Increased oxidative stress in prefrontal cortex and hippocampus is related to depressive-like behavior in streptozotocin-diabetic rats

Antox targeting AGE/RAGE cascades to restore submandibular gland viability in rat model of type 1 diabetes

Diabetes mellitus (DM) is a chronic disorder of glucose metabolism that threatens several organs, including the submandibular (SMG) salivary glands. Antox (ANX) is a strong multivitamin with significant antioxidant benefits. The goal of this study was to demonstrate the beneficial roles of ANX supplementation in combination with insulin in alleviating diabetic SMG changes. For four weeks, 30 rats were divided into equal five groups (n = 6): (1) control group; (2) diabetic group (DM), with DM induced by streptozotocin (STZ) injection (50 mg/kg i.p.); (3) DM + ANX group: ANX was administrated (10 mg/kg/day/once daily/orally); (4) DM + insulin group: insulin was administrated 1U once/day/s.c.; and (5) DM + insulin + ANX group: co-administrated insulin. The addition of ANX to insulin in diabetic rats alleviated hyposalivation and histopathological alterations associated with diabetic rats. Remarkably, combined ANX and insulin exerted significant antioxidant effects, suppressing inflammatory and apoptotic pathways associated with increased salivary advanced glycation end-product (AGE) production and receptor for advanced glycation end-product expression (RAGE) activation in diabetic SMG tissues. Combined ANX and insulin administration in diabetic rats was more effective in alleviating SMG changes (functions and structures) than administration of insulin alone, exerting suppressive effects on AGE production and frustrating RAGE downstream pathways.

Early evidence of beneficial and protective effects of Protectin DX treatment on behavior responses and type-1 diabetes mellitus related-parameters: A non-clinical approach

Protectin DX (PDX), a specialized pro-resolving lipid mediator, presents potential therapeutic applications across various medical conditions due to its anti-inflammatory and antioxidant properties. Since type-1 diabetes mellitus (T1DM) is a disease with an inflammatory and oxidative profile, exploring the use of PDX in addressing T1DM and its associated comorbidities, including diabetic neuropathic pain, depression, and anxiety becomes urgent. Thus, in the current study, after 2 weeks of T1DM induction with streptozotocin (60 mg/kg) in Wistar rats, PDX (1, 3, and 10 ng/animal; i.p. injection of 200 μl/animal) was administered specifically on days 14, 15, 18, 21, 24, and 27 after T1DM induction. We investigated the PDX's effectiveness in alleviating neuropathic pain (mechanical allodynia; experiment 1), anxiety-like and depressive-like behaviors (experiment 2). Also, we studied whether the PDX treatment would induce antioxidant effects in the blood plasma, hippocampus, and prefrontal cortex (experiment 3), brain areas involved in the modulation of emotions. For evaluating mechanical allodynia, animals were repeatedly submitted to the Von Frey test; while for studying anxiety-like responses, animals were submitted to the elevated plus maze (day 26) and open field (day 28) tests. To analyze depressive-like behaviors, the animals were tested in the modified forced swimming test (day 28) immediately after the open field test. Our data demonstrated that PDX consistently increased the mechanical threshold throughout the study at the two highest doses, indicative of antinociceptive effect. Concerning depressive-like and anxiety-like behavior, all PDX doses effectively prevented these behaviors when compared to vehicle-treated T1DM rats. The PDX treatment significantly protected against the increased oxidative stress parameters in blood plasma and in hippocampus and prefrontal cortex. Interestingly, treated animals presented improvement on diabetes-related parameters by promoting weight gain and reducing hyperglycemia in T1DM rats. These findings suggest that PDX improved diabetic neuropathic pain, and induced antidepressant-like and anxiolytic-like effects, in addition to improving parameters related to the diabetic condition. It is worth noting that PDX also presented a protective action demonstrated by its antioxidant effects. To conclude, our findings suggest PDX treatment may be a promising candidate for improving the diabetic condition per se along with highly disabling comorbidities such as diabetic neuropathic pain and emotional disturbances associated with T1DM.

Pharmacological Interaction Between Cannabidiol and Tramadol on Experimental Diabetic Neuropathic Pain: An Isobolographic Analysis

Introduction: Diabetic neuropathies are the most prevalent chronic complications of diabetes, characterized by pain and substantial morbidity. Although many drugs have been approved for the treatment of this type of pain, including gabapentin, tramadol (TMD), and classical opioids, it is common to report short-term results or potentially severe side effects. TMD, recommended as a second-line treatment can lead to unwanted side effects. Cannabidiol (CBD) has been gaining attention recently due to its therapeutic properties, including pain management. This study aimed to characterize the pharmacological interaction between CBD and TMD over the mechanical allodynia associated with experimental diabetes using isobolographic analysis. Materials and Methods: After diabetes induction by streptozotocin (STZ), diabetic rats were systemically treated with CBD or TMD alone or in combination (doses calculated based on linear regression of effective dose 40% [ED40]) and had the mechanical threshold evaluated using the electronic Von Frey apparatus. Both experimental and theoretical additive ED40 values (Zmix and Zadd, respectively) were determined for the combination of CBD plus TMD in this model. Results: Acute treatment with CBD (3 or 10 mg/kg) or TMD (2.5, 5, 10, or 20 mg/kg) alone or in combination (0.38+1.65 or 1.14+4.95 mg/kg) significantly improved the mechanical allodynia in STZ-diabetic rats. Isobolographic analysis revealed that experimental ED40 of the combination (Zmix) was 1.9 mg/kg (95% confidence interval [CI]=1.2-2.9) and did not differ from the theoretical additive ED40 2.0 mg/kg (95% CI=1.5-2.8; Zadd), suggesting an additive antinociceptive effect in this model. Conclusions: Using an isobolographic analysis, these results provide evidence of additive pharmacological interaction between CBD and TMD over the neuropathic pain associated with experimental diabetes induced by STZ.

Type 2 diabetes mellitus facilitates status epilepticus in adult rats: Seizure severity, neurodegeneration, and oxidative stress

OBJECTIVE

The goal of this research was to evaluate the effect of DM type 2 (DM2) on SE severity, neurodegeneration, and brain oxidative stress (OS) secondary to seizures.

METHODS

DM2 was induced in postnatal day (P) 3 male rat pups by injecting streptozocin (STZ) 100 mg/kg; control rats were injected with citrate buffer as vehicle. At P90, SE was induced by the lithium-pilocarpine administration and seizure latency, frequency, and severity were evaluated. Neurodegeneration was assessed 24 h after SE by Fluoro-Jade B (F-JB) staining, whereas OS was estimated by measuring lipid peroxidation and reactive oxygen species (ROS).

