101
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Gyombolai P, Pap D, Turu G, Catt KJ, Bagdy G, Hunyady L. Regulation of endocannabinoid release by G proteins: a paracrine mechanism of G protein-coupled receptor action. Mol Cell Endocrinol 2012; 353:29-36. [PMID: 22075205 PMCID: PMC4169275 DOI: 10.1016/j.mce.2011.10.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 10/12/2011] [Accepted: 10/12/2011] [Indexed: 02/06/2023]
Abstract
In the past years, the relationship between the endocannabinoid system (ECS) and other hormonal and neuromodulatory systems has been intensively studied. G protein-coupled receptors (GPCRs) can stimulate endocannabinoid (eCB) production via activation of G(q/11) proteins and, in some cases, G(s) proteins. In this review, we summarize the pathways through which GPCR activation can trigger eCB release, as well as the best known examples of this process throughout the body tissues. Angiotensin II-induced activation of AT(1) receptors, similar to other G(q/11)-coupled receptors, can lead to the formation of 2-arachidonoylglycerol (2-AG), an important eCB. The importance of eCB formation in angiotensin II action is supported by the finding that the hypertensive effect of angiotensin II, injected directly into the hypothalamic paraventricular nucleus of anaesthetized rats, can be abolished by AM251, an inverse agonist of CB(1) cannabinoid receptors (CB(1)Rs). We conclude that activation of the ECS should be considered as a general consequence of the stimulation of G(q/11)-coupled receptors, and may mediate some of the physiological effects of GPCRs.
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Affiliation(s)
- Pál Gyombolai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Dorottya Pap
- Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary
| | - Gábor Turu
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Kevin J. Catt
- Section on Hormonal Regulation, Program in Developmental Endocrinology and Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - György Bagdy
- Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary
- Group of Neuropsychopharmacology and Neurochemistry, Semmelweis University and Hungarian Academy of Sciences, Budapest, Hungary
| | - László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- Laboratory of Neurobiochemistry and Molecular Physiology, Semmelweis University and Hungarian Academy of Sciences, Budapest, Hungary
- Corresponding author at: Department of Physiology, Faculty of Medicine, Semmelweis University, H-1444 Budapest, P.O. Box 259, Hungary. Tel: +36 1 266 9180; fax: +36 1 266 6504
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102
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Abstract
Synaptic activity in magnocellular neurosecretory neurones is influenced by the retrograde (i.e. somatodendritic) release of vasopressin, oxytocin and cannabinoids (CBs). For oxytocin neurones, oxytocin exerts constitutive effects on pre-synaptic activity through its ability to release CBs post-synaptically. In the present study, we examined evoked inhibitory post-synaptic currents (eIPSCs) and spontaneous inhibitory post-synaptic currents (sIPSCs) in identified vasopressin (VP) neurones in coronal slices from virgin rats to determine: (i) the extent to which CBs may also tonically modulate VP synaptic activity; and (ii) to determine whether depolarisation-induced suppression of inhibition was present in VP neurones, and if so, whether it was mediated by VP or CBs. The CB1 antagonists AM251 (1 μm) and SR14171 (1 μm) consistently increased the frequency of sIPSCs in VP neurones without affecting their amplitude, suggesting a tonic CB presence. This effect on frequency was independent of action potential activity, and blocked by chelating intracellular calcium with 10 mm ethylene glycol tetraacetic acid (EGTA). AM251 also increased the amplitude of eIPSCs and decreased the paired-pulse ratio (PPR) in VP neurones-effects that were completely blocked with even low (1 mm EGTA) internal calcium chelation. Bouts of evoked firing of VP neurones consistently suppressed sIPSCs but had no effect on eIPSCs or the PPR. This depolarisation-induced suppression of IPSCs was reduced by AM251, and was totally blocked by 10 μm of the mixed vasopressin/oxytocin antagonist, Manning compound. We then tested the effect of vasopressin on IPSCs at the same time as blocking CB1 receptors. Vasopressin (10-100 nm) inhibited sIPSC frequency but had no effect on sIPSC or eIPSC amplitudes, or on the PPR, in the presence of AM251. Taken together, these results suggest a tonic, pre-synaptic inhibitory modulation of IPSCs in VP neurones by CBs that is largely dependent on post-synaptic calcium, and an inhibitory effect of VP on IPSCs that is independent of CB release.
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Affiliation(s)
- L Wang
- Department of Anatomy and Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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103
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Zhang Y, Sheng H, Qi J, Ma B, Sun J, Li S, Ni X. Glucocorticoid acts on a putative G protein-coupled receptor to rapidly regulate the activity of NMDA receptors in hippocampal neurons. Am J Physiol Endocrinol Metab 2012; 302:E747-58. [PMID: 22146309 DOI: 10.1152/ajpendo.00302.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucocorticoids (GCs) have been demonstrated to act through both genomic and nongenomic mechanisms. The present study demonstrated that corticosterone rapidly suppressed the activity of N-methyl-D-aspartate (NMDA) receptors in cultured hippocampal neurons. The effect was maintained with corticosterone conjugated to bovine serum albumin and blocked by inhibition of G protein activity with intracellular GDP-β-S application. Corticosterone increased GTP-bound G(s) protein and cyclic AMP (cAMP) production, activated phospholipase Cβ(3) (PLC-β(3)), and induced inositol-1,4,5-triphosphate (IP(3)) production. Blocking PLC and the downstream cascades with PLC inhibitor, IP(3) receptor antagonist, Ca(2+) chelator, and protein kinase C (PKC) inhibitors prevented the actions of corticosterone. Blocking adenylate cyclase (AC) and protein kinase A (PKA) caused a decrease in NMDA-evoked currents. Application of corticosterone partly reversed the inhibition of NMDA currents caused by blockage of AC and PKA. Intracerebroventricular administration of corticosterone significantly suppressed long-term potentiation (LTP) in the CA1 region of the hippocampus within 30 min in vivo, implicating the possibly physiological significance of rapid effects of GC on NMDA receptors. Taken together, our results indicate that GCs act on a putative G protein-coupled receptor to activate multiple signaling pathways in hippocampal neurons, and the rapid suppression of NMDA activity by GCs is dependent on PLC and downstream signaling.
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MESH Headings
- Animals
- Blotting, Western
- CA1 Region, Hippocampal/cytology
- CA1 Region, Hippocampal/drug effects
- CA1 Region, Hippocampal/metabolism
- Cells, Cultured
- Cyclic AMP/metabolism
- Excitatory Postsynaptic Potentials
- Female
- Glucocorticoids/pharmacology
- Hippocampus/cytology
- Hippocampus/drug effects
- Hippocampus/metabolism
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Long-Term Potentiation/drug effects
- Male
- Neurons/drug effects
- Neurons/metabolism
- Patch-Clamp Techniques
- Pregnancy
- Radioimmunoassay
- Rats
- Rats, Sprague-Dawley
- Receptors, G-Protein-Coupled/drug effects
- Receptors, Glucocorticoid/drug effects
- Receptors, N-Methyl-D-Aspartate/metabolism
- Signal Transduction/drug effects
- Synapses/drug effects
- Synapses/physiology
- Type C Phospholipases/metabolism
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Affiliation(s)
- Yanmin Zhang
- Department of Physiology, Second Military Medical University, Shanghai, China
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104
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Ko JY, Wu RW, Kuo SJ, Chen MW, Yeh DW, Ke HC, Wu SL, Wang FS. Cannabinoid receptor 1 mediates glucocorticoid-induced bone loss in rats by perturbing bone mineral acquisition and marrow adipogenesis. ACTA ACUST UNITED AC 2012; 64:1204-14. [DOI: 10.1002/art.33457] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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105
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Groeneweg FL, Karst H, de Kloet ER, Joëls M. Mineralocorticoid and glucocorticoid receptors at the neuronal membrane, regulators of nongenomic corticosteroid signalling. Mol Cell Endocrinol 2012; 350:299-309. [PMID: 21736918 DOI: 10.1016/j.mce.2011.06.020] [Citation(s) in RCA: 195] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 06/15/2011] [Accepted: 06/20/2011] [Indexed: 02/06/2023]
Abstract
The balance between corticosteroid actions induced via activation of the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR) determines the brain's response to stress. While both receptors are best known for their delayed genomic role, it has become increasingly evident that they can also associate with the plasma membrane and act as mediators of rapid, nongenomic signalling. Nongenomic corticosteroid actions in the brain are required for the coordination of a rapid adaptive response to stress; membrane-associated MRs and GRs play a major role herein. However, many questions regarding the underlying mechanism are still unresolved. How do MR and GR translocate to the membrane and what are their downstream signalling partners? In this review we discuss these issues based on insights obtained from related receptors, most notably the estrogen receptor α.
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Affiliation(s)
- Femke L Groeneweg
- Department of Medical Pharmacology, Leiden Amsterdam Centre for Drug Research, Leiden University Medical Centre, Leiden University, Einsteinweg 55, Leiden, The Netherlands.
