Title:The Endocannabinoid System Modulating Levels of Consciousness, Emotions and Likely Dream Contents
Volume: 16
Issue: 4
Author(s): Eric Murillo-Rodriguez*, Jose Carlos Pastrana-Trejo, Mireille Salas-Crisóstomo and Miriel de-la-Cruz
Affiliation:
- Laboratorio de Neurociencias Moleculares e Integrativas, Escuela de Medicina, División Ciencias de la Salud, Universidad Anáhuac Mayab, Carretera Mérida-Progreso Km. 15.5, A.P. 96 Cordemex C.P. 97310, Mérida, Yucatán,Mexico
Keywords:
Anandamide, fatty acid amide hydrolase, dreams, anandamide membrane transporter, CB1 cannabinoid receptor,
rapid eye movement sleep.
Abstract: Background & Objective: Cannabinoids are derivatives that are either compounds occurring
naturally in the plant, Cannabis sativa or synthetic analogs of these molecules. The first and most
widely investigated of the cannabinoids is Δ9-tetrahydrocannabinol (Δ9-THC), which is the main psychotropic
constituent of cannabis and undergoes significant binding to cannabinoid receptors. These
cannabinoid receptors are seven-transmembrane receptors that received their name from the fact that
they respond to cannabinoid compounds, including Δ9-THC. The cannabinoid receptors have been described
in rat, human and mouse brains and they have been named the CB1 and CB2 cannabinoid receptors.
Later, an endogenous molecule that exerts pharmacological effects similar to those described by
Δ9-THC and binds to the cannabinoid receptors was discovered. This molecule, named anandamide,
was the first of five endogenous cannabinoid receptor agonists described to date in the mammalian
brain and other tissues. Of these endogenous cannabinoids or endocannabinoids, the most thoroughly
investigated to date have been anandamide and 2-arachidonoylglycerol (2-AG). Over the years, a significant
number of articles have been published in the field of endogenous cannabinoids, suggesting a
modulatory profile in multiple neurobiological roles of endocannabinoids. The general consensus accepts
that the endogenous cannabinoid system includes natural ligands (such as anandamide and 2-
AG), receptors (CB1 and CB2), and the main enzymes responsible for the hydrolysis of anandamide
and 2-AG (fatty acid amide hydrolase [FAAH] and monoacylglycerol lipase [MAGL], respectively) as
well as the anandamide membrane transporter (AMT). To date, diverse pieces of evidence have shown
that the endocannabinoid system controls multiple functions such as feeding, pain, learning and memory
and has been linked with various disturbances, such as Parkinson´s disease. Among the modulatory
properties of the endocannabinoid system, current data indicate that the sleep-wake cycle is under the
influence of endocannabinoids since the blocking of the CB1 cannabinoid receptor or the pharmacological
inhibition of FAAH activity promotes wakefulness, whereas the obstruction of AMT function
enhances sleep. However, no solid evidence is available regarding the role of the endocannabinoid system
in an unquestionable emotional component of the sleep: Dream activity. Since dreaming is a mental
activity that occurs during sleep (characterized by emotions, sensory perceptions, and bizarre components)
and the endocannabinoid system modulates neurobiological processes involving consciousness,
such as learning and memory, attention, pain perception, emotions and sleep, it is acceptable to
hypothesize that the endocannabinoid system might be modulating dream activity. In this regard, an
accumulative body of evidence in human and animal models has been reported regarding the role of the
endocannabinoid system in the control of emotional states and dreams. Moreover, preliminary studies
in humans have indicated that treatment with cannabinoids may decrease post-traumatic stress disorder
symptoms, including nightmares.
Conclusion: Thus, based on a review of the literature available in PubMed, this article hypothesizes a
conceptual framework within which the endocannabinoid system might influence the generation of dream
experiences.