RESULTS

DM2 rats showed an increase in latency to the first generalized seizure and SE onset, had a higher number and a longer duration of seizures, and displayed a larger neurodegeneration in the hippocampus (CA3, CA1, dentate gyrus, and hilus), the piriform cortex, the dorsomedial nucleus of the thalamus and the cortical amygdala. Our results also show that only SE, neither DM2 nor the combination of DM2 with SE, caused the increase in ROS and brain lipid peroxidation.

SIGNIFICANCE

DM2 causes higher seizure severity and neurodegeneration but did not exacerbate SE-induced OS under these conditions.

PLAIN LANGUAGE SUMMARY

Our research performed in animal models suggests that type 2 diabetes mellitus (DM2) may be a risk factor for causing higher seizure severity and seizure-induced neuron cell death. However, even when long-term seizures promote an imbalance between brain pro-oxidants and antioxidants, DM2 does not exacerbate that disproportion.

Major depressive disorder: hypothesis, mechanism, prevention and treatment

Worldwide, the incidence of major depressive disorder (MDD) is increasing annually, resulting in greater economic and social burdens. Moreover, the pathological mechanisms of MDD and the mechanisms underlying the effects of pharmacological treatments for MDD are complex and unclear, and additional diagnostic and therapeutic strategies for MDD still are needed. The currently widely accepted theories of MDD pathogenesis include the neurotransmitter and receptor hypothesis, hypothalamic-pituitary-adrenal (HPA) axis hypothesis, cytokine hypothesis, neuroplasticity hypothesis and systemic influence hypothesis, but these hypothesis cannot completely explain the pathological mechanism of MDD. Even it is still hard to adopt only one hypothesis to completely reveal the pathogenesis of MDD, thus in recent years, great progress has been made in elucidating the roles of multiple organ interactions in the pathogenesis MDD and identifying novel therapeutic approaches and multitarget modulatory strategies, further revealing the disease features of MDD. Furthermore, some newly discovered potential pharmacological targets and newly studied antidepressants have attracted widespread attention, some reagents have even been approved for clinical treatment and some novel therapeutic methods such as phototherapy and acupuncture have been discovered to have effective improvement for the depressive symptoms. In this work, we comprehensively summarize the latest research on the pathogenesis and diagnosis of MDD, preventive approaches and therapeutic medicines, as well as the related clinical trials.

Anxiolytic and antidepressant like effects of Zamzam water in STZ-induced diabetic rats, targeting oxidative stress, neuroinflammation, BDNF/ERK/CREP pathway with modulation of hypothalamo-pituitary-adrenal axis

Introduction

Recent studies have reported a strong relationship between diabetes and anxiety- and depression-like behaviors; however, there is a lack of information on the underlying pathophysiology. Alkaline Zamzam water (ZW), which is rich in several trace elements, has neuroprotective properties. This study aimed to investigate the anxiolytic and antidepressant effects of ZW against diabetes-induced behavioral changes and shed light on the possible underlying mechanisms.

Methods

Forty-eight rats were divided into four experimental groups (n = 12): group I (control group), group II (Zamzam water group), group III (diabetic group), and group IV (diabetic + Zamzam water group). Diabetes was induced by an intraperitoneal injection of 60 mg/kg streptozotocin (STZ). At the end of the experiment, the forced swimming test (FST) was used to assess depression-like effects. The elevated plus maze test (EPMT) and open field test (OFT) were performed to evaluate anxiety-like behavior. Blood levels of the hypothalamic-pituitary-adrenal (HPA) axis were measured, and prefrontal cortex and hippocampal tissue samples were removed for histological, immunohistochemical, ELISA, and Q-PCR analyses.

Results

ZW significantly decreased the immobility time in the FST, indicating an antidepressant effect (p < 0.001). Additionally, ZW significantly improved the OFT and open field entry (OFE) percentages in the EPMT, increasing center crossing and decreasing grooming and fecal boli in the OFT. This indicated an anxiolytic-like effect in diabetic rats with histological improvement. Interestingly, ZW significantly increased prefrontal cortical and hippocampal levels of antioxidant enzymes and the Nrf2/HO-1 pathway. It also modulated the HPA axis by increasing cortisol and corticotropin-releasing hormone (CRH) levels, with a decrease in ACTH and an increase in monoamine neurotransmitters. Furthermore, diabetic rats that received ZW showed a decrease in the inflammatory markers TNF-α and GFAP by immunohistochemistry and in the mRNA levels of NFκB, IL-1β, and IL6. In addition, ZW downregulated the expression of the BDNF/ERK2/CREP pathway.

Conclusion

Our results suggested a neuroprotective effect of ZW against diabetes-induced anxiety- and depression-like behaviors and explored the underlying mechanisms. These findings suggest a promising therapeutic strategy for patients with diabetes who experience anxiety and depression.

Involvement of Coenzyme Q10 in Various Neurodegenerative and Psychiatric Diseases

Coenzyme Q10 (CoQ10), commonly known as ubiquinone, is a vitamin-like component generated in mitochondrial inner membranes. This molecule is detected broadly in different parts of the human body in various quantities. This molecule can be absorbed by the digestive system from various nutritional sources as supplements. CoQ10 exists in three states: in a of reduced form (ubiquinol), in a semiquinone radical form, and in oxidized ubiquinone form in different organs of the body, playing a crucial role in electron transportation and contributing to energy metabolism and oxygen utilization, especially in the musculoskeletal and nervous systems. Since the early 1980s, research about CoQ10 has become the interest for two reasons. First, CoQ10 deficiency has been found to have a link with cardiovascular, neurologic, and cancer disorders. Second, this molecule has an antioxidant and free-radical scavenger nature. Since then, several investigations have indicated that the drug may benefit patients with cardiovascular, neuromuscular, and neurodegenerative illnesses. CoQ10 may protect the neurological system from degeneration and degradation due to its antioxidant and energy-regulating activity in mitochondria. This agent has shown its efficacy in preventing and treating neurological diseases such as migraine, Parkinson's disease, Alzheimer's disease, Huntington's disease, amyotrophic lateral sclerosis, and Friedreich's ataxia. This study reviews the literature to highlight this agent's potential therapeutic effects in the mentioned neurological disorders.

Amygdala activity and amygdala-hippocampus connectivity: Metabolic diseases, dementia, and neuropsychiatric issues

With rapid aging of the population worldwide, the number of people with dementia is dramatically increasing. Some studies have emphasized that metabolic syndrome, which includes obesity and diabetes, leads to increased risks of dementia and cognitive decline. Factors such as insulin resistance, hyperglycemia, high blood pressure, dyslipidemia, and central obesity in metabolic syndrome are associated with synaptic failure, neuroinflammation, and imbalanced neurotransmitter levels, leading to the progression of dementia. Due to the positive correlation between diabetes and dementia, some studies have called it "type 3 diabetes". Recently, the number of patients with cognitive decline due to metabolic imbalances has considerably increased. In addition, recent studies have reported that neuropsychiatric issues such as anxiety, depressive behavior, and impaired attention are common factors in patients with metabolic disease and those with dementia. In the central nervous system (CNS), the amygdala is a central region that regulates emotional memory, mood disorders, anxiety, attention, and cognitive function. The connectivity of the amygdala with other brain regions, such as the hippocampus, and the activity of the amygdala contribute to diverse neuropathological and neuropsychiatric issues. Thus, this review summarizes the significant consequences of the critical roles of amygdala connectivity in both metabolic syndromes and dementia. Further studies on amygdala function in metabolic imbalance-related dementia are needed to treat neuropsychiatric problems in patients with this type of dementia.

