Adiponectin receptor 2 is regulated by nutritional status, leptin and pregnancy in a tissue-specific manner

The aim of the present work was to study the regulation of circulating adiponectin levels and the expression of adiponectin receptor 2 (Adipo-R2) in several rat tissues in relation to fasting, leptin challenge, pregnancy, and chronic undernutrition. Using real-time PCR, we found Adipo-R2 mRNA expression in the liver, stomach, white and brown adipose tissues (WAT and BAT) of adult rats. Immunohistochemical studies confirmed protein expression in the same tissues. Adipo-R2 mRNA levels were decreased in liver after fasting, with no changes in the other tissues. Leptin decreased Adipo-R2 expression in liver and stomach, but increased its expression in WAT and BAT. Chronic caloric restriction in normal rats increased Adipo-R2 gene expression in stomach, while it decreased hepatic Adipo-R2 levels in pregnant rats. Using radioimmunoassay, we found that plasma adiponectin levels were diminished by fasting and leptin. Conversely, circulating adiponectin was increased in food-restricted rats, whereas its levels decreased in food-restricted pregnant rats by the end of gestation. In conclusion our findings provide the first evidence that (a) Adipo-R2 mRNA is regulated in a tissue-specific manner by fasting, but leptin is not responsible for those changes; (b) chronic caloric restriction in normal and pregnant rats also regulate Adipo-R2 mRNA in a tissue-specific manner; and (c) Adipo-R2 mRNA does not show a clear correlation with plasma adiponectin levels.

Switching to sirolimus in renal transplant recipients with hepatitis C virus: a safe option

INTRODUCTION

The presence of hepatitis C virus (HCV) in renal transplant recipients is an independent risk factor for death and graft failure. Chronic allograft nephropathy (CAN) favored by the use of calcineurin inhibitors (CNI) is one of the main causes of graft loss, whereas sirolimus (SRL) has proven to maintain better graft function with lower rates of CAN.

OBJECTIVES AND METHODS

We developed a protocol to evaluate the safety of SRL in transplant recipients with respect to HCV. We studied 5 patients (3 men) of mean age 52 +/- 9.2 years with HCV who had not received antiviral treatment. The viral genotypes were 1b in 4 cases and 2a/2c in 1 case. Basic immunosuppression was mycophenolate mofetil (MMF) and corticosteroids in all patients, cyclosporine (CsA) in 4 cases, and tacrolimus (Tac) in 1 case. Before the switch, a renal biopsy was performed and viral replication and cryoglobulins determined.

RESULTS

Biopsy provided a diagnosis of CAN in 1 case, CNI toxicity-associated CAN in 2 cases, CNI toxicity in 1 case, and no renal damage in the remaining case. We observed a nonsignificant decrease in the number (log) of viral copies with a stabilization of renal function but with a slight to moderate increase in proteinuria.

CONCLUSIONS

The switch seemed to be safe with no increase in viral copies. Graft renal function remained stable with increased proteinuria that must be supervised, even though it did not reach statistical significance.

Vaspin and amylin are expressed in human and rat placenta and regulated by nutritional status

Amylin (islet amyloid polypeptide) and vaspin (visceral adipose tissue specific serpin) are gut and adipocyte hormones involved in the regulation of body weight homeostasis. The aim of this study was to examine whether amylin and vaspin are expressed in human and rat placenta, as well as their regulation by nutritional status. Our results demonstrate that amylin and vaspin are localized in both human and rat placenta. In the rat term placenta vaspin was demonstrated in the trophoblast of the fetal villi, the labyrinth. Vaspin immunostaining in human placenta was localized in cytotrophoblast and syncytiotrophoblast in the first trimester placentas while in the third trimester vaspin was localized in the syncytiotrophoblast. Regarding amylin, rat placenta of 16 days of gestational age showed an intense immunostaining, mainly localized in the labyrinth. On the other hand, in the human third trimester placenta amylin immunoreactivity was intense in the syncytiotrophoblast of the chorionic villi and in decidual cells. Furthermore, placental amylin and vaspin showed an opposite pattern of expression during pregnancy, with vaspin showing the highest expression level at the end and amylin at the beginning of pregnancy. Finally, food restriction also has contrary effects on their expression, increasing vaspin but decreasing amylin placental mRNA and protein levels. Taken together, our results demonstrate that vaspin and amylin are modulated by energy status in the placenta, which suggests that these proteins may be involved in the regulation of placental metabolic functions.

