scholarly journals Spinal opioid receptor-sensitive muscle afferents contribute to the fatigue-induced increase in intracortical inhibition in healthy humans

2011 ◽  
Vol 96 (5) ◽  
pp. 505-517 ◽  
Author(s):  
Lea Hilty ◽  
Kai Lutz ◽  
Konrad Maurer ◽  
Tobias Rodenkirch ◽  
Christina M. Spengler ◽  
...  
Keyword(s):  
Opioid Receptor ◽  
Intracortical Inhibition ◽  
Muscle Afferents ◽  
Healthy Humans ◽  
Spinal Opioid

scholarly journals Physiological changes underlying bilateral isometric arm voluntary contractions in healthy humans

2011 ◽  
Vol 105 (4) ◽  
pp. 1594-1602 ◽  
Author(s):  
Demetris S. Soteropoulos ◽  
Monica A. Perez
Keyword(s):  
Tibialis Anterior ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Voluntary Contraction ◽  
Triceps Brachii ◽  
Hand Muscles ◽  
Healthy Humans ◽  
Simultaneous Activation ◽  
The Right

Many bilateral motor tasks engage simultaneous activation of distal and proximal arm muscles, but little is known about their physiological interactions. Here, we used transcranial magnetic stimulation to examine motor-evoked potentials (MEPs), interhemispheric inhibition at a conditioning-test interval of 10 (IHI10) and 40 ms (IHI40), and short-interval intracortical inhibition (SICI) in the left first dorsal interosseous (FDI) muscle during isometric index finger abduction. The right side remained at rest or performed isometric voluntary contraction with the FDI, biceps or triceps brachii, or the tibialis anterior. Left FDI MEPs were suppressed to a similar extent during contraction of the right FDI and biceps and triceps brachii but remained unchanged during contraction of the right tibialis anterior. IHI10 and IHI40 were decreased during contraction of the right biceps and triceps brachii compared with contraction of the right FDI. SICI was increased during activation of the right biceps and triceps brachii and decreased during activation of the right FDI. The present results indicate that an isometric voluntary contraction with either a distal or a proximal arm muscle, but not a foot dorsiflexor, decreases corticospinal output in a contralateral active finger muscle. Transcallosal inhibitory effects were strong during bilateral activation of distal hand muscles and weak during simultaneous activation of a distal and a proximal arm muscle, whereas GABAergic intracortical activity was modulated in the opposite manner. These findings suggest that in intact humans crossed interactions at the level of the motor cortex involved different physiological mechanisms when bilateral distal hand muscles are active and when a distal and a proximal arm muscle are simultaneously active.

Anti-μ-opioid-receptor IgG antibodies are commonly present in serum from healthy blood donors: evidence for a role in apoptotic immune cell death

Blood ◽  
2002 ◽  
Vol 100 (9) ◽  
pp. 3261-3268 ◽  
Author(s):  
Gaëtane Macé ◽  
Martial Jaume ◽  
Catherine Blanpied ◽  
Lionel Stephan ◽  
Jérôme D. Coudert ◽  
...  
Keyword(s):  
Opioid Receptor ◽  
Cho Cells ◽  
Blood Donors ◽  
Immune Cell ◽  
Specific Activity ◽  
Chinese Hamster ◽  
Murine Splenocytes ◽  
Healthy Humans ◽  
Extracellular Loops ◽  
Μ Opioid Receptor

Abstract We previously observed the presence of anti-human μ-opioid-receptor (anti-hMOR) autoantibodies in IgG pools prepared from several thousand healthy blood donors. These autoantibodies behaved agonistically because of their ability to bind to the first and third extracellular loops of the receptor. In this study, we found that each healthy donor's serum contained anti-hMOR IgG autoantibodies with a specific activity against both the first and the third extracellular loops of the receptor. Because of the inability of IgG to cross the blood-brain barrier, we investigated the effects of the expression of anti-hMOR autoantibodies on immune cells. In analogy to studies of the effects of morphine, we investigated the ability of antibodies to sensitize splenocytes to Fas (CD95)-mediated apoptosis. We took advantage of the high sequence homology between murine MOR and hMOR extracellular loops to estimate the effect on murine splenocytes of anti-hMOR antibodies raised by immunizing mice. Splenocytes from mice injected with Chinese hamster ovary (CHO) cells expressing MOR were sensitized to Fas-mediated apoptosis, whereas those from mice injected with CHO cells or phosphate-buffered saline were not. Similar sensitization to Fas-mediated apoptosis was observed in splenocytes from mice undergoing passive transfer either with IgG from mice previously immunized against CHO cells expressing MOR or with IgG directed against the first and third extracellular loops of the receptor. Together, our data show that anti-MOR autoantibodies are commonly expressed in healthy humans and could participate in the control of lymphocyte homeostasis by promoting Fas-mediated apoptosis.