Microglial NLRP3 inflammasome activation mediates diabetes-induced depression-like behavior via triggering neuroinflammation

BACKGROUND

Abundant evidence suggests that the prevalence and risk of depression in people with diabetes is high. However, the pathogenesis of diabetes-related depression remains unclear. Since neuroinflammation is associated with the pathophysiology of diabetic complications and depression, this study aims to elucidate the neuroimmune mechanism of diabetes-related depression.

METHODS

Male C57BL/6 mice were injected with streptozotocin to establish a diabetes model. After screening, diabetic mice were treated with the NLRP3 inhibitor MCC950. Then, metabolic indicators and depression-like behaviors were evaluated in these mice, as well as their central and peripheral inflammation. To explore the mechanism of high glucose-induced microglial NLRP3 inflammasome activation, we performed in vitro studies focusing on its canonical upstream signal I (TLR4/MyD88/NF-κB) and signal II (ROS/PKR/P₂X₇R/TXNIP).

RESULTS

Diabetic mice exhibited depression-like behaviors and activation of NLRP3 inflammasome in hippocampus. In vitro high-glucose (50 mM) environment primed microglial NLRP3 inflammasome by promoting NF-κB phosphorylation in a TLR4/MyD88-independent manner. Subsequently, high glucose activated the NLRP3 inflammasome via enhancing intracellular ROS accumulation, upregulating P₂X₇R, as well as promoting PKR phosphorylation and TXNIP expression, thereby facilitating the production and secretion of IL-1β. Inhibition of NLRP3 with MCC950 significantly restored hyperglycemia-induced depression-like behavior and reversed the increase in IL-1β levels in the hippocampus and serum.

CONCLUSION

The activation of NLRP3 inflammasome, probably mainly in hippocampal microglia, mediates the development of depression-like behaviors in STZ-induced diabetic mice. Targeting the microglial inflammasome is a feasible strategy for the treatment of diabetes-related depression.

Cannabidiol modulates contextual fear memory consolidation in animals with experimentally induced type-1 diabetes mellitus

OBJECTIVES

In view of the neuroprotective characteristic of cannabidiol (CBD) and its beneficial action on aversive memory in non-diabetic animals, we aimed to investigate in animals with experimentally induced type-1 diabetes mellitus (T1DM) whether CBD treatment would be able to impair the contextual fear memory consolidation, its generalisation and whether the effect would be lasting. We also investigated the CBD effect on anxiety-like responses.

METHODS

After T1DM induction, animals received single or more prolonged treatment with CBD and were submitted to the contextual fear conditioning test. As expression of activity-regulated cytoskeletal-associated (Arc) protein is necessary for memory consolidation, we evaluated its expression in the dorsal hippocampus (DH). For evaluating anxiety-related responses, animals were submitted to the elevated plus maze test (EPMT), in which the time and number of entries in the open arms were used as anxiety index.

RESULTS

A single injection of CBD impaired the contextual fear memory consolidation and its generalisation, which was evaluated by exposing the animal in a neutral context. This single injection was able to reduce the elevated expression of Arc in the DH from these animals. Interestingly, more prolonged treatment with CBD also impaired the persistence of context-conditioned fear memory and induced an anxiolytic-like effect, as the treated group spent more time in the open arms of the EPMT.

CONCLUSION

CBD interferes with contextual fear memory and the dosage regimen of treatment seems to be important. Moreover, we cannot rule out the involvement of emotional aspects in these processes related to fear memory.

Long-term treatment with roflumilast improves learning of fear extinction memory and anxiety-like response in a type-1 diabetes mellitus animal model

Diabetic encephalopathy is related to serious damage to the Central Nervous System leading to several disturbances in memory processing and emotions. It is known that the cyclic adenosine 3',5'-monophosphate (cAMP) responsive element-binding protein (CREB) pathway participates in neuronal plasticity and prevention of neuroinflammation, as well as the mediation of learning/memory processes and emotions in brain areas such as the hippocampus (HIP) and prefrontal cortex (PFC). We aimed to investigate the effect of acute (one injection) and long-term treatment (21 days) with roflumilast (ROF; i.p.; 0, 0.01, 0.03, 0.1 mg/kg), a drug able to inhibit the enzyme phosphodiesterase-4 (PDE-4) responsible for cAMP hydrolysis, on parameters related to the acquisition of fear extinction memory and anxiety-like responses in animals with type-1 diabetes mellitus (T1DM) induced through one injection of streptozotocin (60 mg/kg; ip; STZ animals). When we performed acute treatment, no difference was observed between all the groups when resubmitted to the same context paired with an aversive stimulus (footshock) or to a neutral context. In contrast, long-term treatment was able to improve learning of extinction fear memory and discriminating between a conditioned and neutral context. Moreover, this treatment decreased the pronounced anxiety-like response of STZ animals. In addition, there was an increase in the product of the CREB signaling pathway, the pro brain-derived neurotrophic factor, in the HIP and PFC of these animals. The treatment did not impair glycemic control, whereas it decreased the animal's blood glucose levels. To conclude, these findings suggest that ROF treatment repositioning has potential for future translational investigations involving diabetic patients considering its beneficial effects on emotional processes related to fear memory and anxiety, in addition to improvement of glycemic control.

