scholarly journals Quantal Mechanism of Transmitter Release during Progressive Depletion of the Presynaptic Stores at a Ganglionic Synapse

1973 ◽  
Vol 61 (3) ◽  
pp. 342-360 ◽  
Author(s):  
Oscar Sacchi ◽  
Virgilio Perri
Keyword(s):  
Transmitter Release ◽  
Ganglion Neuron ◽  
Progressive Decline ◽  
Quantum Content ◽  
High Release ◽  
Cervical Ganglion ◽  
Acetyl Group ◽  
Preganglionic Fiber ◽  
Choline Group ◽  
The Mean

In the present experiments we interfered with the mechanism of acetylcholine (ACh) synthesis in the rat superior cervical ganglion by impairing the supply of either the choline group (hemicholinium no. 3 [HC-3]treatment) or the acetyl group (thiamine deprivation). Under both conditions stimulation causes in the ganglion a progressive decline in ACh output associated with a depletion of transmitter tissue content. ACh release from the terminals of a single preganglionic fiber was estimated from the quantum content value of the evoked excitatory postsynaptic potentials (EPSP's) recorded intracellularly in the ganglion neuron under test. The present observations indicate that Poisson statistics describe transmitter release at either low or high release levels. Furthermore, the progressive decline in the rate of ACh output occurring during repetitive stimulation is shown to correspond to a progressive decrease in the number of transmitter quanta released per impulse and not to any modification in the size of individual quanta. Some 8,000 transmitter quanta proved to represent the presynaptic transmitter store initially present in those terminals on a neuron that are activated by stimulation of a single preganglionic fiber. Speculations are considered about synaptic efficacy and nerve connections in rat autonomic ganglia. It is suggested that six preganglionic fibers represent the mean input to a ganglion neuron.

scholarly journals Primary and secondary motoneurons use different calcium channel types to control escape and swimming behaviors in zebrafish

2020 ◽  
Author(s):  
Hua Wen ◽  
Kazumi Eckenstein ◽  
Vivien Weihrauch ◽  
Christian Stigloher ◽  
Paul Brehm
Keyword(s):  
Calcium Channels ◽  
Calcium Channel ◽  
Muscle Cell ◽  
Transmitter Release ◽  
Escape Response ◽  
Quantal Content ◽  
Release Probability ◽  
High Release ◽  
Postsynaptic Cell ◽  
Rhythmic Contractions

AbstractThe escape response and rhythmic swimming in zebrafish are distinct behaviors mediated by two functionally distinct motoneuron (Mn) types. The primary (1°Mn) type depresses, has a large quantal content (Qc), and a high release probability (Pr). Conversely, the secondary (2°Mn) type facilitates and has low and variable Qc and Pr. This functional duality matches well the distinct associated behaviors, with the 1°Mn providing the strong, singular C-bend initiating escape and the 2°Mn confers weaker, rhythmic contractions. Contributing to these functional distinctions is our identification of P/Q type calcium channels mediating transmitter release in 1°Mns and N type channels in 2°Mns. Remarkably, despite these functional and behavioral distinctions, all ~15 individual synapses on each muscle cell are shared by a 1°Mn bouton and at least one 2°Mn bouton. This novel blueprint of synaptic sharing provides an efficient way of controlling two different behaviors at the level of a single postsynaptic cell.

Variance analysis of excitatory postsynaptic potentials in cat spinal motoneurons during posttetanic potentiation

1989 ◽  
Vol 61 (2) ◽  
pp. 403-416 ◽  
Author(s):  
H. P. Clamann ◽  
J. Mathis ◽  
H. R. Luscher
Keyword(s):  
Transmitter Release ◽  
Background Noise ◽  
Peak Amplitude ◽  
Posttetanic Potentiation ◽  
Excitatory Postsynaptic Potentials ◽  
Spinal Motoneurons ◽  
Postsynaptic Potentials ◽  
Release Probability ◽  
Synaptic Boutons ◽  
The Mean