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106
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Gokulakrishnan G, Estrada IJ, Sosa HA, Fiorotto ML. In utero glucocorticoid exposure reduces fetal skeletal muscle mass in rats independent of effects on maternal nutrition. Am J Physiol Regul Integr Comp Physiol 2012; 302:R1143-52. [PMID: 22422665 DOI: 10.1152/ajpregu.00466.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Maternal stress and undernutrition can occur together and expose the fetus to high glucocorticoid (GLC) levels during this vulnerable period. To determine the consequences of GLC exposure on fetal skeletal muscle independently of maternal food intake, groups of timed-pregnant Sprague-Dawley rats (n = 7/group) were studied: ad libitum food intake (control, CON); ad libitum food intake with 1 mg dexamethasone/l drinking water from embryonic day (ED)13 to ED21 (DEX); pair-fed (PF) to DEX from ED13 to ED21. On ED22, dams were injected with [(3)H]phenylalanine for measurements of fetal leg muscle and diaphragm fractional protein synthesis rates (FSR). Fetal muscles were analyzed for protein and RNA contents, [(3)H]phenylalanine incorporation, and MuRF1 and atrogin-1 (MAFbx) mRNA expression. Fetal liver tyrosine aminotransferase (TAT) expression was quantified to assess fetal exposure to GLCs. DEX treatment reduced maternal food intake by 13% (P < 0.001) and significantly reduced placental mass relative to CON and PF dams. Liver TAT expression was elevated only in DEX fetuses (P < 0.01). DEX muscle protein masses were 56% and 70% than those of CON (P < 0.01) and PF (P < 0.05) fetuses, respectively; PF muscles were 80% of CON (P < 0.01). Muscle FSR decreased by 35% in DEX fetuses (P < 0.001) but were not different between PF and CON. Only atrogin-1 expression was increased in DEX fetus muscles. We conclude that high maternal GLC levels and inadequate maternal food intake impair fetal skeletal muscle growth, most likely through different mechanisms. When combined, the effects of decreased maternal intake and maternal GLC intake on fetal muscle growth are additive.
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Affiliation(s)
- Ganga Gokulakrishnan
- US Department of Agriculture/Agricltural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030-2600, USA
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107
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Atsak P, Roozendaal B, Campolongo P. Role of the endocannabinoid system in regulating glucocorticoid effects on memory for emotional experiences. Neuroscience 2012; 204:104-16. [DOI: 10.1016/j.neuroscience.2011.08.047] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 08/16/2011] [Accepted: 08/22/2011] [Indexed: 11/25/2022]
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108
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Antonio de Luis D, Sagrado MG, Aller R, Conde R, Izaola O, de la Fuente B, Primo D. Role of G1359A polymorphism of the cannabinoid receptor gene on weight loss and adipocytokines levels after two different hypocaloric diets. J Nutr Biochem 2012; 23:287-91. [DOI: 10.1016/j.jnutbio.2010.12.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 12/05/2010] [Accepted: 12/06/2010] [Indexed: 10/18/2022]
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109
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Häring M, Guggenhuber S, Lutz B. Neuronal populations mediating the effects of endocannabinoids on stress and emotionality. Neuroscience 2012; 204:145-58. [DOI: 10.1016/j.neuroscience.2011.12.035] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 12/12/2011] [Accepted: 12/12/2011] [Indexed: 01/17/2023]
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110
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Myers B, McKlveen JM, Herman JP. Neural Regulation of the Stress Response: The Many Faces of Feedback. Cell Mol Neurobiol 2012; 32:10.1007/s10571-012-9801-y. [PMID: 22302180 PMCID: PMC3956711 DOI: 10.1007/s10571-012-9801-y] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 01/10/2012] [Indexed: 12/15/2022]
Abstract
The mammalian stress response is an integrated physiological and psychological reaction to real or perceived adversity. Glucocorticoids (GCs) are an important component of this response, acting to redistribute energy resources to both optimize survival in the face of challenge and restore homeostasis after the immediate threat has subsided. Release of GCs is mediated by the hypothalamo-pituitary-adrenocortical (HPA) axis, driven by a neural signal originating in the paraventricular nucleus (PVN). Stress levels of GCs bind to glucocorticoid receptors (GRs) in multiple body compartments, including brain, and consequently have wide-reaching actions. For this reason, GCs serve a vital function in feedback inhibition of their own secretion. Fast, non-genomic feedback inhibition of the HPA axis is mediated at least in part by GC signaling in the PVN, acting by a cannabinoid-dependent mechanism to rapidly reduce both neural activity and GC release. Delayed feedback termination of the HPA axis response is mediated by forebrain GRs, presumably by genomic mechanisms. GCs also act in the brainstem to attenuate neuropeptidergic excitatory input to the PVN via acceleration of mRNA degradation, providing a mechanism to attenuate future responses to stressors. Thus, rather than having a single defined feedback switch, GCs work through multiple neurocircuits and signaling mechanisms to coordinate HPA axis activity to suit the overall needs of multiple body systems.
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Affiliation(s)
- Brent Myers
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Metabolic Diseases Institute, 2170 E. Galbraith Rd, Cincinnati, OH, 45237-0506, USA,
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111
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Abstract
Stress activates the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS), resulting in cardiovascular responses. The endocannabinoid system (ECS), a ubiquitously expressed lipid signalling system, modulates both HPA and SNS activity. The purpose of this review is to explore the possible involvement/role of the ECS in the cardiovascular response to stress. The ECS has numerous cardiovascular effects including modulation of blood pressure, heart rate, the baroreflex, and direct vascular actions. It is also involved in a protective manner in response to stressors in cardiac preconditioning, and various stressors (for example, pain, orthostasis and social stress) increase plasma levels of endocannabinoids. Given the multitude of vascular effects of endocannabinoids, this is bound to have consequences. Beneficial effects of ECS upregulation could include cardioprotection, vasodilatation, CB(2)-mediated anti-inflammatory effects and activation of peroxisome proliferator-activated receptors. Negative effects of endocannabinoids could include mediation of the effects of glucocorticoids, CB(1)-mediated metabolic changes, and metabolism to vasoconstrictor products. It is also likely that there is a central role for the ECS in modulating cardiovascular activity via the HPA and SNS. However, much more work is required to fully integrate the role of the ECS in mediating many of the physiological responses to stress, including cardiovascular responses.
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Affiliation(s)
- Saoirse E O'Sullivan
- School of Graduate Entry Medicine and Health, University of Nottingham, Nottingham, UK.
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112
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Wang M, Hill MN, Zhang L, Gorzalka BB, Hillard CJ, Alger BE. Acute restraint stress enhances hippocampal endocannabinoid function via glucocorticoid receptor activation. J Psychopharmacol 2012; 26:56-70. [PMID: 21890595 PMCID: PMC3373303 DOI: 10.1177/0269881111409606] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Exposure to behavioural stress normally triggers a complex, multilevel response of the hypothalamic-pituitary-adrenal (HPA) axis that helps maintain homeostatic balance. Although the endocannabinoid (eCB) system (ECS) is sensitive to chronic stress, few studies have directly addressed its response to acute stress. Here we show that acute restraint stress enhances eCB-dependent modulation of GABA release measured by whole-cell voltage clamp of inhibitory postsynaptic currents (IPSCs) in rat hippocampal CA1 pyramidal cells in vitro. Both Ca(2+)-dependent, eCB-mediated depolarization-induced suppression of inhibition (DSI), and muscarinic cholinergic receptor (mAChR)-mediated eCB mobilization are enhanced following acute stress exposure. DSI enhancement is dependent on the activation of glucocorticoid receptors (GRs) and is mimicked by both in vivo and in vitro corticosterone treatment. This effect does not appear to involve cyclooxygenase-2 (COX-2), an enzyme that can degrade eCBs; however, treatment of hippocampal slices with the L-type calcium (Ca(2+)) channel inhibitor, nifedipine, reverses while an agonist of these channels mimics the effect of in vivo stress. Finally, we find that acute stress produces a delayed (by 30 min) increase in the hippocampal content of 2-arachidonoylglycerol, the eCB responsible for DSI. These results support the hypothesis that the ECS is a biochemical effector of glucocorticoids in the brain, linking stress with changes in synaptic strength.
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Affiliation(s)
- Meina Wang
- Department of Physiology, Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, USA 21201
| | - Matthew N. Hill
- Department of Psychology, University of British Columbia, Vancouver, BC Canada
| | - Longhua Zhang
- Department of Physiology, Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, USA 21201
| | - Boris B. Gorzalka
- Department of Psychology, University of British Columbia, Vancouver, BC Canada
| | - Cecilia J. Hillard
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, USA 53226
| | - Bradley E. Alger
- Department of Physiology, Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, USA 21201
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113
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Bermudez-Silva FJ, Cardinal P, Cota D. The role of the endocannabinoid system in the neuroendocrine regulation of energy balance. J Psychopharmacol 2012; 26:114-24. [PMID: 21824982 DOI: 10.1177/0269881111408458] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Animal and human studies carried out so far have established a role for the endocannabinoid system (ECS) in the regulation of energy balance. Here we critically discuss the role of the endocannabinoid signalling in brain structures, such as the hypothalamus and reward-related areas, and its interaction with neurotransmitter and neuropeptide systems involved in the regulation of food intake and body weight. The ECS has been found to interact with peripheral signals, like leptin, insulin, ghrelin and satiety hormones and the resulting effects on both central and peripheral mechanisms affecting energy balance and adiposity will be described. Furthermore, ECS dysregulation has been associated with the development of dyslipidemia, glucose intolerance and obesity; phenomena that are often accompanied by a plethora of neuroendocrine alterations which might play a causal role in determining ECS dysregulation. Despite the withdrawal of the first generation of cannabinoid type 1 receptor (CB1) antagonists from the pharmaceutical market due to the occurrence of psychiatric adverse events, new evidence suggests that peripherally restricted CB1 antagonists might be efficacious for the treatment of obesity and its associated metabolic disorders. Thus, a perspective on new promising strategies to selectively target the ECS in the context of energy balance regulation is given.