Coexpression of matrix metalloproteinase-7 (MMP7) and phosphorylated insulin growth factor receptor I (pIGF-IR) as predictors of resistance to anti-EGFR therapy in advanced colorectal cancer (ACRC): A GEMCAD study

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Background: IGF-IR is supposed to have anti-apoptotic and mitogenic properties in colorectal cancer and by transactivation can promote EGFR phosphorylation. MMP-7 is produced by colorectal cancer cells and by degrading IGFBP-3 can activate IGF-IR. Methods: We retrospectively investigated the role of pIGF-IR immunoreactivity (IHC) (Rubini) and MMP-7 IHC in primary CRC or metastases, to predict response rate (RR), progression free survival (PFS) and overall survival (OS) in ACRC patients (pts) treated with either cetuximab or panitumumab as second or third line therapy. RAS mutational status of codons 12/13 was determined using quantitative PCR-based assay. CT scans were done every 1.5–2 months (m) until progressive disease. Results: A total of 99 pts with available tissue from 168 pts with ACRC treated with anti-EGFR therapy in 4 Spanish Institutions, were analysed for RAS mutational status, pIGF-1R and MMP-7. There were no major differences in RR (18.8 vs 16%), PFS [3.3 vs. 3.1 months (m)] and OS (7.7 vs. 7m) between the whole and selected cohort. Fifty-seven (57.6%) pts were male, the median age was 62 (range 34–79) years, the median number of previous chemotherapy lines was 2 (range 1–3) and PS was distributed as follow: PS0, 17 (17.2 %) pts; PS1, 66 (66.7%) pts and PS2, 16 (16.2%) pts. Expression of MMP-7 and pIGF-1R were observed in 48 (48.5%) and 52 (52.5%) pts respectively. Co-expression of MMP-7 and pIGF-1R [Double Positive (DP)] was observed in 26 (26.3 %) pts and in 16 (24%) out of 66 RAS wild-type (WTRAS) pts. There was no association between RAS mutational status and DP (p=0.52). DP progressed more than non-DP pts both in the overall sample (73 vs. 43%, p=0.028) and in WTRAS pts (75 vs. 32%, p=0.011). In the subset of WTRAS pts, DP pts also have a poorer OS: 6.4 (95% CI 5.8–7.1) m vs. 8.6 (95%CI 6.0–11.3) m (p=0.005), and a trend for worse PFS 2.7 vs 4.0 m (p=0.11). Conclusions: Co-expression of pIGF-1R and MMP7 is associated with resistance to anti- EGFR therapy in WTRAS pts. Our study suggests that pts with WTRAS and DP could be a target population to assay new anti-IGF-1R compounds.

No significant financial relationships to disclose.

Usefulness of PET/CT in the diagnosis of distant metastases of potentially operable gastric adenocarcinoma

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Background: 1) To evaluate the usefulness of Positron Emission Tomography with combined 18F-Fluorodeoxyglucose with Computed Tomography (PET/CT) in the diagnosis of distant metastases in patients with gastric adenocarcinoma (GAC) compared to spiral double contrast thoracoabdominal Computed Tomography (CT); 2) To establish the utility of PET/CT in the detection of peritoneal carcinomatosis compared to laparoscopy. Methods: Thirty prospective patients (22 men, 8 women; mean age 67±11) who underwent endoscopic ultrasound and were classified as T2–3N1 or T3Nx GAC were included in this study. Whole body images were obtained 1 hour after injection of 370 MBq of 18F-Fluorodeoxyglucose. CT was performed within 2 weeks of PET/CT. Laparoscopy was performed without remarkable incidences. All findings were confirmed by histopathology examination and/or by at least 6 months follow- up. Results: Distant metastases were found in 9/30 cases: carcinomatosis (3), retroperitoneal (3) or mediastinal (2) pathological lymph nodes and one case of bone metastases (1). PET/CT diagnosed unsuspected distant metastases by CT in 4/9 patients (retroperitoneal (1) or mediastinal (2) pathological lymph nodes and 1 case of bone metastasis in the spine). In 1/3 patients with histopathological confirmed diagnosis of peritoneal carcinomatosis by laparoscopic findings was negative by PET/CT, and considered as a false negative case. On the other hand, 3 patients with initially positive peritoneal carcinomatosis by invasive laparoscopy were finally diagnosed as benign lesions. These lesions did not show significant uptake in PET/CT and were considered as true negative cases. Conclusions: 1) PET/CT is useful in the diagnosis of distant metastases in patients with GAC 2) Further studies are needed to establish the role of PET/CT to detect peritoneal carcinomatosis.