1. Fluctuations in the peak amplitudes of composite excitatory postsynaptic potentials (EPSPs) in cat spinal motoneurons were analyzed during posttetanic potentiation (PTP). Each of a series of identical tetanic stimulus trains delivered to a muscle nerve was followed by 45 test stimuli applied at 2-s intervals. The mean peak amplitude and mean peak variance were calculated for EPSPs evoked by all those stimuli following a tetanus with the same time interval. It was assumed that the variance arises primarily from the probabilistic all-or-none behavior of single synaptic boutons and background noise due to spontaneous synaptic activity and thermal noise in the recording system. The variance was corrected for the contribution from additive Gaussian background noise. 2. If it is assumed that individual synaptic boutons behave independently, corrected mean peak variance and mean peak amplitude are related by a parabolic function. The expected parabolic relationship was seen in 9 of 31 cases studied, and the parameters of the best parabolic fit to the data allowed estimation of some synaptic properties. From these parameters, the mean amplitude of the unit EPSP (v) was estimated to be 102.1 +/- 57.4 (SD) microV. An average of 3.7 boutons comprised each Ia-motoneuron contact system. 3. On average, only 27% of all synaptic boutons given off by the stimulated Ia fibers to one motoneuron were active and releasing transmitter during unpotentiated reflex transmission. The remaining 73% of the synapse population was intermittently silent. The population of boutons which took part in synaptic transmission could be divided into two subpopulations, one with a release probability P = 1 and a second with a mean release probability P = 0.13 +/- 0.086. 4. We conclude that synaptic boutons connecting Ia afferents to motoneurons exist in two populations, one having a high and one a low probability of transmitter release. Transmitter release is quantal, resulting in a unit EPSP of approximately 100 microV measured at the motoneuron soma.

scholarly journals 1-[4-(4-Hydroxyphenyl)piperazin-1-yl]ethanone

2013 ◽  
Vol 69 (11) ◽  
pp. o1671-o1671 ◽  
Author(s):  
Channappa N. Kavitha ◽  
Jerry P. Jasinski ◽  
Brian J. Anderson ◽  
H. S. Yathirajan ◽  
Manpreet Kaur
Keyword(s):  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Dihedral Angle ◽  
Title Compound ◽  
Chair Conformation ◽  
Piperazine Ring ◽  
Compound C ◽  
Acetyl Group ◽  
The Mean

In the title compound, C12H16N2O2, the piperazine ring has a chair conformation. The dihedral angle between the mean planes of the benzene ring and the acetyl group is 48.7 (1)°. In the crystal, molecules are linkedviaO—H...O hydrogen bonds, forming chains propagating along [010].

COMPARISON OF THE REGULATION OF CALCITONIN IN SERUM OF OLD AND YOUNG BUFFALO RATS

1980 ◽  
Vol 87 (1) ◽  
pp. 73-80 ◽  
Author(s):  
SHERRY F. QUEENER ◽  
N. H. BELL ◽  
SARAH M. LARSON ◽  
D. P. HENRY ◽  
EDUARDO SLATOPOLSKY
Keyword(s):  
Serum Calcium ◽  
Age Groups ◽  
Average Weight ◽  
Adrenergic Blockade ◽  
Serum Calcitonin ◽  
Progressive Decline ◽  
Thyroid Glands ◽  
Old Rats ◽  
The Mean ◽  
Mean Concentration

Studies were carried out to characterize the secretion and the effects of calcitonin in the Buffalo rat. Mean basal concentrations of calcitonin and parathyroid hormone were significantly increased in serum of rats older than 6 months of age as compared with rats between 2 and 3 months of age. The mean concentration of calcium in serum was independent of age. In both age groups, serum calcitonin was increased by administration of calcium (1 mmol/kg body wt) or isoproterenol (100 μg/kg body wt), was diminished by β-adrenergic blockade with dl-propranolol (1 mg/kg body wt) and was not altered by either pentagastrin or glucagon (200 and 100 μg/kg body wt respectively). The average weight of the thyroid glands was significantly greater in the old than in the young animals but the mean concentration of calcitonin in the thyroids was the same. Thyroparathyroidectomy produced a transient increase followed by a fall in mean serum calcium in the old rats. In contrast, a progressive decline in the mean concentration of calcium in serum was observed after thyroparathyroidectomy in the young rats. Treatment of old animals with reserpine (2·5 mg/kg body wt) markedly depleted noradrenaline in the thyroid, lowered calcitonin in serum and converted the pattern of response of serum calcium to thyroparathyroidectomy to that observed in young animals. The results provide evidence that hypercalcitonaemia occurs in aged Buffalo rats, as does hyperparathyroidism, and that the concentrations of calcitonin in blood are modulated by β-adrenergic affectors. Glucagon and pentagastrin exhibit little if any effects on calcitonin secretion in this strain of rat regardless of age.