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114
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Hill MN, Tasker JG. Endocannabinoid signaling, glucocorticoid-mediated negative feedback, and regulation of the hypothalamic-pituitary-adrenal axis. Neuroscience 2011; 204:5-16. [PMID: 22214537 DOI: 10.1016/j.neuroscience.2011.12.030] [Citation(s) in RCA: 224] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 12/13/2011] [Accepted: 12/15/2011] [Indexed: 12/20/2022]
Abstract
The hypothalamic-pituitary-adrenal (HPA) axis regulates the outflow of glucocorticoid hormones under basal conditions and in response to stress. Within the last decade, a large body of evidence has mounted indicating that the endocannabinoid system is involved in the central regulation of the stress response; however, the specific role endocannabinoid signaling plays in phases of HPA axis regulation, and the neural sites of action mediating this regulation, were not mapped out until recently. This review aims to collapse the current state of knowledge regarding the role of the endocannabinoid system in the regulation of the HPA axis to put together a working model of how and where endocannabinoids act within the brain to regulate outflow of the HPA axis. Specifically, we discuss the role of the endocannabinoid system in the regulation of the HPA axis under basal conditions, activation in response to acute stress, and glucocorticoid-mediated negative feedback. Interestingly, there appears to be some anatomical specificity to the role of the endocannabinoid system in each phase of HPA axis regulation, as well as distinct roles of both anandamide and 2-arachidonoylglycerol in these phases. Overall, the current level of information indicates that endocannabinoid signaling acts to suppress HPA axis activity through concerted actions within the prefrontal cortex, amygdala, and hypothalamus.
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Affiliation(s)
- M N Hill
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB T2N 4N1, Canada.
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115
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The intricate link between glucocorticoids and endocannabinoids at stress-relevant synapses in the hypothalamus. Neuroscience 2011; 204:31-7. [PMID: 22155492 DOI: 10.1016/j.neuroscience.2011.11.049] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Revised: 11/18/2011] [Accepted: 11/19/2011] [Indexed: 01/12/2023]
Abstract
The relationship between glucocorticoids and endocannabinoids at hypothalamic synapses in the presence of stress is particularly complex. Under conditions of acute stress, glucocorticoids trigger the synthesis of endocannabinoids, which through activation of type I cannabinoid receptors (CB1Rs), inhibit stress-relevant neurons in the paraventricular nucleus of the hypothalamus (PVN). Through this signaling mechanism, endocannabinoids constrain the activity of the hypothalamic-pituitary-adrenal axis. However, following chronic or repeated stress, the ability of endocannabinoids to modulate synaptic activity is compromised because of a functional down-regulation in CB1Rs. Here we examine recent findings that highlight important aspects of endocannabinoid signaling in response to stress in the PVN and the dorsomedial hypothalamus (DMH), two hypothalamic nuclei that play integral roles in regulating the neuroendocrine and autonomic responses to stress.
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116
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Crosby KM, Inoue W, Pittman QJ, Bains JS. Endocannabinoids gate state-dependent plasticity of synaptic inhibition in feeding circuits. Neuron 2011; 71:529-41. [PMID: 21835348 DOI: 10.1016/j.neuron.2011.06.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2011] [Indexed: 12/27/2022]
Abstract
Changes in food availability alter the output of hypothalamic nuclei that underlie energy homeostasis. Here, we asked whether food deprivation impacts the ability of GABA synapses in the dorsomedial hypothalamus (DMH), an important integrator of satiety signals, to undergo activity-dependent changes. GABA synapses in DMH slices from satiated rats exhibit endocannabinoid-mediated long-term depression (LTD(GABA)) in response to high-frequency stimulation of afferents. When CB1Rs are blocked, however, the same stimulation elicits long-term potentiation (LTP(GABA)), which manifests presynaptically and requires heterosynaptic recruitment of NMDARs and nitric oxide (NO). Interestingly, NO signaling is required for eCB-mediated LTD(GABA). Twenty-four hour food deprivation results in a CORT-mediated loss of CB1R signaling and, consequently, GABA synapses only exhibit LTP(GABA). These observations indicate that CB1R signaling promotes LTD(GABA) and gates LTP(GABA). Furthermore, the satiety state of an animal, through regulation of eCB signaling, determines the polarity of activity-dependent plasticity at GABA synapses in the DMH.
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Affiliation(s)
- Karen M Crosby
- Hotchkiss Brain Institute and Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N4N1, Canada
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117
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Timing is everything: evidence for a role of corticolimbic endocannabinoids in modulating hypothalamic-pituitary-adrenal axis activity across developmental periods. Neuroscience 2011; 204:17-30. [PMID: 22015924 DOI: 10.1016/j.neuroscience.2011.10.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 10/04/2011] [Accepted: 10/05/2011] [Indexed: 02/05/2023]
Abstract
Growing evidence suggests that the endocannabinoid system is vital to ensuring normative maturation of the brain into adulthood. Endocannabinoid signaling contributes to guiding pro-neurogenic processes in early life and the development of neurotransmitter systems. Moreover, there is extensive evidence that recruitment of the endocannabinoid system is crucial in the regulation of neuroendocrine responses to stress via the hypothalamic-pituitary-adrenal (HPA) axis, and contributes to subsequent psychopathological consequences associated with emotionality and anxiety. These stress-induced physiological and behavioural sequelae are regulated by neural structures within the corticolimbic circuit, including the amygdala, hypothalamus, hippocampus, and prefrontal cortex. Based on evidence demonstrating endocannabinoid system involvement in both development and stress-induced changes in HPA axis function, it is reasonable to suggest that endocannabinoid signaling is an important mediator of interactions between stress responsivity and maturational stage. In this review, we discuss the ontogeny of the endocannabinoid system in the central nervous system, clinical and rodent models demonstrating short- and long-term effects of stress exposure, regulation of HPA axis responsivity by endocannabinoid signaling, as well as pharmacological and stress models indicating involvement of the endocannabinoid system in early post-natal and adolescent development on stress reactivity of the HPA, the corticolimbic system, and behaviour.
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118
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Sahu M, Litvin DG, Sahu A. Phosphodiesterase-3B is expressed in proopiomelanocortin and neuropeptide Y neurons in the mouse hypothalamus. Neurosci Lett 2011; 505:93-7. [PMID: 22001576 DOI: 10.1016/j.neulet.2011.09.068] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 09/29/2011] [Indexed: 11/24/2022]
Abstract
Leptin signaling in the hypothalamus is obligatory for normal food intake and body weight homeostasis. It is now well established that besides the signal transducer and activator of transcription-3 (STAT3) pathway, several non-STAT3 pathways mediate leptin signaling in the hypothalamus. We have previously demonstrated that leptin stimulates phosphodiesterase-3B (PDE3B) activity in the hypothalamus, and PDE3 inhibitor cilostamide reverses anorectic and bodyweight reducing effects of leptin. Recently, we have demonstrated that cilostamide reversed the leptin-induced increase in proopiomelanocortin (POMC) gene expression in the hypothalamus. Because POMC and neuropeptide Y (NPY) neurons are thought to be the major targets of leptin signaling in the hypothalamus, to establish the physiological role of the PDE3B pathway it is important to demonstrate if PDE3B is expressed in these neurons. To this end we examined co-localization of PDE3B with POMC and NPY neurons using immunocytochemistry in POMC-GFP and NPY-GFP mice, respectively. Results showed that PDE3B was highly localized throughout the various hypothalamic sites including the arcuate nucleus (ARC), ventromedial nucleus, dorsomedial nucleus, ventral premammillary nucleus, paraventricular nucleus, and lateral hypothalamus. Importantly, almost all NPY (91.7%) and POMC (97.7%) neurons co-expressed PDE3B. These results suggest a direct role of the PDE3B pathway in mediating leptin signaling in the POMC and NPY neurons-a potential mechanism of leptin signaling in the hypothalamus.
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Affiliation(s)
- Maitrayee Sahu
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Magee-Womens Research Institute, Pittsburgh, PA 15213, USA
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The Endocannabinoid System as Pharmacological Target Derived from Its CNS Role in Energy Homeostasis and Reward. Applications in Eating Disorders and Addiction. Pharmaceuticals (Basel) 2011; 4:1101-1136. [PMID: 32143540 PMCID: PMC4058662 DOI: 10.3390/ph4081101] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 07/18/2011] [Accepted: 07/28/2011] [Indexed: 01/26/2023] Open
Abstract
The endocannabinoid system (ECS) has been implicated in many physiological functions, including the regulation of appetite, food intake and energy balance, a crucial involvement in brain reward systems and a role in psychophysiological homeostasis (anxiety and stress responses). We first introduce this important regulatory system and chronicle what is known concerning the signal transduction pathways activated upon the binding of endogenous cannabinoid ligands to the Gi/0-coupled CB1 cannabinoid receptor, as well as its interactions with other hormones and neuromodulators which can modify endocannabinoid signaling in the brain. Anorexia nervosa (AN) and bulimia nervosa (BN) are severe and disabling psychiatric disorders, characterized by profound eating and weight alterations and body image disturbances. Since endocannabinoids modulate eating behavior, it is plausible that endocannabinoid genes may contribute to the biological vulnerability to these diseases. We present and discuss data suggesting an impaired endocannabinoid signaling in these eating disorders, including association of endocannabinoid components gene polymorphisms and altered CB1-receptor expression in AN and BN. Then we discuss recent findings that may provide new avenues for the identification of therapeutic strategies based on the endocannabinod system. In relation with its implications as a reward-related system, the endocannabinoid system is not only a target for cannabis but it also shows interactions with other drugs of abuse. On the other hand, there may be also a possibility to point to the ECS as a potential target for treatment of drug-abuse and addiction. Within this framework we will focus on enzymatic machinery involved in endocannabinoid inactivation (notably fatty acid amide hydrolase or FAAH) as a particularly interesting potential target. Since a deregulated endocannabinoid system may be also related to depression, anxiety and pain symptomatology accompanying drug-withdrawal states, this is an area of relevance to also explore adjuvant treatments for improving these adverse emotional reactions.
