scholarly journals Differential presynaptic inhibition of actions of group II afferents in di‐ and polysynaptic pathways to feline motoneurones

2002 ◽  
Vol 542 (1) ◽  
pp. 287-299 ◽  
Author(s):  
E. Jankowska ◽  
U. Slawinska ◽  
I. Hammar
Keyword(s):  
Presynaptic Inhibition ◽  
Group Ii ◽  
Group Ii Afferents

Group II and III mGluRs-mediated presynaptic inhibition of EPSCs recorded from hippocampal interneurons of CA1 stratum lacunosum moleculare

2005 ◽  
Vol 49 ◽  
pp. 45-56 ◽  
Author(s):  
Christopher J. Price ◽  
Theofanis Karayannis ◽  
Balázs Zoltán Pál ◽  
Marco Capogna
Keyword(s):  
Presynaptic Inhibition ◽  
Group Ii ◽  
Stratum Lacunosum Moleculare

Depression of the recurrent inhibition of extensor motoneurons by the action of group II afferents

1977 ◽  
Vol 120 (3) ◽  
pp. 459-468 ◽  
Author(s):  
Christoph Fromm ◽  
Joachim Haase ◽  
Elmar Wolf
Keyword(s):  
Recurrent Inhibition ◽  
Group Ii ◽  
Group Ii Afferents

Group I Afferent Pathway Contributes to Functional Knee Stability

2010 ◽  
Vol 103 (2) ◽  
pp. 616-622 ◽  
Author(s):  
B. Friemert ◽  
S. Franke ◽  
A. Gollhofer ◽  
L. Claes ◽  
M. Faist
Keyword(s):  
Knee Joint ◽  
Anterior Tibial Translation ◽  
Knee Stability ◽  
Afferent Pathways ◽  
Joint Stabilization ◽  
Ia Afferents ◽  
Anterior Tibial ◽  
Group Ii ◽  
Tibial Translation ◽  
Group Ii Afferents

The hamstring reflex response has been suggested to play a substantial role in knee joint stabilization during anterior tibial translation. The present study was performed to determine which afferent pathways contribute to the hamstring reflex as well as the potential effects of specific afferent pathways on functional knee stability. Short- and medium-latency hamstring reflexes (SLR and MLR) were evoked by anterior tibial translation in 35 healthy subjects during standing with 30° knee flexion. Nerve cooling, tizanidine, and ischemia were employed to differentiate afferent pathways. Two hours of thigh cooling ( n = 10) resulted in a significant increase in MLR latency and, to a lesser extent, SLR latency. No significant changes were recorded in reflex sizes or maximum tibial translation. The ingestion of tizanidine ( n = 10), a suppressor of group II afferents, strongly reduced the MLR size while SLR size or latency of both reflex responses was not significantly affected. Maximum tibial translation was unchanged [5.3 ± 1.9 to 4.8 ± 2 (SD) mm; P = 0.410]. Ischemia in the thigh ( n = 15) led to a highly significant depression in SLR size (89 ± 4%; P < 0.001) but only a slight and not significant decline of MLR size. In these subjects maximum tibial translation increased significantly (6.9 ± 1.6 to 9.4 ± 3.2 mm; P = 0.028). It is concluded that the hamstring SLR is mediated by Ia afferents, while group II afferents mainly contribute to the MLR. Suppression of SLR may increase maximum anterior tibial translation, thus indicating a possible functional role of Ia afferents in knee joint stabilization.

Adenosine A1 and Class II Metabotropic Glutamate Receptors Mediate Shared Presynaptic Inhibition of Retinotectal Transmission

1999 ◽  
Vol 82 (6) ◽  
pp. 2947-2955 ◽  
Author(s):  
Chunyi Zhang ◽  
John T. Schmidt
Keyword(s):  
Calcium Channels ◽  
Synaptic Transmission ◽  
Presynaptic Inhibition ◽  
Metabotropic Glutamate Receptors ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Metabotropic Glutamate ◽  
Adenosine A1 ◽  
A1 Adenosine Receptors ◽  
Group Ii

