Preventing, treating, and predicting barbering: A fundamental role for biomarkers of oxidative stress in a mouse model of Trichotillomania

Towards zebrafish models to unravel translational insights of obsessive-compulsive disorder: A neurobehavioral perspective

Obsessive-compulsive disorder (OCD) is a chronic and debilitating illness that has been considered a polygenic and multifactorial disorder, challenging effective therapeutic interventions. Although invaluable advances have been obtained from human and rodent studies, several molecular and mechanistic aspects of OCD etiology are still obscure. Thus, the use of non-traditional animal models may foster innovative approaches in this field, aiming to elucidate the underlying mechanisms of disease from an evolutionary perspective. The zebrafish (Danio rerio) has been increasingly considered a powerful organism in translational neuroscience research, especially due to the intrinsic features of the species. Here, we outline target mechanisms of OCD for translational research, and discuss how zebrafish-based models can contribute to explore neurobehavioral aspects resembling those found in OCD. We also identify possible advantages and limitations of potential zebrafish-based models, as well as highlight future directions in both etiological and therapeutic research. Lastly, we reinforce the use of zebrafish as a promising tool to unravel the biological basis of OCD, as well as novel pharmacological therapies in the field.

Carbamazepine-induced renal toxicity may be associated with oxidative stress and apoptosis in male rat

Carbamazepine (CBZ) is the antiepileptic drug used in epilepsy and some psychiatric disorders. Besides its widely used, many adverse effects have been reported including hematotoxicity, hepatotoxicity, endocrine disorders, and testicular damages due to oxidative stress. However, the role of CBZ on renal toxicity is not fully known. In this study, we attempted to explain the connected mechanisms by focusing on the metabolism of CBZ-induced renal toxicity in rats. Twenty male Wistar-Albino rats were randomized into 2 groups (n = 10); control (1 mL/day distilled water, orally) and CBZ (25 mg/kg/day CBZ, orally) groups. After 60 days, TAS (total oxidant status) and TOS (total oxidant status) levels, histopathological features, some genes involved in apoptosis, 8-hydroxy-2-deoxyguanosine (8-OHdG) activity, and apoptotic cells were assessed of kidney tissue. The oxidative stress index (OSI) was measured from TAS and TOS levels. TOS levels and OSI significantly increased, while TAS levels decreased in the CBZ group relative to the control group. Histopathological observations, Caspase-3 (Casp3), Poly [ADP-ribose] polymerase-1 (PARP-1), 8-OHdG immunoreactivities, and apoptotic cells markedly raised in the CBZ group compared with the control group. Also, mRNA expression of Cytochrome c (Cytc) and CASP3 significantly increased in the CBZ group compared to the control group. In conclusion, long-term use of CBZ may promote renal damage in rats by inducing oxidative stress and apoptosis.

Lactoferrin Prevents Chronic Alcoholic Injury by Regulating Redox Balance and Lipid Metabolism in Female C57BL/6J Mice

This study aimed to investigate the preventive effects of lactoferrin (Lf) on chronic alcoholic liver injury (ALI) in female mice. Female C57BL/6J mice were randomly divided into four groups: control group (CON), ethanol administration group (EtOH), low-dose Lf treatment group (LLf), and high-dose Lf group (HLf). In the last three groups, chronic ALI was induced by administering 20% ethanol ad libitum for 12 weeks. Mice in the CON and EtOH groups were fed with AIN-93G diet. Meanwhile, 0.4% and 4% casein in the AIN-93G diet were replaced by Lf as the diets of LLf and HLf groups, respectively. HLf significantly reduced hepatic triglyceride content and improved pathological morphology. HLf could inhibit cytochrome P450 2E1 overexpression and promote alcohol dehydrogenase-1 expression. HLf activated protein kinase B and AMP-activated protein kinase (AMPK), as well as upregulating nuclear-factor-erythroid-2-related factor-2 expression to elevate hepatic antioxidative enzyme activities. AMPK activation also benefited hepatic lipid metabolism. Meanwhile, HLf had no obvious beneficial effects on gut microbiota. In summary, Lf could alleviate chronic ALI in female mice, which was associated with redox balance and lipid metabolism regulation.

