Isoniazid-induced reduction in GABAergic neurotransmission alters the function of the cerebellar cortical circuit

Stable Gastric Pentadecapeptide BPC 157 May Recover Brain-Gut Axis and Gut-Brain Axis Function

Conceptually, a wide beneficial effect, both peripherally and centrally, might have been essential for the harmony of brain-gut and gut-brain axes' function. Seen from the original viewpoint of the gut peptides' significance and brain relation, the favorable stable gastric pentadecapeptide BPC 157 evidence in the brain-gut and gut-brain axes' function might have been presented as a particular interconnected network. These were the behavioral findings (interaction with main systems, anxiolytic, anticonvulsive, antidepressant effect, counteracted catalepsy, and positive and negative schizophrenia symptoms models). Muscle healing and function recovery appeared as the therapeutic effects of BPC 157 on the various muscle disabilities of a multitude of causes, both peripheral and central. Heart failure was counteracted (including arrhythmias and thrombosis), and smooth muscle function recovered. These existed as a multimodal muscle axis impact on muscle function and healing as a function of the brain-gut axis and gut-brain axis as whole. Finally, encephalopathies, acting simultaneously in both the periphery and central nervous system, BPC 157 counteracted stomach and liver lesions and various encephalopathies in NSAIDs and insulin rats. BPC 157 therapy by rapidly activated collateral pathways counteracted the vascular and multiorgan failure concomitant to major vessel occlusion and, similar to noxious procedures, reversed initiated multicausal noxious circuit of the occlusion/occlusion-like syndrome. Severe intracranial (superior sagittal sinus) hypertension, portal and caval hypertensions, and aortal hypotension were attenuated/eliminated. Counteracted were the severe lesions in the brain, lungs, liver, kidney, and gastrointestinal tract. In particular, progressing thrombosis, both peripherally and centrally, and heart arrhythmias and infarction that would consistently occur were fully counteracted and/or almost annihilated. To conclude, we suggest further BPC 157 therapy applications.

The First Case of Ceftazidime-Induced Antibiomania: A Case Report and Literature Review

Antibiomania is a rare type of secondary mania caused by antibiotics. Here, we describe the first case report of antibiomania in a peritoneal dialysis patient caused by ceftazidime, a cephalosporin antibiotic. Manic symptoms were noted in the patient described here a few days after starting the antibiotic and worsened over the course of a few weeks of antibiotic treatment. There is a close temporal relationship between the start of antibiotics and the onset of manic symptoms in this case. Antibiotics from various groups have been implicated as the causative agents in a few case reports of antibiomania. Several hypotheses have been postulated regarding the underlying mechanism of antibiomania. The authors of this article highlight the importance of recognizing the psychiatric side effects of antibiotics early and formulating effective management options to prevent detrimental effects on a patient's clinical condition.

OUP accepted manuscript

In vivo developmental neurotoxicity (DNT) testing is resource intensive and lacks information on cellular processes affected by chemicals. To address this, DNT new approach methodologies (NAMs) are being evaluated, including: the microelectrode array neuronal network formation assay; and high-content imaging to evaluate proliferation, apoptosis, neurite outgrowth, and synaptogenesis. This work addresses 3 hypotheses: (1) a broad screening battery provides a sensitive marker of DNT bioactivity; (2) selective bioactivity (occurring at noncytotoxic concentrations) may indicate functional processes disrupted; and, (3) a subset of endpoints may optimally classify chemicals with in vivo evidence for DNT. The dataset was comprised of 92 chemicals screened in all 57 assay endpoints sourced from publicly available data, including a set of DNT NAM evaluation chemicals with putative positives (53) and negatives (13). The DNT NAM battery provides a sensitive marker of DNT bioactivity, particularly in cytotoxicity and network connectivity parameters. Hierarchical clustering suggested potency (including cytotoxicity) was important for classifying positive chemicals with high sensitivity (93%) but failed to distinguish patterns of disrupted functional processes. In contrast, clustering of selective values revealed informative patterns of differential activity but demonstrated lower sensitivity (74%). The false negatives were associated with several limitations, such as the maximal concentration tested or gaps in the biology captured by the current battery. This work demonstrates that this multi-dimensional assay suite provides a sensitive biomarker for DNT bioactivity, with selective activity providing possible insight into specific functional processes affected by chemical exposure and a basis for further research.

Do in vitro assays in rat primary neurons predict drug-induced seizure liability in humans?

Drug-induced seizures contribute to the high attrition rate of pharmaceutical compounds in development. The assessment of drug-induced seizure liability generally occurs in later phases of development using low throughput and intensive in vivo assays. In the present study, we evaluated the potential of an in vitro assay for detecting drug-induced seizure risk compared to evaluation in rats in vivo. We investigated the effects of 8 reference drugs with a known seizurogenic risk using micro-electrode array (MEA) recordings from freshly-dissociated rat primary neurons cultured on 48-well dishes for 28 days, compared to their effects on the EEG in anesthetized rats. In addition, we evaluated functional responses and mRNA expression levels of different receptors in vitro to understand the potential mechanisms of drug-induced seizure risk. Combining the functional MEA in vitro data with concomitant gene expression allowed us to identify several potential molecular targets that might explain the drug-induced seizures occurring in both rats and humans. Our data 1) demonstrate the utility of a group of MEA parameters for detecting potential drug-induced seizure risk in vitro; 2) suggest that an in vitro MEA assay with rat primary neurons may have advantages over an in vivo rat model; and 3) identify potential mechanisms for the discordance between rat assays and human seizure risk for certain seizurogenic drugs.

