scholarly journals Estradiol Replacement Improves High-Fat Diet-Induced Obesity by Suppressing the Action of Ghrelin in Ovariectomized Rats

Nutrients ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 907
Author(s):  
Naoko Yokota-Nakagi ◽  
Haruka Takahashi ◽  
Mizuho Kawakami ◽  
Akira Takamata ◽  
Yuki Uchida ◽  
...  
Keyword(s):  
Growth Hormone ◽  
High Fat Diet ◽  
Ovariectomized Rats ◽  
Mrna Levels ◽  
High Fat ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
Protein Levels ◽  
Ovx Rats ◽  
Hypothalamic Arcuate Nucleus

This study aims to investigate the effects of estradiol replacement on the orexigenic action of ghrelin in ovariectomized (OVX) obese rats fed with a high-fat diet (HFD). Four weeks after OVX at 9 weeks of age, Wistar rats were subcutaneously implanted with either 17β-estradiol (E2) or placebo (Pla) pellets and started on HFD feeding. After 4 weeks, growth hormone-releasing peptide (GHRP)-6, a growth hormone secretagogue receptor (GHSR) agonist injected intraperitoneally, induced changes in HFD intake, and c-Fos-positive neurons in the hypothalamic arcuate nucleus (ARC) were measured in both groups. The ghrelin protein and mRNA levels, as well as GHSR protein in stomach, were analyzed by Western blotting and real-time PCR. HFD increased energy intake and body weight in the Pla group, while it temporarily reduced these in the E2 group. GHRP-6 enhanced HFD intake and activated neurons in the ARC only in the Pla group. Furthermore, gastric ghrelin and GHSR protein levels were lower in the E2 group than in the Pla group, but plasma acyl ghrelin levels were similar in both groups. Our results suggest that E2 replacement improves obesity by inhibiting the orexigenic action of ghrelin via downregulation of ghrelin and its receptor in stomach in HFD-fed OVX rats.

scholarly journals Growth hormone secretagogue receptor in dopamine neurons controls appetitive and consummatory behaviors towards high-fat diet in ad-libitum fed mice

2020 ◽  
Vol 119 ◽  
pp. 104718
Author(s):  
María Paula Cornejo ◽  
Franco Barrile ◽  
Daniela Cassano ◽  
Julieta Paola Aguggia ◽  
Guadalupe García Romero ◽  
...  
Keyword(s):  
Growth Hormone ◽  
High Fat Diet ◽  
Dopamine Neurons ◽  
High Fat ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
Ad Libitum

scholarly journals Evidence Supporting a Role for Constitutive Ghrelin Receptor Signaling in Fasting-Induced Hyperphagia in Male Mice

Endocrinology ◽  
2017 ◽  
Vol 159 (2) ◽  
pp. 1021-1034 ◽  
Author(s):  
Gimena Fernandez ◽  
Agustina Cabral ◽  
María F Andreoli ◽  
Alexandra Labarthe ◽  
Céline M'Kadmi ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Food Intake ◽  
Peptide Hormone ◽  
Negative Energy ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
Ghrelin Receptor ◽  
Orexigenic Peptide ◽  
Hypothalamic Arcuate Nucleus

Abstract Ghrelin is a potent orexigenic peptide hormone that acts through the growth hormone secretagogue receptor (GHSR), a G protein–coupled receptor highly expressed in the hypothalamus. In vitro studies have shown that GHSR displays a high constitutive activity, whose physiological relevance is uncertain. As GHSR gene expression in the hypothalamus is known to increase in fasting conditions, we tested the hypothesis that constitutive GHSR activity at the hypothalamic level drives the fasting-induced hyperphagia. We found that refed wild-type (WT) mice displayed a robust hyperphagia that continued for 5 days after refeeding and changed their food intake daily pattern. Fasted WT mice showed an increase in plasma ghrelin levels, as well as in GHSR expression levels and ghrelin binding sites in the hypothalamic arcuate nucleus. When fasting-refeeding responses were evaluated in ghrelin- or GHSR-deficient mice, only the latter displayed an ∼15% smaller hyperphagia, compared with WT mice. Finally, fasting-induced hyperphagia of WT mice was significantly smaller in mice centrally treated with the GHSR inverse agonist K-(D-1-Nal)-FwLL-NH2, compared with mice treated with vehicle, whereas it was unaffected in mice centrally treated with the GHSR antagonists D-Lys3-growth hormone–releasing peptide 6 or JMV2959. Taken together, genetic models and pharmacological results support the notion that constitutive GHSR activity modulates the magnitude of the compensatory hyperphagia triggered by fasting. Thus, the hypothalamic GHSR signaling system could affect the set point of daily food intake, independently of plasma ghrelin levels, in situations of negative energy balance.

