Protective effect of nicotine on oxidative and cell damage in rats with depression induced by olfactory bulbectomy

Single Administration of the T-Type Calcium Channel Enhancer SAK3 Reduces Oxidative Stress and Improves Cognition in Olfactory Bulbectomized Mice

Alzheimer’s disease (AD), characterized by cognitive impairments, is considered to be one of the most widespread chronic neurodegenerative diseases worldwide. We recently introduced a novel therapeutic agent for AD treatment, the T-type calcium channel enhancer ethyl-8-methyl-2,4-dioxo-2-(piperidin-1-yl)-2H-spiro[cyclopentane-1,3-imidazo[1,2-a]pyridin]-2-ene-3-carboxylate (SAK3). SAK3 enhances calcium/calmodulin-dependent protein kinase II and proteasome activity, thereby promoting amyloid beta degradation in mice with AD. However, the antioxidative effects of SAK3 remain unclear. We investigated the antioxidative effects of SAK3 in olfactory bulbectomized mice (OBX mice), compared with the effects of donepezil as a positive control. As previously reported, single oral administration of both SAK3 (0.5 mg/kg, p.o.) and donepezil (1.0 mg/kg, p.o.) significantly improved cognitive and depressive behaviors in OBX mice. Single oral SAK3 administration markedly reduced 4-hydroxy-2-nonenal and nitrotyrosine protein levels in the hippocampus of OBX mice, which persisted until 1 week after administration. These effects are similar to those observed with donepezil therapy. Increased protein levels of oxidative stress markers were observed in the microglial cells, which were significantly rescued by SAK3 and donepezil. SAK3 could ameliorate oxidative stress in OBX mice, like donepezil, suggesting that the antioxidative effects of SAK3 and donepezil are among the neuroprotective mechanisms in AD pathogenesis.

Peritoneal endometriosis induces time-related depressive- and anxiety-like alterations in female rats: involvement of hippocampal pro-oxidative and BDNF alterations

Endometriosis is a gynecological condition affecting 10% of women in reproductive age. High rates of depression and anxiety are observed in these patients. The mechanisms underlying endometriosis-induced behavioral alterations are still elusive. Animal models provide a useful tool to study the temporal sequence and biological pathways involved in this disease and comorbid states. Here, we sought to characterize time-related behavioral alterations in rats submitted to endometriosis model (EM) induced by peritoneal auto-transplantation of uterine tissues weekly for three weeks. Corticosterone stress reactivity, oxidative stress markers - reduced glutathione (GSH), lipid peroxidation, activity of superoxide dismutase (SOD) and myeloperoxidase (MPO) - and brain-derived-neurotrophic factor (BDNF) levels in the hippocampus were also evaluated. We observed a progressive increase in anxiety-like behavior from 14th to 21st days post-EM. Despair-like behavior was observed from the 14th day post-EM on, while anhedonia and apathetic-like behaviors accompanied by increased corticosterone stress response were detected on 21 days post-EM. Increased pain sensitivity was observed from the 7th day post-EM and was accompanied by increased endometrioma weight. The pro-oxidative alterations, decreased GSH and increased SOD activity were observed on 21 days post-EM, except for lipid peroxidation that was altered from the 14th day. Decreased BDNF also occurred on the 21st day. Therefore, this study demonstrates that EM is related to several features of clinical depression and proposes the contribution of hippocampal oxidative state and neurotrophic support for the emergence of these changes. Our results support the use of this model as a useful tool to test new strategies for endometriosis-related neuropsychiatric symptoms.

Olfactory dysfunction in Parkinson's disease: Positive effect of cigarette smoking

BACKGROUND

There is compelling evidence from over 60 epidemiological studies that smoking significantly reduces the risk of Parkinson's disease (PD). In general, those who currently smoke cigarettes, as well as those with a past history of such smoking, have a reduced risk of PD compared to those who have never smoked. Recently it has been suggested that a cardinal nonmotor sensory symptom of PD, olfactory dysfunction, may be less severe in PD patients who smoke than in PD patients who do not, in contrast to the negative effect of smoking on olfaction described in the general population.

