Hypothalamic galanin and plasma leptin and ghrelin in the maintenance of energy intake in the Brattleboro rat

Beck, Bernard; Max, Jean‐Pierre

doi:10.1016/j.bbrc.2007.09.092

Cited by 10 publications

(8 citation statements)

References 52 publications

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“…These results, which are new for GAL and consistent with a published study of OX after 6 weeks of diet access [30], suggest that these particular orexigenic peptides, which are enhanced by consumption of a high-fat compared to low-fat diet [3, 11], are similarly stimulated by ingestion of a HiSat compared to USat diet. With evidence that fat-preferring Brattleboro rats compared to control Long Evans rats exhibit higher GAL mRNA and lower GAL concentrations in the PVN [40, 41] and that injection of GAL antagonists into this brain area significantly decreases fat consumption [42], it is likely that the elevated GAL expression in the present experiment, particularly as it occurred after consumption of a single meal, may contribute to the initial hyperphagia produced by the HiSat diet. A similar conclusion regarding increased intake may be drawn for OX, which is thought to play a major role in seeking out rewarding substances in general [43].…”

Section: Discussionmentioning

confidence: 93%

Effect of dietary fatty acid composition on food intake, triglycerides, and hypothalamic peptides

Barson

Karatayev

Gaysinskaya

et al. 2012

Regulatory Peptides

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While a high-fat diet when compared to low-fat diet is known to produce overeating and health complications, less is known about the effects produced by fat-rich diets differing in their specific composition of fat. This study examined the effects of a high-fat diet containing relatively high levels of saturated compared to unsaturated fatty acids (HiSat) to a high-fat diet with higher levels of unsaturated fatty acids (USat). A HiSat compared to USat meal caused rats to consume more calories in a subsequent chow test meal. The HiSat meal also increased circulating levels of triglycerides (TG) and expression of the orexigenic peptides, galanin (GAL) in the hypothalamic paraventricular nucleus (PVN) and orexin (OX) in the perifornical lateral hypothalamus (PFLH). A similar increase in TG levels and PVN GAL and PFLH OX was also seen in rats given chronic access to the HiSat compared to USat diet, while neuropeptide Y (NPY) and agouti-related protein (AgRP) in the arcuate nucleus showed decreased expression. The importance of TG in producing these changes was supported by the finding that the TG-lowering medication gemfibrozil as compared to vehicle, when peripherally administered before consumption of a HiSat meal, significantly decreased the expression of OX, while increasing the expression of NPY and AgRP. These findings substantiate the importance of the fat composition in a diet, indicating that those rich in saturated compared to unsaturated fatty acids may promote overeating by increasing circulating lipids and specific hypothalamic peptides, GAL and OX, known to preferentially stimulate the consumption of a fat-rich diet.

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Section: Discussionmentioning

confidence: 93%

Effect of dietary fatty acid composition on food intake, triglycerides, and hypothalamic peptides

Barson

Karatayev

Gaysinskaya

et al. 2012

Regulatory Peptides

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“…AVP deficient di/di Brattleboro rats have elevated mRNA levels encoding preproGAL in the PVN and SON (Rökaeus et al 1988) and also galanin mRNA in PVN (Beck and Max 2007). Galanin concentration in the median eminence of di/di rats did not differ from heterozygous Brattleboro or Sprague-Dawley rats.…”

Section: Son and Pvn Principal Osmoregulatory Neuropeptidesmentioning

confidence: 84%

Response of Substances Co-Expressed in Hypothalamic Magnocellular Neurons to Osmotic Challenges in Normal and Brattleboro Rats

et al. 2008

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The intention of this review is to emphasize the current knowledge about the extent and importance of the substances co-localized with magnocellular arginine vasopressin (AVP) and oxytocin (OXY) as potential candidates for the gradual clarification of their actual role in the regulation of hydromineral homeostasis. Maintenance of the body hydromineral balance depends on the coordinated action of principal biologically active compounds, AVP and OXY, synthesized in the hypothalamic supraoptic and paraventricular nuclei. However, on the regulation of water-salt balance, other substances, co-localized with the principal neuropetides, participate. These can be classified as (1) peptides co-localized with AVP or OXY with unambiguous osmotic function, including angiotensin II, apelin, corticotropin releasing hormone, and galanin and (2) peptides co-localized with AVP or OXY with an unknown role in osmotic regulation, including cholecystokinin, chromogranin/secretogranin, dynorphin, endothelin-1, enkephalin, ferritin protein, interleukin 6, kininogen, neurokinin B, neuropeptide Y, vasoactive intestinal peptide, pituitary adenylate cyclase-activating polypeptide, TAFA5 protein, thyrotropin releasing hormone, tyrosine hydroxylase, and urocortin. In this brief review, also the responses of these substances to different hyperosmotic and hypoosmotic challenges are pointed out. Based on the literature data published recently, the functional implication of the majority of co-localized substances is still better understood in non-osmotic than osmotic functional circuits. Brattleboro strain of rats that does not express functional vasopressin was also included in this review. These animals suffer from chronic hypernatremia and hyperosmolality, accompanied by sustained increase in OXY mRNA in PVN and SON and OXY levels in plasma. They represent an important model of animals with constantly sustained osmolality, which in the future, will be utilizable for revealing the physiological importance of biologically active substances co-expressed with AVP and OXY, involved in the regulation of plasma osmolality.

