No abstract available.
Synaptic Transmission*

Hair* ; Synaptic Transmission*

Growing evidence indicates that the serotonin system is important in learning and memory. In particular, several preclinical and clinical studies suggest that modulating the 5-HT1A receptor can influence learning and memory, and indeed, it has been observed that presynaptic 5-HT1A receptor agonists and postsynaptic 5-HT1A receptor antagonists tend to ameliorate the learning/memory impairment induced by various methods. In contrast, post-synaptic 5-HT1A receptor agonists tend to decrease the learning/memory function. These observations suggest the possibility that modulating neurotransmission mediated by the 5-HT1A receptor may be effective as a therapeutic strategy for enhancing learning and memory in various neuropsychiatric disorders. Unfortunately, there is no available discussion on the relationship between 5-HT1A receptor and learning/memory in Korea. This article reviews the clinical or preclinical literature on this issue.
Korea ; Learning* ; Memory* ; Receptor, Serotonin, 5-HT1A* ; Serotonin ; Synaptic Transmission

The vibration-induced reflexogenic erection (VIE), one of the physiologic erections, was compared with rigigram of the nocturnal penile erection ( NPE), another type of physiologic erection in 36 patients of erectile dysfunction ( psychogenic in 18, vasculogenic in 18). The efficacy of the VIE as a screening test was evaluated. The results obtained were as follows : 1. Among 32 patients with more than 40% of penile rigidity on rigigram of NPE, 14 (46%) were VIE-negative. Out of 18 patients with VIE-positive, none showed rigidity less than 40% on rigigram of NPE, but out of 18 patients with VIE-negative, 4 showed penile rigidity less than 40%, 7 showed that of 40-70% and 7 showed that more than 70% on rigigram of NPE. 2. Among 18 patients with psychogenic erectile dysfunction, there was none with penile rigidity less than 40% on rigigram of NPE but 5 showed VIE-negative. 3. Among 18 patients with vasculogenic erectile dysfunction, 4 (22% ) showed penile rigidity less than 40%, 9 (50%) showed that of 40-70%, 5(28%) showed that more than 70% on rigigram of NPE, and 13 (70% ) were VIE-negative. Therefore, VIE-positive means normal function of the local nerve system, neurotransmission and vascular system, and hence excludes the necessity of the NPE test, but it seems likely that VIE can not always take the place of NPE in VIE-negative patients.
Erectile Dysfunction ; Humans ; Male ; Mass Screening ; Penile Erection* ; Synaptic Transmission

The prevalence of Alzheimer's disease (AD) is increasing as the global population ages. Currently available treatments for AD target cholinergic and glutamatergic neurotransmission. There have been modest symptomatic effects, but disease modifying effects have not been accomplished. This is even true of clinical trials of bapineuzumab and solanezumab, two humanized monoclonal antibodies that bind amyloid. Therefore, innovations in clinical trial designs are necessary, including revised diagnostic criteria and treatment at the earliest stages of AD. Several prevention trials started in 2013, emphasizing these innovative principles of clinical trial design. In this review, we will discuss the paradigm shift for AD clinical treatment trials and ongoing preventative trials.
Alzheimer Disease* ; Amyloid ; Antibodies, Monoclonal ; Humans ; Prevalence ; Synaptic Transmission

Antiepileptic drugs (AEDs) can adversely affect cognitive function by suppressing neuronal excitability or enhancing inhibitory neurotransmission. The main cognitive effects of AEDs are impaired attention, vigilance, and psychomotor speed, but secondary effects can manifest on other cognitive functions. Although the long-term use of AEDs can obviously elicit cognitive dysfunction in epilepsy patients, their cognitive effects over short periods of up to a year are inconclusive due to methodological problems. In general, the effects on cognition are worse for older AEDs (e.g., phenobarbital) than for placebo, nondrug condition, and newer AEDs. However, topiramate is the newer AED that has the greatest risk cognitive impairment irrespective of the comparator group. Since the cognitive impact of AEDs can be serious, clinicians should be alert to adverse events by evaluating cognitive function using screening tests. Adverse cognitive events of AEDs can be avoided by slow titration to the lowest effective dosage and by avoiding polytherapy.
Anticonvulsants ; Cognition ; Epilepsy ; Fructose ; Humans ; Mass Screening ; Neurons ; Synaptic Transmission