Presynaptic glutamate receptors depress inhibitory postsynaptic transmission in lobster neuromuscular synapse

1993 ◽  
Vol 70 (3) ◽  
pp. 1159-1167 ◽  
Author(s):  
A. Miwa ◽  
H. P. Robinson ◽  
N. Kawai
Keyword(s):  
Glutamate Receptors ◽  
Transmitter Release ◽  
Neuromuscular Synapse ◽  
Ibotenic Acid ◽  
Postsynaptic Potentials ◽  
Postsynaptic Currents ◽  
Effective Inhibition ◽  
The Mean ◽  
Gamma S

1. We examined the functional role of GTP-coupled glutamate receptor (GluB-R) in the presynaptic membrane of lobster neuromuscular synapse. 2. Injection of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), a hydrolysis-resistant analogue of GTP, into the excitatory axon mimicked the presynaptic glutamate response and effectively suppressed excitatory postsynaptic potentials or excitatory postsynaptic currents (EPSCs). 3. Statistical analysis revealed that the coefficient of variation (standard deviation divided by the mean of EPSC amplitude) was increased after injection of GTP gamma S into the excitatory axon, indicating a presynaptic inhibition of transmitter release. 4. The effect of glutamate on inhibitory postsynaptic potentials (IPSPs) or inhibitory postsynaptic currents (IPSCs) was studied when the postsynaptic glutamate receptors were blocked by the Joro spider toxin (JSTX). Glutamate depressed IPSPs or IPSCs in the JSTX-treated preparation. Furthermore, repetitive stimulation of the excitatory nerve produced effective inhibition of IPSCs. 5. Quisqualate and kainate suppressed IPSCs in a similar way to glutamate. In contrast, N-methyl-D-aspartate, ibotenic acid, trans-D,L-1-amino-1,3-cyclopentanedicarboxyloc acid, and 2-amino-4-phosphonobutanate had no effect on GluB-R. 6. Our results indicate that GluB-R, which exists in both excitatory and inhibitory nerve terminals, regulates transmitter release by a presynaptic inhibitory mechanism.

A Simple Model of Transmitter Release and Facilitation

1997 ◽  
Vol 9 (3) ◽  
pp. 515-523 ◽  
Author(s):  
Richard Bertram
Keyword(s):  
Transmitter Release ◽  
Voltage Response ◽  
Postsynaptic Receptors ◽  
Minimal Form ◽  
Network Simulations ◽  
The Mean ◽  
Spike Patterns ◽  
Input Spike ◽  
Presynaptic Facilitation ◽  
Neuronal Electrical Activity

We describe a model of synaptic transmitter release and presynaptic facilitation that is based on activation of release sites by single Ca2+ C microdomains. Facilitation is due to Ca2+ that remains bound to release sites between impulses. This model is inherently stochastic, but deterministic equations can be derived for the mean release. The number of equations required to describe the mean release is small, so it is practical to use the model with models of neuronal electrical activity to investigate the effects of different input spike patterns on presynaptic facilitation. We use it in conjunction with a model of dopamine-secreting neurons of the basal ganglia to demonstrate that transmitter release is greater when the neuron bursts than when it spikes continuously, due to the greater facilitation generated by the bursting impulse pattern. Finally, a minimal form of the model is described that is coupled to simple models of postsynaptic receptors and passive membrane to compute the postsynaptic voltage response to a train of presynaptic stimuli. This form of the model is appropriate for neural network simulations.

scholarly journals Lung functions abnormalities among auto mechanics in Ogbomoso, Nigeria: Clinical correlates and determinants

2018 ◽  
Vol 4 (2) ◽  
pp. 120-130 ◽  
Author(s):  
Adeseye A. Akintunde ◽  
Taofeek O. Oloyede ◽  
Afolabi A. Salawu
Keyword(s):  
Lung Function ◽  
Occupational Safety ◽  
Diastolic Pressure ◽  
Demographic Data ◽  
Environmental Pollutant ◽  
Progressive Decline ◽  
Mean Values ◽  
Physical Hazards ◽  
Lung Functions ◽  
The Mean

