Endocannabinoids Mediate Rapid Retrograde Signaling At Interneuron → Pyramidal Neuron Synapses of the Neocortex

2003 ◽  
Vol 89 (4) ◽  
pp. 2334-2338 ◽  
Author(s):  
Joseph Trettel ◽  
Eric S. Levine

In the neocortex, inhibitory interneurons tightly regulate the firing patterns and integrative properties of pyramidal neurons (PNs). The endocannabinoid system of the neocortex may play an important role in the activity-dependent regulation of inhibitory (i.e., GABAergic) inputs received by PNs. In the present study, using whole cell recordings from layer 2/3 PNs in slices of mouse sensory cortex, we have identified a role for PN-derived endocannabinoids in the control of afferent inhibitory strength. Pairing evoked inhibitory currents with repeated epochs of postsynaptic depolarization led to a transient suppression of inhibition that was induced by a rise in postsynaptic Ca2+ and was expressed as a reduction in presynaptic GABA release. An antagonist (AM251) of the type-1 cannabinoid receptor blocked the depolarization-induced suppression of evoked inhibitory postsynaptic currents (eIPSCs), and the cannabinoid WIN55,212-2 reduced eIPSC amplitude and occluded suppression. The degree of WIN55,212-2-mediated inhibition of eIPSCs was strongly correlated with the magnitude of depolarization-induced suppression of the eIPSCs, suggesting that the WIN-sensitive afferents are suppressed by PN depolarization. Moreover, blocking endocannabinoid uptake with AM404 strongly modulated the kinetics and magnitude of eIPSC suppression. We conclude that the release of endocannabinoids from PNs allows for the postsynaptic control of presynaptic inhibition and could have profound consequences for the integrative properties of neocortical PNs.

2007 ◽  
Vol 98 (5) ◽  
pp. 2517-2524 ◽  
Author(s):  
Fouad Lemtiri-Chlieh ◽  
Eric S. Levine

In layer 2/3 of neocortex, brief trains of action potentials in pyramidal neurons (PNs) induce the mobilization of endogenous cannabinoids (eCBs), resulting in a depression of GABA release from the terminals of inhibitory interneurons (INs). This depolarization-induced suppression of inhibition (DSI) is mediated by activation of the type 1 cannabinoid receptor (CB1) on presynaptic terminals of a subset of INs. However, it is not clear whether CB1 receptors are also expressed at synapses between INs, and whether INs can release eCBs in response to depolarization. In the present studies, brain slices containing somatosensory cortex were prepared from 14- to 21-day-old CD-1 mice. Whole cell recordings were obtained from layer 2/3 PNs and from INs classified as regular spiking nonpyramidal, irregular spiking, or fast spiking. For all three classes of INs, the cannabinoid agonist WIN55,212-2 suppressed inhibitory synaptic activity, similar to the effect seen in PNs. In addition, trains of action potentials in PNs resulted in significant DSI. In INs, however, DSI was not seen in any cell type, even with prolonged high-frequency spike trains that produced calcium increases comparable to that seen with DSI induction in PNs. In addition, blocking eCB reuptake with AM404, which enhanced DSI in PNs, failed to unmask any DSI in INs. Thus the lack of DSI in INs does not appear to be due to an insufficient increase in intracellular calcium or enhanced reuptake. These results suggest that layer 2/3 INs receive CB1-expressing inhibitory inputs, but that eCBs are not released by these INs.


2002 ◽  
Vol 88 (1) ◽  
pp. 534-539 ◽  
Author(s):  
Joseph Trettel ◽  
Eric S. Levine

Using whole cell voltage-clamp recordings we investigated the effects of a synthetic cannabinoid (WIN55,212-2) on inhibitory inputs received by layer 2/3 pyramidal neurons in slices of the mouse auditory cortex. Activation of the type 1 cannabinoid receptor (CB1R) with WIN55,212-2 reliably reduced the amplitude of GABAergic inhibitory postsynaptic currents evoked by extracellular stimulation within layer 2/3. The suppression of this inhibition was blocked and reversed by the highly selective CB1R antagonist AM251, confirming a CB1R-mediated inhibition. Pairing evoked inhibitory postsynaptic currents (IPSCs) at short interstimulus intervals while applying WIN55,212-2 resulted in an increase in paired-pulse facilitation suggesting that the probability of GABA release was reduced. A presynaptic site of cannabinoid action was verified by an observed decrease in the frequency with no change in the amplitude or kinetics of action potential–independent postsynaptic currents (mIPSCs). When Cd2+ was added or Ca2+ was omitted from the recording solution, the remaining fraction of Ca2+-independent mIPSCs did not respond to WIN55,212-2. These data suggest that cannabinoids are capable of suppressing the inhibition of neocortical pyramidal neurons by depressing Ca2+-dependent GABA release from local interneurons.


