scholarly journals Induction of long-lasting depolarization in medioventral medulla neurons by cholinergic input from the pedunculopontine nucleus

2005 ◽  
Vol 99 (3) ◽  
pp. 1127-1137 ◽  
Author(s):  
Keiko Mamiya ◽  
Kevin Bay ◽  
R. D. Skinner ◽  
E. Garcia-Rill
Keyword(s):  
Action Potential ◽  
Pedunculopontine Nucleus ◽  
Intracellular Recordings ◽  
Stable States ◽  
Cholinergic Agonist ◽  
Firing Rates ◽  
Cholinergic Antagonist ◽  
Muscarinic Cholinergic ◽  
Stimulation Of

Stimulation of the pedunculopontine nucleus (PPN) is known to induce changes in arousal and postural/locomotor states by activation of such descending targets as the caudal pons and the medioventral medulla (MED). Previously, PPN stimulation was reported to induce prolonged responses (PRs) in intracellularly recorded caudal pontine neurons in vitro. The present study used intracellular recordings in semihorizontal slices from rat brain stem (postnatal days 12–21) to determine responses in MED neurons following PPN stimulation. One-half (40/81) of MED neurons showed PRs after PPN stimulation. MED neurons with PRs had shorter duration action potential, longer duration afterhyperpolarization, and higher amplitude afterhyperpolarization than non-PR MED neurons. PR MED neurons were significantly larger (568 ± 44 μm2) than non-PR MED neurons (387 ± 32 μm2). The longest mean duration PRs and maximal firing rates during PRs were induced by PPN stimulation at 60 Hz compared with 10, 30, or 90 Hz. The muscarinic cholinergic agonist carbachol induced depolarization in all PR neurons tested, and the muscarinic cholinergic antagonist scopolamine reduced or blocked carbachol- and PPN stimulation-induced PRs in all MED neurons tested. These findings suggest that PPN stimulation-induced PRs may be due to activation of muscarinic receptor-sensitive channels, allowing MED neurons to respond to a transient, frequency-dependent depolarization with long-lasting stable states. PPN stimulation appears to induce PRs in large MED neurons using parameters known best to induce locomotion.

Properties of synaptic inputs from myenteric neurons innervating submucosal S neurons in guinea pig ileum

2000 ◽  
Vol 278 (2) ◽  
pp. G273-G280 ◽  
Author(s):  
B. A. Moore ◽  
S. Vanner
Keyword(s):  
Guinea Pig ◽  
Myenteric Plexus ◽  
Intracellular Recordings ◽  
Guinea Pig Ileum ◽  
Myenteric Neurons ◽  
Synaptic Inputs ◽  
Stimulus Train ◽  
Stimulation Of ◽  
Double Chamber

This study examined synaptic inputs from myenteric neurons innervating submucosal neurons. Intracellular recordings were obtained from submucosal S neurons in guinea pig ileal preparations in vitro, and synaptic inputs were recorded in response to electrical stimulation of exposed myenteric plexus. Most S neurons received synaptic inputs [>80% fast (f) excitatory postsynaptic potentials (EPSP), >30% slow (s) EPSPs] from the myenteric plexus. Synaptic potentials were recorded significant distances aboral (fEPSPs, 25 mm; sEPSPs, 10 mm) but not oral to the stimulating site. When preparations were studied in a double-chamber bath that chemically isolated the stimulating “myenteric chamber” from the recording side “submucosal chamber,” all fEPSPs were blocked by hexamethonium in the submucosal chamber, but not by a combination of nicotinic, purinergic, and 5-hydroxytryptamine-3 receptor antagonists in the myenteric chamber. In 15% of cells, a stimulus train elicited prolonged bursts of fEPSPs (>30 s duration) that were blocked by hexamethonium. These findings suggest that most submucosal S neurons receive synaptic inputs from predominantly anally projecting myenteric neurons. These inputs are poised to coordinate intestinal motility and secretion.

Regulation of ciliary beat frequency by autonomic mechanisms: in vitro

1988 ◽  
Vol 65 (4) ◽  
pp. 1895-1901 ◽  
Author(s):  
L. B. Wong ◽  
I. F. Miller ◽  
D. B. Yeates
Keyword(s):  
Laser Light ◽  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Atropine Sulfate ◽  
Adrenergic Agonist ◽  
Muscarinic Cholinergic ◽  
Autonomic Receptors ◽  
Stimulation Of ◽  
Ciliary Beat