scholarly journals Paternal Resistance Exercise Modulates Skeletal Muscle Remodeling Pathways in Fathers and Male Offspring Submitted to a High-Fat Diet

2021 ◽  
Vol 12 ◽  
Author(s):  
Rebecca Salomão ◽  
Ivo Vieira de Sousa Neto ◽  
Gracielle Vieira Ramos ◽  
Ramires Alsamir Tibana ◽  
João Quaglioti Durigan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
High Fat Diet ◽  
Control Diet ◽  
Matrix Remodeling ◽  
Mrna Levels ◽  
High Fat ◽  
Protein Levels ◽  
Gene And Protein Expression ◽  
Muscle Homeostasis ◽  
Muscle Remodeling

Although some studies have shown that a high-fat diet (HFD) adversely affects muscle extracellular matrix remodeling, the mechanisms involved in muscle trophism, inflammation, and adipogenesis have not been fully investigated. Thus, we investigated the effects of 8 weeks of paternal resistance training (RT) on gene and protein expression/activity of critical factors involved in muscle inflammation and remodeling of fathers and offspring (offspring exposed to standard chow or HFD). Animals were randomly distributed to constitute sedentary fathers (SF; n = 7; did not perform RT) or trained fathers (TF n = 7; performed RT), with offspring from mating with sedentary females. After birth, 28 male pups were divided into four groups (n = 7 per group): offspring from sedentary father submitted either to control diet (SFO-C) or high-fat diet (SFO-HF) and offspring from trained father submitted to control diet (TFO-C) or high-fat diet (TFO-HF). Our results show that an HFD downregulated collagen mRNA levels and upregulated inflammatory and atrophy pathways and adipogenic transcription factor mRNA levels in offspring gastrocnemius muscle. In contrast, paternal RT increased MMP-2 activity and decreased IL-6 levels in offspring exposed to a control diet. Paternal RT upregulated P70s6k and Ppara mRNA levels and downregulated Atrogin1 mRNA levels, while decreasing NFκ-B, IL-1β, and IL-8 protein levels in offspring exposed to an HFD. Paternal physical training influences key skeletal muscle remodeling pathways and inflammatory profiles relevant for muscle homeostasis maintenance in offspring submitted to different diets.

scholarly journals Improvement of Adipose Macrophage Polarization in High Fat Diet-Induced Obese GHSR Knockout Mice

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Fang Yuan ◽  
Jian Ma ◽  
Xinxin Xiang ◽  
He Lan ◽  
Yanhui Xu ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
High Fat Diet ◽  
Macrophage Polarization ◽  
Interstitial Cells ◽  
Epididymal Adipose Tissue ◽  
Mrna Levels ◽  
High Fat ◽  
Growth Hormone Secretagogue ◽  
Anti Inflammatory

Purpose. Adipose tissue inflammation is the key linking obesity to insulin resistance. Over 50% of the interstitial cells in adipose tissue are macrophages, which produce inflammatory cytokines and therefore play an important role in the progression of insulin resistance. Within this classification view, macrophage biology is driven by two polarization phenotypes, M1 (proinflammatory) and M2 (anti-inflammatory). The unique functional receptor of ghrelin, growth hormone secretagogue receptor (GHSR), is a classic seven-transmembrane G protein-coupled receptor that is linked to multiple intracellular signaling pathways. Knockout of GHSR improves the obesity and glucose metabolic disorders, suggesting a crucial role of ghrelin activity in insulin resistance. Here, we discussed whether macrophage polarization phenotypes in adipose tissue were changed in GHSR knockout (GHSR-/-) mice. Methods. GHSR-/- mice were fed with normal chow diet (NCD) or high fat diet (HFD). Markers of different macrophage polarization phenotypes were detected by real-time RT-PCR. Results. The size of adipocytes decreased and interstitial cells, especially infiltrated macrophages, reduced in epididymal adipose tissue of GHSR-/- mice fed with HFD. Compared with wild type mice, the mRNA levels of inflammatory adipokines such as resistin, IL-6, and PAI-1 were significantly lower in epididymal adipose tissue of GHSR-/- mice, whereas anti-inflammatory adipokine, adiponectin, was significantly higher. M1 markers, MCP-1, TNF-α, and iNOS, were significantly lower in epididymal adipose tissue of GHSR-/- mice, whereas M2 markers, Arg-1, Mgl-1, were Mrc1, were significantly higher. Conclusion. The GHSR-/- mice fed with HFD showed suppressed adipose inflammation, reduced macrophage infiltration, and enhanced M2 polarization of macrophages in adipose tissue, which improved insulin sensitivity.

