Protocatechuic acids protects against high glucose- induced insulin resistance in human visceral adipose tissue

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Abstract


Adipocytes exposed to high glucose concentrations exhibit impaired insulin signaling. Binding of insulin to its membrane receptor activates insulin metabolic pathway leading to IRS-1 and AKT phosphorylations. The accumulation of visceral adipose tissue (VAT) correlates with insulin resistance and metabolic syndrome. Anthocyanins (ACN) are bioactive food compounds of great nutritional interest. We have shown that protocatechuic acid (PCA), a major metabolite of ACN, might exert insulin-sensitizer activities in human visceral adipose tissue. The aim of this work was to define the protective role of PCA against insulin-resistance induced by high glucose in VAT.

Methodology: VAT obtained from control subject (BMI≤25) were separated in four experimental groups: i) PCA: samples treated for 24 h with 100 μM PCA, ii) GLU: VAT treated with 30 mM glucose for 24 h, iii) PCA+GLU: 1 hour incubation with 100 μM PCA before adding glucose (30 mM, 24 h), iv) CTR: vehicle. After treatment, VAT groups were (or not) acutely stimulated with insulin (20 nM, 20 min). Tyr-IRS-1 and Ser-Akt phosphorylations were assessed by Western blotting (WB) in basal or insulin stimulated tissues in all experimental groups. Samples were assessed for IRS-1, IR, Akt and GLUT4 protein content by WB.

Results: No differences in protein contents between experimental groups were found. GLU tissues showed a lower increment in insulin-stimulated phosphorylation of IRS-1 and Akt compared to CTR and PCA samples. This impaired activation was completely reversed by the pretreatment with PCA.

Conclusion: An in-vitro insulin-resistance condition induced by high glucose was established in biopsies of VAT. PCA restores the ability of GLU-tissues to fully respond to insulin by increasing IRS-1 and Akt phosphorylations. These results confirm the insulin-sensitizer effect of PCA on VAT previously reported by our group. An anthocyanin rich diet might help to protect against insulin-resistance in VAT.


Paulina Ormazabal

Author for correspondence.
pormazabal@uandes.cl
Biomedical Research Center, Universidad de los Andes, Santiago, Chile & Dept Veterinary Public Health and Food Safety, Istituto Superiore di Sanità Rome, Italy
Chile

Biochemist of Universidad de Santiago de Chile (2007), PhD in Biomedical Sciences from University of Chile (2012), postdoctoral fellow of the Nutrition Unit of Istituto Superiore di Sanità, Rome Italy (2014-2015). Currently Dr Ormazabal has a researcher/teacher position at Biomedical Research Center, Faculty of Medicine, Universidad de los Andes, Santiago, Chile

Beatrice Scazzocchio

beatrice.scazzocchio@iss.it
Dept Veterinary Public Health and Food Safety, Istituto Superiore di Sanità Rome
Italy

Biologist of Università La Sapienza Roma, Italy (1998). Dr Scazzocchio has a permanent position as researcher in the Nutrition Unit of Istituto Superiore di Sanità, Rome Italy where she has been working since 2002.

Rosaria Varì

rosaria.vari@iss.it
Dept Veterinary Public Health and Food Safety, Istituto Superiore di Sanità Rome

Biologist of Università La Sapienza Roma (2000). Dr Varì is researcher in the Nutrition Unit of Istituto Superiore di Sanità from 2002 to date.

Annunziata Iacovelli

nunziaiacovelli@yahoo.it
Fabia Mater Hospital, Rome
Italy

M.D. from Università degli Studi di Roma La Sapienza (1977), Obstetrician/gynecologist (1981) and subspeciality in General Oncology (1985) from Università degli Studi di Roma La Sapienza. Currently, Dr. Iacovelli works in the Gynecology Unit of Fabia Mater Hospital, Rome, Italy.

Roberta Masella

roberta.masella@iss.it
Dept Veterinary Public Health and Food Safety, Istituto Superiore di Sanità Rome
Italy

1981 PhD Biological Sciences at University of Rome “La Sapienza”.1985 MSc Pathology at Catholic University of Rome, Italy.Permanent position as senior researcher and group leader at Istituto Superiore di Sanità (ISS), Laboratory of Metabolism and Pathological Biochemistry (1997-2003), Italian National Centre for Food Quality and Risk Assessment, (2004-2007), and Department of Veterinary Public Health and Food Safety (2007-present)

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Copyright (c) 2016 Ormazabal P., Scazzocchio B., Varì R., Iacovelli A., Masella R.

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