Introduction: Some dental sealers have neurotoxic effects on neuronaltissues. These effects appear to be mediated through the inhibition of ionic channels.INTRACELLULAR RECORDING was performed on neuronal cells tocharacterize the underlying ionic mechanisms of neurotoxicity induced by Roth 801. Materials and Methods: Experiments were carried out on F1 neuronal soma membrane located in the right parietal ganglion of snail, Helix aspersa. The properties of action potential were analyzed using singl eelectrode current clamp method. Roth 801 was applied to the bathing solution in invasive and gradual forms. Results: In the current clamp experiments, several parameters, including, resting membrane potential (RMP), the peak amplitude of action potential, spike width, frequency, the peak amplitude of after hyperpolarization (AHP) were analyzed. In both invasive and gradual forms Roth 801 decreased the peak of amplitude and frequency of action potential and the peak amplitude of AHP. But the duration of spike was prolonged. After invasive application of Roth 801, membrane potential was depolarized. However in gradual method, it was initially hyperpolarized and subsequently shifted towards depolarized potential. Conclusion: These results suggest that Roth 801 affects shape and frequency of action potential through inhibition of ionic currents.

Background & Objective:  There is considerable evidence in the field of epilepsy research suggesting that melatonin may have a potential therapeutic role in the treatment of epilepsy. Investigating the effects of melatonin on neuronal electrical activity may provide valuable insight into the development of adjunctive therapies in this context. We aimed to investigate the prophylactic properties of melatonin using the INTRACELLULAR RECORDING technique in an epilepsy model of snail neurons, which exhibit epileptic behavior similar to that in human neurons.  Materials & Methods: To study the impact of melatonin (100 µM) on firing pattern and action potential (AP) configuration in an epileptic condition, the current clamp technique was used on Helix aspersa neurons. RECORDINGs were made before and after administering Pentylenetetrazole (PTZ) (25 mM). Results:  The findings demonstrated that applying melatonin to cells in normal Ringer's solution did not significantly alter the resting membrane potential (RMP) or the amplitude and duration of the AHP and AP. However, a significant decline in frequency was evident (P<0.05).  Application of melatonin after PTZ significantly decreased the firing frequency of APs while concurrently enhancing the amplitude of AHP, which had been reduced by PTZ, and hyperpolarizing the RMP.   Conclusion: Our study demonstrates that melatonin has protective effects against some of the adverse impacts of PTZ on neuronal firing patterns in Helix aspersa neurons. These findings suggest that melatonin may play a crucial role in modulating neuronal excitability, which is important in epilepsy.

Local anesthetic agents are well known to interrupt impulse conduction in peripheral nerve axons when applied locally in high concentration. The phenylpiperidine opioid, meperidirie, in addition to its systemic opioid effects, also shows local anesthetic-like action, when applied directly to peripheral nerves. The opioid meperidine induces anesthesia and blocks action potentials. The local anesthetic effects of meperidine has been demonstrated in both clinical and laboratory studies. Clinically, it can produce segmental sensory anesthesia. However, most of the previous studies on the effects of meperidine on nerve conduction have all made use of peripheral nerve preparations and yielded conflicting results. In the present study, we have characterized the effects of meperidine on ionic currents underlying neuronal excitability, using current-clamp and two-electrode voltage-clamp techniques. The results showed that FI neurons of the garden snail, Helix aspersa, respond to meperidine by significantly decreasing the peak amplitude and significantly increasing the duration of action 11 potentials. Voltage-clamp experiments revealed that meperidine depressed the macroscopic inward and increased outward K + currents. In conclusion, these findings indicate that meperidine decreases the excitability in Helix aspersa nervous system by decreasing inward ionic currents and increasing outward currents underlying the action potential.

Background & Aim: The most detailed information about neural activity comes from INTRACELLULAR RECORDING. Not only this technique shows the pattern of neural action potential, but it also records the cellular events which give rise to the action potential, including variations in the resting potential, changes in cellular resistance and synaptic potentials.Results: Using this method with manipulation of the composition of the bathing solution (c.hanging ionic concentrations or adding drugs) the ionic mechanisms responsible for these potentials can be identified. It is also possible to investigate the mechanisms of actions of drugs such as dental sealers on neuronal excitability.Conclusion: In the present study, INTRACELLULAR RECORDING technique has been introduced in dental materials research as a valuable method to determine the neurotoxicity of endodontic sealers on neuronal cells.