BPC 157 antagonized the general anaesthetic potency of thiopental and reduced prolongation of anaesthesia induced by L-NAME/thiopental combination

AIM

We hypothesized that certain effects of the general anaesthetic thiopental are dependent on NO-related mechanisms, which were consequently counteracted by stable gastric pentadecapeptide BPC 157.

MAIN METHODS

(1) All rats intraperitoneally received thiopental (20, 30, 40, and 50 mg/kg) while medication BPC 157 (10 μg/kg, 10 ng/kg, and 10 pg/kg) was given intraperitoneally at 5 min before thiopental. (2) To determine NO-related mechanisms, all rats received intraperitoneally thiopental 40 mg/kg while BPC 157 (10 μg/kg), L-NAME (10 mg/kg) and L-arginine (30 mg/kg) were applied alone and/or combined. BPC 157 was given at 25 min before thiopental while L-NAME, L-arginine, alone and/or combined, were applied at 20 min before thiopental.

KEY FINDINGS

(1) BPC 157 own effect on thiopental anaesthesia: BPC 157 (10 ng/kg and 10 μg/kg) caused a significant antagonism of general anaesthesia produced by thiopental with a parallel shift of the dose-response curve to the right. (2) L-NAME-L-arginine-BPC 157 interrelations: L-NAME: Thiopental-induced anaesthesia duration was tripled. L-arginine: Usual thiopental anaesthesia time was not influenced. Active only when given with L-NAME or BPC 157: potentiating effects of L-NAME were lessened, not abolished; shortening effect of BPC 157: abolished. BPC 157 and L-NAME: Potentiating effects of L-NAME were abolished. BPC 157 and L-NAME and L-arginine: BPC 157 +L-NAME +L-arginine rats exhibited values close to those in BPC 157 rats.

SIGNIFICANCE

Thiopental general anaesthesia is simultaneously manipulated in both ways with NO system activity modulation, L-NAME (prolongation) and BPC 157 (shortening/counteraction) and L-arginine (interference with L-NAME and BPC 157).

Visual experience prevents dysregulation of GABAB receptor-dependent short-term depression in adult superior colliculus

Progressive loss of plasticity during development prevents refined circuits from regressing to an immature state and is thought to depend on maturation of GABAergic inhibition. For example, a gradual reduction in size of visual receptive fields (RFs) occurs in the superior colliculus (SC) during development. Maintenance of the refined state throughout adulthood requires early light exposure. Here we investigate the potential role of changes in long- or short-term plasticity in experience-dependent maintenance of refined RFs. Using an acute SC slice preparation, we found that long-term plasticity was not affected by visual deprivation, indicating that it does not underlie deprivation-induced RF enlargement. In contrast, visual deprivation altered short-term plasticity in an unexpected way. Specifically, GABAB receptor (GABABR)-mediated paired pulse depression was increased in slices from dark-reared animals. This increase was mimicked by GABAAR blockade in slices from normally reared animals, suggesting that experience-dependent maintenance of GABAAR function prevents an increase in probability of neurotransmitter release. GABABR-mediated short-term depression in response to strong stimulation (such as occurs during vision) was reduced in slices from dark-reared animals. This change was mimicked in slices from normal animals by reducing GABA release. These results are consistent with the hypothesis that early visual experience maintains GABAergic inhibition and prevents later deprivation-induced alterations of short-term depression in SC. Identifying how plasticity is restricted in mature circuits could guide therapies to enhance recovery of function in adults.

GABAA receptor-mediated tonic depolarization in developing neural circuits

The activation of GABAA receptors (the type A receptors for γ-aminobutyric acid) produces two distinct forms of responses, phasic (i.e., transient) and tonic (i.e., persistent), that are mediated by synaptic and extrasynaptic GABAA receptors, respectively. During development, the intracellular chloride levels are high so activation of these receptors causes a net outward flow of anions that leads to neuronal depolarization rather than hyperpolarization. Therefore, in developing neural circuits, tonic activation of GABAA receptors may provide persistent depolarization. Recently, it became evident that GABAA receptor-mediated tonic depolarization alters the structure of patterned spontaneous activity, a feature that is common in developing neural circuits and is important for neural circuit refinement. Thus, this persistent depolarization may lead to a long-lasting increase in intracellular calcium level that modulates network properties via calcium-dependent signaling cascades. This article highlights the features of GABAA receptor-mediated tonic depolarization, summarizes the principles for discovery, reviews the current findings in diverse developing circuits, examines the underlying molecular mechanisms and modulation systems, and discusses their functional specializations for each developing neural circuit.

Neural circuit and its functional roles in cerebellar cortex

OBJECTIVE

To investigate the spike activities of cerebellar cortical cells in a computational network model constructed based on the anatomical structure of cerebellar cortex.

METHODS AND RESULTS

The multicompartment model of neuron and NEURON software were used to study the external influences on cerebellar cortical cells. Various potential spike patterns in these cells were obtained. By analyzing the impacts of different incoming stimuli on the potential spike of Purkinje cell, temporal focusing caused by the granule cell-golgi cell feedback inhibitory loop to Purkinje cell and spatial focusing caused by the parallel fiber-basket/stellate cell local inhibitory loop to Purkinje cell were discussed. Finally, the motor learning process of rabbit eye blink conditioned reflex was demonstrated in this model. The simulation results showed that when the afferent from climbing fiber existed, rabbit adaptation to eye blinking gradually became stable under the Spike Timing-Dependent Plasticity (STDP) learning rule.

CONCLUSION

The constructed cerebellar cortex network is a reliable and feasible model. The model simulation results confirmed the output signal stability of cerebellar cortex after STDP learning and the network can execute the function of spatial and temporal focusing.