Neuroactive Properties in Mammals

 

Cannabinoid System

N-Acylethanolamines (NAEs) are fatty acid amides that are derived from an N-acylated phosphatidylethanolamine precursor and were historically associated with cellular stress and tissue damage in mammals. More recently NAEs have been shown to be part of the endocannabinoid signaling system. Recent investigation has shown that cannabinoid drugs (active ingredient D⁹-THC) act via membrane bound receptors (G-protein coupled) and NAEs act as endogenous ligands that react with the receptors CB1 and CB2.

Anandamide (NAE20:4) binds to and activates CB1 receptors in neurons, initiating an intracellular signaling cascade that leads to changes in ion flux at the plasma membrane

Endocannabinoid Signaling in the brain:  role of N-acylethanolamine metabolism

 

NAE Lipid Mediation in Eukaryotic Cells

Receptor	Tissue	Action	x	Physiological Effect
CB1	Central Nervous System	Anadamide binds and activates CB1 receptors in neurons, initiating an intracellular signaling cascade that leads to changes in ion flux at the plasma membrane. NAEs are released from the plasma membrane and bind to and activate CB1 receptors		neuroprotection
CB2 vanilloid receptor protein kinases ion channels nitric oxide still unknown	Peripheral Tissues Including Immune System	NAEs are released extracellularly where they are believed to act locally via CB2 and other receptors		anti-inflammatory neurotransmission immune responses vasodilation embryo development implantation feeding behavior cell proliferation

NAEs have been shown to accumulate in high levels in ischemic tissues thus supporting the concept that NAEs are produced by cells as a means of cytoprotection. The precise mechanisms of neuroprotection are the subject of active research and in collaboration with the Venables, Gross, and Koulen labs, we are examining this phenomenon in vitro in cell cultures and in vivo in rat stroke models. Efforts are also focused on identifying natural sources of NAEs as candidates for neuroprotective therapeutics.

Effect of NAE 16:0 (palmitoylethanolamide) on spontaneous activity of a spinal cord network in vitro. (A) NAE16:0 decreased spike and burst rates in a dose-dependent manner, with an EC50 of approximately 33µM. The effects were reversible with two full medium changes (W). Spike and burst rates increased about twofold following the medium changes, revealing possible lasting network sensitization effects of NAE16:). Twelve hours after medium changes, both spike and burst rates returned to reference levels (continuation of experiment 12h later in B). (B) NAE18:2 and NAE 16:0 exhibited additive effects on network activity (same network as in A). NAE 16:0 (20µM) decreased spike and burst rates by 70% (compared with -20% in A), reaching maximal effect 40min after application, and attained a stable activity plateau. At 97 min NAE 18:2 was applied to the network, resulting in a combined reduction of 95% from reference activity, 60 min after application. Two medium changes (W) returned the burst rate to reference levels and increased spike rates 23% over reference.

NAE Neuroactive Publications

1. Morefield, S.I., Keefer, E.W., Chapman, K.D., Gross, G.W. (2000) Drug evaluations using neuronal networks on microelectrode arrays: characteristic effects of cannabinoid agonists anandamide and methandamide on cortical and spinal cultures. Biosensors and Bioelectronics 15:383-396.
2. Petersen, G., Chapman, K.D., Hansen, H.S. (2000) A rapid phospholipase D assay using zirconium precipitation of anionic substrate phospholipids: application to N-acylethanolamine formation in vitro. Journal of Lipid Research41(9): 1532-40.
3. Chapman, K.D., Venables, B.J., Dian, E.E. and Gross, G.W.  (2003) Identification and quantification of neuroactive N-acylethanolamines in cottonseed processing fractions. Journal of the American Oil Chemists’ Society (JAOCS) 80(3): 223-229.