Somatostatin enhances tooth-pulp-evoked cervical dorsal horn neuronal activity in the rat via inhibition of GABAergic interneurons.

Somatostatin enhances tooth-pulp-evoked cervical dorsal horn neuronal activity in the rat via inhibition of GABAergic interneurons. Brain Res Bull. 2013 Dec 6; Authors: Takahashi M, Takeda M, Matsumoto S Abstract A recent in vitro electrophysiological analysis combined with anatomical approach suggests that a potential disinhibitory mechanism involving somatostatin (SST), which is released by interneurons in the superficial dorsal horn, contributes to nociceptive transmission (Yasaka et al., 2010); however, whether this mechanism occurs in vivo remains to be determined. The aim of the present study was to investigate whether iontophoretic application of SST facilitates the excitability of nociceptive upper cervical spinal dorsal horn (C1) neurons through GABAergic disinhibiton, using extracellular electrophysiological recording with multibarrel electrodes and immunohistochemical techniques. Immunoreactivity of SST2A receptors was found in layer II of the C1 dorsal horn in the rat and most of these neurons co-expressed the GABA synthesizing enzyme glutamate decarboxylase 67. Single-unit recordings were made from C1 neurons responding to tooth-pulp (TP) electrical stimulation in pentobarbital anesthestized rats. Iontophoretic application of SST significantly increased TP-evokedC1 neuronal discharges in layers I and II of the spinal dorsal horn and this effect occurred in a current-dependent manner. The facilitation of this discharge by SST appli...
Source: Brain Research Bulletin - Category: Neurology Authors: Tags: Brain Res Bull Source Type: research