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120
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Hill MN, McLaughlin RJ, Pan B, Fitzgerald ML, Roberts CJ, Lee TTY, Karatsoreos IN, Mackie K, Viau V, Pickel VM, McEwen BS, Liu QS, Gorzalka BB, Hillard CJ. Recruitment of prefrontal cortical endocannabinoid signaling by glucocorticoids contributes to termination of the stress response. J Neurosci 2011; 31:10506-15. [PMID: 21775596 PMCID: PMC3179266 DOI: 10.1523/jneurosci.0496-11.2011] [Citation(s) in RCA: 257] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 04/21/2011] [Accepted: 05/16/2011] [Indexed: 11/21/2022] Open
Abstract
The mechanisms subserving the ability of glucocorticoid signaling within the medial prefrontal cortex (mPFC) to terminate stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis are not well understood. We report that antagonism of the cannabinoid CB(1) receptor locally within the mPFC prolonged corticosterone secretion following cessation of stress in rats. Mice lacking the CB(1) receptor exhibited a similar prolonged response to stress. Exposure of rats to stress produced an elevation in the endocannabinoid 2-arachidonoylglycerol within the mPFC that was reversed by pretreatment with the glucocorticoid receptor antagonist RU-486 (20 mg/kg). Electron microscopic and electrophysiological data demonstrated the presence of CB(1) receptors in inhibitory-type terminals impinging upon principal neurons within layer V of the prelimbic region of the mPFC. Bath application of corticosterone (100 nm) to prefrontal cortical slices suppressed GABA release onto principal neurons in layer V of the prelimbic region, when examined 1 h later, which was prevented by application of a CB(1) receptor antagonist. Collectively, these data demonstrate that the ability of stress-induced glucocorticoid signaling within mPFC to terminate HPA axis activity is mediated by a local recruitment of endocannabinoid signaling. Endocannabinoid activation of CB(1) receptors decreases GABA release within the mPFC, likely increasing the outflow of the principal neurons of the prelimbic region to contribute to termination of the stress response. These data support a model in which endocannabinoid signaling links glucocorticoid receptor engagement to activation of corticolimbic relays that inhibit corticosterone secretion.
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MESH Headings
- Animals
- Arachidonic Acids/metabolism
- Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism
- Corticosterone/pharmacology
- Disease Models, Animal
- Electric Stimulation/methods
- Endocannabinoids
- Freezing Reaction, Cataleptic/drug effects
- Freezing Reaction, Cataleptic/physiology
- Glycerides/metabolism
- Hormone Antagonists/pharmacology
- In Vitro Techniques
- Long-Term Synaptic Depression/drug effects
- Long-Term Synaptic Depression/genetics
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred ICR
- Mice, Knockout
- Microscopy, Electron, Transmission
- Mifepristone/pharmacology
- Patch-Clamp Techniques/methods
- Piperidines/pharmacology
- Prefrontal Cortex/cytology
- Prefrontal Cortex/drug effects
- Prefrontal Cortex/metabolism
- Pyramidal Cells/drug effects
- Pyramidal Cells/physiology
- Pyrazoles/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/deficiency
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Stress, Psychological/drug therapy
- Stress, Psychological/metabolism
- Stress, Psychological/pathology
- gamma-Aminobutyric Acid/metabolism
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Affiliation(s)
- Matthew N. Hill
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, New York 10065
| | | | - Bin Pan
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Megan L. Fitzgerald
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, New York 10065, and
| | - Christopher J. Roberts
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | | | - Ilia N. Karatsoreos
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, New York 10065
| | - Ken Mackie
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana 47405
| | - Victor Viau
- Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Virginia M. Pickel
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, New York 10065, and
| | - Bruce S. McEwen
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, New York 10065
| | - Qing-song Liu
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | | | - Cecilia J. Hillard
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
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121
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Serrano A, Parsons LH. Endocannabinoid influence in drug reinforcement, dependence and addiction-related behaviors. Pharmacol Ther 2011; 132:215-41. [PMID: 21798285 DOI: 10.1016/j.pharmthera.2011.06.005] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 06/17/2011] [Indexed: 12/12/2022]
Abstract
The endogenous cannabinoid system is an important regulatory system involved in physiological homeostasis. Endocannabinoid signaling is known to modulate neural development, immune function, metabolism, synaptic plasticity and emotional state. Accumulating evidence also implicates brain endocannabinoid signaling in the etiology of drug addiction which is characterized by compulsive drug seeking, loss of control in limiting drug intake, emergence of a negative emotional state in the absence of drug use and a persistent vulnerability toward relapse to drug use during protracted abstinence. In this review we discuss the effects of drug intake on brain endocannabinoid signaling, evidence implicating the endocannabinoid system in the motivation for drug consumption, and drug-induced alterations in endocannabinoid function that may contribute to various aspects of addiction including dysregulated synaptic plasticity, increased stress responsivity, negative affective states, drug craving and relapse to drug taking. Current knowledge of genetic variants in endocannabinoid signaling associated with addiction is also discussed.
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Affiliation(s)
- Antonia Serrano
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA 92037, USA
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122
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Abstract
Stress activation of the hypothalamic-pituitary-adrenal (HPA) axis culminates in increased circulating corticosteroid concentrations. Stress-induced corticosteroids exert diverse actions in multiple target tissues over a broad range of timescales, ranging from rapid actions, which are induced within seconds to minutes and gene transcription independent, to slow actions, which are delayed, long lasting, and transcription dependent. Rapid corticosteroid actions in the brain include, among others, a fast negative feedback mechanism responsible for shutting down the activated HPA axis centrally. We provide a brief review of the cellular mechanisms responsible for rapid corticosteroid actions in different brain structures of the rat, including the hypothalamus, hippocampus, amygdala, and in the anterior pituitary. We propose a model for the direct feedback inhibition of the HPA axis by glucocorticoids in the hypothalamus. According to this model, glucocorticoids activate membrane glucocorticoid receptors to induce endocannabinoid synthesis in the hypothalamic paraventricular nucleus (PVN) and retrograde cannabinoid type I receptor-mediated suppression of the excitatory synaptic drive to PVN neuroendocrine cells. Rapid corticosteroid actions in the hippocampus, amygdala, and pituitary are mediated by diverse cellular mechanisms and may also contribute to the rapid negative feedback regulation of the HPA neuroendocrine axis as well as to the stress regulation of emotional and spatial memory formation.
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Affiliation(s)
- Jeffrey G Tasker
- Department of Cell and Molecular Biology and Neuroscience Program, Tulane University, New Orleans, LA 70118, USA.
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123
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Abstract
Endogenous cannabinoids play an important role in the physiology and behavioral expression of stress responses. Activation of the hypothalamic-pituitary-adrenal (HPA) axis, including the release of glucocorticoids, is the fundamental hormonal response to stress. Endocannabinoid (eCB) signaling serves to maintain HPA-axis homeostasis, by buffering basal activity as well as by mediating glucocorticoid fast feedback mechanisms. Following chronic stressor exposure, eCBs are also involved in physiological and behavioral habituation processes. Behavioral consequences of stress include fear and stress-induced anxiety as well as memory formation in the context of stress, involving contextual fear conditioning and inhibitory avoidance learning. Chronic stress can also lead to depression-like symptoms. Prominent in these behavioral stress responses is the interaction between eCBs and the HPA-axis. Future directions may differentiate among eCB signaling within various brain structures/neuronal subpopulations as well as between the distinct roles of the endogenous cannabinoid ligands. Investigation into the role of the eCB system in allostatic states and recovery processes may give insight into possible therapeutic manipulations of the system in treating chronic stress-related conditions in humans.
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124
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Sidhpura N, Parsons LH. Endocannabinoid-mediated synaptic plasticity and addiction-related behavior. Neuropharmacology 2011; 61:1070-87. [PMID: 21669214 DOI: 10.1016/j.neuropharm.2011.05.034] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 05/26/2011] [Accepted: 05/29/2011] [Indexed: 01/20/2023]
Abstract
Endogenous cannabinoids (eCBs) are retrograde messengers that provide feedback inhibition of both excitatory and inhibitory transmission in brain through the activation of presynaptic CB₁ receptors. Substantial evidence indicates that eCBs mediate various forms of short- and long-term plasticity in brain regions involved in the etiology of addiction. The present review provides an overview of the mechanisms through which eCBs mediate various forms of synaptic plasticity and discusses evidence that eCB-mediated plasticity is disrupted following exposure to a variety of abused substances that differ substantially in pharmacodynamic mechanism including alcohol, psychostimulants and cannabinoids. The possible involvement of dysregulated eCB signaling in maladaptive behaviors that evolve over long-term drug exposure is also discussed, with a particular focus on altered behavioral responses to drug exposure, deficient extinction of drug-related memories, increased drug craving and relapse, heightened stress sensitivity and persistent affective disruption (anxiety and depression).
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Affiliation(s)
- Nimish Sidhpura
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
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125
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The Role of Phosphatidylinositol-3-Kinase and AMP-Activated Kinase in the Rapid Estrogenic Attenuation of Cannabinoid-Induced Changes in Energy Homeostasis. Pharmaceuticals (Basel) 2011. [PMCID: PMC4055882 DOI: 10.3390/ph4040630] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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126
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Sahu A. Intracellular leptin-signaling pathways in hypothalamic neurons: the emerging role of phosphatidylinositol-3 kinase-phosphodiesterase-3B-cAMP pathway. Neuroendocrinology 2011; 93:201-10. [PMID: 21464566 PMCID: PMC3130491 DOI: 10.1159/000326785] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Accepted: 02/24/2011] [Indexed: 01/02/2023]
Abstract
Leptin is secreted primarily by fat cells and acts centrally, particularly in the hypothalamus, to reduce food intake and body weight. Besides the classical JAK2 (Janus kinase-2)-STAT3 (signal transducer and activator of transcription-3) pathway, several non-STAT3 pathways play an important role in mediating leptin signaling in the hypothalamus. We have demonstrated that leptin action in the hypothalamus is mediated by an insulin-like signaling pathway involving stimulation of PI3K (phosphatidylinositol-3 kinase) and PDE3B (phosphodiesterase-3B), and reduction in cAMP levels, and that a PI3K-PDE3B-cAMP pathway interacting with the JAK2-STAT3 pathway constitutes a critical component of leptin signaling in the hypothalamus. It appears that defective regulation of multiple signaling pathways in the hypothalamus causes central leptin resistance, a major cause of obesity. In this regard, we have shown that leptin resistance in hypothalamic neurons following chronic central infusion of this hormone is associated with a defect in the PI3K-PDE3B-cAMP, and not due to compromised signaling in the JAK2-STAT3 pathway. Similarly, the PI3K, but not the STAT3, pathway is impaired in the hypothalamus during the development of diet-induced obesity. Additionally, our recent work suggests that suppressor of cytokine signaling-3 negatively regulates the PI3K pathway of leptin signaling in the hypothalamus, a mechanism expected to play a significant role in diet-induced obesity. Together, the PI3K-PDE3B-cAMP pathway appears to emerge as a major mechanism of leptin signaling in the hypothalamus in regulating energy balance.
