Key to Long-Term Weight Loss

ghrelin human
sequence ghrelin

sequence comparison ghrelin

ghrelin comparison species

structure of the prepro ghrelin gene


Ghrelin and obestatin are gastrointestinal peptides, encoded by the same preproghrelin gene. Both are expressed in breast cancer tissue and ghrelin has been implicated in breast cancer tumorigenesis. Despite recent advances in breast cancer management the need for new prognostic markers and potential therapeutic targets in breast cancer remains high. We studied the prognostic impact of ghrelin and obestatin in women with node negative breast cancer. Within a cohort of women with breast cancer with tumor size < 50 mm, no lymph node metastases and no initiation of adjuvant chemotherapy, 190 women were identified who died from breast cancer and randomly selected 190 women alive at the corresponding time as controls. Tumor tissues were immunostained with antibodies versus the peptides. Ghrelin expression was associated with better breast cancer specific survival in univariate analyses (OR 0.55, 95% CI 0.36-0.84) and in multivariate models, adjusted for endocrine treatment and age (OR 0.57, 95% CI 0.36-0.89). Obestatin expression was non-informative (OR 1.2, 95% CI 0.60-2.46). Ghrelin expression is independent prognostic factor for breast cancer death in node negative patients-halving the risk for dying of breast cancer. Our data implies that ghrelin could be a potential therapeutic target in breast cancer treatment.
The authors used Phoenix’  peptide  Cat # H-031-30 for the IHC staining of more than 190 tissues samples.
Grönberg M, Ahlin C, Naeser Y, Janson ET, Holmberg L, Fjällskog ML. PLoS ONE. 2017;12(4):e0176059.

BACKGROUND: Whether plasma ghrelin/obestatin levels are associated with Helicobacter pylori (H. pylori) infection, subtypes of functional dyspepsia (FD), and gastric mucosal histology has not yet been established in elderly patients.
OBJECTIVE: The aim of this study was to determine whether plasma ghrelin and obestatin levels are related to gastric mucosal histology, H. pylori infection, and FD subtypes in elderly patients with FD. METHODS: Ninety-two patients diagnosed with FD and older than 60 years (median age 69.4; range 60-88) were included. Clinical symptoms investigated included postprandial fullness, epigastric pain, epigastric soreness, nausea, and vomiting. According to the Rome III criteria, patients diagnosed with FD were divided into two subtypes: epigastric pain syndrome (EPS) and postprandial distress syndrome (PDS). Plasma ghrelin and obestatin levels were measured using enzyme immunoassay, and histological examination of gastric mucosa was performed. H. pylori infection was determined by histopathological examination of gastric mucosal biopsy and/or Campylobacter-like organism test.
RESULTS: In our study, plasma ghrelin levels and plasma ghrelin/obestatin (G/O) ratio were significantly lower in subjects with intestinal metaplasia compared with those without intestinal metaplasia (ghrelin, p = 0.010; G/O ratio, p = 0.012). On the other hand, there were no significant differences in plasma ghrelin and obestatin levels between H. pylori-positive and H. pylori-negative groups. (ghrelin, p = 0.130; obestatin, p = 0.888). Similarly, no significant differences were detected between the EPS and PDS groups (ghrelin, p = 0.238; obestatin, p = 0.710).
CONCLUSIONS: Patients with intestinal metaplasia, a known precursor of gastric cancer, had significantly less plasma ghrelin levels and G/O ratio than those without intestinal metaplasia.
The authors used Phoenix’ EK-031-30 for the blood ghrelin levels analysis.
Kim SH, Kim JW, Byun J, Jeong JB, Kim BG, Lee KL. PLoS ONE. 2017;12(4):e0175231.