Metformin Intervention—A Panacea for Cancer Treatment?

The molecular mechanism of action and the individual influence of various metabolic pathways related to metformin intervention are under current investigation. The available data suggest that metformin provides many advantages, exhibiting anti-inflammatory, anti-cancer, hepatoprotective, cardioprotective, otoprotective, radioprotective, and radio-sensitizing properties depending on cellular context. This literature review was undertaken to provide novel evidence concerning metformin intervention, with a particular emphasis on cancer treatment and prevention. Undoubtedly, the pleiotropic actions associated with metformin include inhibiting inflammatory processes, increasing antioxidant capacity, and improving glycemic and lipid metabolism. Consequently, these characteristics make metformin an attractive medicament to translate to human trials, the promising results of which were also summarized in this review.

Evaluation of Treatment Options for Ulcerative Dermatitis in the P Rat

Rotational outbred adult rats, phenotypically selected to prefer drinking alcohol ("P" rats) frequently present with selfinflicted wounds and ulcerative dermatitis, similar to that seen in C57BL/6 mice. Historically, veterinary interventions used to address this clinical condition have included triple antibiotic ointment (TABO), Columbia wound powder (CPW), nail trims, or plastic tubes that allow affected animals to hide. More recent studies have suggested that nail trims are the most successful intervention in mice, but this has not been evaluated previously in rats. In this study, we evaluated nail trims in rats and also tested whether placing a pumice stone in the cage would reduce the need for nail trims to reduce self-inflicted wounds. Our hypothesis was that interacting with the pumice stone would dull/trim the rats' nails without causing stress or illness and allow the wounds time to heal. We used 66 P rats that were assigned to 1 of 6 treatment groups (pumice stone, TABO, CWP, huts, nail trims, and an untreated control group) of 11 rats each. Rats were transferred to this study from a colony of experimentally naïve animals that had evidence of dermatitis. The wounds were photographed and measured for 12 wk at 2 wk intervals. At the end of the study, representative skin samples from the site of the wound were collected for histopathologic evaluation of inflammation. Our data showed no significant differences in the inflammation scores. The rats treated with nail trims healed significantly more often than did all of the other treatment groups. This suggests that nail trims are the most effective intervention for treating self-inflicted wounds in P rats.

A critical inquiry into marble-burying as a preclinical screening paradigm of relevance for anxiety and obsessive-compulsive disorder: Mapping the way forward

Rodent marble-burying behavior in the marble-burying test (MBT) is employed as a model or measure to study anxiety- and compulsive-like behaviors or anxiolytic and anticompulsive drug action. However, the test responds variably to a range of pharmacological interventions, and little consensus exists regarding specific methodologies for its execution. Regardless, the test is widely applied to investigate the effects of pharmacological, genetic, and behavioral manipulations on purported behaviors related to the said neuropsychiatric constructs. Therefore, in the present review we attempt to expound the collective translational significance of the MBT. We do this by (1) reviewing burying behavior as a natural behavioral phenotype, (2) highlighting key aspects of anxiety and obsessive-compulsive disorder from a translational perspective, (3) reviewing the history and proof of concept of the MBT, (4) critically appraising potential methodological confounds in execution of the MBT, and (5) dissecting responses of the MBT to various pharmacological interventions. We conclude by underlining that the collective translational value of the MBT will be strengthened by contextually valid experimental designs and objective reporting of data.

SM22α (Smooth Muscle 22α) Prevents Aortic Aneurysm Formation by Inhibiting Smooth Muscle Cell Phenotypic Switching Through Suppressing Reactive Oxygen Species/NF-κB (Nuclear Factor-κB)