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Affiliation(s)
- Abhiram Sahu
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Magee-Womens Research Institute, Pittsburgh, PA 15213, USA.
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127
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Abstract
PURPOSE OF REVIEW The endogenous cannabinoids (endocannabinoids) are long-chain polyunsaturated fatty acids synthesized on demand in situ by catabolism of phospholipid precursors in the cell membrane. Here we discuss the emerging role of the endocannabinoids in the function of the pancreatic islet of Langerhans in particular on the secretion of insulin from the islet beta cell. RECENT FINDINGS It is now established that there is a functional endocannabinoid system in the pancreatic islet of Langerhans and that endocannabinoids are released concurrently with glucose-induced insulin secretion. The majority of the published papers show evidence of negative effects of the endocannabinoids on insulin secretion with antagonism of the cannabinoid 1 receptor improving beta cell function. This indicates that there is a tonic inhibition of insulin secretion by endocannabinoids. Here we examine these reports and recent papers showing that endocannabinoids increase insulin secretion and discuss the discrepancies in these observations. SUMMARY Conclusions on the exact nature of the effects of endocannabinoids on insulin secretion require rigorous study examining both acute and long-term effects at physiologically relevant doses employing both whole animal and clinically relevant models such as human islets in vitro and explanted in vivo, in rodent models of diabetes.
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Affiliation(s)
- Máire E Doyle
- The Johns Hopkins University School of Medicine, Division of Endocrinology, Johns Hopkins Bayview Medical Center, Baltimore, Maryland 21224, USA.
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128
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Rogers RC, McDougal DH, Hermann GE. Leptin amplifies the action of thyrotropin-releasing hormone in the solitary nucleus: an in vitro calcium imaging study. Brain Res 2011; 1385:47-55. [PMID: 21334313 DOI: 10.1016/j.brainres.2011.02.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 02/11/2011] [Accepted: 02/11/2011] [Indexed: 12/28/2022]
Abstract
Leptin exerts a powerful permissive influence on neurogenic thermogenesis. During starvation and an absence of leptin, animals cannot produce thermogenic reactions to cold stress. However, thermogenesis is rescued by restoring leptin. We have previously observed a highly cooperative interaction between leptin and thyrotropin-releasing hormone [TRH] to activate hindbrain-generated thermogenic responses (Hermann et al., 2006). In vivo physiological studies (Rogers et al., 2009) suggested that the thermogenic impact of TRH in the hindbrain is amplified by the action of leptin through a leptin receptor-mediated production of phosphoinositol-trisphosphate [PIP3]. In turn, PIP3 can activate a tyrosine kinase whose target is the Src-SH2 regulatory site on the phospholipase C [PLC] complex. The TRH receptor signals through the PLC complex. Our immunohistochemical studies (Barnes et al., 2010) suggest that this transduction interaction between leptin and TRH occurs within neurons of the solitary nucleus [NST], though this interaction had not been verified. The present in vitro live cell calcium imaging study shows that while medial NST neurons are rarely activated by leptin alone, leptin pre-treatment significantly augments NST neurons' responsiveness to TRH. This leptin-mediated priming of NST neurons was uncoupled by pre-treatment with the phosphoinositide 3-kinase [PI3K] inhibitor [wortmannin], the phospholipase C inhibitor [U73122] and the Src-SH2 antagonist [PP2]. TTX did not eliminate the synergistic response of the agonists, thus the sensitization cannot be attributed to pre-synaptic mechanisms. It seems likely that NST neurons are involved in the leptin-mediated increase in BAT temperature by sensitizing the TRH-PLC-IP3-calcium release mechanism.
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Affiliation(s)
- Richard C Rogers
- Laboratory of Autonomic Neurosciences, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
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129
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Opposing actions of endothelin-1 on glutamatergic transmission onto vasopressin and oxytocin neurons in the supraoptic nucleus. J Neurosci 2011; 30:16855-63. [PMID: 21159956 DOI: 10.1523/jneurosci.5079-10.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Endothelin (ET-1) given centrally has many reported actions on hormonal and autonomic outputs from the CNS. However, it is unclear whether these effects are due to local ischemia via its vasoconstrictor properties or to a direct neuromodulatory action. ET-1 stimulates the release of oxytocin (OT) and vasopressin (VP) from supraoptic magnocellular (MNCs) neurons in vivo; therefore, we asked whether ET-1 modulates the excitatory inputs onto MNCs that are critical in sculpting the activity of these neurons. To investigate whether ET-1 modulates excitatory synaptic transmission, we obtained whole-cell recordings and analyzed quantal glutamate release onto MNCs in the supraoptic nucleus (SON). Neurons identified as VP-containing neurosecretory cells displayed a decrease in quantal frequency in response to ET-1 (10-100 pm). This decrease was mediated by ET(A) receptor activation and production of a retrograde messenger that targets presynaptic cannabinoid-1 receptors. In contrast, neurons identified as OT-containing MNCs displayed a transient increase in quantal glutamate release in response to ET-1 application via ET(B) receptor activation. Application of TTX to block action potential-dependent glutamate release inhibited the excitatory action of ET-1 in OT neurons. There were no changes in quantal amplitude in either MNC type, suggesting that the effects of ET-1 were via presynaptic mechanisms. A gliotransmitter does not appear to be involved as ET-1 failed to elevate astrocytic calcium in the SON. Our results demonstrate that ET-1 differentially modulates glutamate release onto VP- versus OT-containing MNCs, thus implicating it in the selective regulation of neuroendocrine output from the SON.
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130
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Di Marzo V, Piscitelli F, Mechoulam R. Cannabinoids and endocannabinoids in metabolic disorders with focus on diabetes. Handb Exp Pharmacol 2011:75-104. [PMID: 21484568 DOI: 10.1007/978-3-642-17214-4_4] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The cannabinoid receptors for Δ(9)-THC, and particularly, the CB(1) receptor, as well as its endogenous ligands, the endocannabinoids anandamide and 2-arachidonoylglycerol, are deeply involved in all aspects of the control of energy balance in mammals. While initially it was believed that this endocannabinoid signaling system would only facilitate energy intake, we now know that perhaps even more important functions of endocannabinoids and CB(1) receptors in this context are to enhance energy storage into the adipose tissue and reduce energy expenditure by influencing both lipid and glucose metabolism. Although normally well controlled by hormones and neuropeptides, both central and peripheral aspects of endocannabinoid regulation of energy balance can become dysregulated and contribute to obesity, dyslipidemia, and type 2 diabetes, thus raising the possibility that CB(1) antagonists might be used for the treatment of these metabolic disorders. On the other hand, evidence is emerging that some nonpsychotropic plant cannabinoids, such as cannabidiol, can be employed to retard β-cell damage in type 1 diabetes. These novel aspects of endocannabinoid research are reviewed in this chapter, with emphasis on the biological effects of plant cannabinoids and endocannabinoid receptor antagonists in diabetes.
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Affiliation(s)
- Vincenzo Di Marzo
- Endocannabinoid Research Group, Institute of Biomolecular Chemistry, National Research Council, Via Campi Flegrei 34 Comprensorio Olivetti, 80078, Pozzuoli, NA, Italy
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131
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Functional interactions between stress and the endocannabinoid system: from synaptic signaling to behavioral output. J Neurosci 2010; 30:14980-6. [PMID: 21068301 DOI: 10.1523/jneurosci.4283-10.2010] [Citation(s) in RCA: 175] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Endocannabinoid signaling is distributed throughout the brain, regulating synaptic release of both excitatory and inhibitory neurotransmitters. The presence of endocannabinoid signaling within stress-sensitive nuclei of the hypothalamus, as well as upstream limbic structures such as the amygdala, suggests it may play an important role in regulating the neuroendocrine and behavioral effects of stress. The evidence reviewed here demonstrates that endocannabinoid signaling is involved in both activating and terminating the hypothalamic-pituitary-adrenal axis response to both acute and repeated stress. In addition to neuroendocrine function, however, endocannabinoid signaling is also recruited by stress and glucocorticoid hormones to modulate cognitive and emotional processes such as memory consolidation and extinction. Collectively, these data demonstrate the importance of endocannabinoid signaling at multiple levels as both a regulator and an effector of the stress response.
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132
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Abstract
Since the first endocannabinoid anandamide was identified in 1992, extensive research has been conducted to characterize the elements of the tightly controlled endocannabinoid signaling system. While it was established that the activity of endocannabinoids are terminated by a two-step process that includes cellular uptake and degradation, there is still a continuing debate about the mechanistic role of these processes in inactivating anandamide signals.
