Coincidence and Cause: A Discussion on Correlations Between Activity in Primary Afferents and Perceptive Experience in Cutaneous Sensibility

1979 ◽  
pp. 299-311 ◽  
Author(s):  
Å. B. Vallbo ◽  
R. S. Johansson
Keyword(s):  
Primary Afferents

Inhibition of Glutamatergic Synaptic Input to Spinal Lamina IIo Neurons by Presynaptic α2-Adrenergic Receptors

2002 ◽  
Vol 87 (4) ◽  
pp. 1938-1947 ◽  
Author(s):  
Yu-Zhen Pan ◽  
De-Pei Li ◽  
Hui-Lin Pan
Keyword(s):  
Receptor Antagonist ◽  
Synaptic Input ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Dorsal Root ◽  
Primary Afferents ◽  
Noradrenergic System ◽  
Analgesic Action ◽  
Adrenergic Agonists ◽  
Excitatory Synaptic Input

Activation of spinal α2-adrenergic receptors by the descending noradrenergic system and α2-adrenergic agonists produces analgesia. However, the sites and mechanisms of the analgesic action of spinally administered α2-adrenergic receptor agonists such as clonidine are not fully known. The dorsal horn neurons in the outer zone of lamina II (lamina IIo) are important for processing nociceptive information from C-fiber primary afferents. In the present study, we tested a hypothesis that activation of presynaptic α2-adrenergic receptors by clonidine inhibits the excitatory synaptic input to lamina IIo neurons. Whole cell voltage-clamp recordings were performed on visualized lamina IIo neurons in the spinal cord slice of rats. The miniature excitatory postsynaptic currents (mEPSCs) were recorded in the presence of tetrodotoxin, bicuculline, and strychnine. The evoked EPSCs were obtained by electrical stimulation of the dorsal root entry zone or the attached dorsal root. Both mEPSCs and evoked EPSCs were abolished by application of 6-cyano-7-nitroquinoxaline-2,3-dione. Clonidine (10 μM) significantly decreased the frequency of mEPSCs from 5.8 ± 0.9 to 2.7 ± 0.6 Hz (means ± SE) without altering the amplitude and the decay time constant of mEPSCs in 25 of 27 lamina IIo neurons. Yohimbine (2 μM, an α2-adrenergic receptor antagonist), but not prazosin (2 μM, an α1-adrenergic receptor antagonist), blocked the inhibitory effect of clonidine on the mEPSCs. Clonidine (1–20 μM, n = 8) also significantly attenuated the peak amplitude of evoked EPSCs in a concentration-dependent manner. The effect of clonidine on evoked EPSCs was abolished in the presence of yohimbine ( n = 5). These data suggest that clonidine inhibits the excitatory synaptic input to lamina IIo neurons through activation of α2-adrenergic receptors located on the glutamatergic afferent terminals. Presynaptic inhibition of glutamate release from primary afferents onto lamina IIoneurons likely plays an important role in the analgesic action produced by activation of the descending noradrenergic system and α2-adrenergic agonists.

A nonlinear model of semicircular canal primary afferents in bullfrog.

1982 ◽  
Vol 47 (4) ◽  
pp. 563-578 ◽  
Author(s):  
B N Segal ◽  
J S Outerbridge
Keyword(s):  
Nonlinear Model ◽  
Semicircular Canal ◽  
Primary Afferents

Group III mGluRs interact with TRPA1 on primary afferents

2013 ◽  
Vol 14 (4) ◽  
pp. S49
Author(s):  
R. Govea ◽  
S. Carlton
Keyword(s):  
Primary Afferents ◽  
Group Iii

2. Peripheral injury in the rat: behavioural and neuronal correlates

1985 ◽  
Vol 308 (1136) ◽  
pp. 408-408
Keyword(s):  
Tissue Injury ◽  
Primary Afferents ◽  
Peripheral Tissue ◽  
Peripheral Injury ◽  
Induced Changes

Peripheral tissue injury alters dramatically the relation between a cutaneous stimulus and the sensation experienced by producing both a decrease in the threshold necessary to elicit pain and an increase in the pain resulting from suprathreshold stimuli (hyperalgesia). We have now investigated whether these injury-induced changes result from alterations in the properties of primary afferents (sensitization) (Lynn 1977) or whether the injury triggers a change within the c.n.s. (Woolf 1983).

Excitability of primary afferents in feline spinal cord: taurine, homotaurine, and γ-aminobutyric acid compared

1982 ◽  
Vol 60 (6) ◽  
pp. 850-855 ◽  
Author(s):  
Radan Čapek ◽  
Barbara Esplin
Keyword(s):  
Primary Afferents ◽  
Aminobutyric Acid ◽  
Primary Afferent Depolarization ◽  
Conditioning Stimulation ◽  
Primary Afferent ◽  
Antagonistic Muscle ◽  
Consistent Change ◽  
Muscle Nerve ◽  
Gaba Synthesis ◽  
Stimulation Of

Effects of taurine and homotaurine (3-aminopropancsuIfonic acid), on excitability of primary afferents were compared with effects of γ-aminobutyric acid (GABA) in spinal unanaesthesized cats. Homotaurine and GABA, administered intravenously or topically, produced a marked increase in afferent excitability. Homotaurine was about 10 times more potent than GABA. Taurine (up to 2 mmol/kg i.v., or 10 mM topically) did not produce a consistent change in afferent excitability. The effect of homotaurine was antagonized by bicuculline or picrotoxin in doses which suppressed the primary afferent depolarization, as indicated by an increase of afferent excitability, evoked by conditioning stimulation of an antagonistic muscle nerve. Semicarbazidc, an inhibitor of GABA synthesis, did not attenuate the homotaurine-induced excitability changes of afferents while suppressing entirely the primary afferent depolarization. These findings suggest that homotaurine exerts a direct GABA-like action on feline primary afferents.

scholarly journals Sensory Neurons, Ion Channels, Inflammation and the Onset of Neuropathic Pain

2012 ◽  
Vol 39 (4) ◽  
pp. 416-435 ◽  
Author(s):  
Patrick L. Stemkowski ◽  
Peter A. Smith
Keyword(s):  
Spinal Cord ◽  
Neuropathic Pain ◽  
Peripheral Neuropathy ◽  
Pain Management ◽  
Sensory Neurons ◽  
Inflammatory Mediators ◽  
Primary Afferents ◽  
Ectopic Activity ◽  
Management Procedures

Neuropathic pain often fails to respond to conventional pain management procedures. here we review the aetiology of neuropathic pain as would result from peripheral neuropathy or injury. We show that inflammatory mediators released from damaged nerves and tissue are responsible for triggering ectopic activity in primary afferents and that this, in turn, provokes increased spinal cord activity and the development of ‘central sensitization’. Although evidence is mounting to support the role of interleukin-1β, prostaglandins and other cytokines in the onset of neuropathic pain, the clinical efficacy of drugs which antagonize or prevent the actions of these mediators is yet to be determined. basic science findings do, however, support the use of pre-emptive analgesia during procedures which involve nerve manipulation and the use of anti-inflammatory steroids as soon as possible following traumatic nerve injury.

Sign in / Sign up

Export Citation Format

Share Document