Neuroprotective Effect of Wharton's Jelly-Derived Mesenchymal Stem Cell-Conditioned Medium (WJMSC-CM) on Diabetes-Associated Cognitive Impairment by Improving Oxidative Stress, Neuroinflammation, and Apoptosis

According to strong evidence, diabetes mellitus increases the risk of cognitive impairment. Mesenchymal stem cells have been shown to be potential therapeutic agents for neurological disorders. In the current study, we aimed to examine the effects of Wharton's jelly-derived mesenchymal stem cell-conditioned medium (WJMSC-CM) on learning and memory, oxidative stress, apoptosis, and histological changes in the hippocampus of diabetic rats. Randomly, 35 male Sprague Dawley rats weighing 260-300 g were allocated into five groups: control, diabetes, and three diabetic groups treated with insulin, WJMSC-CM, and DMEM. The injections of insulin (3 U/day, S.C.) and WJMSC-CM (10 mg/week, I.P.) were done for 60 days. The Morris water maze and open field were used to measure cognition and anxiety-like behaviors. Colorimetric assays were used to determine hippocampus glutathione (GSH), malondialdehyde (MDA) levels, and antioxidant enzyme activity. The histopathological evaluation of the hippocampus was performed by Nissl staining. The expression levels of Bax, Bcl-2, BDNF, and TNF-α were detected by real-time polymerase chain reaction (RT-PCR). According to our findings, WJMSC-CM significantly reduced and increased blood glucose and insulin levels, respectively. Enhanced cognition and improved anxiety-like behavior were also found in WJMSC-CM-treated diabetic rats. In addition, WJMSC-CM treatment reduced oxidative stress by lowering MDA and elevating GSH and antioxidant enzyme activity. Reduced TNF-α and enhanced Bcl-2 gene expression levels and elevated neuronal and nonneuronal (astrocytes and oligodendrocytes) cells were detected in the hippocampus of WJMSC-CM-treated diabetic rats. In conclusion, WJMSC-CM alleviated diabetes-related cognitive impairment by reducing oxidative stress, neuroinflammation, and apoptosis in diabetic rats.

A single injection of pregabalin induces short- and long-term beneficial effects on fear memory and anxiety-like behavior in rats with experimental type-1 diabetes mellitus

Anxiety Disorders and Posttraumatic Stress Disorders (PTSD) associated with type-1 diabetes mellitus (T1DM) are increasingly common comorbidities and the treatment is quite challenging. In that sense, evidence indicates that the anticonvulsant pregabalin is highly effective in treating severe cases of anxiety, as well as PTSD and diabetic neuropathic pain which is also very prevalent in T1DM. Herein, the short- and long-term effects of a single injection of pregabalin on the acquisition of a fear extinction memory and parameters of anxiety in induced-T1DM animals were investigated. For that, we used the contextual fear conditioning (CFC) and elevated plus maze paradigms, respectively. A putative antioxidant activity was also evaluated. Our findings demonstrated that induced-T1DM animals presented greater expression of fear memory, difficulty in extinguishing this fear memory, associated with a more pronounced anxiety-like response. Pregabalin was able to induce a short and long-lasting effect by facilitating the acquisition of the fear extinction memory and inducing a later anxiolytic-like effect. Also, the increased lipid peroxidation levels in the hippocampus and prefrontal cortex of induced-T1DM rats were reduced after pregabalin injection, while the decreased levels of reduced glutathione were increased in the hippocampus. Despite the need for more studies to understand the mechanism of action of pregabalin under these conditions, our data demonstrate for the first time that a single injection of pregabalin in a specific time window was able to improve behavioral parameters in addition to inducing neuroprotective effect. Thus, pregabalin has potential worth exploring for the treatment of PTSD and/or Anxiety associated with T1DM.

Melatonin reverses depressive and anxiety like-behaviours induced by diabetes: involvement of oxidative stress, age, rage and S100B levels in the hippocampus and prefrontal cortex of rats

Diabetes is associated with depression and anxiety symptoms. The current investigation was designed to explore the effect of melatonin on depressive and anxiety like-behaviours, oxidative stress, levels of AGE, RAGE and S100B in streptozotocin-induced diabetic rats. The animals were divided into four groups: Normoglycemic; Normoglycemic + melatonin; diabetic; diabetic + melatonin (10 mg/kg, for 4 weeks). The malondialdehyde (MDA), reduced glutathione (GSH), AGE, RAGE and S100B were measured and the depressive and anxiety like-behaviours were assessed by forced swimming and elevated plus maze tests, respectively. Melatonin ameliorates depressive and anxiety like-behaviours. Concomitantly, melatonin reversed diabetes induced increase of MDA, AGE and decrease of GSH and S100B levels in the hippocampus and prefrontal cortex. In conclusion, our results showed that melatonin administration may exert antidepressant-like and anxiolytic effects in diabetic rats through normalising of AGE/RAGE, S100B and oxidative stress in the prefrontal cortex and hippocampus.

LC/ESI/TOF-MS Characterization, Anxiolytic and Antidepressant-like Effects of Mitragyna speciosa Korth Extract in Diabetic Rats

In this study, the attenuative effects of the hydro-alcoholic extract from Mitragyna speciosa (MSE) against diabetes-induced anxiety and depression-like behaviors were examined. In addition, UPLC/ESI/TOF-MS analysis was performed to identify the phytochemical nature of MSE. DM was induced using a combination of high fructose/streptozotocin, and the diabetic rats were treated with MSE (50 and 200 mg/kg) for 5 weeks. After treatment, the animals were subjected to a forced swim test, open field test and elevated plus-maze tests. Additionally, proinflammatory cytokines and oxidative stress parameters were evaluated in the brain tissues of the rats. UPLC/ESI/TOF-MS analysis revealed that MSE is abundantly rich in polyphenolic constituents, notably flavonoid and phenolic glycosides. Behavioral tests and biochemical analyses indicated that diabetic rats showed significantly increased anxiety and depressive-like behavioral deficits, brain oxidative stress and pro-inflammatory cytokines levels (IL-1β, IL-6 and TNF-α). Treatment with MSE (50 and 200 mg/kg) significantly attenuated increased blood glucose level, depressive and anxiety-like behaviors in diabetic rats. Additionally, the antioxidant enzymes activities were markedly increased in MSE-treated animals, while TNF-α, IL-1β and IL-6 cytokines were notably suppressed. Taken together, these results suggested that MSE has potentials as antidepressant and anxiolytic-like effects and improves the brain oxido-inflammatory status in diabetic rats.

Protective effect of Myrcia pubipetala Miq. against the alterations in oxidative stress parameters in an animal model of depression induced by corticosterone

Depression is a debilitating disorder in humans that significantly affects quality of life. As such, alternative therapies are highly sought after by patients seeking treatment for depression. Experimentally, the chronic administration of corticosterone (CORT) in rodents has been reported to promote depressive-like behaviors. Herein, animals received saline or CORT for 21 days and, during the last 7 days, they were treated with the crude hydroalcoholic extract (CHE) of Myrcia pubipetala Miq (50, 100 or 150 mg/Kg), or vehicle (distilled water), by oral route. After 24 h, animals were subjected to the open field (OFT) and forced swimming tests (FST), and then sacrificed for the removal of the hippocampus and cerebral cortex for biochemical analysis. Results showed enhanced catalase (CAT) and superoxide dismutase (SOD) activities, as well as an elevated formation of thiobarbituric acid reactive substances (TBARS), in the cerebral cortex of CORT-treated mice. The chronic administration of the CHE (100 and 150 mg/Kg) reduced TBARS and the increased total sulfhydryl content, and also reversed the increase in TBARS induced by CORT. In the hippocampus, CORT increased CAT and SOD activities and reduced glutathione peroxidase (GSH-Px) (C) activity, while Myrcia pubipetala Miq. CHE (100 and 150 mg/Kg) increased GSH-Px activity when administered alone and reversed decreased GSH-Px (100 and 150 mg/Kg) activity when given during CORT administration. Neither CORT administration nor CHE treatment significantly altered the immobility time of the animals in FST and no changes were observed in the locomotor activity of the animals in the OFT. Findings indicate that the CHE of Myrcia pubipetala Miq. exerts antioxidant effects in the cerebral cortex and hippocampus of mice induced to depression by CORT. Since phenolic compounds are reported to have antioxidant effects in this species, the effects of the CHE may be, at least in part, mediated by the presence of these compounds in Myrcia extract.