The ciliated epithelium of the mammalian trachea separates the neurohumoral milieu of the tissue from that of the environment of the airway lumen. To determine whether specific autonomic receptors regulating ciliary beat frequency (CBF) were located on mucosal or serosal sides, we measured CBF by heterodyne mode correlation analysis laser light scattering in bovine tracheal tissues mounted in a two-sided chamber. A beta 2-adrenergic agonist, fenoterol, at 10(-7) M, stimulated serosal CBF from 7.9 +/- 1.3 to 20.2 +/- 5.8 Hz (P less than 0.01) and mucosal CBF from 6.6 +/- 0.9 to 14.7 +/- 4.6 Hz (P less than 0.01). A muscarinic cholinergic agonist, methacholine, at 10(-7) M, increased mucosal CBF from 8.4 +/- 1.0 to 19.5 +/- 5.5 Hz (P less than 0.01) and serosal CBF from 8.0 +/- 0.9 to 15.4 +/- 5.0 Hz (P less than 0.01). The differences in stimulation of CBF on the mucosal and serosal sides between fenoterol and methacholine were significant (P less than 0.01). Studies in which these autonomic agonist stimulating effects were inhibited by their respective antagonists, propranolol and atropine sulfate, demonstrated that CBF can be regulated independently by mediators both in the submucosa and within the mucus lining.

Intestinal mucosal cyclic GMP: regulation and relation to ion transport

1976 ◽  
Vol 231 (1) ◽  
pp. 275-282 ◽  
Author(s):  
TA Brasitus ◽  
M Field ◽  
DV Kimberg
Keyword(s):  
Causal Relationship ◽  
Cyclic Gmp ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Ileal Mucosa ◽  
Muscarinic Cholinergic Receptors ◽  
Cholecystokinin Octapeptide ◽  
Muscarinic Cholinergic ◽  
Stimulation Of

Stimulation of alpha-adrenergic and muscarinic cholinergic receptors in rabbit ileal mucosa in vitro produced 5- to 15-fold increases in cyclic GMP (cGMP) concentration that were maximal within 2 min and gone within 30 min. Cholecystokinin octapeptide and insulin caused similar increases in cGMP. None of these agents affected cAMP. The epinephrine-induced increase in cGMP was blocked by atropine at 100 but not at 1 muM concentration. Epinephrine stimulates active NaCl absorption and decreases short-circuit current (SCC) in vitro, the latter effect due to inhibition of HCO3 secretion. Atropine (100 muM) blocked the former but not the latter effect of epinephrine. In vitro additions of several concentrations of cGMP and 8-bromo-cGMP did not decrease SCC or alter Na fluxes. Thus, changes in cGMP concentration have been directly correlated with changes in active absorption of NaCl, but a causal relationship has not been proven.

Rate of rise of the cumulative depolarization evoked by repetitive stimulation of small-caliber afferents is a predictor of action potential windup in rat spinal neurons in vitro

1993 ◽  
Vol 69 (5) ◽  
pp. 1621-1631 ◽  
Author(s):  
L. G. Sivilotti ◽  
S. W. Thompson ◽  
C. J. Woolf
Keyword(s):  
Spinal Cord ◽  
Action Potential ◽  
Ventral Horn ◽  
Repetitive Stimulation ◽  
Current Injection ◽  
Low Frequencies ◽  
The Absolute ◽  
Stimulation Of ◽  
Absolute Duration

1. The summation of depolarizing postsynaptic potentials (PSPs) evoked by stimulation of primary afferent fibers in lumbar dorsal roots was studied in dorsal and ventral horn neurons in the rat hemisected spinal cord in vitro with current-clamp intracellular recording techniques. PSPs evoked by activation of A delta and/or C fibers could summate after repetitive stimulation at low frequencies: this resulted in a progressive, long-lasting change in the neuronal membrane potential (Vm) (cumulative depolarization). Cumulative depolarization was not observed after stimulation at A beta-fiber intensity or at frequencies < 0.2 Hz. 2. Effective PSP summation resulting in a significant cumulative depolarization (> 5 mV) was observed only if the PSPs evoked were longer than 4 s. On the other hand, there was no correlation between the amplitude of cumulative depolarization achieved in a neuron and the absolute duration of the PSP or the neuronal resting membrane properties (Vm and input resistance). 3. With relation to the changes in Vm during the stimulation train, three patterns of response to repetitive stimuli could be detected in both dorsal horn (DH) and ventral horn (VH) neurons: 1) little or no depolarization throughout the train; 2) an initial depolarization, which either remained stationary or decayed to the resting Vm after the first 3-4 s of stimulation; or 3) a progressive cumulative depolarization increasing throughout the train. 4. Depolarizing the cell by DC current injection resulted in a steeper rise in Vm in response to repetitive stimuli in one half of VH neurons and in one out of nine DH neurons tested. 5. Action potential windup, an increase in the number of action potentials elicited by each stimulus as the train progresses, was observed both in DH and in VH cells. C-fiber strength stimulation was the most effective in eliciting windup. Windup was associated with Vm responses to repetitive stimulation belonging to the progressive cumulative depolarization pattern. Indeed, cumulative depolarizations that resulted in windup had significantly steeper slopes for the Vm trajectory than those that did not. In those neurons in which DC depolarization by intracellular current injection increased the slope of the Vm trajectory, DC depolarization could also bring about action potential windup. 6. These results indicate that, although the generation of long-lasting "slow" PSPs by high-threshold primary afferents is necessary for the summation of synaptic activity in the spinal cord at low frequencies, the rate and pattern of the summation does not depend on the absolute duration of the PSPs.(ABSTRACT TRUNCATED AT 400 WORDS)