Prader-Willi syndrome (PWS) is caused by a loss of paternally expressed genes in an imprinted region of chromosome 15q. Among the canonical PWS phenotypes are hyperphagic obesity, central hypogonadism, and low growth hormone (GH). Rare microdeletions in PWS patients define a 91-kb minimum critical deletion region encompassing 3 genes, including the noncoding RNA gene SNORD116. Here, we found that protein and transcript levels of nescient helix loop helix 2 (NHLH2) and the prohormone convertase PC1 (encoded by PCSK1) were reduced in PWS patient induced pluripotent stem cell-derived (iPSC-derived) neurons. Moreover, Nhlh2 and Pcsk1 expression were reduced in hypothalami of fasted Snord116 paternal knockout (Snord116p-/m+) mice. Hypothalamic Agrp and Npy remained elevated following refeeding in association with relative hyperphagia in Snord116p-/m+ mice. Nhlh2-deficient mice display growth deficiencies as adolescents and hypogonadism, hyperphagia, and obesity as adults. Nhlh2 has also been shown to promote Pcsk1 expression. Humans and mice deficient in PC1 display hyperphagic obesity, hypogonadism, decreased GH, and hypoinsulinemic diabetes due to impaired prohormone processing. Here, we found that Snord116p-/m+ mice displayed in vivo functional defects in prohormone processing of proinsulin, pro-GH-releasing hormone, and proghrelin in association with reductions in islet, hypothalamic, and stomach PC1 content. Our findings suggest that the major neuroendocrine features of PWS are due to PC1 deficiency.
The authors used Phoenix’ RK-031-30 for the blood ghrelin levels analysis.
Burnett LC, Leduc CA, Sulsona CR, et al. J Clin Invest. 2017;127(1):293-305.

Ghrelin is a gut-brain peptide hormone that plays an important role in the control of energy metabolism. In the mouse, the expression of its receptor, growth hormone secretagogue receptor (GHSR), was reported to be highest in two brain regions, the arcuate nucleus (ARC) in the hypothalamus and non-preganglionic Edinger-Westphal nucleus (npEW) in the midbrain. The npEW is also the most dominant site of urocortin 1 (Ucn1) expression in the mammalian brain and the npEW-Ucn1 neurons play an important role in stress adaptation response. Despite the importance of ghrelin for regulating food intake and body weight, mice lacking ghrelin or GHSR show no, or only a modest metabolic phenotype. Because GHSR mRNA is abundantly present in the stress-sensitive npEW, we hypothesized that ghrelin is not only involved in metabolism control but also in the stress response. To test this we studied the ghrelin-KO mice, under basal non-stressed and acute stressed conditions. Under basal conditions, KO mice have higher activation of npEW-Ucn1 neurons as demonstrated by dual label Ucn-1 and Fos immunohistochemistry. After restraint stress both wild-type (WT) and KO mice revealed an increased activation of the npEW nucleus, but we found that stress recruited Ucn1-ir neurons only in WT, but not in KO mice. We also determined Ucn1 mRNA expression in stressed and non-stressed conditions in KO and WT mice by in situ hybridization and found a strong up-regulation of Ucn1 mRNA in KO than in WT mice. Moreover, KO but not WT mice revealed stress-induced Ucn1 mRNA expression. Taken together, our data provide evidence for ghrelin actions in stress response. We propose that Ucn1 neurons in the npEW are instrumental in ghrelin´s action on the animal´s stress adaptation response.

L. Xu et al., C137 Deletion of ghrelin alters the response of Edinger-Westphal nucleus to restraint stress in the mouse. Poster session presented at IBRO 2011. 8th International Brain Research Organization World Congress of Neuroscience; 2011 July 14-18; Florence, Italy.

We provide the first evidence for the existence in human plasma of peptides derived from the 66 carboxyl-terminal amino acids of pro-ghrelin (C-ghrelin). C-ghrelin immunoreactivity in plasma was higher than ghrelin, and did not significantly correlate with body mass index in normal health. In patients with myocardial infarction, plasma levels of both ghrelin and C-ghrelin were significantly decreased ( approximately 30%, P<0.05), whereas in patients with heart failure, C-ghrelin levels were significantly elevated ( approximately 32%, P<0.05) compared with controls. HPLC coupled with RIA showed circulating C-ghrelin to be primarily of low molecular weight (M(r) approximately 3500), but in chronic heart failure, a higher molecular weight form (M(r) approximately 7500) is also present. This is the first evidence for potential circulating hormones derived from the carboxyl terminus of pro-ghrelin and for their modulation in cardiovascular diseases.