Securidaca inappendiculata Polyphenol Rich Extract Counteracts Cognitive Deficits, Neuropathy, Neuroinflammation and Oxidative Stress in Diabetic Encephalopathic Rats via p38 MAPK/Nrf2/HO-1 Pathways

Diabetic encephalopathy is one of the serious emerging complication of diabetes. Securidaca inappendiculata is an important medicinal plant with excellent antioxidant and anti-inflammatory properties. This study investigated the neuroprotective effects of S. inappendiculata polyphenol rich extract (SiPE) against diabetic encephalopathy in rats and elucidated the potential mechanisms of action. Type 2 diabetes mellitus (T2DM) was induced using high fructose solution/intraperitoneal injection of streptozotocin and the diabetic rats were treated with SiPE (50, 100 and 200 mg/kg) for 8 weeks. Learning and memory functions were assessed using the Morris water and Y maze tests, depressive behaviour was evaluated using forced swimming and open field tests, while neuropathic pain assessment was assessed using hot plate, tail immersion and formalin tests. After the experiments, acetylcholinesterase (AChE), oxidative stress biomarkers and proinflammatory cytokines, caspase-3 and nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) were determined by ELISA kits. In addition, the expression levels of p38, phospho-p38 (p-p38), nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were determined by western blot analyses. The results indicated that SiPE administration significantly lowered blood glucose level, attenuated body weight loss, thermal/chemical hyperalgesia, improved behavioural deficit in the Morris water maze, Y maze test and reduced depressive-like behaviours. Furthermore, SiPE reduced AChE, caspase-3, NF-κB, malonaldehyde malondialdehyde levels and simultaneously increased antioxidant enzymes activity in the brain tissues of diabetic rats. SiPE administration also significantly suppressed p38 MAPK pathway and upregulated the Nrf2 pathway. The findings suggested that SiPE exerted antidiabetic encephalopathy effects via modulation of oxidative stress and inflammation.

Myrsinoic acid B from Myrsine coriacea reverses depressive-like behavior and brain oxidative stress in streptozotocin-diabetic rats

AIMS

Major depressive disorder (MDD) affects approximately 322 million people worldwide and is a common comorbidity in patients with diabetes mellitus (DM). A possible pathophysiological mechanism correlating both diseases is the increased oxidative stress in brain regions due to hyperglycemia. Myrsine coriacea (Primulaceae) is popularly known as "capororoca" and studies have been shown that this plant exhibits several pharmacological properties attributed to myrsinoic acid A (MAA) and B (MAB). Indeed, previous results have been shown its effects on the central nervous system, leading us to explore possible psychotropic effects.

MAIN METHODS

The effects of treatment with hydroalcoholic extract of the barks from Myrsine coriacea (HEBMC, 150 mg/kg, o.g.), MAA (5 mg/kg, o.g.), and MAB (3 mg/kg, o.g.) were evaluated in streptozotocin (75 mg/kg, i.p.)-induced diabetic female rats. After 28 days of treatments, rats were submitted to the forced swim test (FST) and open field test (OFT). Also, superoxide dismutase (SOD) and catalase (CAT) activities, reduced glutathione (GSH) and lipid hydroperoxides (LOOH) levels were evaluated in the hippocampus (HIP) and prefrontal cortex (PFC) of these rats.

KEY FINDINGS

The treatment with MAA or MAB increased the latency of first immobility in diabetic rats, and the HEBMC administration decreased the immobility time, and increase the climbing in FST. However, only MAB treatment reduces the immobility time, increases the climbing, and swimming in FST, and increases the crossing of diabetic animals in the OFT. Besides, this behavioral improvement promoted by MAB administration was accompanied by reducing in oxidative stress in the HIP and PFC, but not reducing hyperglycemia in diabetic rats.

SIGNIFICANCE

The results suggest that MAB's antioxidant effect in the HIP of diabetic animals may be essential to its antidepressant-like effect.

Catalpol Weakens Depressive-like Behavior in Mice with Streptozotocin-induced Hyperglycemia via PI3K/AKT/Nrf2/HO-1 Signaling Pathway

Depression has huge social risks of high incidence, disability, and suicide. Its prevalence and harm in people with hyperglycemia are 2-3 times higher than in normal people. However, antidepressants with precise curative effects and clear mechanisms for patients with hyperglycemia are currently lacking. Prescriptions containing Rehmannia glutinosa, a traditional medicinal herb with a wide range of nutritional and medicinal values, are often used as antidepressants in Chinese clinical medicine. Catalpol is one of the main effective compounds of R. glutinosa, with multiple biological activities such as hypoglycemia. Here, the antidepressant effect of catalpol on the pathological state of streptozotocin (STZ)-induced hyperglycemia and the underlying molecular mechanisms were analyzed. Results showed that administering catalpol orally to hyperglycemic mice for 21 consecutive days significantly reversed the abnormalities in tail suspension, forced swimming, and open field tests. Catalpol also reversed the abnormal phosphorylation of phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT) and the abnormal levels of nuclear factor erythroid 2-related factor 2 (Nrf2) protein, heme oxygenase-1 (HO-1), and antioxidants, including superoxide dismutase, glutathione peroxidase, glutathione-s transferase, reduced glutathione, and malondialdehyde in the hippocampus and frontal cortex of STZ-induced hyperglycemic mice. Thus, catalpol attenuates depressive-like behavior in pathological hyperglycemic state, and the antidepressant mechanism could at least be partly attributed to the upregulation of the PI3K/AKT/Nrf2/HO-1 signaling pathway in both brain regions, thus restoring the balance between oxidative and antioxidant damage. These data expanded the scientific understanding of catalpol and provided preclinical experimental evidence for its application.

Polygonatum sibiricum polysaccharide prevents depression-like behaviors by reducing oxidative stress, inflammation, and cellular and synaptic damage

ETHNOPHARMACOLOGICAL RELEVANCE

According to traditional Chinese medicine (TCM) theory (Yi Xue Zheng Zhuan), the main factors associated with the pathogenesis of depression are deficiencies relating to five zang organs, Qi, and blood. Polygonatum sibiricum F. Delaroche (PS), which may avert these pathological changes, has been used in a variety of formulas to treat depression. However, the effects and mechanism of action of PS, alone, and especially those of its main active component PS polysaccharide (PSP), on depression remain unexplored.