scholarly journals Parallel modulation of intracortical excitability of somatosensory and visual cortex by the gonadal hormones estradiol and progesterone

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nasim Schloemer ◽  
Melanie Lenz ◽  
Martin Tegenthoff ◽  
Hubert R. Dinse ◽  
Oliver Höffken
Keyword(s):  
Visual Cortex ◽  
Evoked Potentials ◽  
Single Pulse ◽  
Intracortical Inhibition ◽  
Gonadal Hormones ◽  
Paired Pulse ◽  
Healthy Humans ◽  
Hormonal Action ◽  
Intracortical Excitability ◽  
Pulse Stimulation

AbstractThe levels of the gonadal hormones estradiol and progesterone vary throughout the menstrual cycle thereby affecting cognition, emotion, mood, and social behaviour. However, how these hormones modulate the balance of neural excitation and inhibition, which crucially regulate processing and plasticity, is not fully understood. We here used paired-pulse stimulation to investigate in healthy humans the action of low and high estradiol and progesterone on intracortical inhibition in somatosensory (SI) and visual cortex (V1). We found that paired-pulse suppression in both SI and VI depended on estradiol. During high estradiol levels, paired-pulse suppression was significantly reduced. No comparable effects were found for progesterone, presumably due to a confounding effect of estradiol. Also, no hormone level-depending effects were observed for single-pulse evoked SEPs (somatosensory evoked potentials) and VEPs (visual evoked potentials) indicating a specific hormonal action on intracortical processing. The results demonstrate that estradiol globally modulates the balance of excitation and inhibition of SI and VI cortex.

scholarly journals Combined, but not individual, blockade of ASIC3, P2X, and EP4 receptors attenuates the exercise pressor reflex in rats with freely perfused hindlimb muscles

2015 ◽  
Vol 119 (11) ◽  
pp. 1330-1336 ◽  
Author(s):  
Audrey J. Stone ◽  
Steven W. Copp ◽  
Joyce S. Kim ◽  
Marc P. Kaufman
Keyword(s):  
Lactic Acid ◽  
Receptor Antagonist ◽  
Time Course ◽  
P2x Receptors ◽  
Muscle Afferents ◽  
P2x Receptor ◽  
Exercise Pressor Reflex ◽  
Healthy Humans ◽  
Ep4 Receptor ◽  
Pressor Reflex

In healthy humans, tests of the hypothesis that lactic acid, PGE2, or ATP plays a role in evoking the exercise pressor reflex proved controversial. The findings in humans resembled ours in decerebrate rats that individual blockade of the receptors to lactic acid, PGE2, and ATP had only small effects on the exercise pressor reflex provided that the muscles were freely perfused. This similarity between humans and rats prompted us to test the hypothesis that in rats with freely perfused muscles combined receptor blockade is required to attenuate the exercise pressor reflex. We first compared the reflex before and after injecting either PPADS (10 mg/kg), a P2X receptor antagonist, APETx2 (100 μg/kg), an activating acid-sensing ion channel 3 (ASIC) channel antagonist, or L161982 (2 μg/kg), an EP4 receptor antagonist, into the arterial supply of the hindlimb of decerebrated rats. We then examined the effects of combined blockade of P2X receptors, ASIC3 channels, and EP4 receptors on the exercise pressor reflex using the same doses, intra-arterial route, and time course of antagonist injections as those used for individual blockade. We found that neither PPADS ( n = 5), APETx2 ( n = 6), nor L161982 ( n = 6) attenuated the reflex. In contrast, combined blockade of these receptors ( n = 7) attenuated the peak (↓27%, P < 0.019) and integrated (↓48%, P < 0.004) pressor components of the reflex. Combined blockade injected intravenously had no effect on the reflex. We conclude that combined blockade of P2X receptors, ASIC3 channels, and EP4 receptors on the endings of thin fiber muscle afferents is required to attenuate the exercise pressor reflex in rats with freely perfused hindlimbs.

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