METHODS

We evaluated University of Pennsylvania Smell Identification Test (UPSIT) scores from 323 PD patients and 323 controls closely matched individually on age, sex, and smoking history (never, past, or current).

RESULTS

Patients exhibited much lower UPSIT scores than did the controls (P < 0.0001). The relative decline in dysfunction of the current PD smokers was less than that of the never- and past-PD smokers (respective Ps = 0.0005 and 0.0019). Female PD patients outperformed their male counterparts by a larger margin than did the female controls (3.66 vs. 1.07 UPSIT points; respective Ps < 0.0001 and 0.06). Age-related declines in UPSIT scores were generally present (P < 0.0001). No association between the olfactory measure and smoking dose, as indexed by pack-years, was evident.

CONCLUSIONS

PD patients who currently smoke do not exhibit the smoking-related decline in olfaction observed in non-PD control subjects who currently smoke. The physiological basis of this phenomenon is yet to be defined.

Etazolate, a phosphodiesterase-4 enzyme inhibitor produces antidepressant-like effects by blocking the behavioral, biochemical, neurobiological deficits and histological abnormalities in hippocampus region caused by olfactory bulbectomy

RATIONALE

Olfactory bulbectomy (OBX) is a widely used model for antidepressant screening and known to induce neurodegeneration in several brain areas. Our earlier studies demonstrated that etazolate produced antidepressant-like effects in behavioral despair models of depression; however, the potential role of etazolate on behavior and morphological changes in the hippocampus region along with its underlying mechanism(s) following OBX has not been adequately addressed.

OBJECTIVES

We evaluated if etazolate could protect against OBX-induced depression-like behavioral deficits and neurodegeneration. The possible underlying mechanism of etazolate in OBX model was also investigated.

METHODS

The effects of etazolate were measured in a battery of behavioral paradigms, including the forced swim test (FST), sucrose consumption, open arm activity in elevated plus maze (EPM), and hyperemotionality tests. The underlying mechanisms were investigated by measuring serum corticosterone (CORT), cyclic adenosine monophosphate (cAMP), cAMP response element binding protein (CREB), brain-derived neurotrophic factor (BDNF), and oxidative/nitrosative stress (lipid peroxidation and nitrite) levels and antioxidant enzymes, like reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) levels in the hippocampus.

RESULT

OBX rats showed depression-like behavior anomalies in behavioral paradigms. OBX rats also showed high CORT and decreased cAMP, phosphorylated CREB (pCREB), and BDNF levels. Additionally, we found increased oxidative/nitrosative stress and reduced antioxidant enzyme levels in the hippocampus. Histopathological analysis showed morphological changes and neuronal loss in the hippocampus. Etazolate (0.5 and 1 mg/kg) attenuated the OBX-induced behavioral, biochemical, neurobiological, and histopathological alterations.

CONCLUSION

The aforesaid results suggest that etazolate produces an antidepressant-like effect and neuroprotection in OBX, which is possibly mediated by modulating biochemical and neurobiological markers in the hippocampus.

Oxidative stress as an etiological factor and a potential treatment target of psychiatric disorders. Part 2. Depression, anxiety, schizophrenia and autism

The pathophysiology of psychiatric diseases, including depression, anxiety, schizophrenia and autism, is far from being fully elucidated. In recent years, a potential role of the oxidative stress has been highlighted in the pathogenesis of neuropsychiatric disorders. A body of clinical and preclinical evidence indicates that psychiatric diseases are characterized by higher levels of oxidative biomarkers and with lower levels of antioxidant defense biomarkers in the brain and peripheral tissues. In this article, we review current knowledge on the role of the oxidative stress in psychiatric diseases, based on clinical trials and animal studies, in addition, we analyze the effects of drug-induced modulation of oxidative balance and explore pharmacotherapeutic strategies for oxidative stress reduction.