AIM OF THE STUDY

To determine the effects of PSP on depression-like behaviors and to elucidate its mechanism of action.

METHODS

PSP was isolated from dried PS rhizomes and qualified using transmission electron microscopy and Fourier transform infrared spectroscopy. Lipopolysaccharide (LPS) and chronic unpredictable mild stress (CUMS)-induced depression models were used to evaluate the antidepressive effects of PSP. Veinal blood and brain tissue were collected to determine the levels of hippocampal 5-HT, serum cortisol (CORT), brain and serum cytokines, and hippocampal oxidation-related indicators. The protein expression levels of phosphorylated extracellular signal-regulated kinase (p-ERK1/2), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), glial fibrillary acidic protein (GFAP), phosphorylated protein kinase B (p-Akt), phosphorylation of the mammalian target of rapamycin (mTOR), caspase-3, GluA1 and GluA2, and GluN2A and GluN2B were determined using western blotting and immunofluorescence. Nissl staining was performed to detect histopathological changes in brain tissues.

RESULTS

Injection of LPS (i.p.) induced depression-like behaviors, reduced the level of hippocampal 5-HT, increased the serum CORT level and hippocampal oxidative stress (ROS), and prompted the activation of ERK1/2, NF-κB, and GFAP and an inflammatory response. Conversely, PSP administration reduced these changes and prevented depression-like behaviors. PSP administration also promoted hippocampal expression of p-Akt, p-mTOR, GluA1, and GluA2; reduced the expression of caspase-3, GluN2A, and GluN2B; and prohibited the loss of granular cells in the DG region.

CONCLUSION

These results indicate that PSP prevents depression-like behaviors, and synaptic and neuronal damage probably by reducing ROS/HPA axis hyperfunction and the inflammatory response.

Subchronic neurotoxicity of diazinon in albino mice: Impact of oxidative stress, AChE activity, and gene expression disturbances in the cerebral cortex and hippocampus on mood, spatial learning, and memory function

Diazinon (DZN) with prominent neurotoxic effects perturbs CNS function via multiple mechanisms. This investigation intends to explore mood, spatial learning, and memory dysfunction, acetylcholine esterase (AChE) activity, and neurodegeneration-related gene expression in the cortex and hippocampus regions of mice exposed to DZN for 63 consecutive days (subchronic exposure). Adult male albino mice were orally given sublethal DZN (DZNL = 0.1 mg/kg, DZNM = 1 mg/kg and DZNH = 10 mg/kg). All mice in the DZNH group died within 3 weeks postexposure. DZNL and DZNM caused body and brain weight loss (p < 0.05). Completing 9 weeks of DZN exposure, a marked decline in AChE activity and oxidative stress level was indicated in both brain regions (p < 0.05). Also, synaptophysin, vesicular acetylcholine transferase, and glutamate decarboxylase gene expressions were affected in both brain regions (p < 0.05). Furthermore, the present study revealed that DZN administration increased anxiety and depressive-like behaviors (p < 0.0001). Spatial learning and short- and long-memory were severely affected by DZNL and DZNM treatments (p < 0.0001). Taken together, subchronic exposure to low and medium doses of DZN can cause AChE inhibition, oxidative damage, and neurotransmitter disturbances in brain cells and induce neurodegeneration. These changes would impair mood, spatial learning, and memory function.

Increase in brain l-lactate enhances fear memory in diabetic mice: Involvement of glutamate neurons

Previous reports suggest that diabetes mellitus is associated with psychiatric disorders, including depression and anxiety, but the mechanisms involved are unknown. We have reported that streptozotocin (STZ)-induced diabetic mice show enhancement of conditioned fear memory. To clarify the mechanisms through which diabetes affects conditioned fear memory, the present study investigated the role of l-lactate and glutamatergic function in enhancement of conditioned fear memory in diabetes. l-lactate levels in the amygdala and hippocampus, which are known to play important roles in fear memory, were significantly increased in STZ-induced diabetic mice. The glucose transporter (GLUT) 1 was significantly increased both in the amygdala and in the hippocampus. In contrast, GLUT3, the monocarboxylic acid transporter (MCT) 1 and MCT2 in the amygdala and hippocampus were not altered in STZ-induced diabetic mice. I.c.v. injection of l-lactate to non-diabetic mice significantly increased duration of freezing, whereas the MCT inhibitor 4-CIN significantly inhibited duration of freezing in STZ-induced diabetic mice. Injection of l-lactate significantly increased glutamate levels in the amygdala and hippocampus. Duration of freezing induced by l-lactate was significantly inhibited by the AMPA receptor antagonist NBQX. In addition, injection of NBQX into the amygdala and hippocampus significantly inhibited duration of freezing in STZ-induced diabetic mice. These results suggest that l-lactate levels are increased in the amygdala and hippocampus in diabetic mice, which may enhance fear memory though activation of glutamatergic function in the amygdala and hippocampus.

Bixin attenuates mechanical allodynia, anxious and depressive-like behaviors associated with experimental diabetes counteracting oxidative stress and glycated hemoglobin

Neuropathic pain, depression, and anxiety are common comorbidities in diabetic patients, whose pathophysiology involves hyperglycemia-induced increased oxidative stress. Bixin (BIX), an apocarotenoid extracted from the seeds of Bixa orellana, has been used in traditional medicine to treat diabetes and has been recognized by its antioxidant profile. We aimed to investigate the effect of the BIX over the mechanical allodynia, depressive, and anxious-like behaviors associated with experimental diabetes, along with its involved mechanisms. Streptozotocin-induced diabetic rats were treated for 17 days (starting 14 days after diabetes induction) with the corresponding vehicle, BIX (10, 30 or 90 mg/kg; p.o), or INS (6 IU; s.c.). Mechanical allodynia, depressive, and anxious-like behavior were assessed by electronic Von Frey, forced swimming, and elevated plus-maze tests, respectively. Locomotor activity was assessed by the open field test. Blood glycated hemoglobin (HbA1) and the levels of lipid peroxidation (LPO) and reduced glutathione (GSH) were evaluated on the hippocampus, pre-frontal cortex, lumbar spinal cord, and sciatic nerve. Diabetic animals developed mechanical allodynia, depressive and anxious-like behavior, increased plasma HbA1, increased LPO, and decreased GSH levels in tissues analyzed. Repeated BIX-treatment (at all tested doses) significantly attenuated mechanical allodynia, the depressive (30 and 90 mg/kg) and, anxious-like behaviors (all doses) in diabetic rats, without changing the locomotor performance. BIX (at all tested doses) restored the oxidative parameters in tissues analyzed and reduced the plasma HbA1. Thereby, bixin may represent an alternative for the treatment of comorbidities associated with diabetes, counteracting oxidative stress and plasma HbA1.

