PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 1682013

Opioids at low concentration decrease openings of K+ channels in sensory ganglion neurons.

S F Fan·K F Shen·S M Crain
View original source ↗Export metadata ↓

Abstract

Previous studies showed that low concentrations of opioids prolong the calcium-dependent component of the action potential duration (APD) of dorsal root ganglion (DRG) neurons, whereas higher concentrations shorten the APD. In the present study whole-cell voltage-clamp, as well as cell-attached membrane-patch voltage-clamp, recordings demonstrate that application of picomolar to nanomolar concentrations of mu, delta or kappa opioid agonists (DAGO, DPDPE or dynorphin) to DRG neurons in dissociated cell cultures reversibly decreased the activities of voltage-sensitive K+ channels. Pretreatment of DRG neurons with the opioid receptor antagonists, naloxone (30 nM) or diprenorphine (1 nM) prevented mu/delta or kappa opioid-induced decreases in K+ channel activities, respectively. Since opioids added to the bath solution decreased the activities of K+ channels in the membrane patch sealed off by the pipette tip, our results provide strong evidence that some modes of excitatory modulation of the action potential of DRG neurons are mediated by diffusible second messengers. The data are consonant with our previous studies indicating that opioids can elicit excitatory effects on sensory neurons via cholera toxin-sensitive Gs-linked excitatory opioid receptors coupled to cyclic AMP-dependent ionic channels.

Explore related subjects

Action PotentialsAnimalsDynorphinsElectrophysiologyEnkephalin, Ala(2)-MePhe(4)-Gly(5)-Enkephalin, D-Penicillamine (2,5)-EnkephalinsGanglia, SpinalNarcotic AntagonistsNarcoticsNeurons, AfferentOsmolar ConcentrationPotassium ChannelsJournal ArticleResearch Support, U.S. Gov't, P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

S F Fan, K F Shen, S M Crain. 1991-08-30. Opioids at low concentration decrease openings of K+ channels in sensory ganglion neurons.. https://doi.org/10.1016/0006-8993(91)90737-g

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1995

Blockade of action potential activity alters initial arborization of thalamic axons within cortical layer 4.

In the formation of connections during the development of the nervous system, it is generally accepted that there is an early phase not requiring neural activity and a later activity-dependent phase. The initial processes of axonal pathfinding and target selection are not thought to require neural activity, whereas the later fine-tuning of connections into their final adult patterns does. We report an apparent exception to this rule in which action potential activity seems to be required very early in development for thalamic axons to form appropriate patterns of terminal arborizations with their ultimate target neurons in layer 4 of the cerebral cortex. Blockade of sodium action potentials during the 2-week fetal period when visual thalamic axons initially grow into the primary visual cortex in cats prevents the normally occurring branching of lateral geniculate nucleus axons within layer 4. This observation implies a role for action-potential activity in cerebral cortical development far earlier than previously suspected, weeks before eye-opening and the onset of the well-known process of activity-dependent reorganization of axonal terminal arbors that leads to the formation of ocular dominance columns.

Action Potentials↗
PubMed1995

Concerted signaling by retinal ganglion cells.

To analyze the rules that govern communication between eye and brain, visual responses were recorded from an intact salamander retina. Parallel observation of many retinal ganglion cells with a microelectrode array showed that nearby neurons often fired synchronously, with spike delays of less than 10 milliseconds. The frequency of such synchronous spikes exceeded the correlation expected from a shared visual stimulus up to 20-fold. Synchronous firing persisted under a variety of visual stimuli and accounted for the majority of action potentials recorded. Analysis of receptive fields showed that concerted spikes encoded information not carried by individual cells; they may represent symbols in a multineuronal code for vision.

Action Potentials↗