs found in HCC tissue seems to indicate an increased functional activity of these receptors and opens up the possibility of new pharmacological and diagnostic approaches while the changes in the circulating endogenous ligands for the above receptors might be envisaged as early markers of tumorigenesis in liver cirrhosis.

Developmental changes in localization of NMDA receptor subunits in primary cultures of cortical neurons.

Immunoblot analysis, using antibodies against distinct N-methyl-D-aspartic acid (NMDA) receptor subunits, illustrated that the NR2A and NR2B subunit proteins have developmental profiles in cultured cortical neurons similar to those seen in vivo. NR1 and NR2B subunits display high levels of expression within the first week. In contrast, the NR2A subunit is barely detectable at 7 days in vitro (DIV) and then gradually increased to mature levels at DIV21. Immunocytochemical analysis indicated that NMDA receptor subunits cluster in the dendrites and soma of cortical neurons. Clusters of NR1 and NR2B subunits were observed as early as DIV3, while NR2A clusters were rarely observed before DIV10. At DIV18, NR2B clusters partially co-localize with those of NR2A subunits, but NR2B clusters always co-localize with those of NR1 subunits. Synapse formation, as indicated by the presence of presynaptic synaptophysin staining, was observed as early as 48-72 h after plating. However, in several neurons at ages less than DIV5 where synapses were scarce, NR2B and NR1 clusters were abundant. Furthermore, while NR2B subunit clusters were seen both at synaptic and extrasynaptic sites, NR2A clusters occurred almost exclusively in front of synaptophysin-labelled boutons. This result was supported by electrophysiological recording of NMDA-mediated synaptic activity [NMDA-excitatory postsynaptic currents (EPSCs)] in developing neurons. At DIV6, but not at DIV12, CP101, 606, a NR1/NR2B receptor antagonist, antagonized spontaneously occurring NMDA-EPSCs. Our data indicate that excitatory synapse formation occurs when NMDA receptors comprise NR1 and NR2B subunits, and that NR2A subunits cluster preferentially at synaptic sites.

Endogenous benzodiazepine-like compounds and diazepam binding inhibitor in serum of patients with liver cirrhosis with and without overt encephalopathy.

BACKGROUND/AIM: Despite some controversy, it has been suggested that endogenous benzodiazepine plays a role in the pathogenesis of hepatic encephalopathy. The aim of the present study was to evaluate the concentrations of endogenous benzodiazepines and the peptide, diazepam binding inhibitor, in the blood of patients with liver cirrhosis with and without overt encephalopathy, and to compare these levels with those of consumers of commercial benzodiazepines. SUBJECTS: Normal subjects (90), benzodiazepine consumers (14), and cirrhotic patients (113) were studied. METHODS: Endogenous benzodiazepines were measured by the radioligand binding technique after high performance liquid chromatography (HPLC) purification. The presence of diazepam and N-desmethyldiazepam was assayed by HPLC-electrospray tandem mass spectrometry. Diazepam binding inhibitor was studied in serum by radioimmunoassay. RESULTS: Endogenous benzodiazepines were below the limit of detection in 7% of patients with encephalopathy. When detectable, their levels were at least comparable with those of benzodiazepine consumers and correlated with the liver dysfunction but not the stage of encephalopathy. Serum levels of diazepam binding inhibitor tended to decrease when endogenous benzodiazepines levels increased. CONCLUSIONS: Endogenous benzodiazepines may accumulate in patients with liver cirrhosis during the course of the disease, and the phenomenon appears to be independent of the presence or absence of encephalopathy.

Lanthanum-mediated modification of GABAA receptor deactivation, desensitization and inhibitory synaptic currents in rat cerebellar neurons.

1. We investigated La3+ effects on recombinant and native gamma-aminobutyric acid A (GABAA) receptors using rapid agonist applications and on inhibitory synaptic currents (IPSCs) in granule and stellate neurons of rat cerebellar slices. 2. Rapid desensitization of currents elicited by 200 ms pulses of 1 mM GABA to small lifted cells transfected with alpha1beta3gamma2 cDNAs was greatly decreased by the coapplication of 100 microM LaCl3. 3. GABA responses were unaffected when coapplication lasted only 2 ms. In contrast, with LaCl3 pre-perfusion, a significant slowing of deactivation in response to 2 ms applications was observed. LaCl3 pre-perfusion also prolonged the duration of responses to 20 mM taurine. 4. Outside-out patches excised from cells transfected with alpha1beta3gamma2 subunit cDNAs were briefly exposed to a saturating concentration of GABA, eliciting a transient activation of single channel currents with a main conductance of 30 pS. Opening and burst durations increased by pre-equilibration of patches with LaCl3. 5. LaCl3 depressed the peak amplitude without affecting the slow deactivation and desensitization of GABA responses in cells transfected with alpha6beta3gamma2 and alpha6beta3delta cDNAs. No significant difference in La3+ modulation of GABA-gated currents was observed between alpha1beta3gamma2 and alpha1beta3delta receptors. 6. The effects of LaCl3 on deactivation and desensitization of GABA responses observed in nucleated patches excised from rat cerebellar granule and stellate neurons were comparable to those in the cells transfected with alpha1beta3gamma2 cDNAs. In addition, La3+ clearly prolonged the spontaneous IPSC time course without changing the amplitude. 7. Our results indicate that La3+ has a dual action on GABA-gated currents: it decreases desensitization and increases channel opening duration. These actions depend on receptor subunit composition and contribute to the prolongation of IPSCs.

Chronic dizocilpine (MK-801) reversibly delays GABA(A) receptor maturation in cerebellar granule neurons in vitro.

We investigated the effect of chronically blocking NMDA receptor stimulation to examine changes in GABA(A) receptor expression and pharmacology in cerebellar granule cells at different stages of maturation. We have previously shown that NMDA-selective glutamate receptor stimulation alters GABA(A) receptor pharmacology in cerebellar granule neurons in vitro by altering the levels of selective subunits. When NMDA receptor stimulation is blocked with MK-801 during the first week in vitro, a decrease in the alpha1, gamma2S, and gamma2L receptor subunit mRNAs occurred. When present only during the second week, changes were limited to the alpha1 and gamma2L mRNAs. Finally, if MK-801 was present during the first week and removed during the second week, these changes reversed. Whole-cell voltage-clamp recordings showed that treatment with MK-801 during either the first or second week increased the EC50 of the receptors for GABA and attenuated the potentiation mediated by flunitrazepam. Last, these properties were reversed if MK-801 was removed after the first week in vitro. Our results suggest that MK-801 reversibly inhibits GABA(A) receptor maturation by modulating receptor subunit expression and that the altered pharmacological responses appear to be dominated by changes in the levels of allosteric modulation mediated by the gamma2 receptor subunit.