Pemberton C, Wimalasena P, Yandle T, Soule S, Richards M. C-terminal pro-ghrelin peptides are present in the human circulation. Biochem Biophys Res Commun. 2003;310(2):567-7

Experimental studies have suggested that ghrelin plays a role in glucose homeostasis and in the regulation of blood pressure (BP). We therefore assessed the hypothesis that a low ghrelin concentration may be a risk factor for type 2 diabetes and hypertension. We also characterized the effect of the ghrelin Arg51Gln and Leu72Met mutations on ghrelin concentrations in the population-based hypertensive (n = 519) and control (n = 526) cohorts of our OPERA (Oulu Project Elucidating Risk of Atherosclerosis) study. The fasting plasma ghrelin concentrations of 1,040 subjects were analyzed using the radioimmunoassay method. Insulin sensitivity was assessed using the quantitative insulin sensitivity check index (QUICKI). Ghrelin concentrations were negatively associated with fasting insulin (P < 0.001), systolic (P = 0.026) and diastolic BP (P = 0.018), and the prevalence of type 2 diabetes (P = 0.015) and insulin resistance (P < 0.001) in the multivariate models. In the control cohort, low ghrelin was associated with hypertension (BP >140/90 mmHg) (P = 0.031). The subjects with the ghrelin 51Gln allele had lower ghrelin concentrations than the Arg51Arg homozygotes (P = 0.001). We conclude that low ghrelin is independently associated with type 2 diabetes, insulin concentration, insulin resistance, and elevated BP. Therefore, it might have some role in the etiology of type 2 diabetes and the regulation of BP. The ghrelin Arg51Gln mutation is associated with low plasma ghrelin concentrations.

Pöykkö SM, Kellokoski E, Hörkkö S, Kauma H, Kesäniemi YA, Ukkola O. Low plasma ghrelin is associated with insulin resistance, hypertension, and the prevalence of type 2 diabetes. Diabetes. 2003;52(10):2546-53

A human study investigating the biological activities of non-acylated ghrelin revealed antagonizing properties of this peptide on the hyperglycemic effects of acylated (or active) ghrelin. More specifically, bolus injections (i.v.) of this inactive form of ghrelin caused a significant reversal of the active ghrelin-induced reduction in insulin levels and ghrelin-induced increase in plasma glucose levels. This indicates a novel mechanism for the control of glucose levels in the blood and hence may lead to potential therapeutic applications of the non-acylated form of ghrelin in the treatment of type II diabetes and insulin resistance-related conditions.

Broglio F, Prodam F, Benso A , et al.,Endo 2003, PHiladelphia, June 2003, Abstract #553

Ghrelin, a growth hormone-releasing hormone produced by gastroenteropancreatic endocrine cells, hypothalamus, and pituitary, was recently identified in medullary thyroid carcinomas and derived cell lines. However, no data exist on its expression in either normal or neoplastic thyroid follicular cells. We analyzed ghrelin expression by immunohistochemistry, in situ hybridization, and reverse transcriptase-polymerase chain reaction in 15 fetal, 4 infant, and 10 adult thyroids, and in 54 tumors of follicular origin. We also analyzed the effects of ghrelin on cell proliferation in N-PAP and ARO thyroid carcinoma cell lines. Ghrelin-binding sites were investigated using reverse transcriptase-polymerase chain reaction to detect its growth hormone secretagogue receptor (GHS-R) mRNA and an in situ-binding localization procedure. Strong ghrelin immunoreactivity was found in fetal but not in infant or adult thyroids. Ghrelin protein and mRNA were present, in variable amounts, in benign and malignant tumors. Normal thyroids, thyroid tumors, and cell lines showed ghrelin binding sites by binding localization, in the absence of the specific GHS receptor mRNA (with the exception of one normal thyroid). Moreover, ghrelin induced dose-dependent inhibition of growth in cell lines. In conclusion, ghrelin is expressed in fetal but not in adult thyroid, and is re-expressed in tumors; the presence of ghrelin receptors other than GHS-R in normal and neoplastic adult thyroid is suggested; ghrelin inhibits cell proliferation of thyroid carcinoma cell lines in vitro.

