Functional and morphological changes in endocrine pancreas following cola drink consumption in rats

PLoS One. 2015 Mar 19;10(3):e0118700. doi: 10.1371/journal.pone.0118700. eCollection 2015.

Abstract

Aim: We report the effects of long-term cola beverage drinking on glucose homeostasis, endocrine pancreas function and morphology in rats.

Methods: Wistar rats drank: water (group W), regular cola beverage (group C, sucrose sweetened) or "light" cola beverage (group L, artificially sweetened). After 6 months, 50% of the animals in each group were euthanized and the remaining animals consumed water for the next 6 months when euthanasia was performed. Biochemical assays, insulinemia determination, estimation of insulin resistance (HOMA-IR), morphometry and immunohistochemistry evaluations were performed in pancreas.

Results: Hyperglycemia (16%, p<0.05), CoQ10 (coenzyme-Q10) decrease (-52%,p<0.01), strong hypertriglyceridemia (2.8-fold, p<0.01), hyperinsulinemia (2.4 fold, p<0.005) and HOMA-IR increase (2.7 fold, p<0.01) were observed in C. Group C showed a decrease in number of α cells (-42%, p<0.01) and β cells (-58%, p<0.001) and a moderate increase in α cells' size after wash-out (+14%, p<0.001). Group L showed reduction in β cells' size (-9%, p<0.001) and only after wash-out (L12) a 19% increase in size (p<0.0001) with 35% decrease in number of α cells (p<0.01). Groups C and L showed increase in α/β-cell ratio which was irreversible only in C (α/β = +38% in C6,+30% in C12, p<0.001vs.W6). Regular cola induced a striking increase in the cytoplasmic expression of Trx1 (Thioredoxin-1) (2.25-fold in C6 vs. W6; 2.7-fold in C12 vs. W12, p<0.0001) and Prx2 (Peroxiredoxin-2) (3-fold in C6 vs. W6; 2-fold in C12 vs. W12, p<0.0001). Light cola induced increase in Trx1 (3-fold) and Prx2 (2-fold) after wash-out (p<0.0001, L12 vs. W12).

Conclusion: Glucotoxicity may contribute to the loss of β cell function with depletion of insulin content. Oxidative stress, suggested by increased expression of thioredoxins and low circulating levels of CoQ10, may follow sustained hyperglycemia. A likely similar panorama may result from the effects of artificially sweetened cola though via other downstream routes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Blood Glucose / metabolism
  • Carbonated Beverages / adverse effects*
  • Carbonated Beverages / analysis
  • Cola / chemistry*
  • Immunohistochemistry
  • Insulin Resistance / physiology
  • Islets of Langerhans / drug effects*
  • Islets of Langerhans / pathology
  • Oxidative Stress / drug effects*
  • Rats
  • Triglycerides / blood
  • Ubiquinone / analogs & derivatives
  • Ubiquinone / metabolism

Substances

  • Blood Glucose
  • Triglycerides
  • Ubiquinone
  • coenzyme Q10

Grant support

This work was supported by PIP 6549, http://www.conicet.gov.ar/, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina (JM); UBACYT M052, http://www.uba.ar/, Universidad de Buenos Aires, Argentina (JM); Framework Agreement between the University of Buenos Aires – Instituto de Investigaciones Cardiológicas – and the University of Perugia – Division of Cardiology. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.