No significant financial relationships to disclose.

Serum IGFBP3, IGF-I, and MMP7 changes in advanced colorectal cancer (ACRC) patients (pts) treated with anti-EGFR therapy: A GEMCAD study

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Background: Insulin-like growth factor-I (IGF-I) is a potent mitotic and anti-apoptotic peptide, whereas IGF binding protein-3 (IGFBP3) seems to have pro-apoptotic effects. Matrix metalloproteinase-7 (MMP7), an enzyme with in vitro ability to degrade IGFBP3, has been shown to be a prognostic factor in ACRC. Methods: This is a prospective single cohort traslational study. Pts undergoing second/third line with irinotecan plus anti-EGFR therapy were eligible as cases. Patients with ACRC not undergoing therapy were eligible as controls. IGFBP3 and MMP7 were measured in serum with immunoassays at baseline and at 48h after treatment start. KRAS mutation status in codons 12/13 was determined by sequencing in 53 pts. The primary endpoint is to define the IGFBP3 and MMP7 variation under anti-EGFR therapy. IGFBP3 was used as a continuous variable and MMP7 was used to create two groups by its third quartile. Results: Eighty-five cases and 25 controls were recruited. No significant changes at 48h in IGF-I and IGFBP3 were found, but a significant decrease in MMP7 from 10.8 (95%IC 8.3–13.3) to 8.4 ng/ml (95%IC 6–10.9) was observed in cases (p<0.001) in contrast with controls, where no changes were found. Splitting the sample by the third quartile of MMP7 interesting changes in IGFBP3 variations were found. In the group with low levels of MMP7, IGFBP3 increases from 1,859 to 1,959 ng/ml (p=0.043) 48h after treatment initiation; on the contrary, in the group with high levels of MMP7, IGFBP3 decreases from 1,811 to 1,757 ng/ml (p=0.741). We found no association with IGFBP3 and neither response rate, time to progression nor overall survival. This latter analysis was also done only in pts with wild-type KRAS, without any change in the results. Conclusions: In pts with ACRC treated with anti-EGFR therapy, serum levels of IGFBP3 variations depend on basal MMP7 levels. IGFBP3 failed to be a predictive/prognostic factor in our sample although the limited number of KRAS pts analyzed can influence our results. [Table: see text]

No significant financial relationships to disclose.

Bevacizumab (B), cisplatin, and vinorelbine in chemotherapy-naive patients (p) with nonsquamous non-small cell lung cancer (NSCLC): A Galician Lung Cancer Group phase II study

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Background: Bevacizumab, an anti-VEGF monoclonal antibody, improves response rates and prolongs survival in p with non squamous NSCLC when combined with carboplatin-paclitaxel or cisplatin-gemcitabine. This single-arm, open-labeled phase II trial aims to evaluate the efficacy and safety profile of B in combination with another widely used chemotherapy doublet for NSCLC: cisplatin and vinorelbine. Methods: Chemotherapy-naïve p diagnosed with stage IIIB or IV non squamous NSCLC received cisplatin (80 mg/m2), vinorelbine (25 mg/m2 IV days 1 and 8) and B (15 mg/kg IV) on day 1 every 3 weeks for up to 6 cycles followed by B 15 mg/kg alone every 3 weeks until disease progression. Main eligibility criteria were: PS 0–1, no brain metastases, no history of hemoptysis, stable cardiac condition and no full dose anticoagulation. Primary endpoint was progression-free survival and secondary endpoints were RR, duration of response, OS, 1-year survival and safety profile of the combination. Results: 38 p have been enrolled in the study and data of 27 p have been included in this analysis. P characteristics were: male 66.7%; median age 57 years (range 41–74); ECOG PS 0/1 (%) 33.3/66.7; adenocarcinoma/other (%) 74.1/25.9; stage IIIB/IV (%) 25.9/74.1. Median number of cycles for B/cisplatin/vinorelbine was 4.0 (range 1–6) and median number of cycles for B maintenance was 2 (range 1–4). 17 p were evaluable for response according to RECIST criteria: PR 29.4% and SD 41.2%. With a median follow-up of 3.9 months (range 0.7–11.1), median PFS was 4.6 months (95% CI: 2.6–6.6) and median OS has not been reached yet. Hematological toxicities were: 1 p gr. 3 anemia; 2 p gr. 3 and 2 p gr. 4 leucopenia; 10 p gr. 3, 1 p gr. 4 neutropenia and 3 p febrile neutropenia. Most common grade 3/4 non hematological toxicities were: vomiting (1p gr. 4), high blood pressure, asthenia and hyperglycemia. 1 p experienced gr. 4 abdominal pain, 1 p. gr. 4 constipation, 1 p. gr. 4 nausea and 1 p gr. 4 respiratory infection. No grade 3/4 hemoptysis were reported. Conclusions: This interim analysis shows that B in combination with cisplatin and vinorelbine is safe and well tolerated and has a promising activity in chemo-naïve p with non squamous NSCLC. Survival data will be updated.

