Self-selecting albino rats exhibit differential preferences for pure macronutrient diets: Characterization of three subpopulations

Shor‐Posner, Gail; Ian, Christopher; Brennan, Glen; Cohn, Tamara; Moy, Harvey; Ning, Autumn; Leibowitz, Sarah F.

doi:10.1016/0031-9384(91)90581-8

Cited by 90 publications

(38 citation statements)

References 23 publications

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“…In seeking to identify subtle disturbances in outbred strains before their exhibiting an obese pattern, investigators have taken advantage of the fact that subjects within these populations show considerable variability in their behavioral phenotype and propensity toward obesity. For example, in adult SpragueDawley rats on pure macronutrient or fat-rich diets, measures of weight gain, energy intake or fat preference are found to vary considerably in direct proportion to ultimate body fat accrual, [1][2][3][4][5] with the weight-gain measure providing the basis for selective breeding of rats prone vs resistant to obesity. 6,7 This variability has enabled investigators to identify measures in adult rats, at normal body weight, that can accurately and reproducibly differentiate distinct subgroups that are obesity-prone (OP) or obesity-resistant (OR).…”

Section: Introductionmentioning

confidence: 99%

Weight gain model in prepubertal rats: prediction and phenotyping of obesity-prone animals at normal body weight

et al. 2007

Int J Obes

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Objective: Male Sprague-Dawley rats maintained from birth on a high-fat diet were examined to determine whether a specific measure before puberty can identify and allow one to characterize prepubertal rats at normal weight with high vs low risk for adult obesity. Materials and methods: Measures from weaning (day 21) to around puberty (day 45) were taken of weight gain, absolute body weight and daily energy intake on a high-fat diet and related to the amount of body fat accumulated at maturity (80-100 days of age). Rats identified by a specific prepubertal measure as obesity-prone (OP) vs obesity-resistant (OR) were then characterized before and after puberty. Results: Prepubertal weight gain from days 30 to 35 of age was the strongest and earliest positive correlate of ultimate body fat accrual in adult rats. The highest (8-10 g/day) compared to lowest (5-7 g/day) weight-gain scores identified accurately and reproducibly distinct OP and OR subgroups at day 35 that became obese or remained lean, respectively, as adults. The OP rats with rapid prepubertal weight gain and 50% greater adiposity at maturity (day 100) exhibited the expected phenotype of already-obese rats. These included elevated levels of leptin, insulin, triglycerides and glucose, increased galanin (GAL) peptide levels in the paraventricular nucleus (PVN) and reduced neuropeptide Y (NPY) levels in the arcuate nucleus (ARC). Before puberty (day 35), the OP rats with normal fat pad weights, energy intake and endocrine profile similar to OR rats exhibited these disturbances characteristic of obese rats. They had decreased capacity for fat oxidation in muscle, increased GAL expression in PVN and reduced expression of NPY and agouti-related protein in ARC. Conclusion: Prepubertal weight gain can identify OP rats on day 35 when they have minimal body fat but exhibit specific metabolic and neurochemical disturbances expected to promote obesity and characteristics of already-obese adult rats.

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Section: Introductionmentioning

confidence: 99%

Weight gain model in prepubertal rats: prediction and phenotyping of obesity-prone animals at normal body weight

et al. 2007

Int J Obes

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“…It has been reported that baseline macronutrient preferences are an important consideration in studies examining the effects of pharmacological or physiological treatments on macronutrient selection (3,13,24,25). The present study was designed to qualify the neuromodulatory effects of GAL and 5 -HT on macronutrient intake in self-selecting rats with macronutrient preferences.…”

Section: Discussionmentioning

confidence: 99%

“…It has been shown that animals' baseline macronutrient preferences can significantly affect macronutrient selection in response to various feeding stimuli, thus these preferences may confound results unless accounted for through experimental design or statistical controls (9)(10)(11)(12)(13). The aim of this investigation was to elucidate the relationship between GAL and 5 -HT in the regulation of post-fast macronutrient self-selection in carbohydrate-and fat-preferring rats.…”

Section: Introductionmentioning

confidence: 99%

Serotonergic regulation of galanin-induced selective macronutrient intake in self-selecting rats