The antidepressant effect of Cynanchum auriculatum in mice

CONTEXT

Antidepressant effects of various plants are generally attributed to their anti-inflammation and antioxidant activities. Cynanchum auriculatum Royle ex Wight (Asclepiadaceae) is a traditional medicinal plant in China and India used for immunological regulation, anti-inflammation, and antioxidant purposes. However knowledge about its antidepressant activity has been poorly investigated.

OBJECTIVE

To investigate the antidepressant activities of the total glycosides of C. auriculatum (TGC) and its CHCl₃/MeOH (10:1) fractions (TGC-D and TGC-E) in mice.

MATERIALS AND METHODS

TGC, TGC-D and TGC-E (20, 40 and 80 mg/kg) were intragastrically administered to mice twice a day for 5 days. The tail suspension test, forced swimming test, and locomotor activity test in mice were used to evaluate the effect of C. auriculatum. The inhibition of [³H]-serotonin reuptake in rat brain synaptosomes was detected to investigate their mechanism.

RESULTS

TGC, TGC-D and TGC-E (80 mg/kg) decreased the immobility time by 61.7, 64.5, and 61.9% in tail suspension test. TGC (80 mg/kg), TGC-D (80 mg/kg) and TGC-E (20 mg/kg) decreased the immobility time by 32.6, 47.3, and 48.7% in forced swimming test. TGC (80 mg/kg) and TGC-E (20 and 40 mg/kg) decreased the crossing distances by 28.8, 29.5, and 36.2% in locomotor activity test. TGC, TGC-D and TGC-E (10 mg/L) inhibited serotonin reuptake by 7.4, 4.5, and 71.1% in rat brain synaptosomes, and IC₅₀ value of TGC-E was 5.2 mg/L.

DISCUSSION AND CONCLUSION

TGC, TGC-D and TGC-E have potential antidepressant activities. The antidepressive effect of TGC-E maybe attributed partly by the inhibiting effect on serotonin reuptake.

[A depression model of social defeat etiology using tree shrews]

Depression is a common neuropsychiatric disorder, marked by depressed mood for at least two weeks. The World Health Organization predicts that depression will be the number one leading cause of disease and injury burden by 2030. Clinical treatment faces at least three serious obstacles. First, the disease mechanism is not fully understood and thus there are no effective ways to predict and prevent depression and no biological method of diagnosis. Second, available antidepressants are based on monoamine mechanisms that commonly have a long delay of action and possibly cause a higher risk of suicide. Third, no other antidepressant mechanisms are available, with fast action and few side effects. Unfortunately, several decades of research based on rodent models of depression have not been successful in resolving these problems, at least partially due to the huge differences in brain function between rodents and people. Tree shrews are the closest sister to primates, and brain functions in these species are closer to those of humans. In this review, we discuss a tree shrew model of depression with social defeat etiology and aspects of construct, face and predicted validity of an animal model. Although a tree shrew model of depression has long been ignored and not fully established, its similarities to those aspects of depression in humans may open a new avenue to address this human condition.

Oxidative stress in anxiety and comorbid disorders

Anxiety disorders, depression, and alcohol use disorder are common neuropsychiatric diseases that often occur together. Oxidative stress has been suggested to contribute to their etiology. Oxidative stress is a consequence of either increased generation of reactive oxygen species or impaired enzymatic or non-enzymatic defense against it. When excessive it leads to damage of all major classes of macromolecules, and therefore affects several fundamentally important cellular functions. Consequences that are especially detrimental to the proper functioning of the brain include mitochondrial dysfunction, altered neuronal signaling, and inhibition of neurogenesis. Each of these can further contribute to increased oxidative stress, leading to additional burden to the brain. In this review, we will provide an overview of recent work on oxidative stress markers in human patients with anxiety, depressive, or alcohol use disorders, and in relevant animal models. In addition, putative oxidative stress-related mechanisms important for neuropsychiatric diseases are discussed. Despite the considerable interest this field has obtained, the detailed mechanisms that link oxidative stress to the pathogenesis of neuropsychiatric diseases remain largely unknown. Since this pathway may be amenable to pharmacological intervention, further studies are warranted.