Role of calorie restriction on pathophysiological changes in tongue fat and its relation to increased risk factors of obstructive sleep apnea in WNIN/Ob obese rats

Abstract

Purpose

Obstructive sleep apnea is an outcome of obesity, resulting from abnormal upper airway structures. Our main objective was to assess the fat infiltration into the tongue of calorie-restricted rats and its consequences on upper airway obstruction in comparison with lean and obese rats.

Methods

A total of 24 adults lean, obese and CR obese rats were included in the study. Body fat and lean body mass were determined by TOBEC, DXA measured fat depositions around the neck region, and radiographs of upper airway structure were analysed by digital X-ray. Ex vivo biochemistry was carried out for leptin, and lipids in blood/tissues, and fat infiltration by ORO staining. The tongue, masseter muscle fat, fibre and taste bud morphology was assessed by SEM.

Results

Body composition analysis showed higher body fat and low lean body mass in obese animals; DXA results showed excess fat around the neck region of obese rats. Higher triglyceride and reduced leptin levels were observed in CR obese rats compared to lean and obese rats. ORO and SEM analysis showed varying degree of fat accumulation among the groups. Tongue muscle fibres of obese rats showed rugged abnormal folding with an increase in width in comparison with calorie-restricted obese rats. The distance and width between the taste buds of calorie-restricted obese rats were reduced to the levels of lean rats.

Conclusion

The calorie restriction in obese rats reduced the fat deposition around the neck and improves the upper airway structures, the morphology of tongue fibre and increased the stiffness of the tongue, thereby reducing the risk of obstructive sleep apnea.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5

Abbreviations

OSA:

Obstructive Sleep Apnea

CR:

Calorie restricted

TOBEC:

Total body electrical conductivity

LBM:

Lean body mass

LS:

Longitudinal Sections

PBS:

Phospate buffer saline

SEM:

Scanning electron microscopy

ORO:

Oil Red-O

H&E:

Haematoxylin and Eosin

TG:

Triglycerides

DXA:

dual X-ray absorptiometry

References

  1. 1.

    Folch J, Lees M. Sloane SGH.A simple method for the isolation and purification of total lipides from animal tissues. J Biol Chem. 1957;226:497–509.

    CAS  Google Scholar 

  2. 2.

    Argmann CA, Houten SM, Champy MF, et al. Lipid and bile acid analysis. Curr Prot Mol Biol. 2006;29:Unit 29B 2–24.

    Google Scholar 

  3. 3.

    Nashi N, Kang S, Barkdull GC, Lucas J, Davidson TM. Lingual fat at autopsy. Laryngoscope. 2007;117:1467–73.

    Article  Google Scholar 

  4. 4.

    Hayter AJ. Pairwise comparisons of generally correlated means. J Am Stat Assoc. 1989;84:208–13.

    Article  Google Scholar 

  5. 5.

    Boyd JH, Petrof BJ, Hamid Q, et al. Upper airway muscle inflammation and denervation changes in obstructive sleep apnea. Am J RespirCrit Care Med. 2004;170:541–6.

    Article  Google Scholar 

  6. 6.

    Kim AM, Keenan BT, Jackson N, Chan EL, Staley B, Poptani H, et al. Tongue fat and its relationship to obstructive sleep apnea. Sleep. 2014;37(10):1639–48.

    Article  Google Scholar 

  7. 7.

    Brennick MJ, Delikatny J, Pack AI, et al. Tongue fat infiltration in obese versus lean Zucker rats. Sleep. 2014;37(6):1095–102.

    Article  Google Scholar 

  8. 8.

    Walford RL, Mock D, MacCallum T, et al. Physiologic changes in humans subjected to severe, selective calorie restriction for two years in the biosphere: health, ageing, and toxicological perspectives. Toxicol Sci. 1999;52(2):61–5.

    CAS  Article  Google Scholar 

  9. 9.

    Walford RL, Mock D, Verdery R, et al. Calorie restriction in the biosphere: alterations in physiologic, hematologic, hormonal, and biochemical parameters in humans restricted for 2 years. J GerontolBiolSci Med Sci. 2002;57:211–24.

    Article  Google Scholar 

  10. 10.

    Robertson RP. Chronic oxidative stress as a central mechanism for glucose toxicity in pancreatic islet beta cells in diabetes. J Biol Chem. 2004;279:42351–4.

    CAS  Article  Google Scholar 

  11. 11.