scholarly journals Protective Effects of N1-Methylnicotinamide Against High-Fat Diet- and Age-Induced Hearing Loss via Moderate Overexpression of Sirtuin 1 Protein

2021 ◽  
Vol 15 ◽  
Author(s):  
Toru Miwa
Keyword(s):  
Hearing Loss ◽  
High Fat Diet ◽  
Sirtuin 1 ◽  
Mrna Levels ◽  
Protective Effects ◽  
High Fat ◽  
Protein Levels ◽  
Low Fat Diet ◽  
Age Related ◽  
Cochlear Morphology

Age-related hearing loss (ARHL) is the most common form of hearing loss and the predominant neurodegenerative disease associated with aging. Sirtuin 1 (SIRT1) is associated with the most complex physiological processes, including metabolism, cancer onset, and aging. SIRT1 protein levels are enhanced by the conversion of nicotinamide to N1-methylnicotinamide (MNAM), independent of its mRNA levels. Moreover, MNAM has implications in increased longevity achieved through its mitohormetic effects. Nicotinamide N-methyltransferase (Nnmt) is an enzyme involved in MNAM metabolism, and its level increases under caloric restriction (CR) conditions. The CR condition has implications in delaying ARHL onset. In this study, we aimed to determine the relationship between diet, hearing function, SIRT1 and SIRT3 expression levels in the inner ear, and cochlear morphology. Mice fed with a high-fat diet (HFD), HFD + 1% MNAM, and low-fat diet (LFD) were monitored for age-related auditory-evoked brainstem responses, and changes in cochlear histology, metabolism, and protein and mRNA expressions were analyzed. Our results revealed that the HFD- and aging-mediated downregulated expression of SIRT1 and SIRT3 promoted hearing loss that was obfuscated by MNAM supplementation-induced upregulated expression of cochlear SIRT1 and SIRT3. Thus, our results suggest that MNAM can be used as a therapeutic agent for preventing ARHL.

Effects of ghrelin administration on decreased growth hormone status in obese animals

2007 ◽  
Vol 293 (3) ◽  
pp. E819-E825 ◽  
Author(s):  
Hiroshi Iwakura ◽  
Takashi Akamizu ◽  
Hiroyuki Ariyasu ◽  
Taiga Irako ◽  
Kiminori Hosoda ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Food Intake ◽  
High Fat Diet ◽  
Low Dose ◽  
Diabetic Mouse ◽  
Mrna Levels ◽  
High Fat ◽  
Gh Secretion ◽  
Akita Mice ◽  
Stimulation Of

Obesity is characterized by markedly decreased ghrelin and growth hormone (GH) secretion. Ghrelin is a GH-stimulating, stomach-derived peptide that also has orexigenic action. Ghrelin supplement may restore decreased GH secretion in obesity, but it may worsen obesity by its orexigenic action. To reveal effects of ghrelin administration on obese animals, we first examined acute GH and orexigenic responses to ghrelin in three different obese and/or diabetic mouse models: db/db mice, mice on a high-fat diet (HFD mice), and Akita mice for comparison. GH responses to ghrelin were significantly suppressed in db/db, HFD, and Akita mice. Food intake of db/db and Akita mice were basally higher, and further stimulation of food intake by ghrelin was suppressed. Pituitary GH secretagogue receptor mRNA levels in db/db and HFD mice were significantly decreased, which may partly contribute to decreased GH response to ghrelin in these mice. In Akita mice for comparison, decreased hypothalamic GH-releasing hormone (GHRH) mRNA levels may be responsible for decreased GH response, since maximum GH response to ghrelin needs GHRH. When ghrelin was injected into HFD mice with GHRH coadministrated, GH responses to ghrelin were significantly emphasized. HFD mice injected with low-dose ghrelin and GHRH for 10 days did not show weight gain. These results indicate that low-dose ghrelin and GHRH treatment may restore decreased GH secretion in obesity without worsening obesity.

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