Early Platelet-Collagen Interactions in Whole Blood and Their Modifications by Aspirin and Dipyridamole Evaluated by a New Method (Basic Wave)

1985 ◽  
Vol 54 (04) ◽  
pp. 799-803 ◽  
Author(s):  
José Luís Pérez-Requejo ◽  
Justo Aznar ◽  
M Teresa Santos ◽  
Juana Vallés
Keyword(s):  
Whole Blood ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
White Blood Cells ◽  
Reversible Aggregation ◽  
Inhibitory Compounds ◽  
Rapid Generation ◽  
Stimulation Of ◽  
Collagen Stimulation

SummaryIt is shown that the supernatant of unstirred whole blood at 37° C, stimulated by 1 μg/ml of collagen for 10 sec, produces a rapid generation of pro and antiaggregatory compounds with a final proaggregatory activity which can be detected for more than 60 min on a platelet rich plasma (PRP) by turbidometric aggregometry. A reversible aggregation wave that we have called BASIC wave (for Blood Aggregation Stimulatory and Inhibitory Compounds) is recorded. The collagen stimulation of unstirred PRP produces a similar but smaller BASIC wave. BASIC’s intensity increases if erythrocytes are added to PRP but decreases if white blood cells are added instead. Aspirin abolishes “ex vivo” the ability of whole blood and PRP to generate BASIC waves and dipyridamole “in vitro” significantly reduces BASIC’s intensity in whole blood in every tested sample, but shows little effect in PRP.

DER EINFLUSS VON RESERPIN AUF DIE ANTITHYREOIDALE WIRKUNG VON KALIUMPERCHLORAT

1962 ◽  
Vol 39 (3) ◽  
pp. 423-430
Author(s):  
H. L. Krüskemper ◽  
F. J. Kessler ◽  
E. Steinkrüger
Keyword(s):  
Thyroid Gland ◽  
Male Rats ◽  
Normal Male ◽  
Tissue Respiration ◽  
List Type ◽  
Morphological Alterations ◽  
Hormone Synthesis ◽  
Stimulation Of

ABSTRACT 1. Reserpine does not inhibit the tissue respiration of liver in normal male rats (in vitro). 2. The decrease of tissue respiration of the liver with simultaneous morphological stimulation of the thyroid gland after long administration of reserpine is due to a minute inhibition of the hormone synthesis in the thyroid gland. 3. The morphological alterations of the thyroid in experimental hypothyroidism due to perchlorate can not be prevented with reserpine.

EFFECT OF ACTINOMYCIN D ON TSH-INDUCED STIMULATION OF THYROIDAL PROTEIN SYNTHESIS IN THE RAT

1974 ◽  
Vol 77 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Gustav Wägar
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
The Other ◽  
Leucine Incorporation ◽  
Short Term ◽  
Other Hand ◽  
Thyroid Glands ◽  
Translational Level ◽  
Stimulation Of

ABSTRACT Whether the short-term regulation of thyroidal protein synthesis by TSH occurs at the transcriptional or the translational level was tested by measuring the effect of actinomycin D (act D) on the TSH-induced stimulation of L-14C-leucine incorporation into the thyroidal proteins of rats. TSH was injected 6 h before the rats were killed. The thyroid glands were then removed and incubated in vitro in the presence of L-14C-leucine for 2 h. The pronounced stimulation of leucine incorporation in the TSH-treated animals was depressed as compared with controls but still significant even when the animals had been pre-treated with 100 μg act D 24 and 7 h before sacrifice. On the other hand, act D strongly decreased incorporation of 3H-uridine into RNA. Short-term regulation of thyroidal protein synthesis by TSH appears to be partly but not wholly dependent on neosynthesis of RNA. Hence regulation may partly occur at the translation level of protein synthesis.

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