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Khalifa AM, Watson-Siriboe A, Shukry SG, Chiu WL, Nelson ME, Geng Y, Fischer-Stenger K, Porter JH, Stewart JK. Thr136Ile polymorphism of human vesicular monoamine transporter-1 (SLC18A1 gene) influences its transport activity in vitro. Neural Plast. 2012;33:546-551. [PMID: 23213575 PMCID: PMC3504448 DOI: 10.1155/2012/945373] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 09/22/2012] [Accepted: 09/23/2012] [Indexed: 12/23/2022] Open
Abstract
The hippocampus has the extraordinary capacity to process and store information. Consequently, there is an intense interest in the mechanisms that underline learning and memory. Synaptic plasticity has been hypothesized to be the neuronal substrate for learning. Ca2+ and Ca2+-activated kinases control cellular processes of most forms of hippocampal synapse plasticity. In this paper, I aim to integrate our current understanding of Ca2+-mediated synaptic plasticity and metaplasticity in motivational and reward-related learning in the hippocampus. I will introduce two representative neuromodulators that are widely studied in reward-related learning (e.g., ghrelin and endocannabinoids) and show how they might contribute to hippocampal neuron activities and Ca2+-mediated signaling processes in synaptic plasticity. Additionally, I will discuss functional significance of these two systems and their signaling pathways for its relevance to maladaptive reward learning leading to addiction.
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Pulkkinen L, Ukkola O, Kolehmainen M, Uusitupa M. Ghrelin in diabetes and metabolic syndrome. Int J Pept. 2010;2010. [PMID: 20700400 PMCID: PMC2911592 DOI: 10.1155/2010/248948] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 02/09/2010] [Indexed: 02/07/2023]
Abstract
Metabolic syndrome is a cluster of related risk factors for cardiovascular disease, type 2 diabetes and liver disease. Obesity, which has become a global public health problem, is one of the major risk factors for development of metabolic syndrome and type 2 diabetes. Obesity is a complex disease, caused by the interplay between environmental and genetic factors. Ghrelin is one of the circulating peptides, which stimulates appetite and regulates energy balance, and thus is one of the candidate genes for obesity and T2DM. During the last years both basic research and genetic association studies have revealed association between the ghrelin gene and obesity, metabolic syndrome or type 2 diabetes.
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Tong J, Tschöp MH, Aulinger BA, Davis HW, Yang Q, Liu J, Gaylinn BD, Thorner MO, D'Alessio D, Tso P. The intestinal lymph fistula model--a novel approach to study ghrelin secretion. Am J Physiol Gastrointest Liver Physiol 2010; 298:G474-80. [PMID: 20044509 PMCID: PMC2838510 DOI: 10.1152/ajpgi.00367.2009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The orexigenic hormone ghrelin is secreted from the stomach and has been implicated in the regulation of energy and glucose homeostasis. We hypothesized that ghrelin, like other gastrointestinal (GI) hormones, is present in intestinal lymph, and sampling this compartment would provide advantages for studying ghrelin secretion in rodents. Blood and lymph were sampled from catheters in the jugular vein and mesenteric lymph duct before and after intraduodenal (ID) administration of isocaloric Ensure, dextrin, or Liposyn meals or an equal volume of saline in conscious Sprague-Dawley rats. Total ghrelin levels were measured using an established radioimmunoassay. Acyl and des-acyl ghrelin were measured using two-site ELISA. Fasting ghrelin levels in lymph were significantly higher than in plasma (means +/- SE: 3,307.9 +/- 272.9 vs. 2,127.1 +/- 115.0 pg/ml, P = 0.004). Postingestive acyl and des-acyl ghrelin levels were also significantly higher, whereas the ratio of acyl:des-acyl ghrelin was similar in lymph and plasma (0.91 +/- 0.28 vs. 1.20 +/- 0.36, P = 0.76). The principle enzymes responsible for deacylation of ghrelin were lower in lymph than in plasma. Following ID Ensure, maximum ghrelin suppression occurred at 2 h in lymph compared with at 1 h in plasma. The return of suppressed ghrelin levels to baseline was also delayed in lymph. Similarly, dextrin also induced significant suppression of ghrelin (two-way ANOVA: P = 0.02), whereas Liposyn did not (P = 0.32). On the basis of these findings, it appears that intestinal lymph, which includes drainage from the interstitium of the GI mucosa, is enriched in ghrelin. Despite reduced deacylating activity in lymph, there is not a disproportionate amount of acyl ghrelin in this pool. The postprandial dynamics of ghrelin are slower in lymph than plasma, but the magnitude of change is greater. Assessing ghrelin levels in the lymph may be advantageous for studying its secretion and concentrations in the gastric mucosa.
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Affiliation(s)
- Jenny Tong
- Departments of Medicine, University of Cincinnati, Ohio, 45267-0547, USA.
| | - Matthias H. Tschöp
- Departments of 1Medicine, Division of Endocrinology, Diabetes and Metabolism, and
| | - Benedikt A. Aulinger
- Departments of 1Medicine, Division of Endocrinology, Diabetes and Metabolism, and
| | - Harold W. Davis
- Departments of 1Medicine, Division of Endocrinology, Diabetes and Metabolism, and
| | - Qing Yang
- 2Pathology, University of Cincinnati, Cincinnati, Ohio;
| | - Jianhua Liu
- 3Department of Medicine, Division of Endocrinology and Metabolism, University of Virginia, Charlottesville, Virginia
| | - Bruce D. Gaylinn
- 3Department of Medicine, Division of Endocrinology and Metabolism, University of Virginia, Charlottesville, Virginia
| | - Michael O. Thorner
- 3Department of Medicine, Division of Endocrinology and Metabolism, University of Virginia, Charlottesville, Virginia
| | - David D'Alessio
- Departments of 1Medicine, Division of Endocrinology, Diabetes and Metabolism, and
| | - Patrick Tso
- 2Pathology, University of Cincinnati, Cincinnati, Ohio;
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