Volante M, Allia E, Fulcheri E, et al. Ghrelin in fetal thyroid and follicular tumors and cell lines: expression and effects on tumor growth. Am J Pathol. 2003;162(2):645-54

The novel hormone ghrelin is a potent orexigen that may counterbalance leptin. Ghrelin is the only secreted molecule requiring post-translational acylation with octanoic acid to ensure bioactivity. Ghrelin, predominantly derived from the stomach, may target neuroendocrine networks within the central nervous system (CNS) to regulate energy homeostasis. This would require ghrelin to cross the blood-brain barrier (BBB). In mice, we examined whether ghrelin crosses the BBB and whether its lipophilic side chain is involved in this process. We found that saturable systems transported human ghrelin from brain-to-blood and from blood-to-brain. Mouse ghrelin, differing from human ghrelin by two amino acids, was a substrate for the brain-to-blood but not for the blood-to-brain transporter and so entered the brain to a far lesser degree. des-Octanoyl ghrelin entered the brain by nonsaturable transmembrane diffusion and was sequestered once within the CNS. In summary, we show that ghrelin transport across the BBB is a complex, highly regulated bidirectional process. The direction and extent of passage are determined by the primary structure of ghrelin, defining a new role for the unique post-translational octanoylation.

Banks WA, Tschöp M, Robinson SM, Heiman ML. Extent and direction of ghrelin transport across the blood-brain barrier is determined by its unique primary structure. J Pharmacol Exp Ther. 2002;302(2):822-7

Ghrelin is an acyl-peptide gastric hormone acting on the pituitary and hypothalamus to stimulate growth hormone (GH) release, adiposity, and appetite. Ghrelin endocrine activities are entirely dependent on its acylation and are mediated by GH secretagogue (GHS) receptor (GHSR)-1a, a G protein–coupled receptor mostly expressed in the pituitary and hypothalamus, previously identified as the receptor for a group of synthetic molecules featuring GH secretagogue (GHS) activity. Des-acyl ghrelin, which is far more abundant than ghrelin, does not bind GHSR-1a, is devoid of any endocrine activity, and its function is currently unknown. Ghrelin, which is expressed in heart, albeit at a much lower level than in the stomach, also exerts a cardio protective effect through an unknown mechanism, independent of GH release. Here we show that both ghrelin and des-acyl ghrelin inhibit apoptosis of primary adult and H9c2 cardiomyocytes and endothelial cells in vitro through activation of extracellular signal–regulated kinase-1/2 and Akt serine kinases. In addition, ghrelin and des-acyl ghrelin recognize common high affinity binding sites on H9c2 cardiomyocytes, which do not express GHSR-1a. Finally, both MK-0677 and hexarelin, a nonpeptidyl and a peptidyl synthetic GHS, respectively, recognize the common ghrelin and des-acyl ghrelin binding sites, inhibit cell death, and activate MAPK and Akt.

These findings provide the first evidence that, independent of its acylation, ghrelin gene product may act as a survival factor directly on the cardiovascular system through binding to a novel, yet to be identified receptor, which is distinct from GHSR-1a.

Baldanzi G, Filigheddu N, Cutrupi S, et al. Ghrelin and des-acyl ghrelin inhibit cell death in cardiomyocytes and endothelial cells through ERK1/2 and PI 3-kinase/AKT. J Cell Biol. 2002;159(6):1029-37

Circulating Ghrelin Levels Are Decreased in Human Obesity

  Lean Caucasians Obese Caucasians Lean Pima Indians Obese Pima Indians
n 7 8 7 8
Sex-Female 3 4 3 4
Sex-Male 4 4 4 4
Age (Years) 32±11 30±7 33±4 32±5
Body weight (kg) 71.4±9.8 109.8±16.8 70.3±9.6 109±15.2
BMI (kg/m2) 25.4±2.3 38.2±4.8 24.0±1.9 37.9±6.6
Body fat (%) 22±9 35±7 24±7 35±5
Plasma Ghrelin (fmol/ml) 155±25 106±23 95±13> 80±36
Plasma Glucose (mg/dl) 87±7 91±4 89±6 95±7
Plasma Insulin (uU/ml) 4±3 10±3 6±3 18±10
Plasma Leptin (ng/ml) 8±7 53±47 10±9 35±27
Tschöp, M., et al. Diabetes 50, 707-709, 2001

