Thiol/Disulfide Homeostasis in Bipolar and Unipolar Depression

Thiol/Disulfide Homeostasis: A Potential New Peripheral Biomarker in Adolescent Depression

Background

Thiol-disulfide homeostasis (TDH), one of the most important antioxidants, is involved in the non-enzymatic removal of reactive oxygen molecules in the body and is one of the many methods to measure the level of oxidative stress (OS). In the present study, TDH is investigated in adolescent depression, and its relationship to clinical variables is examined.

Methods

Thirty-two (50.0%) patients diagnosed with major depressive disorder (MDD) and without psychotropic drug use and 32 (50.0%) healthy controls were included in the present study. The subjects MDD and control groups were between 13 and 18 years old. Participants completed the DSM-5 Level-2 scales for depression and irritability. A colorimetric method proposed by Erel and Neselioglu was used to analyze the TDH parameters of serum samples.

Results

Biochemical analyses of samples from the MDD and control groups showed significant differences between the groups in native thiol (SH) levels (P = .002), disulfide (SS) levels (P = .021), disulfide/total thiol (SS/ToSH) (P = .009), and disulfide/native thiol (SS/SH) (P = .003) levels. Analysis of receiver operating characteristic showed that the area under the curve values with "acceptable discrimination potential" for the TDH parameters were significantly able to discriminate individuals with MDD from healthy controls.

Conclusion

Thiol-disulfide homeostasis, one of the OS parameters, was found to be impaired in adolescents with depression. Our results suggest that TDH may contribute to the etiopathogenesis of adolescent MDD and that TDH may be a novel approach to assess OS in adolescent depression.

Comparison of oxidative stress parameters, thiol-disulfide homeostasis, and pro-inflammatory cytokines levels in patients with bipolar disorder and their first-degree relatives

BACKGROUND

In this study, we aimed to compare the oxidative stress parameters, thiol-disulfide homeostasis, and plasma pro-inflammatory cytokines levels of patients with bipolar disorder (BD), BD patients' first-degree relatives (FDRs), and the healthy controls (HCs).

METHODS

Thirty-five patients with BD, 35 FDRs of BD, and 35 healthy controls (HCs) were included. The individuals' ages varied from 28 to 58, and the groups were well-matched in terms of age and gender. The total thiol (TT), native thiol (NT), disulfide (DIS), total oxidant status (TOS), total antioxidant status (TAS), IL-1β, IL-6, and TNF-α concentrations were measured from serum samples. The oxidative stress index (OSI) was calculated using mathematical formulas.

RESULTS

TOS was significantly higher in both patients and FDRs than HCs (p < 0.01 for all pairwise comparisons). OSI, DIS, oxidized thiol, and the ratio of thiol oxidation-reduction levels were significantly higher in both patients with BD and FDRs than HCs (p < 0.01 for all pairwise comparisons). TAS, TT, NT, and reduced thiol levels were significantly lower in both patients with BD and FDRs than HCs (p < 0.01 for all pairwise comparisons). IL-1β, IL-6, and TNF-α were significantly higher in both patients and FDRs than HCs (p < 0.01 for all pairwise comparisons).

LIMITATIONS

Small sample size.

CONCLUSIONS

Early diagnosis is important for treating of bipolar disorder. TT, NT, DIS, TOS, TAS, OSI, IL1-β, IL-6, and TNF-α can be used as potential biomarkers in the early diagnosis and intervention of BD. Furthermore, oxidative/antioxidative markers and plasma pro-inflammatory cytokine parameters may guide the determination of the disease's activity and response to treatment.

Thiol disulfide homeostasis in psychiatric disorders: A comprehensive review

Thiol-disulfide couple maintains an intracellular redox status. Dynamic thiol-disulfide homeostasis acts crucial parts in metabolic processes involving signal mechanisms, inflammation, antioxidant defense. Thiol-disulfide homeostasis have been implicated in numerous diseases. In this comprehensive review we identified the studies that examined the thiol-disulfide homeostasis in psychiatric disorders. Most cases demonstrated alterations in thiol-disulfide homeostasis and in most of them the thiol-disulfide balance tended to change direction to the disulfide side, that is, to the oxidative side. Currently, the fact that N-acetylcysteine, a thiol-containing compound, is of great interest as a new treatment approach in psychiatric disorders and the role of glutathione, the most abundant thiol, in the brain highlights the importance of evaluating the thiol-disulfide balance in psychiatric disorders.

