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Noradrenaline‐mediated facilitation of inhibitory synaptic transmission in the dorsal horn of the rat spinal cord involves interlaminar communications
Author(s) -
Seibt Frederik,
Schlichter Rémy
Publication year - 2015
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.13077
Subject(s) - inhibitory postsynaptic potential , neuroscience , spinal cord , facilitation , dorsum , french horn , neurotransmission , chemistry , anatomy , biology , psychology , receptor , biochemistry , pedagogy
In the dorsal horn of the spinal cord ( DH ), noradrenaline ( NA ) is released by axons originating from the locus coeruleus and induces spinal analgesia, the mechanisms of which are poorly understood. Here, the effects of NA on synaptic transmission in the deep laminae ( III –V) of the DH were characterized. It was shown that exogenously applied, as well as endogenously released, NA facilitated inhibitory [γ‐aminobutyric acid ( GABA )ergic and glycinergic] synaptic transmission in laminae III – IV of the DH by activating α 1 ‐, α 2 ‐ and β‐adrenoceptors ( AR s). In contrast, NA had no effect on excitatory (glutamatergic) synaptic transmission. Physical interruption of communications between deep and more superficial laminae (by a mechanical transection between laminae IV and V) totally blocked the effects of α 2 ‐ AR agonists and strongly reduced the effects of α 1 ‐ AR agonists on inhibitory synaptic transmission in laminae III – IV without directly impairing synaptic release of GABA or glycine from neurons. Short‐term pretreatment of intact spinal cord slices with the glial cell metabolism inhibitor fluorocitrate or pharmacological blockade of ionotropic glutamate and ATP receptors mimicked the consequences of a mechanical transection between laminae IV and V. Taken together, the current results indicate that the facilitation of inhibitory synaptic transmission in laminae III – IV of the DH by NA requires functional interlaminar connections between deep and more superficial laminae, and might strongly depend on glia to neuron interactions. These interlaminar connections and glia to neuron interactions could represent interesting targets for analgesic strategies.