2020 ◽  
Vol 21 (20) ◽  
pp. 7693
Author(s):  
Dhanush Haspula ◽  
Michelle A. Clark

The identification of the human cannabinoid receptors and their roles in health and disease, has been one of the most significant biochemical and pharmacological advancements to have occurred in the past few decades. In spite of the major strides made in furthering endocannabinoid research, therapeutic exploitation of the endocannabinoid system has often been a challenging task. An impaired endocannabinoid tone often manifests as changes in expression and/or functions of type 1 and/or type 2 cannabinoid receptors. It becomes important to understand how alterations in cannabinoid receptor cellular signaling can lead to disruptions in major physiological and biological functions, as they are often associated with the pathogenesis of several neurological, cardiovascular, metabolic, and inflammatory diseases. This review focusses mostly on the pathophysiological roles of type 1 and type 2 cannabinoid receptors, and it attempts to integrate both cellular and physiological functions of the cannabinoid receptors. Apart from an updated review of pre-clinical and clinical studies, the adequacy/inadequacy of cannabinoid-based therapeutics in various pathological conditions is also highlighted. Finally, alternative strategies to modulate endocannabinoid tone, and future directions are also emphasized.


2007 ◽  
Vol 97 (4) ◽  
pp. 2580-2589 ◽  
Author(s):  
Elisa L. Hill ◽  
Thierry Gallopin ◽  
Isabelle Férézou ◽  
Bruno Cauli ◽  
Jean Rossier ◽  
...  

The cannabinoid receptor CB1 is found in abundance in brain neurons, whereas CB2 is essentially expressed outside the brain. In the neocortex, CB1 is observed predominantly on large cholecystokinin (CCK)-expressing interneurons. However, physiological evidence suggests that functional CB1 are present on other neocortical neuronal types. We investigated the expression of CB1 and CB2 in identified neurons of rat neocortical slices using single-cell RT-PCR. We found that 63% of somatostatin (SST)-expressing and 69% of vasoactive intestinal polypeptide (VIP)-expressing interneurons co-expressed CB1. As much as 49% of pyramidal neurons expressed CB1. In contrast, CB2 was observed in a small proportion of neocortical neurons. We performed whole cell recordings of pyramidal neurons to corroborate our molecular findings. Inhibitory postsynaptic currents (IPSCs) induced by a mixed muscarinic/nicotinic cholinergic agonist showed depolarization-induced suppression of inhibition and were decreased by the CB1 agonist WIN-55212-2 (WIN-2), suggesting that interneurons excited by cholinergic agonists (mainly SST and VIP neurons) possess CB1. IPSCs elicited by a nicotinic receptor agonist were also reduced in the presence of WIN-2, suggesting that neurons excited by nicotinic agonists (mainly VIP neurons) indeed possess CB1. WIN-2 largely decreased excitatory postsynaptic currents evoked by intracortical electrical stimulation, pointing at the presence of CB1 on glutamatergic pyramidal neurons. All WIN-2 effects were strongly reduced by the CB1 antagonist AM 251. We conclude that CB1 is expressed in various neocortical neuronal populations, including glutamatergic neurons. Our combined molecular and physiological data suggest that CB1 widely mediates endocannabinoid effects on glutamatergic and GABAergic transmission to modulate cortical networks.


2021 ◽  
Author(s):  
Martin Montmerle ◽  
Fani Koukouli ◽  
Andrea Aguirre ◽  
Jeremy Peixoto ◽  
Vikash Choudhary ◽  
...  

Perisomatic inhibition of neocortical pyramidal neurons (PNs) coordinates cortical network activity during sensory processing, and it has been mainly attributed to parvalbumin-expressing basket cells (BCs). However, cannabinoid receptor type 1 (CB1)-expressing interneurons also inhibit the perisomatic region of PNs but the connectivity and function of these elusive, yet prominent, neocortical GABAergic cells is unknown. We found that the connectivity pattern of CB1-positive BCs strongly differs between primary and high-order cortical visual areas. Moreover, persistently active CB1 signaling suppresses GABA release from CB1 BCs in the medial secondary visual cortex (V2M), but not in the primary (V1) visual area. Accordingly, in vivo, tonic CB1 signaling is responsible for higher but less coordinated PN activity in V2M than in V1. Our results indicate a differential CB1-mediated mechanism controlling PN activity, and suggest an alternative connectivity schemes of a specific GABAergic circuit in different cortical areas


Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 4948
Author(s):  
Enrique Sánchez-Pastor ◽  
Xóchitl Trujillo ◽  
Christian Ramos-Flores ◽  
Mónica Ríos-Silva ◽  
Felipa Andrade ◽  
...  