Background:  Auto mechanics are exposed to various organic, inorganic and particulate matters as a result of their occupation. Determining the association between environmental pollutant and risk of lung function abnormalities among auto mechanics is important to prevent long-termCem>Objective: To describe lung function abnormalities and their determinants among auto mechanics in Ogbomoso, Nigeria. Methods: One hundred and three auto mechanics were randomly selected from Ogbomoso, Nigeria. Their clinical and demographic data were obtained using a data form. Spirometry was performed using the CONTEC handheld Spirometer. The personal best values of three measurements FEV1, FVC and PEFR were determined. Lung function abnormalities were described according to standardized criteria. Results: The mean (SD) age of the participants was 38.5 (11.9) years. The mean systolic blood pressure, mean diastolic pressure and mean duration of the job as auto mechanics were 128.7 (17.9) mmHg, 81.2 (11.4) mmHg and 20.2 (12.5) years respectively. Restrictive, obstructive and mixed lung function abnormalities were demonstrated among 53%, 10% and 2% respectively. The mean values of FEV1 and FVC reduced significantly with increasing job duration. Conclusion: Lung function abnormalities occurred frequently among auto mechanics in Ogbomoso, Nigeria. There seemed to be a progressive decline in lung functions with age and duration of exposure to organic and inorganic pollutants by auto mechanics. Strict environmental and occupational safety measures may limit the hazards associated with poor air quality and other chemical/physical hazards among auto mechanics in Nigeria.

scholarly journals Trends in the consumption rates of benzodiazepines and benzodiazepine-related drugs in the Health Region of Lleida from 2002 to 2015

2019 ◽  
Author(s):  
Francisco Torres-Bondia ◽  
Jordi De Batlle ◽  
Leonardo Galvan ◽  
Miquel Buti ◽  
Ferran Barbé-Illa ◽  
...  
Keyword(s):  
Billing Data ◽  
Progressive Decline ◽  
The Public ◽  
Health Region ◽  
Cognitive Risk ◽  
Patterns Of Use ◽  
Time Period ◽  
Drug Agency ◽  
Consumption Rates ◽  
The Mean

Abstract Background: To determine the trend in the consumption prevalence of benzodiazepines (BZDs) and drugs related to BZDs (Z-drugs) in the population of the Health Region of Lleida to explore patterns of use and characteristics associated between 2002 and 2015. Methods: Retrospective community cohort study carried out between 2002 and 2015 consisting of individuals from a Health Region of 358,157 inhabitants in 2015. The consumption of BZDs was evaluated using prescription billing data from the Public Health System . All types of BZDs and their analogues that have been approved by the drug agency were included. Trends regarding age and sex were investigated. Results: A total of 249,471 individuals generated 338,148 dispensations. Overall, 53% were women, and the mean age was 60 years. The prevalence of BZD use in 2015 was 14.2%—18.8% in women and 9.6% in men—and was 36% in those over 65 years. According to the half-life of BZDs, the prevalence of short-intermediate BZD use was 9.7%, 5.5% for intermediate-long BZDs, and 0.8% for Z-drugs. The evolution in consumption showed a progressive decline, from 15.3% in 2002 to 14.2% in 2015, which is attributed to a decrease in consumption of intermediate-long BZDs (8.0% vs. 5.5%) and Z-drugs (1.4% vs. 0.8%). Conclusion: The prescription prevalence of BZDs and Z-drugs was high, although a small reduction was observed during this time period. The population over 65 was the most prevalent in their consumption despite cognitive risk and falls. Integral actions are required to lower their prescription rate.

scholarly journals 1-Acetyl-5-(4-fluorophenyl)-2-sulfanylideneimidazolidin-4-one

2013 ◽  
Vol 69 (11) ◽  
pp. o1699-o1699
Author(s):  
Soh-ichi Kitoh ◽  
Yijing Feng ◽  
Shuhei Fujinami ◽  
Masaki Ichitani ◽  
Mitsunori Honda ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Title Compound ◽  
Dihedral Angles ◽  
Maximum Deviation ◽  
Axis Direction ◽  
Compound C ◽  
Acetyl Group ◽  
The Mean

In the title compound, C11H9FN2O2S, the 2-sulfanylideneimidazolidin-4-one moiety is essentially planar, with a maximum deviation of 0.0183 (14) Å. The mean plane of this moiety is approximately coplanar with the attached acetyl group and perpendicular to the benzene ring, making dihedral angles of 9.70 (14) and 86.70 (6)°, respectively. In the crystal, molecules are linked by N—H...O hydrogen bonds between the amide NH and acetyl C=O groups, forming aC(6) chain along thea-axis direction.

Sign in / Sign up

Export Citation Format

Share Document