Ghrelin Level

Fasting plasma Ghrelin (Human) 514+/-63 pg/ml n=24 Otto B, et al. Eur J Endocrinol 2001 Nov;145(5):669-73
Fasting plasma Ghrelin (Human) 1057+/-95 pg/ml (anorectic patients Otto B, et al. Eur J Endocrinol 2001 Nov;145(5):669-73
Ghrelin (Human) 307 +/- 164 [Prader-Willi syndrome (PWS)] DelParigi A., et al. J Clin Endocrinol Metab 2002 Dec;87(12):5461-4
Ghrelin (Human) 109 +/- 24 fmol/ml DelParigi A., et al. J Clin Endocrinol Metab 2002 Dec;87(12):5461-4
Fasting serum ghrelin levels (Human) 270 +/- 102 pmol/liter Haqq AM, et al. J Clin Endocrinol Metab 2003 Jan;88(1):174-8
Fasting serum ghrelin levels (Human) 429 +/- 374 pmol/liter [Prader-Willi Syndrome (PWS)] Haqq AM, et al. J Clin Endocrinol Metab 2003 Jan;88(1):174-8
Fasting serum ghrelin levels (Human) 139 +/- 70 pmol/liter (Obese group) Haqq AM, et al. J Clin Endocrinol Metab 2003 Jan;88(1):174-8
Fasting plasma ghrelin 87+/-28 pmol/liter (Pima Indians) Tschop M, et al. Diabetes 2001 Apr;50(4):707-9
Fasting plasma ghrelin 129+/-34 fmol/ml (Caucasians) Tschop M, et al. Diabetes 2001 Apr;50(4):707-9
fasting healthy lean children (NC) 426.0; 183.0-618.0 pg/ml Bellone S., et al. J Endocrinol Invest 2002 May;25(5):RC13-5
fasting obese children (OBC) 229.5; 162.5-339.5 pg/ml Bellone S., et al. J Endocrinol Invest 2002 May;25(5):RC13-5
Fastin healthy lean adults (NA) 380.5; 257.7-551.7 pg/ml Bellone S., et al. J Endocrinol Invest 2002 May;25(5):RC13-5


Extraction of plasma sample is not necessary with Phoenix's human Ghrelin RIA Kit 

Time of Use* Week 0 Week 2 Week 4
1 x 5.75pg (57.5pg/ml) 12.3pg (123pg/ml) 7.65pg (76.5pg/ml)
1/2 x 1.88pg 6.53pg 3.41pg
1/4 x   2.59pg 1.61pg
1/8 x>   0.98pg 0.58pg
* Kits used in Week 0 were used within 2 days of manufacture. All kits used in Week 2 and 4 were stored as dry power (not reconstituted) at 4°C.
**100 µl of plasma (non-extracted, normal human subjects) was used to perform the RIA. To calculate the level of Ghrelin-like immunoreactivity, the level obtained by extrapolation of the standard curve must be multiplied by 10 to obtain the level at 1 ml (ex. 12.3 pg x 10 = 123 pg/ml).

Stability of Ghrelin (Human) RIA Kit(at least 3 weeks in liquid form)

Time of Rehydrate B/T (%) R/T (%) ED20 (pg/tube) ED50 (pg/tube) ED80(pg/tube)
hour 1 0.04 0.44 23.78 8.74 3.14
Day 2 0.04 0.52 14.19 5.51 2.19
Week 1 0.05 0.50 23.72 8.18 2.65
Week 2 0.03 0.43 38.21 11.88 4.57
Week 3 0.03 0.44 31.82 11.12 3.64
Rehydrate one kit contents with RIA buffer keep them at 4oC. Kits was used in above scheduled time. 

