Actions of ethanolamine on cultured sensory neurones from neonatal rats

• Published in: Neuroscience letters Vol. 468; no. 3; pp. 326 - 329
• Main Authors: Khairy, Hesham, Adjei, Gloria, Allen-Redpath, Keith, Scott, Roderick H.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 14.01.2010; Elsevier
• Subjects: Animals; Animals, Newborn; Biological and medical sciences; Calcium Signaling; Cells, Cultured; Dorsal root ganglion; Endocannabinoids; Ethanolamine - metabolism; Ethanolamine - pharmacology; Fundamental and applied biological sciences. Psychology; Ganglia, Spinal - cytology; Intracellular calcium stores; Patch-Clamp Techniques; Potassium Channels, Voltage-Gated - physiology; Potassium Chloride - pharmacology; Rats; Sensory Receptor Cells - drug effects; Sensory Receptor Cells - physiology; Thapsigargicin; Vertebrates: nervous system and sense organs; Voltage-activated potassium currents; Intracellular calcium stores; Voltage-activated potassium currents; Dorsal root ganglion; Endocannabinoids; Thapsigargicin; Spinal cord; Calcium; Rat; Rodentia; Central nervous system; Ionic current; Cannabinoid; Vertebrata; Mammalia; Endocannabinoid; Animal; Spinal ganglion; Intracellular; Potassium
• ISSN: 0304-3940; 1872-7972; 1872-7972
• DOI: 10.1016/j.neulet.2009.11.025

Some of the analgesic and antinociceptive properties of the endocannabinoid anandamide can be explained by modulation of voltage-activated ion channels. However, the products of anandamide metabolism by fatty acid amide hydroxylase may also contribute to the altered excitability of sensory neurones. Ethanolamine is a product of metabolism of acylethanolamines including anandamide. In this study whole cell patch clamp recording and fura-2 Ca 2+ imaging techniques were used to characterize its actions on neonatal rat cultured dorsal root ganglion neurones. Ethanolamine (1 μM) increased the mean Ca 2+ transient produced by 1 mM caffeine and modulated Ca 2+ transients evoked by 60 mM KCl. Thapsigargicin (500 nM) inhibited the ethanolamine-evoked enhancement of Ca 2+ transients evoked by depolarisation. Voltage-activated K + currents were evoked from a holding potential of −70 mV by voltage step commands to 0 mV. Acute application of 1 μM ethanolamine produced irreversible current modulation. However, application of 100 nM ethanolamine reversibly increased or decreased K + currents. These effects of ethanolamine on voltage-activated K + currents were not sensitive to continual application of thapsigargicin. When applied alone thapsigargicin (500 nM) had no action on the mean K + current. In conclusion, ethanolamine may play distinct roles in the modulation of sensory neurone excitability by acting via different mechanisms to modulate K + channels and a component of intracellular Ca 2+ signalling. These data suggest that in a therapeutic context it may be difficult to predict the consequences of manipulating anandamide levels.