A Comparative Study On Plasma Neuropeptide Y And Substance P Levels In Patients With Unipolar And Bipolar Depressive Disorders

Objective:To explore the effects of plasma neuropeptide Y and substance P in the etiology of unipolar and bipolar depressive disorders, and to explore the difference in the plasma neuropeptide Y and substance P levels between patients with unipolar and bipolar depressive disorders.Methods:35 patients with unipolar depressive disorders(UDD),38 patients with bipolar depressive disorder(BDD) and 35 controls were recruited in the study, and interviewed by the MINI International Neuropsychiatric terview for DSM-Ⅳby a senior psychiatrist at the department of psychiatry in the First Affiliated Hospital of Jinan University. Hamilton Depression Scale, Hamilton Anxiety Scale and Young Mania Rating Scale were used to assess the severity of clinical symptoms. Mood Disorder Questionnaire (MDQ)and The 32-item Hypomania Symptom Check List (HCL-32) were used to explore the history of Manic/hypomanic episode. The plasma substance P and neuropeptide Y levels were determined with the enzyme linked immunosorbent assay.Results:1.Compared with BDD group, the UDD group presented the first depression onset at older ages,longer duration of single episodes of depression, more anxiety symptoms, somatization symptoms and melancholic features, more severe depressive symptoms, but less relapse times.2. The plasma neuropeptide Y levels were significantly lower in the patients with UDD and BDD than those in the controls (5.838±1.793.5.951±2.148V.S. 8.071±.224, P<0.05).The plasma substance P levels were significantly higher in the patients with UDD and BDD than those in the controls (6.239±2.617,5.784±1.498 V.S4.081±1.540, P<0.05), but there was no significant difference in plasma neuropeptide Y and substance P levels between UDD group and BDD group.(P> 0.05)3. There was no significant difference in plasma neuropeptide Y (6.030±1.853v.s5.789±2.083, P=0.624) and substance P levels (5.766±1.741 v.s6.192±1.932, P=0.351) between female patients and male ones. 4. Plasma neuropeptide Y levels(5.101±1.871,6.669±1.744,5.708±1.789 and 6.054±0.859) and substance P levels (5.418±2.624,6.099±1.744,6.172±1.721 and 5.716±2.703) showed no significant difference (P> 0.05) among no suicide risk group, low suicide risk group, moderate suicide risk group and high suicide risk group.5. There was no significant difference in plasma neuropeptide Y levels between severe depressive episode group and the moderate group (5.889±1.910v.s5.904±2.06, P> 0.05); the plasma substance P levels was higher in severe depressive episode group than those in moderate depressive episode group, the difference was statistically significant (6.498±1.863v.s5.519±1.725, P<0.05).6. The neuropeptide Y concentrations in the patients with recurrent depression were similar to those ones with first-episode depression (6.271±1.88v.s5.307±2.000, P>0.05).The plasma substance P levels were higher than that in first-episode depression patients (6.341±1.890v.s 5.466±1.676,P<0.05).7. The plasma levels of neuropeptide Y and substance P were similar among severe anxiety level group, moderate anxiety level group and mild anxiety group. The difference was no statistically significant8. The plasma neuropeptide Y levels had no correlation with sex, age, age of first depression onset, total duration, duration of single attack, HAMA total score and HAMD total score and factor scores. The plasma substance P levels were significantly correlated with sleep disturbance factors in HAMD,but had no correlation with other factors.Conclusion:The plasma neuropeptide Y and substance P levels in patients with UDD and BDD were first detected and compared, and the results demonstrated that:1.The change of substance P and neuropeptide Y may be involved in the pathogenesis or pathophysiology of UDD and BDD, the abnormalities wre remarkably similar in BDD and UDD. There is no evidence shows that the substance P and neuropeptide Y could been useful biomarkers for differential diagnosis of BDD and UDD.2. Different subtypes of depressive episode were similar in the NPY dysfunction side,but SP dysfunction was more serious in the major depressive episode group and recurrent depressive episode group than moderate depressive episode and firstdepressive episode group.3. Sleep disturbance was the main factor that affected the plasma substance P levels in patients with UDD and BDD.