PI3K/AKT pathway mediates the antidepressant- and anxiolytic-like roles of hydrogen sulfide in streptozotocin-induced diabetic rats via promoting hippocampal neurogenesis

We have previously demonstrated that hydrogen sulfide (H₂S), the third endogenous gasotransmitter, ameliorates the depression- and anxiety-like behaviors in diabetic rats, but the underlying mechanism remains unclear. The present was aimed to investigate whether the hippocampal phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway mediates H₂S-ameliorated depression- and anxiety-like behaviors in diabetic rats by improving the hippocampal neurogenesis. The depression-like behaviors were examined by Tail suspension test (TST), the anxiety-like behaviors were examined by Elevated plus maze test (EPM), and the locomotor activity was detected by Open Field Test (OFT). The expressions of doublecortin (DCX), neuron-specific nuclear protein (NeuN), glial fibrillary acidic protein (GFAP), p-AKT, and AKT in the hippocampus were determined by Western blot analysis. Results showed that NaHS, a donor of exogenous H₂S, not only activated the hippocampal PI3K/AKT pathway, as evidenced by the increase of phosphorylated AKT, but also favorably reversed streptozotocin (STZ)-disturbed hippocampal neurogenesis, as evidenced by the increases in the expressions of DCX and NeuN as well as the decrease in the expression of GFAP in the hippocampus of STZ-induced diabetic rats. Furthermore, inhibited PI3K/AKT pathway by LY294002 significantly abolished H₂S-exerted the improvement of hippocampal neurogenesis and the antidepressant- and anxiolytic-like effects in the STZ-induced diabetic rats. Taken together, these results uncover that the activation of hippocampal PI3K/AKT pathway plays an important role to restore hippocampal neurogenesis and subsequently to mediate the antidepressant- and anxiolytic-like roles of H₂S in STZ-induced diabetic rats and enhance our understanding of the robustness of H₂S as a therapeutic strategy for treatment of depression in diabetes mellitus.

Cannabidiol induces antidepressant and anxiolytic-like effects in experimental type-1 diabetic animals by multiple sites of action

Cannabidiol (CBD), a phytocannabinoid compound, presents antidepressant and anxiolytic-like effects in the type-1 diabetes mellitus(DM1) animal model. Although the underlying mechanism remains unknown, the type-1A serotonin receptor (5-HT1A) and cannabinoids type-1 (CB1) and type-2 (CB2) receptors seem to play a central role in mediating the beneficial effects on emotional responses. We aimed to study the involvement of these receptors on an antidepressant- and anxiolytic-like effects of CBD and on some parameters of the diabetic condition itself. After 2 weeks of the DM1 induction in male Wistar rats by streptozotocin (60 mg/kg; i.p.), animals were treated continuously for 2-weeks with the 5-HT1A receptor antagonist WAY100635 (0.1 mg/kg, i.p.), CB1 antagonist AM251 (1 mg/kg i.p.) or CB2 antagonist AM630 (1 mg/kg i.p.) before the injection of CBD (30 mg/kg, i.p.) or vehicle (VEH, i.p.) and then, they were submitted to the elevated plus-maze and forced swimming tests. Our findings show the continuous treatment with CBD improved all parameters evaluated in these diabetic animals. The previous treatment with the antagonists - 5-HT1A, CB1, or CB2 - blocked the CBD-induced antidepressant-like effect whereas only the blockade of 5-HT1A or CB1 receptors was able to inhibit the CBD-induced anxiolytic-like effect. Regarding glycemic control, only the blockade of CB2 was able to inhibit the beneficial effect of CBD in reducing the glycemia of diabetic animals. These findings indicated a therapeutic potential for CBD in the treatment of depression/anxiety associated with diabetes pointing out a complex intrinsic mechanism in which 5-HT1A, CB1, and/or CB2 receptors are differently recruited.

Effects of date seeds administration on anxiety and depressive symptoms in streptozotocin-induced diabetic rats: biochemical and behavioral evidences

OBJECTIVES

Several epidemiological data indicate that chronic hyperglycemia is associated with behavioral changes such as anxiety and depressive symptoms. Date seeds, one of the most potent products with potential antioxidant activities and possess many benefits against hyperglycemia and its complication. The aim of the current study was to explore the potential effect of date seeds extract on biochemical and behavioral changes (anxiety and depression) in streptozotocin (STZ)-diabetic rats.

METHODS

Rats were divided into four groups as follows: normal control, diabetic control, diabetic treated with the lyophilized aqueous extract of the date seed (2,000 mg/kg) (LAE-DS) and diabetics treated with insulin (4 UI/day). Experimental diabetes was induced by a single intraperitoneal injection of STZ (60 mg/kg). After 24 days treatment period, anxiety and depressive behaviors were evaluated using four behavioral tests. After sacrifice, blood samples were collected to evaluate lipid parameters. In addition, rat organs (kidney, liver and brain) were dissected out in order to estimate lipid peroxidation levels as oxidative stress marker.

RESULTS

Oral administration of the lyophilized aqueous extract of date seeds and insulin injection for 30 days significantly decreased blood glucose levels in STZ-diabetic rats and protected them against undesirable changes in lipid parameters, including cholesterol, triglycerides, LDL cholesterol, VLDL cholesterol and atherosclerosis index. Compared to untreated diabetic rat, a significant decrease in lipid peroxidation levels in kidney, liver and brain (Hippocampus and prefrontal cortex) were observed after treatment with insulin or LAE-DS in diabetic rats. Furthermore, insulin and LAE-DS administration prevented anxiety-related behaviors in STZ-diabetic rats.

CONCLUSIONS

Therefore, it would be possible to combine this extract with insulin and use it as an antioxidant supplement for type 1 diabetic patients.

Astrocyte Intracellular Ca2+and TrkB Signaling in the Hippocampus Could Be Involved in the Beneficial Behavioral Effects of Antidepressant Treatment

Although monoaminergic-based antidepressant drugs are largely used to treat major depressive disorder (MDD), their mechanisms are still incompletely understood. Intracellular Ca²⁺ (iCa²⁺) and Calmodulin 1(CaM-1) homeostasis have been proposed to participate in the therapeutic effects of these compounds. We investigated whether intra-hippocampal inhibition of CaM-1 would modulate the behavioral responses to chronic treatment with imipramine (IMI) or 7-nitroindazole (7-NI), a selective inhibitor of the neuronal nitric oxide synthase 1 (NOS1) enzyme that shows antidepressant-like effects. We also investigated the interactions of IMI and CaM-1 on transient astrocyte iCa²⁺ evoked by glutamate stimuli. Intra-hippocampal microinjection of the lentiviral delivered (LV) short hairpin iRNA-driven against the CaM-1 mRNA (LV-shRNA-CaM-1) or the CaM-1 inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalene sulphonamide (W-7) blocked the antidepressant-like effect of chronic treatment with IMI or 7-NI. The shRNA also inhibited the mRNA expression of the tropomyosin receptor kinase B (TrkB) in the microinjection region. The iCa²⁺ in ex vivo hippocampus slices stained with fluorescent Ca²⁺indicator Oregon Green 488 BAPTA-1 revealed that IMI increased the intensity and duration of iCa²⁺ oscillation and reduced the number of events evoked by glutamate stimuli, evaluated by using CCD imaging and the % ΔF/Fo parameters. The pre-treatment with W-7 fully antagonized this effect. The present results indicate that the behavioral benefits of chronic antidepressant treatment might be associated with astrocyte intracellular Ca²⁺dynamics and TrkB mRNA expression in the hippocampus.