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133
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Hill MN, Karatsoreos IN, Hillard CJ, McEwen BS. Rapid elevations in limbic endocannabinoid content by glucocorticoid hormones in vivo. Psychoneuroendocrinology 2010; 35:1333-8. [PMID: 20399021 PMCID: PMC2914801 DOI: 10.1016/j.psyneuen.2010.03.005] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2009] [Revised: 03/05/2010] [Accepted: 03/15/2010] [Indexed: 01/13/2023]
Abstract
Functional interactions between glucocorticoids and the endocannabinoid system have been repeatedly documented; yet, to date, no studies have demonstrated in vivo that glucocorticoid hormones regulate endocannabinoid signaling. We demonstrate that systemic administration of the glucocorticoid corticosterone (3 and 10 mg/kg) resulted in an increase in the tissue content of the endocannabinoid N-arachidonylethanolamine (AEA) within several limbic structures (amygdala, hippocampus, hypothalamus), but not the prefrontal cortex, of male rats. Tissue AEA content was increased at 10min and returned to control 1h post-corticosterone administration. The other primary endocannabinoid, 2-arachidonoylglycerol, was found to be elevated by corticosterone exclusively within the hypothalamus. The rapidity of the change suggests that glucocorticoids act through a non-genomic pathway. Tissue contents of two other N-acylethanolamines, palmitoylethanolamide and oleolyethanolamide, were not affected by corticosterone treatment, suggesting that the mechanism of regulation is neither fatty acid amide nor N-acylphosphatidylethanolamine phospholipase D. These data provide in vivo support for non-genomic steroid effects in mammals and suggest that AEA is a mediator of these effects.
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Affiliation(s)
- Matthew N. Hill
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY USA
| | - Ilia N. Karatsoreos
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY USA
| | - Cecilia J. Hillard
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI USA
| | - Bruce S. McEwen
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY USA
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134
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Evanson NK, Tasker JG, Hill MN, Hillard CJ, Herman JP. Fast feedback inhibition of the HPA axis by glucocorticoids is mediated by endocannabinoid signaling. Endocrinology 2010; 151:4811-9. [PMID: 20702575 PMCID: PMC2946139 DOI: 10.1210/en.2010-0285] [Citation(s) in RCA: 218] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Glucocorticoid hormones are secreted in response to stimuli that activate the hypothalamo-pituitary-adrenocortical (HPA) axis and self-regulate through negative feedback. Negative feedback that occurs on a rapid time scale is thought to act through nongenomic mechanisms. In these studies, we investigated fast feedback inhibition of HPA axis stress responses by direct glucocorticoid action at the paraventricular nucleus of the hypothalamus (PVN). Local infusion of dexamethasone or a membrane-impermeant dexamethasone-BSA conjugate into the PVN rapidly inhibits restraint-induced ACTH and corticosterone release in a manner consistent with feedback actions at the cell membrane. The dexamethasone fast feedback response is blocked by the cannabinoid CB1 receptor antagonist AM-251, suggesting that fast feedback requires local release of endocannabinoids. Hypothalamic tissue content of the endocannabinoid 2-arachidonoyl glycerol is elevated by restraint stress, consistent with endocannabinoid action on feedback processes. These data support the hypothesis that glucocorticoid-induced fast feedback inhibition of the HPA axis is mediated by a nongenomic signaling mechanism that involves endocannabinoid signaling at the level of the PVN.
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Affiliation(s)
- Nathan K Evanson
- Department of Psychiatry, University of Cincinnati, GRI E205 (ML: 0506), 2170 E Galbraith Road, Cincinnati, Ohio 45237, USA.
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135
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Endocannabinoid-mediated modulation of stress responses: Physiological and pathophysiological significance. Immunobiology 2010; 215:629-46. [DOI: 10.1016/j.imbio.2009.05.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 05/30/2009] [Accepted: 05/30/2009] [Indexed: 12/18/2022]
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136
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Maccarrone M, Gasperi V, Catani MV, Diep TA, Dainese E, Hansen HS, Avigliano L. The Endocannabinoid System and Its Relevance for Nutrition. Annu Rev Nutr 2010; 30:423-40. [DOI: 10.1146/annurev.nutr.012809.104701] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Mauro Maccarrone
- Department of Biomedical Sciences, University of Teramo, Teramo, Italy; ,
- European Center for Brain Research (CERC)/Santa Lucia Foundation, Rome, Italy
| | - Valeria Gasperi
- Department of Experimental Medicine and Biochemical Sciences, University of Rome, Tor Vergata, Rome, Italy; , ,
| | - Maria Valeria Catani
- Department of Experimental Medicine and Biochemical Sciences, University of Rome, Tor Vergata, Rome, Italy; , ,
| | - Thi Ai Diep
- Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark; ,
| | - Enrico Dainese
- Department of Biomedical Sciences, University of Teramo, Teramo, Italy; ,
| | - Harald S. Hansen
- Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark; ,
| | - Luciana Avigliano
- Department of Experimental Medicine and Biochemical Sciences, University of Rome, Tor Vergata, Rome, Italy; , ,
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137
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Roelfsema F, Kok P, Pereira AM, Pijl H. Cortisol production rate is similarly elevated in obese women with or without the polycystic ovary syndrome. J Clin Endocrinol Metab 2010; 95:3318-24. [PMID: 20410226 DOI: 10.1210/jc.2009-2701] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT The pituitary-adrenal axis in obesity and polycystic ovary syndrome (PCOS) is marked by increased urinary excretion of cortisol and its metabolites. It is not as yet clear whether the increased cortisol production in PCOS is related to obesity per se. INTERVENTION AND METHODS We investigated 15 obese PCOS women with a body mass index of 30-54 kg/m(2) and 15 healthy obese controls (body mass index 31-60 kg/m(2)) with a regular menstrual cycle. Patients and control women underwent 24-h blood sampling at 20-min intervals. Cortisol concentrations were measured with a sensitive assay. Data were analyzed with a new deconvolution program, approximate entropy, and cosinor regression. OUTCOME Basal, pulsatile, and total cortisol production expressed per liter distribution volume, per square meter body surface, and as absolute amount per 24 h was similar in PCOS patients and matched healthy control women. In addition, the regularity of cortisol secretion and the diurnal properties were identical. Compared with 10 lean control women, mean cortisol production per liter distribution volume was similar in the three groups, but the total 24-h cortisol production was increased in obese control women and PCOS women. CONCLUSION This study demonstrates equally increased cortisol production in PCOS women and obese healthy control women.
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Affiliation(s)
- Ferdinand Roelfsema
- Leiden University Medical Center, Department of Endocrinology and Metabolic Diseases, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
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138
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Hill MN, McEwen BS. Involvement of the endocannabinoid system in the neurobehavioural effects of stress and glucocorticoids. Prog Neuropsychopharmacol Biol Psychiatry 2010; 34:791-7. [PMID: 19903506 PMCID: PMC2945244 DOI: 10.1016/j.pnpbp.2009.11.001] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 10/29/2009] [Accepted: 11/03/2009] [Indexed: 11/16/2022]
Abstract
The endocannabinoid system is a neuroactive lipid signaling system that functions to gate synaptic transmitter release. Accumulating evidence has demonstrated that this system is responsive to modulation by both stress and glucocorticoids within the hypothalamus and limbic structures; however, the nature of this regulation is more complex than initially assumed. The aim of the current review is to summarize the research to date which examines the effects of acute stress and glucocorticoid administration on endocannabinoid signaling in limbic-hypothalamic-pituitary-adrenal (LHPA) axis, and in turn the role endocannabinoid signaling plays in the neurobehavioural responses to acute stress and glucocorticoid administration. The majority of research suggests that acute stress produces a mobilization of the endocannabinoid 2-arachidonoylglycerol (2-AG) while concurrently reducing the tissue content of the other endocannabinoid ligand anandamide. Genetic and pharmacological studies demonstrate that the reduction in anandamide signaling may be involved in the initiation of HPA axis activation and the generation of changes in emotional behaviour, while the increase in 2-AG signaling may be involved in terminating the stress response, limiting neuronal activation and contributing to changes in motivated behaviours. Collectively, these studies reveal a complex interplay between endocannabinoids and the HPA axis, and further identify endocannabinoid signaling as a critical regulator of the stress response.
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Affiliation(s)
- Matthew N Hill
- Laboratory of Neuroendocrinology, Rockefeller University, New York, NY 10065, USA.
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139
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Hill MN, Titterness AK, Morrish AC, Carrier EJ, Lee TTY, Gil-Mohapel J, Gorzalka BB, Hillard CJ, Christie BR. Endogenous cannabinoid signaling is required for voluntary exercise-induced enhancement of progenitor cell proliferation in the hippocampus. Hippocampus 2010; 20:513-23. [PMID: 19489006 DOI: 10.1002/hipo.20647] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Voluntary exercise and endogenous cannabinoid activity have independently been shown to regulate hippocampal plasticity. The aim of the current study was to determine whether the endocannabinoid system is regulated by voluntary exercise and if these changes contribute to exercise-induced enhancement of cell proliferation. In Experiment 1, 8 days of free access to a running wheel increased the agonist binding site density of the cannabinoid CB(1) receptor; CB(1) receptor-mediated GTPgammaS binding; and the tissue content of the endocannabinoid anandamide in the hippocampus but not in the prefrontal cortex. In Experiment 2, the CB(1) receptor antagonist AM251 (1 mg kg(-1)) was administered daily to animals given free access to a running wheel for 8 days, after which cell proliferation in the hippocampus was examined through immunohistochemical analysis of the cell cycle protein Ki-67. Voluntary exercise increased proliferation of progenitor cells, as evidenced by the increase in the number of Ki-67 positive cells in the granule cell layer of the dentate gyrus (DG) in the hippocampus. However, this effect was abrogated by concurrent treatment with AM251, indicating that the increase in endocannabinoid signaling in the hippocampus is required for the exercise-induced increase in cell proliferation. These data demonstrate that the endocannabinoid system in the hippocampus is sensitive to environmental change and suggest that it is a mediator of experience-induced plasticity.