Previous studies have suggested a role of the endocannabinoid system in metabolic diseases, such as diabetes. We investigated the effect of diabetes on cannabinoid receptor type 1 (CB1) expression and cannabinoid-induced vasorelaxation in rat aorta rings. Aortas from healthy rats and from rats with experimentally induced diabetes were used to compare the vasorelaxant effect of the cannabinoid agonist arachidonylcyclopropylamide (ACPA) and CB1 expression and localization. After 4–8 weeks of diabetes induction, CB1 receptor expression and CB1 phosphorylation were higher in aortic rings, in association with greater vasorelaxation induced by the CB1 agonist ACPA compared to healthy rats. The vasorelaxant effect observed in healthy rats is similar throughout the study. Further studies are needed to elucidate the implications of CB1 receptor overexpression in diabetes and its influence on the progression of the cardiovascular complications of this metabolic disease.


2020 ◽  
Vol 4 (6) ◽  
pp. 382-389
Author(s):  
V.A. Dudareva ◽  
◽  
M.L. Maksimov ◽  
I.G. Djadikova ◽  
A.A. Zveginceva ◽  
...  

Obesity that results in various metabolic disorders is one of the central concerns of modern healthcare system. Only 4% to 5% of patients with metabolic syndrome achieve favorable outcomes without any additional pharmacotherapy. Therefore, many patients require weight-loss drugs in addition to non-pharmacological treatments. The endocannabinoid system and the drugs that affect its functions receive a widespread attention of medical society due to its effects on behavioral and cerebral functions and its potential use as a therapeutic “target” in various peripheral and neurological psychiatric disorders. Among known to date cannabinoid receptors, type 1 receptors play a role in the development of obesity. It was demonstrated that the blockade of these receptors in the hypothalamus reduces appetite, inhibits adipocyte activation in peripheral tissues, prevents lipogenesis, and increases the level of adiponectin. The result is the decreased levels of atherogenic lipoproteins and improved insulin resistance. This article addresses the results of fundamental and clinical studies on Dietressa, a drug composed of affine-purified antibodies to cannabinoid receptor 1. Case report of a patient with obesity that analyzes pharmaceutical and non-pharmaceutical treatment approaches is described.KEYWORDS: obesity, metabolic syndrome, diet, endocannabinoid system, cannabinoids, cannabinoid receptors, affine-purified antibodies.FOR CITATION: Dudareva V.A., Maksimov M.L., Djadikova I.G. et al. Role of endocannabinoid system in the pathogenesis of obesity: how can we help a patient? From theory to practice. Russian Medical Inquiry. 2020;4(6):382–389. DOI: 10.32364/2587-6821-2020-4-6-382-389.


Endocrinology ◽  
2007 ◽  
Vol 148 (4) ◽  
pp. 1574-1581 ◽  
Author(s):  
Daniela Cota ◽  
Michel-Alexander Steiner ◽  
Giovanni Marsicano ◽  
Cristina Cervino ◽  
James P. Herman ◽  
...  

The endocannabinoid system affects the neuroendocrine regulation of hormone secretion, including the activity of the hypothalamus-pituitary-adrenal (HPA) axis. However, the mechanisms by which endocannabinoids regulate HPA axis function have remained unclear. Here we demonstrate that mice lacking cannabinoid receptor type 1 (CB1−/−) display a significant dysregulation of the HPA axis. Although circadian HPA axis responsiveness is preserved, CB1−/− mice are characterized by an enhanced circadian drive on the HPA axis, resulting in elevated plasma corticosterone concentrations at the onset of the dark as compared with wild-type (CB1+/+) littermates. Moreover, CB1−/−-derived pituitary cells respond with a significantly higher ACTH secretion to CRH and forskolin challenges as compared with pituitary cells derived from CB1+/+ mice. Both CBL−/− and CB1+/+ mice properly respond to a high-dose dexamethasone test, but response to low-dose dexamethasone is influenced by genotype. In addition, CB1−/− mice show increased CRH mRNA levels in the paraventricular nucleus of the hypothalamus but not in other extrahypothalamic areas, such as the amygdala and piriform cortex, in which CB1 and CRH mRNA have been colocalized. Finally, CB1−/− mice have selective glucocorticoid receptor mRNA down-regulation in the CA1 region of the hippocampus but not in the dentate gyrus or paraventricular nucleus. Conversely, mineralocorticoid receptor mRNA expression levels were found unchanged in these brain areas. In conclusion, our findings indicate that CB1 deficiency enhances the circadian HPA axis activity peak and leads to central impairment of glucocorticoid feedback, thus further outlining the essential role of the endocannabinoid system in the modulation of neuroendocrine functions.


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