Stability of Ghrelin (Human) RIA Kit (at least 4 weeks in dry form)

Time of Use* B/T (%) R/T (%) ED20 (pg/tune) ED50 (pg/tune) ED80(pg/tune)
Week 0 0.05 0.37 20.90 5.78 1.99
Week 2 0.03 0.45 19.03 8.25 3.14
Week 4 0.03 0.35 15.75 6.28 2.27
*Kits used in Week 0 were used within 2 days of manufacture. All kits used in Week 2 and 4 were stored as dry power (not reconstituted) at 4oC.
Phoenix strongly recommends using the RIA kit as soon as possible. Always store the unused kit as dry power at 4oC if not used immediately. Never store reconstituted kit components as they are unstable. Use of stored reconstituted kit components to perform RIA may yield poor and unacceptable results. Phoenix's Ghrelin (Human) RIA Kit detects "total" Ghrelin, including Ser3- octanoyl and Ser3-des-octanoyl Ghrelins.

Related Products

Catalog# Product Standard Size Price
031-31 Ghrelin (Rat, Mouse) 100 µg $102
EK-031-30 Ghrelin (Human) - EIA Kit, extraction-free 96 wells $458
031-49 Ghrelin (1-11) (Rat, Mouse, Porcine) 100 µg $194
031-30 Ghrelin (Human) 100 µg $102
RK-031-30 Ghrelin (Human) - RIA Kit 125 tubes $406
031-52 Ghrelin (Porcine) 100 µg $194
EK-031-31 Ghrelin (Rat, Mouse) - EIA Kit, extraction-free 96 wells $458
EK-031-50 Ghrelin (Canine) - EIA Kit, extraction-free 96 wells $458
H-031-31 Ghrelin (Rat, Mouse) - Antibody 100 µl $459
031-33 [Ser3(Des-Octanoyl)]-Ghrelin (Rat, Mouse) 100 µg $153
T-031-31 Ghrelin (Rat, Mouse) - I-125 Labeled 10 µCi $723
031-32 [Ser3(Des-Octanoyl)]-Ghrelin (Human) 100 µg $133
031-42 [Ser3(Des-Octanoyl)]-Ghrelin (1-5) amide (Human, Rat, Mouse, Bovine, Canine) 200 µg $28
EK-031-30CE Ghrelin (Human) - EIA Kit, extraction-free, CE Mark Certified 96 wells $478
RK-031-52 Ghrelin (Porcine) - RIA Kit 125 tubes $671
032-33 [Dap3-Octanoyl]-GMA-Ghrelin (1-9) amide (Rat, Mouse) 200 µg $153
032-34 [Dap3-Octanoyl]-GMA-Ghrelin amide (Rat, Mouse) 200 µg $224
031-73 Ghrelin (1-11) amide (Human) 100 µg $163
T-031-73 Ghrelin (1-11) amide (Human) - I-125 Labeled 10 µCi $723
031-39 Ghrelin (1-14) (Human) 100 µg $133
031-40 [Ser3(Des-Octanoyl)]-Ghrelin (1-14) (Human) 100 µg $66
031-71 Ghrelin (1-14) amide (Human) 100 µg $163
T-031-71 Ghrelin (1-14) amide (Human) - I-125 Labeled 10 µCi $723
031-47 [Ser3(Des-Octanoyl)]-Ghrelin (1-18) / Motlin-Related Peptide (Human) 100 µg $153
031-48 [Ser3(Des-Octanoyl)]-Ghrelin (1-18) / Motlin-Related Peptide (Rat, Mouse) 100 µg $153
031-68 Ghrelin (1-18) amide (Human) 100 µg $214
B-031-68 Ghrelin (1-18) amide (Human) - Biotin Labeled 10 µg $306
FG-031-68A Ghrelin (1-18) amide (Human) - FAM Labeled 1 nmol $306
T-031-68 Ghrelin (1-18) amide (Human) - I-125 Labeled 10 µCi $723
FR-031-68 Ghrelin (1-18) amide (Human) - Rhodamine Labeled 1 nmol $357

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