[Table: see text]

Phase II study of bevacizumab in combination with cisplatin and docetaxel as first-line treatment of patients (p) with metastatic non-squamous non-small cell lung cancer (NSCLC)

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Background: Bevacizumab (B), in addition to platinum-based chemotherapy, is indicated for 1st-line treatment of p with advanced NSCLC other than predominantly squamous cell histology. B has been shown to improve progression free survival (PFS) and overall survival (OS) when combined with cisplatin/gemcitabine and carboplatin/paclitaxel, respectively. However, there are limited data on the safety and efficacy of B in combination with other widely used chemotherapy doublets for NSCLC. This is a single-arm, open- labeled, single-stage phase II trial of cisplatin (C), docetaxel (D) and B for NSCLC. Methods: Eligibility criteria: chemo- naïve, stage IIIB wet or IV, non-squamous NSCLC, PS 0–1, no brain metastases and no history of gross hemoptysis. P received D (75 mg/m2), C (75 mg/m2), and B (15 mg/kg iv) on day 1 every 3 weeks for up to 6 cycles, followed by B 15 mg/kg alone every 3 weeks until disease progression or toxicity. Primary endpoint: PFS. Results: 50 p were enrolled (enrollment completed): 24% female, median age 60 (36–74), PS 1: 64%, adenocarcinoma: 72%; stage IV: 92%. Two p did not start treatment. Median follow-up is 5.3 months (range 0–13.6). Median number of cycles of B was 7 (range 0–18). 56% completed 6 cycles of treatment; 24% received ≥ 12 cycles of B. Most frequent grade ≥ 3 toxicities: diarrhea (14.6%), fatigue (14.6%), dyspnea (9.8%), anorexia (4.9%), alopecia (4.9%), esophagitis (4.9%), constipation (4.9%), mucositis (12.2%), proteinuria (4.9%); hematological toxicities: neutropenia (22%), febrile neutropenia (9.8%), leucopenia (14.6%), lymphopenia (4.9%). Of interest, 41.5% developed grade <3 epistaxis and 17% hypertension (1 p grade 3). One p died due to hemoptysis. 46 p were evaluable for response: 29 PRs (ORR: 63%). 18 of 48 p have experienced progression or death with a median SLP of 7.8 months (95% CI: 6.6-NR). Median OS is 13.5 months (95% CI: 12.7–13.6; 81.2% p censored); 1-year survival is 83.9% (95% CI: 67.4%-92.5%). Conclusions: Treatment with C, D and B, followed by maintenance B in 1st line of advanced non-squamous NSCLC shows an acceptable toxicity profile and promising efficacy. Final results will be presented.

[Table: see text]

Phase II study with preoperative oxaliplatin (O), cisplatin (P), 5-fluorouracil (F) (OPF) and radiation (XRT) in patients with esophageal (ES), gastroesophageal (GE), and gastric (G) cancer