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Affiliation(s)
- Matthew N Hill
- Department of Psychology, University of British Columbia, Vancouver, B.C., Canada.
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140
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André A, Gonthier MP. The endocannabinoid system: its roles in energy balance and potential as a target for obesity treatment. Int J Biochem Cell Biol 2010; 42:1788-801. [PMID: 20541029 DOI: 10.1016/j.biocel.2010.06.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 05/28/2010] [Accepted: 06/02/2010] [Indexed: 01/28/2023]
Abstract
Obesity and cardiometabolic risk continue to be major public health concerns. A better understanding of the physiopathological mechanisms leading to obesity may help to identify novel therapeutic targets. The endocannabinoid system discovered in the early 1990s is believed to influence body weight regulation and cardiometabolic risk factors. This article aims to review the literature on the endocannabinoid system including the biological roles of its major components, namely, the cannabinoid receptors, their endogenous ligands the endocannabinoids and the ligand-metabolising enzymes. The review also discusses evidence that the endocannabinoid system constitutes a new physiological pathway occurring in the central nervous system and peripheral tissues that has a key role in the control of food intake and energy expenditure, insulin sensitivity, as well as glucose and lipid metabolism. Based on the important finding that there is a close association between obesity and the hyperactivity of the endocannabinoid system, interest in blocking stimulation of this pathway to aid weight loss and reduce cardiometabolic risk factor development has become an important area of research. Among the pharmacological strategies proposed, the antagonism of the cannabinoid receptors has been particularly investigated and several clinical trials have been conducted. One challenging pharmacological task will be to target the endocannabinoid system in a more selective, and hence, safe way. As the management of obesity also requires lifestyle modifications in terms of healthy eating and physical activity, the targeting of the endocannabinoid system may represent a novel approach for a multifactorial therapeutic strategy.
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Affiliation(s)
- Aurore André
- Groupe d'Etude sur l'Inflammation Chronique et l'Obésité, Laboratoire de Biochimie et Génétique Moléculaire, Université de La Réunion, La Réunion, France
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141
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D'Asti E, Long H, Tremblay-Mercier J, Grajzer M, Cunnane SC, Di Marzo V, Walker CD. Maternal dietary fat determines metabolic profile and the magnitude of endocannabinoid inhibition of the stress response in neonatal rat offspring. Endocrinology 2010; 151:1685-94. [PMID: 20160134 DOI: 10.1210/en.2009-1092] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Endocannabinoids (eCBs) are products of phospholipid (PL)-derived arachidonic acid (AA) that regulate hypothalamus-pituitary-adrenal axis activity. We hypothesized that differences in the quality and quantity of maternal dietary fat would modulate the PL AA content in the neonatal brain affecting stress responsiveness via differences in eCB production and activity in stress-activated brain areas. Pregnant rats were fed a 5% [control (C)] or 30% fat [high fat (HF)] diet rich in either n-6 (HF-n-6) or n-3 (HF-n-3) fat during the last week of gestation and lactation. Postnatal d 10 offspring were tested for metabolic hormones, AA (n-6) and eCB brain content, and hormonal effects of eCB receptor antagonism (AM251, 1 or 3 mg/kg ip) on stress responses. Like maternal diet, milk from HF-n-3 mothers had a reduced n-6/n-3 fat ratio compared with that of C and HF-n-6 mothers. Hypothalamic and hippocampal levels of PL AA were diet specific, reflecting the maternal milk and dietary n-6/n-3 ratio, with HF-n-3 offspring displaying reduced AA content relative to C and HF-n-6 offspring. Plasma corticosterone and insulin were elevated in HF-fed pups, whereas leptin was increased only in HF-n-6 pups. Basal eCB concentrations were also diet and brain region specific. In C pups, eCB receptor antagonist pretreatment increased stress-induced ACTH secretion, but not in the HF groups. Stress-induced corticosterone secretion was not sensitive to AM251 treatment in HF-n-3 pups. Thus, the nature of preweaning dietary fat differentially influences neonatal metabolic hormones, brain PL AA levels, and eCB, with functional consequences on hypothalamus-pituitary-adrenal axis modulation in developing rat pups.
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Affiliation(s)
- Esterina D'Asti
- Douglas Mental Health University Institute, McGill University, 6875 LaSalle Boulevard, Verdun, Quebec, Canada H4H 1R3
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142
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Veldhuis JD, Bowers CY. Integrating GHS into the Ghrelin System. INTERNATIONAL JOURNAL OF PEPTIDES 2010; 2010:879503. [PMID: 20798846 PMCID: PMC2925380 DOI: 10.1155/2010/879503] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 12/30/2009] [Indexed: 12/21/2022]
Abstract
Oligopeptide derivatives of metenkephalin were found to stimulate growth-hormone (GH) release directly by pituitary somatotrope cells in vitro in 1977. Members of this class of peptides and nonpeptidyl mimetics are referred to as GH secretagogues (GHSs). A specific guanosine triphosphatate-binding protein-associated heptahelical transmembrane receptor for GHS was cloned in 1996. An endogenous ligand for the GHS receptor, acylghrelin, was identified in 1999. Expression of ghrelin and homonymous receptor occurs in the brain, pituitary gland, stomach, endothelium/vascular smooth muscle, pancreas, placenta, intestine, heart, bone, and other tissues. Principal actions of this peptidergic system include stimulation of GH release via combined hypothalamopituitary mechanisms, orexigenesis (appetitive enhancement), insulinostasis (inhibition of insulin secretion), cardiovascular effects (decreased mean arterial pressure and vasodilation), stimulation of gastric motility and acid secretion, adipogenesis with repression of fat oxidation, and antiapoptosis (antagonism of endothelial, neuronal, and cardiomyocyte death). The array of known and proposed interactions of ghrelin with key metabolic signals makes ghrelin and its receptor prime targets for drug development.
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Affiliation(s)
- Johannes D. Veldhuis
- Department of Medicine, Endocrine Research Unit, Mayo School of Graduate Medical Education, Clinical Translational Science Center, Mayo Clinic, Rochester, MN 55905, USA
| | - Cyril Y. Bowers
- Division of Endocrinology, Department of Internal Medicine, Tulane University Health Sciences Center, New Orleans, LA 70112, USA
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143
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Izzo AA, Piscitelli F, Capasso R, Marini P, Cristino L, Petrosino S, Di Marzo V. Basal and fasting/refeeding-regulated tissue levels of endogenous PPAR-alpha ligands in Zucker rats. Obesity (Silver Spring) 2010; 18:55-62. [PMID: 19521349 DOI: 10.1038/oby.2009.186] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
N-oleoylethanolamine (OEA) and N-palmitoylethanolamine (PEA) are endogenous lipids that activate peroxisome proliferator-activated receptor-alpha with high and intermediate potency, and exert anorectic and anti-inflammatory actions in rats, respectively. We investigated OEA and PEA tissue level regulation by the nutritional status in lean and obese rats. OEA and PEA levels in the brainstem, duodenum, liver, pancreas, and visceral (VAT) or subcutaneous (SAT) adipose tissues of 7-week-old wild-type (WT) and Zucker rats, fed ad libitum or following overnight food deprivation, with and without refeeding, were measured by liquid chromatography-mass spectrometry. In WT rats, duodenal OEA, but not PEA, levels were reduced by food deprivation and restored by refeeding, whereas the opposite was observed for OEA in the pancreas, and for both mediators in the liver and SAT. In ad lib fed Zucker rats, PEA and OEA levels were up to tenfold higher in the duodenum, slightly higher in the brainstem, and lower in the other tissues. Fasting/refeeding-induced changes in OEA levels were maintained in the duodenum, liver, and SAT, and lost in the pancreas, whereas fasting upregulated this compound also in the VAT. The observed changes in OEA levels in WT rats are relevant to the actions of this mediator on satiety, hepatic and adipocyte metabolism, and insulin release. OEA dysregulation in Zucker rats might counteract hyperphagia in the duodenum, but contribute to hyperinsulinemia in the pancreas, and to fat accumulation in adipose tissues and liver. Changes in PEA levels might be relevant to the inflammatory state of Zucker rats.
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Affiliation(s)
- Angelo A Izzo
- Department of Experimental Pharmacology, University of Naples Federico II, Naples, Italy
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144
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Grossmann C, Gekle M. New aspects of rapid aldosterone signaling. Mol Cell Endocrinol 2009; 308:53-62. [PMID: 19549592 DOI: 10.1016/j.mce.2009.02.005] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 01/22/2009] [Accepted: 02/17/2009] [Indexed: 12/20/2022]
Abstract
Aldosterone, the endogenous ligand of the mineralocorticoid receptor (MR) in humans, is a steroid hormone that regulates salt and water homeostasis. Recently, additional pathophysiological effects in the renocardiovascular system have been identified. Besides genomic effects mediated by activated MR, rapid aldosterone actions that are independent of translation and transcription have been documented. While these nongenomic actions influence electrolyte homeostasis, pH and cell volume in classical MR target organs, they also participate in pathophysiological effects in the renocardiovascular system causing endothelial dysfunction, inflammation and remodeling. The mechanisms conveying these rapid effects consist of a multitude of signaling molecules and include a cross-talk with genomic aldosterone effects as well as with angiotensin II and epidermal growth factor receptor signaling. Rapid corticosteroid signaling via the MR has also been demonstrated in the brain. Altogether, the function of nongenomic aldosterone effects seems to be to modulate other signaling cascades, depending on the surrounding milieu.
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Affiliation(s)
- C Grossmann
- Julius-Bernstein-Institut für Physiologie, Universität Halle-Wittenberg, Halle/Saale, Germany.
