An analysis of the possible relationship between serum bdnf level and TRPC3 gene in patients with major depressi̇ve disorder

Brain-derived neurotrophic factor (BDNF) has been demonstrated by many studies to have a significant role in the pathophysiology of psychiatric disorders and the action mechanism of psychotropic drugs. Based on our literature review, we know much less about transient receptor potential channel 3 (TRPC3) than about BDNF. The purpose of this thesis is to investigate the possible correlation between the TRPC3 gene polymorphism rs13121031 in individuals diagnosed with depression/disease and BDNF levels; and to compare it with healthy control individuals. The study included 192 patients who applied to the Fırat University Hospital Psychiatry Polyclinic and underwent outpatient treatment, and 200 healthy controls with similar sociodemogra"phic characteristics to the patient group. The participants were evaluated with the Sociodemographic and Clinical Data Form, the 90-item Revised Symptom Checklist (SCL-90-R), the Beck Anxiety Inventory (BAI), and the Beck Depression Inventory (BDI). Venous blood samples were then taken from the subjects. BDNF levels were examined using the Enzyme Linked Immunosorbent Assay (ELISA) method from serum samples. TRPC3 gene polymorphism rs13121031 analyses were performed using TaqMan probes on an ABI 7500 Fast Real Time System device. SPSS 22 package program was used for data analysis. BDNF levels were found to be significantly higher in patients with a disease duration of <5 years than those with a disease duration of >5 years (p<0,001). In the patient group, BDNF levels were significantly higher in smokers compared to non-smokers (p=0,037). A significant negative correlation was found between BDNF level and BAI, BDI and age (r=-0,705; p<0,001) (r=-0,850; p<0,001) (r=-0,246; p=0,001). BAI and BDI scores were found to be significantly lower in patients with a disease duration of <5 years than in patients with a disease duration of >5 years (p<0,001) (p<0,001). In the patient group, a significant positive correlation was found between age (r=0,158; p=0,029) and BDI (r=0,203; p=0,005). Family history of psychiatric illness was significantly higher in the patient group compared to the control group (p<0,001). Age at disease onset was found to be significantly lower in patients with a family history of psychiatric illness than in controls (p<0,001). No significant difference was found between the patient and control groups in terms of TRPC3 gene rs13121031 polymorphism genotypes (p=0,373). No significant correlation was found between genotypes and BDNF levels, disease duration and family history of psychiatric illness in the patient group (p=0,643) (p=0,598) (p=0,356). There was no significant difference between the groups in terms of BDNF levels (p=0,333). In conclusion, significant correlations were found between BDNF levels and duration of disease, age, smoking, BAI and BDI scores in accordance with the previous studies. The family history of psychiatric disease was significantly higher in the patient group and was found to be associated with an earlier onset of the disease. No statistically significant data were obtained in terms of the genotypes of TRPC3 gene rs13121031 polymorphism and the association of genotypes with the disease and BDNF levels between MDD (major depressive disorder) patients and healthy controls. However, we believe that our study is valuable since this is the first study to investigate the relationship between TRPC3 gene rs13121031 polymorphism, disease and serum BDNF levels in MDD. We believe that more studies, especially longitudinal ones in which biological factors that may affect the results are minimized, are needed. Keywords: Major Depressive Disorder, TRPC3, Polymorphism, BDNF