Tanaka

Kido

2008

J. Med. Invest.

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: We investigated macronutrient intake after intraventricular injection of galanin (GAL, 3 nmol/5 μl/rat) and/or serotonin (5-HT, 50 nmol/5 μl/rat) in self-selecting fasted rats with preferences for either carbohydrates or fats. GAL injection significantly increased carbohydrate and total intake in all rats irrespective of macronutrient preference, whereas 5-HT alone did not affect macronutrient intake. The GAL-induced increase in total intake decreased to the level of saline controls when GAL was coinjected with 5-HT. The ratio of kilocalories of carbohydrates, fats and proteins (macronutrient energy ratio) after injections of GAL and/or 5-HT was similar to the saline control. In carbohydrate-preferring rats, GAL increased carbohydrate, protein and fat intake as well as total intake. Coinjection of GAL and 5-HT tended to decrease carbohydrate intake, but increase protein and fat intake. The macronutrient energy ratio after injection of GAL did not change, but the carbohydrate energy ratio decreased after 5-HT was injected, with or without GAL. In contrast, in fat-preferring rats, GAL significantly increased carbohydrate intake. Injection of 5-HT with or without GAL did not change total macronutrient intake. The macronutrient energy ratio did not change after GAL injection with or without 5-HT. These differences suggest that macronutrient preferences should be considered in any macronutrient intake study, and that serotonergic neurons play a part in the regulation of GAL-induced macronutrient intake.

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“…Diurnal Rhythms -In relation to the lighddark cycle, for example, there exists a diurnal rhythm of nutrient intake and metabolism (93,128,156,157,175). Subsequentto aperiod of little eating resulting in low carbohydrate stores, the early hours of the feeding cycle are characterized by a strong preference for carbohydrate; they are then followed by arise in fat consumption 3 to 4 hours later.…”

Section: Shifts In Brain Peptides Across Physiological States and Stagesmentioning

confidence: 99%

“…In support of this idea (175), endogenous NPY, in associationwith CORT, is released inthe PVN inresponse to a physiological state of low carbohydrate stores (5,7 1,SS). Thismay occurjustpriorto anaturalcarbohydratemeal atthe beginning of the feeding cycle (156,157). However, this pattern may similarly develop before any meal that is preceded by an extended period of little food consumption (23,37 ,7 1,80,115,145,150,1 SS), by asignificantdeclineincirculatirig levels of glucose (38), and by pharmacological agents that produce hypoglycemia or block glucose utilization (11,19,81,82).…”

Section: Possible Physiological Functions Of Hypothalamic Peptidesmentioning

confidence: 99%

Brain Peptides and Obesity: Pharmacologic Treatment

Leibowitz

1995

Obesity Research

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104

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LEIBOWITZ, SARAH F. Brain peptides and obesity: pharmacologic treatment. ObesRes. 1995;3(Supp14):573S-5893. Obesity results from an imbalance between nutrient ingestion andmetabolism,withmore calories being ingested than utilized. Thebrain plays animportant roleincoordinating these complex behavioral and physiologicalfunctions, operating through multiple neurochemical systems with distinct properties. This review focuses on two hypothalamicpeptide systems, neuropeptide Y (NPY) and galanin (GAL), that illustrate how the brain operates through different mechanisms to control the body's nutrient stores, in different states o r conditions. These peptides have different behavioralandphysiologicaleffects andare,themselves,differentially responsive to feedback signals from circulating steroids,peptides,and nutrients. They canbedistinguishedby their relation to natural feeding patterns and endogenous hormones and by their specificity of action in relation to natural biological rhythms.Theneuroanatomicalsubstrates involved in these actionsaf NPY and GAL are also distinct. The neurocircuit mediating NPY's actions originates in the arcuatenucleus and terminates in the medial portion of the paraventricular nucleus; the GAGcontaining neurons, in contrast, are concentrated in the lateral portion of the paraventricular nucleus, in addition to the medial preoptic area, which contribute to 1ocalGALinnervation as wellas projections to the median eminence. Regarding their distinct functions, the evidence suggests that the NPY system is more closely related to patterns of carbohydrate ingestion andcarbohydrate utilization, channeling nutrients towards the synthesisoffat. Itismost strongly activatedatthestartoftheactive feeding cycle or afterweaning,in close association with the adrenal steroid,corticosterone. The GAL system,in contrast, is more closely associated with patterns of fat consumption and signals related to fat oxidation. This peptide systemis most active duringthemiddleof the feeding cycle or immediately afterpuberty,in close associationwith the gonadal steroids. The gene expression and synthesis of these peptides in their respective neuronal cell groups is inhibited by circulating insulin and altered by dietary nutriFrom the Rockefeller University, New York, NY

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Self-selecting albino rats exhibit differential preferences for pure macronutrient diets: Characterization of three subpopulations

Cited by 90 publications

References 23 publications

Weight gain model in prepubertal rats: prediction and phenotyping of obesity-prone animals at normal body weight

Weight gain model in prepubertal rats: prediction and phenotyping of obesity-prone animals at normal body weight

Serotonergic regulation of galanin-induced selective macronutrient intake in self-selecting rats

Brain Peptides and Obesity: Pharmacologic Treatment

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