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Harris RBS. Sucrose solution, but not liquid sucrose diet, leads to leptin resistance irrespective of the time of day that sucrose is available. Physiol Behav 2023; 258:114002. [PMID: 36273496 DOI: 10.1016/j.physbeh.2022.114002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/11/2022] [Accepted: 10/18/2022] [Indexed: 11/29/2022]
Abstract
Rats offered free access to sucrose solution in addition to a sucrose-free composite diet develop leptin resistance whereas those consuming a similar amount of sucrose from a dry diet remain leptin responsive. Here we tested whether rats consuming a complete high sucrose diet in liquid form also became leptin resistant. Female Sprague Dawley rats were offered a sucrose free diet (NS), a dry high sucrose diet (HS), NS diet plus 30% sucrose solution (LiqS), NS diet in liquid form (NSLiq) or HS diet in Liquid form (HSLiq). After 30 days LiqS rats were leptin resistant, but all other groups were leptin responsive even though HSLiq rats consumed as much sucrose as LiqS rats and NSLiq rats had the greatest amount of body fat. Therefore, development of leptin resistance is dependent upon the consumption of sucrose independent of any other nutrients. Because LiqS rats consume sucrose throughout the day and night we tested whether limiting sucrose solution access to either the light or dark period prevented development of leptin resistance. Leptin resistant LiqS rats were either given free access to sucrose, had access to sucrose only at night or had access only during the day. The intake of rats with limited access was supplemented to the level of those with free access by tube-feeding. The results of this study show that leptin resistance of LiqS rats is independent of when the sucrose is consumed and is unrelated to total energy intake, body fat mass or serum leptin concentration.
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Affiliation(s)
- Ruth B S Harris
- Department of Physiology, Medical College of Georgia at Augusta University, Natural Science Annex, Room 420, 29 Peachtree Center Ave NE, Atlanta, GA 30303, United States.
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Harris RBS. Consuming sucrose solution promotes leptin resistance and site specifically modifies hypothalamic leptin signaling in rats. Am J Physiol Regul Integr Comp Physiol 2020; 320:R182-R194. [PMID: 33206557 DOI: 10.1152/ajpregu.00238.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rats consuming 30% sucrose solution and a sucrose-free diet (LiqS) become leptin resistant, whereas rats consuming sucrose from a formulated diet (HS) remain leptin responsive. This study tested whether leptin resistance in LiqS rats extended beyond a failure to inhibit food intake and examined leptin responsiveness in the hypothalamus and hindbrain of rats offered HS, LiqS, or a sucrose-free diet (NS). Female LiqS Sprague-Dawley rats initially only partially compensated for the calories consumed as sucrose, but energy intake matched that of HS and NS rats when they were transferred to calorimetry cages. There was no effect of diet on energy expenditure, intrascapular brown fat tissue (IBAT) temperature, or fat pad weight. A peripheral injection of 2 mg of leptin/kg on day 23 or day 26 inhibited energy intake of HS and NS but not LiqS rats. Inhibition occurred earlier in HS rats than in NS rats and was associated with a smaller meal size. Leptin had no effect on energy expenditure but caused a transient rise in IBAT temperature of HS rats. Leptin increased the phosphorylation of signal transducer and activator of transcription 3 (pSTAT3) in the hindbrain and ventromedial hypothalamus of all rats. There was a minimal effect of leptin in the arcuate nucleus, and only the dorsomedial hypothalamus showed a correlation between pSTAT3 and leptin responsiveness. These data suggest that the primary response to leptin is inhibition of food intake and the pattern of sucrose consumption, rather than calories consumed as sucrose, causes leptin resistance associated with site-specific differences in hypothalamic leptin signaling.
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Affiliation(s)
- Ruth B S Harris
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia
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McCluskey LP, He L, Dong G, Harris R. Chronic exposure to liquid sucrose and dry sucrose diet have differential effects on peripheral taste responses in female rats. Appetite 2019; 145:104499. [PMID: 31669578 DOI: 10.1016/j.appet.2019.104499] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/18/2019] [Accepted: 10/22/2019] [Indexed: 11/29/2022]
Abstract
Sugar-sweetened beverages are the major source of added calories in the Western diet and their prevalence is associated with obesity and metabolic disruption. Despite the critical role of the taste system in determining food selection and consumption, the effects of chronic sucrose consumption on the peripheral taste system in mammals have received limited attention. We offered female Sprague Dawley rats free access to water and one of three diets for up to 40 days: (1) sucrose-free chow or "NS" diet; (2) a high-sucrose dry diet or "HS"; or (3) 30% sucrose solution and the NS diet, designated "LiqS" diet. Sucrose consumption by LiqS rats gradually increased and by day 14 was equal to that of HS rats. Food intake decreased in LiqS rats, but their energy intake remained higher than for NS or HS rats. There was no significant difference in weight gain of the groups during the study. Recordings from the chorda tympani nerve (CT), which innervates taste buds on the anterior tongue, revealed decreased responses to 1 M sucrose in both LiqS and HS rats and to acesulfame K and salt tastants in LiqS rats after 40 days on diet. Umami, bitter, and acid response magnitudes were unchanged in both groups. These results demonstrate that chronic sucrose exposure inhibits taste responses to higher concentrations of sweet stimuli. More surprisingly, CT responses to NaCl and 0.5M NaAc were significantly reduced in rats on the LiqS diet. Thus, the physical form of the diet influences taste responsiveness to salt and sweet taste function. These data suggest that taste buds are previously unappreciated targets of chronic sucrose consumption.