The Evaluation of Thiol/Disulfide Homeostasis and Oxidative DNA Damage in Patients with Obsessive Compulsive Disorder

Objective

In this study, we aimed to examine thiol/disulfide homeostasis and oxidative DNA damage in patients with OCD and compare them with healthy controls.

Methods

Thirty-five patients previously diagnosed with OCD in Van Yuzuncu Yil University Department of Psychiatry and thirty-three healthy volunteers were included in the study. The severity of the symptoms was measured using the Yale-Brown Obsessive-Compulsive Scale. Five μL of blood samples were taken from the patient and control groups. The samples were stored at appropriate conditions until use. Leukocyte DNA was isolated and the levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) and deoxyguanosine were detected to assess the oxidative DNA damage. The level of oxidative DNA damage was expressed as 8-OHdG/10⁶dG. Total thiol/native thiol levels were measured for thiol/disulfide homeostasis. The level of disulfide was determined by subtracting the native thiol value from the total thiol value and the result was divided by two. Results were given as percentages.

Results

The total and native thiol levels in patients with OCD were significantly lower, and the disulfide levels were significantly higher in patients with OCD than healthy control subjects. In addition, 8-OHdG, an indicator of DNA damage, was significantly lower in the control group compared to the patient group.

Conclusion

Increased levels of disulfide/native thiol and disulfide/total thiol in patients with OCD show that levels of oxidative stress were elevated and therefore, higher 8-OHdG levels in patients with OCD is a marker of oxidative DNA damage.

Dynamic Thiol/Disulfide Homeostasis and Oxidative DNA Damage in Adult Attention Deficit Hyperactivity Disorder

Objective

Insufficient number of oxidative stress studies have been conducted in patients with adult attention deficit hyperactivity disorder (ADHD). The objective of the current study is to examine the thiol/disulfide homeostasis as well as oxidative DNA damage levels in adult ADHD patients and to compare them with the results of healthy control subjects.

Methods

The study was inclusive of forty-nine patients who were diagnosed with adult ADHD, as well as thirty-three healthy volunteers to be used as the control group. The diagnosis of the patients was conducted according to the DSM-5 diagnostic criteria. Blood were stored under appropriate laboratory conditions. For the purpose of detecting the oxidative DNA damage level, an extraction of genomic DNA from leukocytes was carried out, and furthermore the levels of 8-hydroxy-2-deoxyguanosine (8-OHdG), apart from deoxyguanosine, were measured accordingly.

Results

Total thiol and the native thiol levels were observed to be statistically lower in adult ADHD patients as compared to the subjects in the healthy control group (p = 0.001). It was observed that the disulfide levels were higher in adult ADHD patients as compared to the healthy control subjects (p = 0.001). In addition, the levels of 8-OHdG, which are considered as a marker for assessing DNA damage, were found to be significantly lower in the control group as compared to the adult ADHD patients (p = 0.001).

Conclusion

It was observed that the thiol/disulfide homeostasis had shifted towards disulfide, and 8-OHdG levels were increased in adult ADHD patients.

Thiol/disulfide homeostasis in medication-naive children and adolescents with obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) causes significant psychic distress and affects children's social and academic functioning. Approximately 80% of OCD cases begin in childhood. Earlier onset is associated with more severe OC symptoms, poorer treatment response, and a more unfavorable clinical course. A particular oxidative stress marker, thiol/disulfide homeostasis, using a new, comparatively inexpensive, easily calculated, easily accessible, repeatable, and fully automated method was investigated between pediatric patients diagnosed with OCD and a healthy control group in this study. This study is the first to address this subject in pediatric patients with OCD and aims to contribute to our knowledge of the etiopathogenesis and treatment of pediatric OCD. The study included children with OCD (n = 35, 52.2%) (drug free, comorbidity free) between 11 and 18 years of age and age- and sex-matched healthy controls (n = 32, 47.8%). The total thiol (p = 0.025) and disulfide (p = 0.001) levels and the disulfide/native thiol (p = 0.001) and disulfide/total thiol ratios (p = 0.001) were significantly different between the groups. Also, in the patient group, biochemical analysis revealed that the disulfide level (p = 0.05) and the disulfide/native thiol (p = 0.034) and disulfide/total thiol ratios (p = 0.039) differed significantly according to the presence of a family history of psychiatric disorders. Consequently, the results of our study show that thiol/disulfide homeostasis may affect the etiopathogenesis of pediatric OCD and can be utilized as a new method when evaluating oxidative stress.