Influence of Nonspecific Inhibitor of NO-Synthase L-NAME on Electric Characteristics of Premotor Interneurons of Terrestrial Snails

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. It has been found that the application of nonspecific inhibitor of NO-synthase L-NAME caused the depolarization shift of the membrane potential of premotor interneurons of defensive behavior of terrestrial snails. This effect is opposite to hyperpolarization shift of the membrane potential caused by the action of the nitric oxide donor—sodium nitroprusside

Impairing of Serotonin synthesis by P-Chlorphenylanine prevents the forgetting of contextual memory after reminder and the protein synthesis inhibition

© 2018 Deryabina, Muranova, Andrianov and Gainutdinov. HIGHLIGHTS • The injection of p-chlorophenylalanine, specific blocker of 5-HT synthesis 3 days before reminder with anisomycin administration prevented forgetting. It is known that the reminder cause reactivation of the long-term memory and it leads to reconsolidation of memory. We showed earlier that the disruption of the reconsolidation of contextual memory in terrestrial snail was caused by anisomycin, the inhibitor of protein syntheses (Gainutdinova et al., 2005; Balaban et al., 2014). In this paper we investigated the possible changes of the memory reconsolidation under the conditions of serotonin deficit, caused by administration of p-chlorophenylalanine, the inhibitor of tryptophan hydroxylase synthesis (intermediate stage of the synthesis of serotonin). It was shown that the forgetting process for contextual memory after reminder and inhibition of protein synthesis did not occur if the serotonin transmission in nervous system was impaired. This effect was significantly different from the direct action of anisomycin, which blocked the reconsolidation of contextual memory. We concluded that the serotonin system was included to the process of memory reconsolidation

Effects of NO Donors and Inhibitors of NO Synthase and Guanylate Cyclase on the Acquisition of a Conditioned Defense Food Aversion Response in Edible Snails

© 2016, Springer Science+Business Media New York.Experiments on edible snails revealed that NO synthase blockade with a nonspecific neuronal NO synthase inhibitor L-NAME before defense food aversion conditioning is followed by a decrease in the rate of learning. Exogenous NO donors, sodium nitroprusside and dinitrosyl iron complex, were shown to improve learning. Chronic administration of a specific soluble guanylate cyclase inhibitor ODQ also increased the rate of learning. Our results indicate that NO has a modulatory effect on the formation of a conditioned response in this type of learning

Influence of a Nitric Oxide Donor on Electrical Characteristics of the Premotor Interneurons of Terrestrial Snails

© 2016, Springer Science+Business Media New York.It has been found that application of a nitric oxide donor—the sodium nitroprusside—causes the hyperpolarization shift of the membrane potential of the premotor interneurons of defensive behavior of terrestrial snails. It is assumed that the response of a neuron to NO depends on its location in the neural network

Serotonin Modulation of Premotor Interneuron Excitability in the Snail during Associative Learning

© 2016, Springer Science+Business Media New York.It is shown that after the elaboration of a conditioned reflex in snails, a reliable decrease can be observed in the membrane potential (Vm) of the premotor interneurons at 4 mV, daily injection of serotonin (5-HT) causes a decrease in Vm at 4.5 mV, the same change is observed for Vm in the snails trained after the injection of 5-HT. A single injection of 5-HT causes a depolarization shift of Vm at 5 mV. After the initial stage of training (10–12 pairs) the snails, injected by 5-HT, there is a depolarization at 4.5 mV

Serotonin Application Effects on Electrical Characteristics of the Premotor Interneurons in Intact and Trained Snails

© 2016, Springer Science+Business Media New York.Experimentally, it was shown that the action potential threshold in neurons of the trained snails increases in response to serotonin (5-HT) application, in contrast to intact snails. This result demonstrates a decrease of excitability of the premotor interneurons in response to extracellular 5-HT after the training

The effects of 6-hydroxydopamine on the electrical characteristics of snail neurons in long-term sensitization

The effects of the neurotoxin 6-hydroxydopamine on the formation of long-term sensitization and changes in the membrane characteristics of identified neurons were studied. Injections of the neurotoxin 6-hydroxydopamine blocked the acquisition of long-term sensitization; when neurotoxin injections were given after the formation of long-term sensitization, they had no subsequent effect on conduction parameters. At the cellular level, recording of the electrical characteristics of common snail defensive behavior command neurons (LPa3, RPa3, LPa2, and RPa2) showed that the effects of 6-hydroxydopamine consisted of a small depolarization shift in the membrane potential and a change in the action potential generation threshold. Formation of long-term sensitization after injections of 6-hydroxydopamine did not lead to further decreases in the membrane and threshold potentials of command neurons as compared with snails only given injections of 6-hydroxydopamine. The changes in electrical measures of command neurons induced by administration of the neurotoxin 6-hydroxydopamine lasted at least two weeks. © 2005 Springer Science+Business Media, Inc

