Abstract
Objective: Orexins (hypocretins) are neuropeptides expressed in hypothalamic neurons and have regulatory roles in feeding/drinking behaviours, endocrine functions and sleep/wakefulness state. Major depressive disorder (MDD) is a major mood disorder and neurotransmitter dysfunction in hypothalamic neurons may have roles in its formation. Hence, we conducted experiments to determine whether orexin receptor 1 and 2 (Orx1, Orx2) genes were associated with MDD development.
Methods: Seventy-five MDD patients and 87 healthy controls were enrolled for the study. Genotyping was carried out with real-time polymerase chain reaction (RT-PCR). Hamilton Rating-Scale for Depression (HRSD) and Beck Depression Inventory (BDI) were utilized to evaluate depressive symptom severity.
Results: A significant relation was found in genotype frequencies of Orx1 rs10914456 and rs2271933 variants between MDD patients and controls (p = .009, p = .006). Rs10914456 CC genotype increased MDD risk 3.57 times more than carrying other genotypes (p = .008, OR =3.57;95% CI: 1.39–9.14). However, no association was observed in Orx2 rs2653349 genotypes for MDD development (p > .05). Although statistically not significant, HRSD scores were diminished in MDD subjects carrying rs10914456 CC variants when compared with CT and TT variants (p = .069). Conclusion. This study suggests that, Orx1 rs10914456 and rs2271933 can be associated with MDD development. Hence, Orx1 rs10914456 variants may affect depressive symptom severity.
Acknowledgments
The preliminary findings of this study were presented at the 1st International TURAZ (Turkey-Azerbaijan) Forensic Medicine and Pathology Congress (October 13–16, 2016) in Baku, Azerbaijan.
Disclosure statement
No potential conflict of interest was reported by the author.