Objective- Vascular smooth muscle cell phenotypic transition plays a critical role in the formation of abdominal aortic aneurysms (AAAs). SM22α (smooth muscle 22α) has a vital role in maintaining the smooth muscle cell phenotype and is downregulated in AAA. However, whether manipulation of the SM22α gene influences the pathogenesis of AAA is unclear. Here, we investigated whether SM22α prevents AAA formation and explored the underlying mechanisms. Approach and Results- In both human and animal AAA tissues, a smooth muscle cell phenotypic switch was confirmed, as manifested by the downregulation of SM22α and α-SMA (α-smooth muscle actin) proteins. The methylation level of the SM22α gene promoter was dramatically higher in mouse AAA tissues than in control tissues. SM22α knockdown in ApoE^-/- (apolipoprotein E-deficient) mice treated with Ang II (angiotensin II) accelerated the formation of AAAs, as evidenced by a larger maximal aortic diameter and more medial elastin degradation than those found in control mice, whereas SM22α overexpression exerted opposite effects. Similar results were obtained in a calcium chloride-induced mouse AAA model. Mechanistically, SM22α deficiency significantly increased reactive oxygen species production and NF-κB (nuclear factor-κB) activation in AAA tissues, whereas SM22α overexpression produced opposite effects. NF-κB antagonist SN50 or antioxidant N-acetyl-L-cysteine partially abrogated the exacerbating effects of SM22α silencing on AAA formation. Conclusions- SM22α reduction in AAAs because of the SM22α promoter hypermethylation accelerates AAA formation through the reactive oxygen species/NF-κB pathway, and therapeutic approaches to increase SM22α expression are potentially beneficial for preventing AAA formation.

The pseudogene PTENP1 regulates smooth muscle cells as a competing endogenous RNA

The long non-coding RNA (lncRNA) PTENP1 is a pseudogene of phosphatase and tensin homologue deleted on chromosome ten (PTEN), has been implicated in smooth muscle cell (SMC) proliferation and apoptosis. PTENP1 is the pseudogene of PTEN. However, it is unclear whether and how PTENP1 functions in the proliferation and apoptosis of human aortic SMCs (HASMCs). Here, we hypothesised that PTENP1 inhibits HASMC proliferation and enhances apoptosis by promoting PTEN expression. PCR analysis and Western blot assays respectively showed that both PTENP1 and PTEN were up-regulated in human aortic dissection (AD) samples. PTENP1 overexpression significantly increased the protein expression of PTEN, promoted apoptosis and inhibited the proliferation of HASMCs. PTENP1 silencing exhibited the opposite effects and mitigated H₂O₂-induced apoptosis of HASMCs. In an angiotensin II (Ang II)-induced mouse aortic aneurysm (AA) model, PTENP1 overexpression potentiated aortic SMC apoptosis, exacerbated aneurysm formation. Mechanistically, RNA pull-down assay and a series of luciferase reporter assays using miR-21 mimics or inhibitors identified PTENP1 as a molecular sponge for miR-21 to endogenously compete for the binding between miR-21 and the PTEN transcript, releasing PTEN expression. This finding was further supported by in vitro immunofluorescent evidence showing decreased cell apoptosis upon miR-21 mimic administration under baseline PTENP1 overexpression. Ex vivo rescue of PTEN significantly mitigated the SMC apoptosis induced by PTENP1 overexpression. Finally, Western blot assays showed substantially reduced Akt phosphorylation and cyclin D1 and cyclin E levels with up-regulated PTENP1 in HASMCs. Our study identified PTENP1 as a mediator of HASMC homeostasis and suggests that PTENP1 is a potential target in AD or AA intervention.

Potential for therapeutic use of hydrogen sulfide in oxidative stress-induced neurodegenerative diseases

Oxidative phosphorylation is a source of energy production by which many cells satisfy their energy requirements. Endogenous reactive oxygen species (ROS) are by-products of oxidative phosphorylation. ROS are formed due to the inefficiency of oxidative phosphorylation, and lead to oxidative stress that affects mitochondrial metabolism. Chronic oxidative stress contributes to the onset of neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS). The immediate consequences of oxidative stress include lipid peroxidation, protein oxidation, and mitochondrial deoxyribonucleic acid (mtDNA) mutation, which induce neuronal cell death. Mitochondrial binding of amyloid-β (Aβ) protein has been identified as a contributing factor in AD. In PD and HD, respectively, α-synuclein (α-syn) and huntingtin (Htt) gene mutations have been reported to exacerbate the effects of oxidative stress. Similarly, abnormalities in mitochondrial dynamics and the respiratory chain occur in ALS due to dysregulation of mitochondrial complexes II and IV. However, oxidative stress-induced dysfunctions in neurodegenerative diseases can be mitigated by the antioxidant function of hydrogen sulfide (H₂S), which also acts through the potassium (K_ATP/K⁺) ion channel and calcium (Ca²⁺) ion channels to increase glutathione (GSH) levels. The pharmacological activity of H₂S is exerted by both inorganic and organic compounds. GSH, glutathione peroxidase (Gpx), and superoxide dismutase (SOD) neutralize H₂O₂-induced oxidative damage in mitochondria. The main purpose of this review is to discuss specific causes and effects of mitochondrial oxidative stress in neurodegenerative diseases, and how these are impacted by the antioxidant functions of H₂S to support the development of advancements in neurodegenerative disease treatment.