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Background: A phase I study showed the feasibility of the triplet combination (OPF) with XRT in ES and GE cancer (Maurel et al, IJRBOP, 2005). We conducted a phase II study to evaluate the efficacy of the regimen. Methods: Enrolled pts had resectable, high-risk (HR) based on endoscopic ultrasonography (EUS) (uT3, uN1 or uT4 if deemed resectable) ES, GE and G cancer. The primary objective was to determine the pathologic complete response (pCR). If 2 or more pCR were reported in the first 18 pts treated, enrollment continues with 23 additional pts. Eligibility criteria: squamous cell or adenocarcinoma of the ES, GE or G cancer and ECOG Performance status (PS) 0–1. Staging was done with EUS and computed spiral tomography. Laparoscopic staging was mandatory for pts with ES, GE and G adenocarcinoma. Pts received 2 cycles of O 85 mg/m2, P 55 mg/m2, F (3 g/m2 in 96h CI) q4w, with concomitant 45 Gy XRT in 25 fractions; surgery was planned 5–8 weeks after XRT. All pathological specimens were reviewed by a unique pathologist and regression analysis was recorded using Cologne (C) and M.D.Anderson (MDA) classification for ES and European Journal of Surgical Oncology (EJSO) for GE and G. Results: Between 5/04 to 12/07, 41 pts were enrolled in 5 Spanish Institutions. Median age 62 yrs (39–75 yrs); Male/female 83%/17%; PS 0/1 27%/73%; ES/GE/G 39%/32%/29%; EUS stageT3N0 (20%), T2–3N1 (65%) and T4 (10%). G3/4 adverse events included asthenia (27%), infection (7%), diarrhea (7%) and stomatitis (5%). There were 2 toxic deaths. Of the 31 pts who underwent surgery, there were R0=94%/R1=3%/R2= 3%. 7/41 pts (17%) achieved pCR. Using C and MDA classification, 9/14 (61%) and 12/14 (85%) ES achieved grade IV/III and P0/P1 regression, respectively. With EJSO classification 3/17 (18%) GE and G tumors achieved pCR. Median time to progression or death (PFS) was 16.2 (CI:12.2-NR) months (mo). Median overall survival (OS) was 28.9 mo. (CI: 22.5-NR). Conclusions: Although in the whole group pCR, PFS and OS does not appear superior to results achieved in other trials with preoperative P/F/XRT in HR pts, the OPF regimen seems specially active in ES cancer.

No significant financial relationships to disclose.

Morphological and functional evaluation of visual disturbances in a bilateral hand allograft recipient

Allograft recipients are exposed to risks owing to immunosuppression, and there is always the possibility that psychological issues interfere with the procedure's outcomes. An episode of blindness was suspected in a bilateral hand allograft recipient. The patient underwent a multidisciplinary evaluation, and clinical, electrophysiological, laboratory and a combination of functional and morphological magnetic resonance imaging (MRI) tests ruled out any visual process and revealed a secondary benefit, which turned out to be the use of privileges of the transplant support centre for several months. Composite tissue allograft recipients require a thorough psychological assessment before and after transplant procedures to prevent malingering.

A new player in cartilage homeostasis: adiponectin induces nitric oxide synthase type II and pro-inflammatory cytokines in chondrocytes

OBJECTIVE

Recent studies revealed a close connection between adipose tissue, adipokines and articular degenerative inflammatory diseases such as rheumatoid arthritis (RA) and osteoarthritis (OA). The goal of this work was to investigate the activity of adiponectin in human and murine chondrocytes and to study its functional role in the modulation of nitric oxide synthase type II (NOS2). For completeness, interleukin (IL)-6, IL-1beta, matrix metalloproteinase (MMP)-2, MMP-3, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1, prostaglandin E2 (PGE2), leukotriene B4 (LTB4), tumor necrosis factor alpha (TNF)-alpha and monocyte chemoattractant protein-1 (MCP-1) accumulation have been evaluated in adiponectin-stimulated chondrocytes cell culture supernatants.

METHODS

Murine ATDC5 cell line, C28/I2, C20A4, TC28a2 human immortalized chondrocytes, and human cultured chondrocytes were used. Nitrite accumulation was determined by Griess reaction. Adiponectin receptors (AdipoRs) expression was evaluated by immunofluorescence microscopy and confirmed by reverse transcriptase-polymerase chain reaction. NOS2 expression was evaluated by Western blot analysis whereas cytokines, prostanoids and metalloproteinases production was evaluated by specific enzyme-linked immunosorbent assays.

RESULTS

Human and murine chondrocytes express functional AdipoRs. Adiponectin induces NOS2. This effect is inhibited by aminoguanidine, dexamethasone and by a selective inhibitor of phosphatidylinositol 3-kinase. In addition, adiponectin is able to increase IL-6, MMP-3, MMP-9 and MCP-1 by murine cultured chondrocytes whereas it was unable to modulate TNF-alpha, IL-1beta, MMP-2, TIMP-1, PGE2 and LTB4 release.

CONCLUSIONS

These results bind more closely the interactions between fat-derived adipokines and articular inflammatory diseases, and suggest that adiponectin is a novel key element in the maintenance of cartilage homeostasis which might be considered as a potential therapeutical target in joint degenerative diseases.