Metabotropic glutamate receptors (mGluRs), classified into three groups (group I, II, III), play a critical role in modulation of synaptic transmission at central and peripheral synapses. In the present study, extracellular field potential recording techniques were used to investigate effects of mGluR agonists on excitatory synaptic transmission at thalamic input synapses onto the lateral amygdala. The non-selective mGluR agonist t-ACPD (100 microM) produced reversible, short-term depression, but the group III mGluR agonist L-AP4 (50 microM) did not have any significant effects on amygdala synaptic transmission, suggesting that group I and/or II mGluRs are involved in the modulation by t-ACPD. The group I mGluR agonist DHPG (100 microM) produced reversible inhibition as did t-ACPD. Unexpectedly, the group II mGluR agonist LCCG-1 (10 microM) induced long-term as well as short-term depression. Thus, our data suggest that activation of group I or II mGluRs produces short-term, reversible depression of excitatory synaptic transmission at thalamic input synapses onto the lateral amygdala. Considering the long-term effect upon activation of group II mGluRs, lack of long-term effects upon activation of group I and II mGluRs may indicate a possible cross-talk among different groups of mGluRs.
Amygdala* ; Depression ; Receptors, Metabotropic Glutamate* ; Synapses ; Synaptic Transmission*

Long-Term Potentiation ; Neuronal Plasticity ; Receptors, Metabotropic Glutamate ; Synaptic Transmission

Acetylcholine (ACh) is an important neuromodulator in various cognitive functions. However, it is unclear how ACh influences neural circuit dynamics by altering cellular properties. Here, we investigated how ACh influences reverberatory activity in cultured neuronal networks. We found that ACh suppressed the occurrence of evoked reverberation at low to moderate doses, but to a much lesser extent at high doses. Moreover, high doses of ACh caused a longer duration of evoked reverberation, and a higher occurrence of spontaneous activity. With whole-cell recording from single neurons, we found that ACh inhibited excitatory postsynaptic currents (EPSCs) while elevating neuronal firing in a dose-dependent manner. Furthermore, all ACh-induced cellular and network changes were blocked by muscarinic, but not nicotinic receptor antagonists. With computational modeling, we found that simulated changes in EPSCs and the excitability of single cells mimicking the effects of ACh indeed modulated the evoked network reverberation similar to experimental observations. Thus, ACh modulates network dynamics in a biphasic fashion, probably by inhibiting excitatory synaptic transmission and facilitating neuronal excitability through muscarinic signaling pathways.
Cholinergic Agents/pharmacology* ; Acetylcholine/metabolism* ; Neurons/metabolism* ; Synaptic Transmission/physiology*

Neurotransmission begins with neurotransmitter being released from synaptic vesicles. To achieve this function, synaptic vesicles endure the dynamic "release-recycle" process to maintain the function and structure of presynaptic terminal. Synaptic transmission starts with a single action potential that depolarizes axonal bouton, followed by an increase in the cytosolic calcium concentration that triggers the synaptic vesicle membrane fusion with presynaptic membrane to release neurotransmitter; then the vesicle membrane can be endocytosed for reusing afterwards. This process requires delicate regulation, intermediate steps and dynamic balances. Accumulating evidence showed that the release ability and mobility of synapses varies under different stimulations. Synaptic vesicle heterogeneity has been studied at molecular and cellular levels, hopefully leading to the identification of the relationships between structure and function and understanding how vesicle regulation affects synaptic transmission and plasticity. People are beginning to realize that different types of synapses show diverse presynaptic activities. The steady advances of technology studying synaptic vesicle recycling promote people's understanding of this field. In this review, we discuss the following three aspects of the research progresses on synaptic vesicle recycling: 1) presynaptic vesicle pools and recycling; 2) research progresses on the differences of glutamatergic and GABAergic presynaptic vesicle recycling mechanism and 3) comparison of the technologies used in studying presyanptic vesicle recycling and the latest progress in the technology development in this field.
Action Potentials ; Axons ; physiology ; Calcium ; physiology ; Endocytosis ; Humans ; Presynaptic Terminals ; physiology ; Synapses ; physiology ; Synaptic Transmission ; Synaptic Vesicles ; physiology