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Affiliation(s)
- Lynnette Phillips McCluskey
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, United States.
| | - Lianying He
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, United States; Department of Pathology and Laboratory Medicine, Medical University of South Carolina, United States
| | - Guankuo Dong
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, United States
| | - Ruth Harris
- Department of Physiology, Medical College of Georgia at Augusta University, United States
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Seamon M, Ahn W, Li AJ, Ritter S, Harris RBS. Leptin receptor-expressing neurons in ventromedial nucleus of the hypothalamus contribute to weight loss caused by fourth ventricle leptin infusions. Am J Physiol Endocrinol Metab 2019; 317:E586-E596. [PMID: 31361549 PMCID: PMC6842917 DOI: 10.1152/ajpendo.00205.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/11/2019] [Accepted: 07/22/2019] [Indexed: 12/24/2022]
Abstract
Leptin administration into the hindbrain, and specifically the nucleus of the solitary tract, increases phosphorylated signal transducer and activator of transcription 3 (pSTAT3), a marker of leptin receptor activation, in hypothalamic nuclei known to express leptin receptors. The ventromedial nucleus of the hypothalamus (VMH) shows the greatest response, with a threefold increase in pSTAT3. This experiment tested the importance of VMH leptin receptor-expressing neurons in mediating weight loss caused by fourth ventricle (4V) leptin infusion. Male Sprague-Dawley rats received bilateral VMH 75-nL injections of 260 ng/μL of leptin-conjugated saporin (Lep-Sap) or blank-saporin (Blk-Sap). After 23 days they were fitted with 4V infusion cannulas and 1 wk later adapted to housing in a calorimeter before they were infused with 0.9 μg leptin/day for 14 days. There was no effect of VMH Lep-Sap on weight gain or glucose clearance before leptin infusion. Leptin inhibited food intake and respiratory exchange ratio in Blk-Sap but not Lep-Sap rats. Leptin had no effect on energy expenditure or brown adipose tissue temperature of either group. Inguinal and epididymal fat were significantly reduced in leptin-treated Blk-Sap rats, but the response was greatly attenuated in Lep-Sap rats. VMH pSTAT3 was increased in leptin-treated Blk-Sap but not Lep-Sap rats. These results support the concept that leptin-induced weight loss results from an integrated response across different brain areas. They also support previous reports that VMH leptin receptors do not play a significant role in maintaining energy balance in basal conditions but limit weight gain during positive energy balance.
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Affiliation(s)
- Marissa Seamon
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia
| | - WonMo Ahn
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia
| | - Ai-Jun Li
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, Washington
| | - Sue Ritter
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, Washington
| | - Ruth B S Harris
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia
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Slomp M, Belegri E, Blancas‐Velazquez AS, Diepenbroek C, Eggels L, Gumbs MC, Joshi A, Koekkoek LL, Lamuadni K, Ugur M, Unmehopa UA, la Fleur SE, Mul JD. Stressing the importance of choice: Validity of a preclinical free-choice high-caloric diet paradigm to model behavioural, physiological and molecular adaptations during human diet-induced obesity and metabolic dysfunction. J Neuroendocrinol 2019; 31:e12718. [PMID: 30958590 PMCID: PMC6593820 DOI: 10.1111/jne.12718] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 03/06/2019] [Accepted: 03/28/2019] [Indexed: 12/23/2022]
Abstract
Humans have engineered a dietary environment that has driven the global prevalence of obesity and several other chronic metabolic diseases to pandemic levels. To prevent or treat obesity and associated comorbidities, it is crucial that we understand how our dietary environment, especially in combination with a sedentary lifestyle and/or daily-life stress, can dysregulate energy balance and promote the development of an obese state. Substantial mechanistic insight into the maladaptive adaptations underlying caloric overconsumption and excessive weight gain has been gained by analysing brains from rodents that were eating prefabricated nutritionally-complete pellets of high-fat diet (HFD). Although long-term consumption of HFDs induces chronic metabolic diseases, including obesity, they do not model several important characteristics of the modern-day human diet. For example, prefabricated HFDs ignore the (effects of) caloric consumption from a fluid source, do not appear to model the complex interplay in humans between stress and preference for palatable foods, and, importantly, lack any aspect of choice. Therefore, our laboratory uses an obesogenic free-choice high-fat high-sucrose (fc-HFHS) diet paradigm that provides rodents with the opportunity to choose from several diet components, varying in palatability, fluidity, texture, form and nutritive content. Here, we review recent advances in our understanding how the fc-HFHS diet disrupts peripheral metabolic processes and produces adaptations in brain circuitries that govern homeostatic and hedonic components of energy balance. Current insight suggests that the fc-HFHS diet has good construct and face validity to model human diet-induced chronic metabolic diseases, including obesity, because it combines the effects of food palatability and energy density with the stimulating effects of variety and choice. We also highlight how behavioural, physiological and molecular adaptations might differ from those induced by prefabricated HFDs that lack an element of choice. Finally, the advantages and disadvantages of using the fc-HFHS diet for preclinical studies are discussed.
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Affiliation(s)
- Margo Slomp
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Evita Belegri
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Aurea S. Blancas‐Velazquez
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Charlene Diepenbroek
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Leslie Eggels
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Myrtille C.R. Gumbs
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Anil Joshi
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Laura L. Koekkoek
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Khalid Lamuadni
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Muzeyyen Ugur
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Unga A. Unmehopa
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Susanne E. la Fleur
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
| | - Joram D. Mul
- Department of Endocrinology and Metabolism, Laboratory of EndocrinologyDepartment of Clinical ChemistryAmsterdam Neuroscience, Amsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
- Metabolism and Reward GroupNetherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and Sciences (KNAW)AmsterdamThe Netherlands
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