Presynaptic inhibition is one of the major control mechanisms in the CNS. Previously we reported that adenosine A1 receptors mediate presynaptic inhibition at the retinotectal synapse of goldfish. Here we extend these findings to metabotropic glutamate receptors (mGluRs) and report that presynaptic inhibition produced by both A1 adenosine receptors and group II mGluRs is due to Gi protein coupling to inhibition of N-type calcium channels in the retinal ganglion cells. Adenosine (100 μM) and an A1 (but not A2) receptor agonist reduced calcium current ( I Ca2+) by 16–19% in cultured retinal ganglion cells, consistent with their inhibition of retinotectal synaptic transmission (−30% amplitude of field potentials). The general metabotropic glutamate receptor (mGluR) agonist 1S,3R-1-amino-cyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD, 50 μM) and the selective group II mGluR receptor agonist (2S,2′R,3′R)-2-(2′,3′-dicarboxy-cyclopropyl)glycine (DCG-IV, 300 nM) inhibited both synaptic transmission and I Ca2+, whereas the group III mGluR agonistl-2-amino-4-phosphono-butyrate (l-AP4) inhibited neither synaptic transmission nor I Ca2+. When the N-type calcium channels were blocked with ω-conotoxin GVIA, both adenosine and DCG-IV had much smaller percentage effects on the residual 20% of I Ca2+, suggesting effects mainly on the N-type calcium channels. The inhibitory effects of A1 adenosine receptors and mGluRs were both blocked by pertussis toxin, indicating that they are mediated by either Gi or Go. They were also inhibited by activation of protein kinase C (PKC), which is known to phosphorylate and inhibit Gi. Finally, when applied sequentially, inhibition by adenosine and DCG-IV were not additive but occluded each other. Together these results suggest that adenosine A1 receptors and group II mGluRs mediate presynaptic inhibition of retinotectal synaptic transmission by sharing a pertussis toxin (PTX)–sensitive, PKC-regulated Gi protein coupled to N-type calcium channels.

scholarly journals Collateral Actions of Premotor Interneurons on Ventral Spinocerebellar Tract Neurons in the Cat

2010 ◽  
Vol 104 (4) ◽  
pp. 1872-1883 ◽  
Author(s):  
E. Jankowska ◽  
P. Krutki ◽  
I. Hammar
Keyword(s):  
Muscle Spindles ◽  
Feedback Information ◽  
Inhibitory Postsynaptic Potentials ◽  
Group I ◽  
Muscle Nerve ◽  
Spinocerebellar Tract ◽  
Motor Nuclei ◽  
Group Ii ◽  
Tendon Organs ◽  
Group Ii Afferents

Strong evidence that premotor interneurons provide ventral spinocerebellar tract (VSCT) neurons with feedback information on their actions on motoneurons was previously found for Ia inhibitory interneurons and Renshaw cells, while indications for similar actions of other premotor interneurons were weaker and indirect. Therefore the aim of the present study was to reexamine this possibility with respect to interneurons relaying actions of group Ib afferents from tendon organs and group II afferents from muscle spindles. In all, 133 VSCT neurons in the L3–L5 segments (including 41 spinal border neurons) were recorded from intracellularly in deeply anesthetized cats to verify that stimuli applied in motor nuclei evoked monosynaptic inhibitory postsynaptic potentials (IPSPs) attributable to stimulation of axon collaterals of premotor interneurons. IPSPs were found in over two thirds of the investigated neurons. When intraspinal stimuli were preceded by stimuli applied to a muscle nerve at critical intervals, IPSPs evoked from motor nuclei were considerably reduced, indicating a collision of nerve volleys in axons of interneurons activated by group I and group II afferents. In individual VSCT neurons monosynaptic IPSPs were evoked from both biceps–semitendinosus and gastrocnemius–soleus motor nuclei, in parallel with disynaptic IPSPs from group Ib and group II as well as group Ia afferents. These observations indicate that individual VSCT neurons may monitor the degree of inhibition of both flexor and extensor motoneurons by premotor interneurons in inhibitory pathways from group Ib and group II afferents to motoneurons. They may thus be providing the cerebellum with feedback information on actions of these premotor interneurons on motoneurons.

scholarly journals Effects of stimulation of hindlimb flexor group II afferents during fictive locomotion in the cat.

1995 ◽  
Vol 487 (1) ◽  
pp. 211-220 ◽  
Author(s):  
M C Perreault ◽  
M J Angel ◽  
P Guertin ◽  
D A McCrea
Keyword(s):  
Fictive Locomotion ◽  
Group Ii ◽  
Group Ii Afferents ◽  
Stimulation Of

The distribution pattern of boutons of muscle spindle group II afferents in relation to the homonymous motor column in the cat

1985 ◽  
Vol 1 ◽  
pp. S51 ◽  
Author(s):  
Norio Ishizuka ◽  
Toshinori Hongo ◽  
Norio Kudo ◽  
Shigeto Sasaki ◽  
Masayuki Yamashita ◽  
...  
Keyword(s):  
Distribution Pattern ◽  
Muscle Spindle ◽  
Group Ii ◽  
Group Ii Afferents
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