The role of neuropeptide Y, orexin-A, and ghrelin in differentiating unipolar and bipolar depression: a preliminary study

Abstract

Background

When depressive symptoms in bipolar and unipolar patients were compared, a number of studies reported that atypical vegetative features such as hypersomnia and hyperphagia were more common in bipolar patients. Moreover, neuropeptides such as orexin-A (ORX-A), ghrelin (GRL), and neuropeptide Y (NPY) are involved in the regulation of these vegetative functions.

Materials and methods

A total of 45 unipolar and 24 bipolar depressive patients, and 36 euthymic healthy controls were included in the study. The groups were compared in terms of peripheral blood samples of ORX-A, GRL, and NPY levels, as well as HAM-D, Epworth Sleepiness Scale, Three-Factor Eating Questionnaire-Revised, and Suicide Probability Scale scores.

Results

Both unipolar and bipolar patients had lower ORX-A, GRL, and NPY levels compared to the controls, whereas NPY levels of bipolar patients were lower than unipolar patients. There was a negative correlation between NPY levels and emotional eating in the bipolar group.

Conclusion

While lower ORX-A, GRL, and NPY levels are associated with depressive episodes regardless of the diagnosis; NPY levels also differ in bipolar and unipolar depression patients.

Keywords:

• Bipolar depression
• atypical vegetative functions
• neuropeptide Y
• orexin-A
• ghrelin

Acknowledgments

We would like to show our great gratitude to all participants of the study. We would like to thank Prof. Rukiye Filiz Karadağ, Çisem Hayriye Utku and Ayşegül Yay for their contribution to the study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by Gazi University Scientific Research Projects under Grant number: 01/2019-18.

Notes on contributors

Mehmet Ünler

Mehmet Ünler, MD graduated from Ankara University faculty of Medicine and works in Gaziantep 25 Aralık State Hospital as a psychiatrist. He works on mood disorders and suicide.

İrem Ekmekçi Ertek

İrem Ekmekci Ertek, MD, PhD is an assistant professor in Gazi University Faculty of Medicine Department of Psychiatry. Besides being a psychiatrist, she has a PhD in Public Health. Her research interest focuses on community mental health, psychiatric epidemiology, and psychosomatic medicine.

Nigar Afandiyeva

Nigar Afandiyeva graduated from Azerbaijan Medical Faculty and completed her specialization in Gazi University, Department of Biochemistry. She is currently working as a biochemistry specialist at Lokman Hekim Hospitals. She works on interference problems in biochemical analysis.

Mustafa Kavutçu

Mustafa Kavutçu graduated from Cumhuriyet University, Faculty of Arts and Sciences, Department of Chemistry, and then completed his doctorate at Ankara University, Faculty of Medicine, Department of Biochemistry. He is currently working at Gazi University, Department of Medical Biochemistry. He has many studies on oxidative stress markers.

Nevzat Yüksel

Nevzat Yüksel, MD, is an emeritus professor now working in his private office. He mainly focuses on psychopharmacology and has textbooks on psychopharmacology and psychiatry.