Aqueous and salt solutions of quinine of low concentrations: Self-organization, physicochemical properties and actions on the electrical characteristics of neurons

© 2014, Pleiades Publishing, Inc. Self-organization, the physicochemical properties of aqueous and salt solutions of quinine and the effects of salt quinine solutions in a wide range of concentrations (1 · 10−22−1 · 10−3 M) on the electrical characteristics of the edible snail’s identified neurons were studied. Similar non-monotonic concentration dependencies of physicochemical properties of aqueous and salt quinine solutions at low concentrations are obtained. This allows of predicting the occurrence of biological effects at low concentrations of quinine solutions. Intrinsic (within 5% of the interval) changes in membrane potential, the amplitude and duration of the neuron action potential under the influence of quinine salt solutions at concentrations of quinine of 1 · 10−20, 1 · 10−18, 1 · 10−10 M are found. For these concentrations the extreme values of specific conductivity and pH are shown

Green manure - corn rotation and phosphorus adsorption in an Oxisol

Este estudo teve como objetivos quantificar a capacidade máxima de adsorção de P em sistemas de cultivo com adubos verdes e avaliar a influência da taxa de decomposição do adubo verde e de algumas propriedades químicas do solo sobre esta adsorção. Avaliou-se a camada de 0 a 20 cm de um Latossolo Vermelho-Escuro sob dois tratamentos: solo sob cerrado nativo e solo descoberto (cinco anos); e os seguintes adubos verdes cultivados na entressafra após o milho (cv. Pioneer 3072): crotalária (Crotalaria juncea), guandu (Cajanus cajan), mucuna preta (Mucuna aterrima) e braquiária (Brachiaria ruziziensis). Os valores de adsorção foram ajustados à isoterma de Langmuir para determinação da capacidade máxima de adsorção de P (CMAF). Os tratamentos em ordem decrescente de adsorção máxima foram: solo descoberto > guandu > crotalária > mucuna preta > braquiária > cerrado nativo. O teor de matéria orgânica e a taxa de decomposição dos adubos verdes apresentaram correlação negativa com a adsorção máxima de P, com coeficientes de correlação, respectivamente, de 0,705 (P Cajanus cajan > Crotalaria juncea > Mucuna aterrima > Brachiaria ruziziensis > native cerrado. Soil organic matter amount and green manure decomposition rate had negative correlation with the P maximum adsorption, with correlation coefficients of 0.705 (P < 0.06) and 0.983 (P < 0.01), respectively. The PAMC for the deepest layer was 56% higher than that of the superficial layer, suggesting the importance of organic matter on reducing P adsorption

Responses of withdrawal interneurons to serotonin applications in naïve and learned snails are different

© 2017 Bogodvid, Andrianov, Deryabina, Muranova, Silantyeva, Vinarskaya, Balaban and Gainutdinov. Long-term changes in membrane potential after associative training were described previously in identified premotor interneurons for withdrawal of the terrestrial snail Helix. Serotonin was shown to be a major transmitter involved in triggering the long-term changes in mollusks. In the present study we compared the changes in electrophysiological characteristics of identifiable premotor interneurons for withdrawal in response to bath applications of serotonin (5-HT) or serotonin precursor 5-hydroxytryptophan (5-HTP) in preparations from naïve, neurotoxin-injected or associatively trained snails. It was found that 5-HT or 5-HTP applications caused a significant decrease of membrane potential in premotor interneurons of naïve snails, associatively trained snails and snails with impaired serotonergic system by injection of a selective neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) 1 week before the experiments. Applications of 5-HT or 5-HTP did not cause significant changes in the action potential (AP) threshold potential of these neurons in naïve snails. Conversely, applications of 5-HT or 5-HTP to the premotor interneurons of previously trained or 5,7-DHT-injected snails caused a significant increase in the firing threshold potential in spite of a depolarizing shift of the resting membrane potential. Results demonstrate that responsiveness of premotor interneurons to extracellularly applied 5-HT or 5-HTP changes for days after the associative training or serotonin depletion. Similarity of the effects in trained and 5,7-DHT-injected animals may be due to massive release of serotonin elicited by 5,7-DHT injection. Our results suggest that serotonin release due to aversive conditionining or elicited by the neurotoxin administration triggers similar changes in resting membrane potential and AP threshold in response to bath applications of 5-HT or its precursor 5-HTP