A Pilot Examination of Oxidative Stress in Trichotillomania

OBJECTIVE

Trichotillomania is a relatively common illness whose neurobiology is poorly understood. One treatment for adult trichotillomania, n-acetyl cysteine (NAC), has antioxidative properties, as well as effects on central glutamatergic transmission. Preclinical models suggest that excessive oxidative stress may be involved in its pathophysiology.

METHODS

Adults with trichotillomania provided a blood sample for analysis of compounds that may be influenced by oxidative stress [glutathione, angiotensin II, ferritin, iron, glucose, insulin and insulin growth factor 1 (IGF1), and hepcidin]. Participants were examined on symptom severity, disability, and impulsivity. The number of participants with out-of-reference range oxidative stress measures were compared against the null distribution. Correlations between oxidative stress markers and clinical measures were examined.

RESULTS

Of 14 participants (mean age 31.2 years; 92.9% female), 35.7% (n=5) had total glutathione levels below the reference range (p= 0.041). Other oxidative stress measures did not have significant proportions outside the reference ranges. Lower levels of glutathione correlated significantly with higher motor impulsiveness (Barratt Impulsiveness Scale sub-score) (r=0.97, p=0.001).

CONCLUSION

A third of patients with trichotillomania had low levels of glutathione, and lower levels of glutathione correlated significantly with higher motor impulsiveness. Because NAC is a precursor for cysteine, and cysteine is a rate limiting step for glutathione production, these results may shed light on the mechanisms through which NAC can have beneficial effects for impulsive symptoms. Confirmation of these results requires a suitable larger follow-up study, including an internal normative control group.

The significance of meaning: why do over 90% of behavioral neuroscience results fail to translate to humans, and what can we do to fix it?

The vast majority of drugs entering human trials fail. This problem (called "attrition") is widely recognized as a public health crisis, and has been discussed openly for the last two decades. Multiple recent reviews argue that animals may be just too different physiologically, anatomically, and psychologically from humans to be able to predict human outcomes, essentially questioning the justification of basic biomedical research in animals. This review argues instead that the philosophy and practice of experimental design and analysis is so different in basic animal work and human clinical trials that an animal experiment (as currently conducted) cannot reasonably predict the outcome of a human trial. Thus, attrition does reflect a lack of predictive validity of animal experiments, but it would be a tragic mistake to conclude that animal models cannot show predictive validity. A variety of contributing factors to poor validity are reviewed. The need to adopt methods and models that are highly specific (i.e., which can identify true negative results) in order to complement the current preponderance of highly sensitive methods (which are prone to false positive results) is emphasized. Concepts in biomarker-based medicine are offered as a potential solution, and changes in the use of animal models required to embrace a translational biomarker-based approach are outlined. In essence, this review advocates a fundamental shift, where we treat every aspect of an animal experiment that we can as if it was a clinical trial in a human population. However, it is unrealistic to expect researchers to adopt a new methodology that cannot be empirically justified until a successful human trial. "Validation with known failures" is proposed as a solution. Thus new methods or models can be compared against existing ones using a drug that has translated (a known positive) and one that has failed (a known negative). Current methods should incorrectly identify both as effective, but a more specific method should identify the negative compound correctly. By using a library of known failures we can thereby empirically test the impact of suggested solutions such as enrichment, controlled heterogenization, biomarker-based models, or reverse-translated measures.