Nocturnal ultrafiltration profiles in patients on APD: impact on fluid and solute transport

In order to prevent morbidity and mortality in peritoneal dialysis (PD), sodium and water balance as well as a minimal level of small-solute clearances are needed. The impact of three nocturnal peritoneal ultrafiltration (UF) profiles on UF and small solute clearance in patients on automated PD (APD) was studied: constant glucose concentration of 1.36% (flat) or modifying the glucose concentration of the heater bag (descendant: 3.86-1.36%; ascendant: 1.36-3.86%). Sixty-two patients were enrolled in the study and received each profile within a four-month period, thus serving as their own controls. UF was lower with the flat profile (367+/-420ml; P<0.01), but no difference was seen between the two higher glucose concentration profiles. Peritoneal Kt/V (pKt/V) and peritoneal creatinine clearance (CrpC) showed statistically higher values from the descendant vs ascendant vs flat profiles (pKt/V: 1.54+/-0.30 vs 1.45+/-0.30 vs 1.38+/-0.27, and CrpC: 36.9+/-7.9 vs 33.5+/-7.48 vs 29.92+/-7.5 mlmin(-1)). Multivariate analysis showed statistical significance for the following: in the intrasubject comparisons, the profile for pKt/V (F=9.109, P<0.001) and CrpC (F=11.697, P<0.001), and in the intersubjects comparisons, the effects of both gender (F=14.334, P<0.01) for pKt/V and peritoneal permeability for both parameters (pKt/V: F=4.37, P<0.05; CrpC: F=11.697, P<0.001). In conclusion, the application of ascendant and descendant UF profiles in automated PD is feasible and results in better UF and small solute clearances, thus preventing inadequate dialysis and volume overload..

Hypothalamic fatty acid metabolism mediates the orexigenic action of ghrelin

Current evidence suggests that hypothalamic fatty acid metabolism may play a role in regulating food intake; however, confirmation that it is a physiologically relevant regulatory system of feeding is still incomplete. Here, we use pharmacological and genetic approaches to demonstrate that the physiological orexigenic response to ghrelin involves specific inhibition of fatty acid biosynthesis induced by AMP-activated protein kinase (AMPK) resulting in decreased hypothalamic levels of malonyl-CoA and increased carnitine palmitoyltransferase 1 (CPT1) activity. In addition, we also demonstrate that fasting downregulates fatty acid synthase (FAS) in a region-specific manner and that this effect is mediated by an AMPK and ghrelin-dependent mechanisms. Thus, decreasing AMPK activity in the ventromedial nucleus of the hypothalamus (VMH) is sufficient to inhibit ghrelin's effects on FAS expression and feeding. Overall, our results indicate that modulation of hypothalamic fatty acid metabolism specifically in the VMH in response to ghrelin is a physiological mechanism that controls feeding.

Ghrelin localization in the medulla of rat and human adrenal gland and in pheochromocytomas

OBJECTIVE

Ghrelin is predominantly produced by neuroendocrine cells of stomach and has been expressed in several normal and tumour endocrine tissues. It has been reported that the localization of ghrelin is exclusively in the cortex of human and rat adrenal gland and in adrenocortical tumours. This prompted us to analyze the expression of this peptide in medulla of human and rat adrenal glands and in human pheochromocytomas.

DESIGN AND METHODS

Analysis of ghrelin mRNA expression in rat adrenal gland was conducted by means of semi-quantitative RT-PCR. Ghrelin localization was studied in medulla of human and rat adrenal gland by immunohistochemistry. In addition, we have carried out a double immunofluorescence with chromogranin A to determine the specific cell type expressing ghrelin immunoreactivity. Ghrelin expression was also analyzed in five cases of pheochromocytoma by immunohistochemistry. Finally, Western blotting analysis was performed with goat ghrelin antibody in the cortex and in the medulla of rat adrenal gland.

RESULTS

RT-PCR demonstrated expression of ghrelin mRNA in rat adrenal gland. We also detected ghrelin expression in virtually all rat pheochromocytes by immunohistochemistry and double immunofluorescence. Furthermore, we showed ghrelin immunoreactivity in the medulla of human adrenal gland and in pheochromocytomas. By Western blotting, we found the expression of ghrelin precursor, proghrelin and mature ghrelin in the medulla of rat adrenals. However, the cortex of rat adrenal gland only expressed ghrelin precursor.

CONCLUSIONS

Our study is the first to demonstrate a medullar expression of ghrelin in human and rat adrenal gland; we also showed ghrelin expression in pheochromocytomas.