    Stenkula KG, Said L, Karlsson M, Thorn H, Kjølhede P, Gustavsson J, et al. Expression of a mutant IRS inhibits metabolic and mitogenic signalling of insulin in human adipocytes. Mol Cell Endocrinol. 2004;221:1–8.

    CAS  Article  Google Scholar 

  12. 12.

    Anandam A, Morohunfolu A, Jahan P, et al. Effect of dietary weight loss on obstructive sleep apnea; a meta analysis. Sleep Breath. 2013;17(4):227–34.

    Article  Google Scholar 

  13. 13.

    Johansson K, Neouilu M, Laggerros YT, et al. Effect of a very low energy diet on moderate and severe obstructive sleep apnoea in obese men: a randomised controlled trial. BMJ. 2009;339:b4609.

    Article  Google Scholar 

  14. 14.

    Suratt PM, Mc Tier F, Findley LJ, et al. Changes in breathing and the pharynx after weight loss in obstructive sleep apnea. Chest. 1987;92(4):631–7.

    CAS  Article  Google Scholar 

  15. 15.

    Kansanen M, Vanninen E, Tuunainen A, Pesonen P, Tuononen V, Hartikainen J, et al. The effect of a very low calorie diet induced weight loss on the severity of obstructive sleep apnoea syndrome. Clin Physiol. 1998;18(4):377–85.

    CAS  Article  Google Scholar 

  16. 16.

    Tuomilehto HPI, Seppa JM, Partinen MM, et al. Life style intervention with weight reduction, first line treatment in mild obstructive sleep apnea. Am J Respir Crit Care Med. 2009;179:320–7.

    Article  Google Scholar 

  17. 17.

    Thomasouli MA, Brady EM, Davies MJ, et al. The impact of diet and lifestyle management strategies for obstructive sleep apnoea in adults; a systematic review and meta analysis of randomised controlled trials. Sleep Breth. 2013;17(3):925–35.

    Article  Google Scholar 

  18. 18.

    Giridharan NV, Lakshmi CN, Raghuramulu N. Identification of impaired glucose tolerant animals from a Wistar inbred rat colony. Lab Anim Sci. 1997;47:428–31.

    CAS  PubMed  Google Scholar 

  19. 19.

    Giridharan NV, Satyavani M, Harishankar N. WNIN/Ob a new rat model for the study of obesity. Scand J Lab Anim Sci. 1996;23(3):131–7.

    Google Scholar 

  20. 20.

    Harishankar N, Vajreswari A, Giridharan NV. WNIN/GR-Ob – an insulin-resistant obese rat model from inbred WNIN strain. Indian J Med Res. 2011;134:320–9.

    CAS  PubMed  PubMed Central  Google Scholar 

  21. 21.

    Padmavathi IJN, RajenderRao K, Venu L, et al. Chronic dietary restriction modulates visceral adiposity probable underlying mechanism. Diabetes. 2010;59:98–104.

    CAS  Article  Google Scholar 

  22. 22.

    Morbach CA, Brans YW. Determination of body composition in growing rats by total body electrical conductivity. J PediatGastroenterolNutr. 1992;14:283–92.

    CAS  Google Scholar 

  23. 23.

    Shivaram N, Uday KP, Madhusudhanachary P, et al. Botulinum neurotoxin effects on masseter muscle fibre in WNIN obese rats – scanning electron microscope analysis. Scanning. 2015. https://doi.org/10.1002/sca.21283.

  24. 24.

    Bindhu M, Barry Y, Rani S, et al. Evaluation of organ weights for rodent and non-rodent toxicity studies: A review of regulatory guidelines and a survey of current practices. ToxicolPathol. 2007;35:742–50.

    Google Scholar 

  25. 25.

    Roland TJ. Obesity as a disease. Br Med Bull. 1997;53(2):307–21.

    Article  Google Scholar 

  26. 26.

    Riley V. Adaptation of orbital bleeding technic to rapid serial blood studies. Proc Soc Exp Biol Med. 1960;104:751–4.

    CAS  Article  Google Scholar 

  27. 27.

    Allen CC, Poon SL, Chan SG, et al. Enzymatic determination of total serum cholesterol. Clin Chem. 1974;20:470–5.

    Article  Google Scholar 

  28. 28.

    Farkas GA, Schienker EH. Pulmonary ventilation and mechanics in morbidly obese Zucker rats. Am J RespirCrit Care Med. 1994;150:356–62.

    CAS  Article  Google Scholar 

  29. 29.