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“…Gene expression and peptide production of GAL in the PVN is also stimulated by consumption of dietary fat but not by carbohydrate or protein (Akabayashi et al 1994), demonstrating a positive relationship between GAL and fat intake. Interestingly, GAL expression and levels are also elevated in situations where fat intake is preferred, such as in female rats at puberty onset and during proestrus (Leibowitz et al 2009; Leibowitz et al 1998) and in Brattelboro rats that have a high preference for fat (Beck and Max 2007). Studies with genetically modified mice also support this relationship.…”

Section: Neurochemicals Involved In Food and Macronutrient Intakementioning

confidence: 99%

“…Ingestion of any of the three macronutrients can reduce ghrelin, although the most prolonged suppression occurs with protein (Koliaki et al 2010). Unlike GHRF, fasting potently increases plasma ghrelin levels (Bagnasco et al 2002), and fat-preferring rats have higher levels of plasma ghrelin (Beck and Max 2007), demonstrating that ghrelin shares some similarities with the fat- and carbohydrate-related peptides. This peptide may not be as important as others in food consumption, despite its ability to stimulate intake, as ghrelin knockout mice show no difference from WT mice in consumption of chow or a high-fat diet (Sun et al 2003; Sun et al 2008), and ghrelin overexpressors show no difference in chow intake (Reed et al 2008) and actually consume less of a high-fat diet (Gardiner et al 2010).…”

Section: Neurochemicals Involved In Food and Macronutrient Intakementioning

confidence: 99%

Neurobiology of Consummatory Behavior: Mechanisms Underlying Overeating and Drug Use

Barson¹,

Morganstern²,

Leibowitz³

2012

ILAR Journal

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Consummatory behavior is driven not just by caloric need but also by emotional need. In the last several decades, a wide variety of models have been used to study the systems that drive food and drug intake. These include selective breeding for a specific trait, manipulation of gene expression, forced or voluntary exposure to a substance, and identification of biomarkers that predict which animals are prone to overconsuming specific substances. From this research, numerous brain areas and neurochemicals have been identified that drive consummatory behavior. While energy homeostasis is primarily mediated by the hypothalamus, reinforcement is more strongly mediated by nuclei outside of the hypothalamus, in mesocorticolimbic regions. Orexigenic neurochemicals that control food intake can provide a general signal for promoting caloric intake or a more specific signal for stimulating consumption of a particular macronutrient, fat, carbohydrate or protein. Those involved in controlling fat ingestion, including galanin, enkephalin, orexin, melanin-concentrating hormone and the endocannabinoids, show positive feedback with this macronutrient, with these peptides both increasing fat intake and being further stimulated by its intake. This positive relationship offers some explanation for why foods high in fat are so often overconsumed. Consumption of ethanol, a drug of abuse that also contains calories, is similarly driven by these neurochemical systems involved in fat intake, consistent with evidence closely relating fat and ethanol consumption. Further understanding of these systems involved in consummatory behavior will allow researchers to develop effective therapies for the treatment of overeating as well as drug abuse.

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Hypothalamic galanin and plasma leptin and ghrelin in the maintenance of energy intake in the Brattleboro rat

Cited by 10 publications

References 52 publications

Effect of dietary fatty acid composition on food intake, triglycerides, and hypothalamic peptides

Effect of dietary fatty acid composition on food intake, triglycerides, and hypothalamic peptides

Response of Substances Co-Expressed in Hypothalamic Magnocellular Neurons to Osmotic Challenges in Normal and Brattleboro Rats

Neurobiology of Consummatory Behavior: Mechanisms Underlying Overeating and Drug Use

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