Background: Epilepsy is a chronic central nervous system disorder with a high prevalence in modern society. Despite using common anticonvulsant drugs, its control is not adequately achieved. Animal models for seizures play the leading role in advancing our understanding of the cellular mechanisms of epilepsy. The present study was an attempt to elucidate the electrophysiological mechanism of the effect of sodium valproate on the cellular model of epilepsy. Understanding the cellular mechanisms of this drug may help clarify the pharmacological screening of other drugs. Methods: The INTRACELLULAR RECORDING was made from F1 cells of garden Helix aspersa in the presence of Ringer solution. Following the extracellular application of valproate sodium at a concentration of 10 mM after and before the use of (25mM) epileptogenic agent (pentylenetetrazol (PTZ)), we evaluated its effect on paroxysmal depolarization shift (PDS) and electrophysiological characteristics. Results: These results showed that valproate sodium could reduce neuronal excitability. It could significantly hyperpolarize rest action potential by decreasing the frequency of firing rate and increasing the amplitude of afterhyperpolarization (AHP) and can prevent depolarization of rest action potential by PTZ. Conclusions: The results suggested that valproate sodium could reduce the PTZ-induced hyperexcitation by hyperpolarization of resting membrane potential (RMP), a reduction in AHP amplitude, and firing the frequency.

Background: Epilepsy is one of the most common neurological diseases in the world. INTRACELLULAR RECORDING from neurons with epileptiform activity has well shown the burst firing pattern. Previous studies have shown that melatonin anti-epileptic effects, although effective on the neuronal properties and alteration of the firing pattern, has not been determined yet. Therefore, in the present study, we investigated the effect of melatonin on the electrophysiological parameters in an epileptic model induced by pentylenetetrazole (PTZ). Methods and materials: An experimental study was performed on the soma membrane of F1 neurons of sub-esophageal ganglia of Helix aspersa (Iranian garden snail). The firing pattern and action potential were recorded using a single electrode INTRACELLULAR RECORDING under controlled conditions. The epileptiform activity was induced using pentylenetetrazole and treatment was done using melatonin (100μ M). Data analysis was carried out using Prism (version 8, GraphPad Software, Inc. ) running one-way ANOVA followed by Tukey’ s test. Results: Melatonin significantly prevented the depolarizing effect of pentylenetetrazole on resting membrane potential at concentration of 100μ M (P<0. 001). In addition, it caused a significant (P<0. 001) reduction in firing frequency and an increase in the afterhyperpolarization potential. Furthermore, it resulted in changes in the electrical firing activity of neurons from bursting in the present of PTZ to a tonic firing in the control condition. Conclusions: It seems that, by altering the electrophysiological parameters, melatonin caused a reduction of epileptiform activity and changed the bursting pattern due to PTZ to a tonic pattern. Thus, it can be concluded that melatonin can be effective in the treatment of epilepsy by reducing neuronal excitability.

Introduction: Anethole is the main constituent of Pimpinella anisum L. (anise), a herbaceous annual plant which has several therapeutic effects. In the folk medicine, anise is employed as an antiepileptic drug. Specifically, this study was focused on the cellular effect of anethole, an aromatic compound in essential oils from anise and camphor.Anethole has various physiological effects on the cardiovascular system and smooth and skeletal muscles. However, despite these persistent effects, there is little information available about the actions of anethole on nerve cells.Therefore, a major goal of the present research was to investigate the possible cellular mechanisms underlying the effect of anethole on the neural excitability and action potential characteristics in snail neurons.Methods: INTRACELLULAR RECORDINGs were made under the current clamp condition on F1 cells of Helix aspersa.Following extracellular application of anethole (0.5% or 2%), changes in thefiring pattern and action potential parameters were assessed and compared to control condition.Results: Application of anethole (0.5% and 2%) led to a significant increase in the action potential amplitude and a reduction in the peak area and time to peak. In the presence of 0.5% anethole, the after hyperpolarization (AHP) amplitude was significantly decreased, while the firing frequency of neurons was increased. However, 2% anethole did not affect the AHP amplitude, but significantly reduced the firing frequency of action potentials.Conclusion: Based on the effect of anethole on the action potential parameters, it can be concluded that it probably affects the voltage gated ion channels function, including Ca2+channels and/or Ca2+dependent K+channels activity.