    Schienker EH, Farks GA. Endogenous opioids modulate ventilation in the obese Zucker rats. Respir Pathol. 1995;99:97–103.

    Google Scholar 

  30. 30.

    Kawano K, Hirushima T, Mori S, et al. Spontaneous long-term hyperglycemic with diabetic complications in otsuka long evanstokushima fatty (OLETF) strain. Diabetes. 1992;41:1422–8.

    CAS  Article  Google Scholar 

  31. 31.

    Zucker TF, Zucker LM. Hereditary obesity in the rat associated with high serum fat and cholesterol. Proc Soc ExptlBiol Med. 1962;110:165–71.

    CAS  Article  Google Scholar 

  32. 32.

    Considine RV, Sinha MK, Heiman ML, et al. Serum immunoreactive-leptin concentration in normal weight and obese humans. N Engl J Med. 1996;334(5):292–5.

    CAS  Article  Google Scholar 

  33. 33.

    Christopher PO, Charles D, Schaub AS, et al. Leptin prevents respiratory depression in obesity. Am J RespirCrit Care Med. 1999;159:177–1484.

    Google Scholar 

  34. 34.

    Zohar Y, Sabo R, Strauss M, et al. Oropharyngeal fatty infiltration in obstructive sleep apnea patients: a histologic study. Ann OtolRhinolLaryngol. 1998;107:170–4.

    CAS  Google Scholar 

  35. 35.

    Friberg D, Ansved T, Borg K, et al. Histological indications of a progressive snorer’s disease in an upper airway muscle. Am J Respir Crit Care Med. 1998;157:586–93.

    CAS  Article  Google Scholar 

  36. 36.

    Series F, Cote C, Simoneau J, et al. Physiologic, metabolic, and muscle fiber type characteristics of musculus uvulae in sleep apnea hypopnea syndrome and in snorers. J Clin Invest. 1995;95:20–5.

    CAS  Article  Google Scholar 

  37. 37.

    Longobardo GS, Evangelisti CJ, Cherniack NS. Analysis of the interplay between neurochemical control of respiration and upper airway mechanics producing upper airway obstruction during sleep in humans. Exp Physiol. 2007;93:271–87.

    Article  Google Scholar 

  38. 38.

    Edström L, Larsson H, Larsson L. Neurogenic effects on the palatopharyngeal muscle in patients with obstructive sleep apnea: a muscle biopsy study. J NeurolNeurosurg Psych. 1992;55:916–20.

    Article  Google Scholar 

  39. 39.

    Brown EC, Cheng S, McKenzie DK, Butler JE, Gandevia SC, Bilston LE. Respiratory movement of upper airway tissue in obstructive sleep apnea. Sleep. 2013;36:1069–76.

    Article  Google Scholar 

Download references

Acknowledgements

Authors acknowledge the Indian Council of Medical Research (ICMR), Governmentof India, New Delhi, for the financial support, and Shriyut K. Satyanarayana, and N. Yadagiri Animal Caretakers, for their co-operation in the maintenance of the obese rat colony. Mr. P. Madhusudhanachari for technical assistance. Authors also thank Dr. R. Hemalatha, Director, National Institute of Nutrition for her support.

Funding

The present experiment is an intramural research project of the National Centre for Laboratory Animal Sciences, National Institute of Nutrition, funded by Indian Council of Medical Research. The findings expressed in the manuscript represent the view of the authors and do not pose the views of the National Institute of Nutrition.

Author information

Affiliations

Authors

Contributions

K. Prathap Reddy carried out the animal experiment and analysis. N. Shivaram helped in the surgical removal of masseter muscle and tongue from lean and obese rats. P. UdayKumar helped in analysing the results of scanning electron microscopy. M.V. Surekha carried out the haemogram analysis and histopathology of masseter and tongue muscle tissues. P. Suresh contributed equally to this paper in various aspects of this study. N. Harishankar drafted and evaluated the manuscript along with the other authors. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Nemani Harishankar.

Ethics declarations

Conflict of interest

The authors declare that they have no conflict of interests.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Reddy, K.P., Shivaram, N., Kumar, P.U. et al. Role of calorie restriction on pathophysiological changes in tongue fat and its relation to increased risk factors of obstructive sleep apnea in WNIN/Ob obese rats. Nutrire 45, 10 (2020). https://doi.org/10.1186/s41110-019-0112-7

Download citation

Keywords

  • Calorie restriction
  • Lipids
  • Masseter muscle
  • Obesity
  • Upper airway structures