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145
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Kellert BA, Nguyen MC, Nguyen C, Nguyen QH, Wagner EJ. Estrogen rapidly attenuates cannabinoid-induced changes in energy homeostasis. Eur J Pharmacol 2009; 622:15-24. [PMID: 19758570 DOI: 10.1016/j.ejphar.2009.09.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 08/28/2009] [Accepted: 09/08/2009] [Indexed: 12/31/2022]
Abstract
We examined whether estrogen negatively modulates cannabinoid-induced regulation of food intake, core body temperature and neurotransmission at proopiomelanocortin (POMC) synapses. Food intake was evaluated in ovariectomized female guinea pigs abdominally implanted with thermal DataLoggers and treated s.c. with the cannabinoid CB(1)/CB(2) receptor agonist WIN 55,212-2, the CB(1) receptor antagonist AM251 or their cremephor/ethanol/0.9% saline vehicle, and with estradiol benzoate (EB) or its sesame oil vehicle. Whole-cell patch clamp recordings were performed in slices through the arcuate nucleus. WIN 55,212-2 produced dose- and time-dependent increases in food intake. EB decreased food intake 8-24h after administration, but rapidly and completely blocked the increase in consumption caused by WIN 55,212-2. EB also attenuated the WIN 55,212-2-induced decrease in core body temperature. The AM251-induced decrease in food intake was unaffected. The diminution of the WIN 55,212-2-induced increase in food intake caused by EB correlated with a marked attenuation of cannabinoid receptor-mediated decreases in glutamatergic miniature excitatory postsynaptic current frequency occurring within 10-15min of steroid application. Furthermore, EB completely blocked the depolarizing shift in the inactivation curve for the A-type K(+) current caused by WIN 55,212-2. The EB-mediated, physiologic antagonism of these presynaptic and postsynaptic actions elicited upon cannabinoid receptor activation was observed in arcuate neurons immunopositive for phenotypic markers of POMC neurons. These data reveal that estrogens negatively modulate cannabinoid-induced changes in appetite, body temperature and POMC neuronal activity. They also impart insight into the neuroanatomical substrates and effector systems upon which these counter-regulatory factors converge in the control of energy homeostasis.
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Affiliation(s)
- Brian A Kellert
- Department of Basic Medical Sciences, College of OsteopathicMedicine, Western University of Health Sciences, 309 E. Second Street, Pomona, CA 91766, USA
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146
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Prager EM, Johnson LR. Stress at the synapse: signal transduction mechanisms of adrenal steroids at neuronal membranes. Sci Signal 2009; 2:re5. [PMID: 19724063 DOI: 10.1126/scisignal.286re5] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
As the key neuron-to-neuron interface, the synapse is involved in learning and memory, including traumatic memories during times of stress. However, the signal transduction mechanisms by which stress mediates its lasting effects on synapse transmission and on memory are not fully understood. A key component of the stress response is the increased secretion of adrenal steroids. Adrenal steroids (e.g., cortisol) bind to genomic mineralocorticoid and glucocorticoid receptors (gMRs and gGRs) in the cytosol. In addition, they may act through membrane receptors (mMRs and mGRs), and signal transduction through these receptors may allow for rapid modulation of synaptic transmission as well as modulation of membrane ion currents. mMRs increase synaptic and neuronal excitability; mechanisms include the facilitation of glutamate release through extracellular signal-regulated kinase signal transduction. In contrast, mGRs decrease synaptic and neuronal excitability by reducing calcium currents through N-methyl-D-aspartate receptors and voltage-gated calcium channels by way of protein kinase A- and G protein-dependent mechanisms. This body of functional data complements anatomical evidence localizing GRs to the postsynaptic membrane. Finally, accumulating data also suggest the possibility that mMRs and mGRs may show an inverted U-shaped dose response, whereby glutamatergic synaptic transmission is increased by low doses of corticosterone acting at mMRs and decreased by higher doses acting at mGRs. Thus, synaptic transmission is regulated by mMRs and mGRs, and part of the stress signaling response is a direct and bidirectional modulation of the synapse itself by adrenal steroids.
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Affiliation(s)
- Eric M Prager
- Center for the Study of Traumatic Stress, Department of Psychiatry and Program in Neuroscience, Uniformed Services University, Bethesda, MD 20814, USA
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147
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Roelfsema F, Kok P, Frolich M, Pereira AM, Pijl H. Disordered and increased adrenocorticotropin secretion with diminished adrenocorticotropin potency in obese in premenopausal women. J Clin Endocrinol Metab 2009; 94:2991-7. [PMID: 19454578 DOI: 10.1210/jc.2009-0350] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT The pituitary-adrenal ensemble of obese humans is marked by increased urinary excretion of cortisol and its metabolites in the face of normal circulating cortisol levels. For better understanding of the (patho) physiological meaning of these changes, the mechanistic underpinnings need to be clarified. INTERVENTION AND METHODS We investigated 17 obese women [body mass index (BMI) 30-39.4 kg/m(2)] and 14 normal women (BMI, 18.3-24.8 kg/m(2)) who underwent 24-h blood sampling at 10-min intervals, and plasma ACTH and cortisol concentrations were measured with sensitive assays. Data were analyzed with a new deconvolution program, approximate entropy (ApEn) analyses, and cosinor regression. OUTCOME ACTH and cortisol production rates were higher in obese women than in controls and correlated with BMI. Secretion of ACTH correlated with leptin (R = 0.63; P = 0.0001) and insulin (R = 0.67; P = 0.0001). ACTH ApEn and forward ACTH-cortisol cross-ApEn were diminished in obese women. The half-maximal effective concentration (ED(50)) of ACTH pulses vs. cortisol pulses was higher in obese women (38.3 +/- 4.9 vs. 25.1 +/- 3.7 ng/liter; P = 0.03), indicating decreased potency of ACTH. The diurnal properties of ACTH and cortisol secretion were unchanged in obese females. CONCLUSION Obese women exhibit enhanced ACTH and cortisol 24-h production compared with lean controls. The amplified ACTH drive is accompanied by decreased secretory regularity and diminished forward coupling between ACTH and cortisol. In addition, the potency of ACTH is decreased in obesity.
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Affiliation(s)
- Ferdinand Roelfsema
- Department of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Albinusdreef 2, Leiden, The Netherlands.
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148
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Leptin "gates" thermogenic action of thyrotropin-releasing hormone in the hindbrain. Brain Res 2009; 1295:135-41. [PMID: 19643094 DOI: 10.1016/j.brainres.2009.07.063] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 07/16/2009] [Accepted: 07/18/2009] [Indexed: 12/19/2022]
Abstract
Leptin, acting as a measure of metabolic fuel availability, exerts a powerful permissive influence on neurogenic thermogenesis. During starvation and an absence of leptin, animals cannot produce thermogenic reactions to cold stress. However, thermogenesis is rescued by restoring leptin. We have previously observed (Hermann, G.E., Barnes, M.J., Rogers, R.C., 2006. Leptin and thyrotropin-releasing hormone: cooperative action in the hindbrain to activate brown adipose thermogenesis. Brain Res. 1117, 118-124.) a highly cooperative interaction between leptin and thyrotropin-releasing hormone [TRH] to activate hindbrain generated thermogenic responses. Specifically, exposure to both leptin and TRH elicited a 3.5 degrees C increase in brown adipose tissue [BAT] thermogenesis, while leptin alone did not evoke any change, and TRH alone caused only approximately 1 degrees C increase. The present study shows that the leptin-TRH synergy in controlling brown adipose [BAT] thermogenesis is order-specific and dependent on the feeding status of the animal. That is, fourth ventricular [4V] application of leptin to the food-deprived animal, before TRH injection, yields a substantial increase in BAT; while the reverse order yields a significantly smaller effect. If the animal were fed within minutes of anesthesia, then exogenous leptin was not necessary for TRH to yield a large increase in BAT temperature. The leptin-TRH synergy was uncoupled by pretreatment with the phosphoinositol-tris phosphate kinase [PI3K] inhibitor, wortmannin and the Src-SH2 antagonist, PP2. The TRH transduction mechanism utilizes phospholipase C [PLC] potently regulated by the SH2 site. Previous work in culture systems suggests that the product of PI3K activity [PIP3] potently upregulates PLC by activating the SH2 domain of the PLC complex. Perhaps leptin "gates" the thermogenic action of TRH in the hindbrain by invoking this same mechanism.
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149
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Kuzmiski JB, Pittman QJ, Bains JS. Metaplasticity of hypothalamic synapses following in vivo challenge. Neuron 2009; 62:839-49. [PMID: 19555652 DOI: 10.1016/j.neuron.2009.05.027] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 02/17/2009] [Accepted: 05/20/2009] [Indexed: 11/28/2022]
Abstract
Neural networks that regulate an organism's internal environment must sense perturbations, respond appropriately, and then reset. These adaptations should be reflected as changes in the efficacy of the synapses that drive the final output of these homeostatic networks. Here we show that hemorrhage, an in vivo challenge to fluid homeostasis, induces LTD at glutamate synapses onto hypothalamic magnocellular neurosecretory cells (MNCs). LTD requires the activation of postsynaptic alpha2-adrenoceptors and the production of endocannabinoids that act in a retrograde fashion to inhibit glutamate release. In addition, both hemorrhage and noradrenaline downregulate presynaptic group III mGluRs. This loss of mGluR function allows high-frequency activity to potentiate these synapses from their depressed state. These findings demonstrate that noradrenaline controls a form of metaplasticity that may underlie the resetting of homeostatic networks following a successful response to an acute physiological challenge.
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Affiliation(s)
- J Brent Kuzmiski
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N4N1, Canada
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Role of endocannabinoids and endovanilloids in Ca2+ signalling. Cell Calcium 2009; 45:611-24. [DOI: 10.1016/j.ceca.2009.03.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 03/03/2009] [Accepted: 03/11/2009] [Indexed: 12/14/2022]
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