Hippocampal monoamine changes in the Flinders sensitive line rat: A case for the possible use of selective α2C-AR-antagonists in stress and anxiety disorders in companion animals

Non-selective α₂-adrenoreceptor (AR) stimulation delivers favourable sedative, analgesic, muscle relaxant and anxiolytic actions in companion animals, but is associated with cardiovascular and respiratory side effects. Anxiety conditions underscore monoamine disturbances amenable to α₂-AR modulation. We investigated sub-chronic (14 day s.c.) treatment with the selective α_2C-AR antagonist, ORM-10921 (0.03, 0.1, 0.3 mg/kg/d) on hippocampal noradrenaline (NA), dopamine (DA), serotonin (5-HT) and their turnover levels in stress sensitive Flinders Sensitive Line (FSL) rats versus Flinders Resistant Line (FRL) controls, using high performance liquid chromatography. The effects of ORM-10921 were compared to the non-selective α₂-AR antagonist, idazoxan (IDAZ; 3 mg/kg/d), and to imipramine (IMI; 15 mg/kg/d), a reference antidepressant in this model. FSL rats displayed significantly reduced 5-HT (p = 0.03) and DA (p = 0.02) levels vs. FRL controls, while NA levels showed a similar trend. ORM-10921 significantly increased NA (all doses p ≤ 0.02), 5-HT (0.1 and 0.3 mg/kg p ≤ 0.03) and DA levels (all doses p ≤ 0.03), which correlated with decreased monoamine turnover. In contrast, IDAZ significantly elevated NA (p < 0.005) and DA (p < 0.004) but not 5-HT levels. IMI also significantly increased 5-HT (p < 0.009), with a tendency to increase NA (p = 0.09) but not DA. ORM-10921 exerts similar albeit broader effects on hippocampal monoamines than IDAZ, explaining earlier established efficacy associated with α_2C-AR antagonism in animal models of depression and cognitive dysfunction. These and the current studies encourage application of ORM-10921 in depression in humans, as well as raise the intriguing possibility that selective α_2C-AR antagonists may be beneficial in anxiety and stress-related disorders in companion animals. Both warrant further study.

Garlic (Allium sativum) improves anxiety- and depressive-related behaviors and brain oxidative stress in diabetic rats

This study investigated the effects of garlic on anxiety- and depression-related behaviors and brain oxidative markers in streptozotocin (STZ)-induced diabetes in rats. Fifty-six male Wistar rats were randomly divided into seven experimental groups (n = 8/group): control, diabetic + saline, diabetic + garlic, diabetic + imipramine, and diabetic + diazepam groups. Animals received garlic homogenate (0.1, 0.25, and 0.5 g/kg) for 10 days. At the end of the treatments, anxiety- and depressive-related behaviors were evaluated by elevated plus maze (EPM) and forced swimming test (FST), respectively. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and malondialdehyde (MDA) levels were measured in the brain. Diabetic + garlic (0.5 g/kg) group showed lower anxiety- and- depressive-like behaviors as compared to the diabetic rats. Furthermore, garlic treatment (0.5 g/kg) attenuated MDA levels and enhanced SOD and GPx activities in the brain. Our findings indicate that garlic alleviates anxiety- and depression-related behaviors in the diabetic rats possibly by attenuation of brain oxidative stress.

Activation of mineralocorticoid receptors facilitate the acquisition of fear memory extinction and impair the generalization of fear memory in diabetic animals

RATIONALE

Studies point out a higher prevalence of posttraumatic stress disorder (PTSD) in individuals with diabetes mellitus. It is known that glucocorticoid (GR) and mineralocorticoid (MR) receptors are implicated in fear memory processes and PTSD. However, there is no preclinical studies addressing the involvement of these receptors on abnormal fear memories related to diabetic condition.

OBJECTIVES

By inducing a contextual conditioned fear memory, we generate a suitable condition to investigate the extinction and the generalization of the fear memory in streptozotocin-induced diabetic (DBT) rats alongside the expression of the cytosolic and nuclear GR and MR in the hippocampus (HIP) and prefrontal cortex (PFC). Moreover, we investigated the involvement of the MR or GR on the acquisition of fear memory extinction and on the generalization of this fear memory. When appropriate, anxiety-related behavior was evaluated.

METHODS

Male Wistar rats received one injection of steptozotocin (i.p.) to induce diabetes. After 4 weeks, the animals (DBTs and non-DBTs) were subjected to a conditioned contextual fear protocol.

RESULTS

The expression of MR and GR in the HIP and PFC was similar among all the groups. The single injection of MR agonist was able to facilitate the acquisition of the impaired fear memory extinction in DBTs animals together with the impairment of its generalization. However, the GR antagonism impaired only the generalization of this fear memory which was blocked by the previous injection of the MR antagonist. All treatments were able to exert anxiolytic-like effects.

CONCLUSIONS

The results indicate that MR activation in DBT animals disrupts the overconsolidation of aversive memory, without discarding the involvement of emotional behavior in these processes.

Antidepressant, Anxiolytic and Neuroprotective Activities of Two Zinc Compounds in Diabetic Rats

Behavioral disorders affect most diabetic patients and Zinc (Zn) has been used among adjuvant therapies for involvement in the etiology of depression and anxiety, however, the results are still controversial. The objective of this study was to compare the antidepressant, anxiolytic and neuroprotective activity of the supplementation of two Zn compounds in an animal model of Diabetes Mellitus type 1 (DM1). Thirty-eight (38) adult rats were randomized into four groups: Control (C; n = 8); Diabetic (D; n = 10); Diabetic Zn Sulfate Supplement (DSZ; n = 10) and Diabetic Zn Gluconate Supplement (DGZ; n = 10). The DSZ group received Zn sulfate supplementation and the DGZ group received Zn gluconate supplementation at a dose of 15 mg/kg for 4 weeks. Data (mean ±SEM) were analyzed by the Mann-Whitney test with a significance level of p < 0.05. The results indicate that Zn gluconate supplementation in diabetic animals presented an antidepressant effect demonstrated through the results obtained in the Forced Swim Test, and neuroprotective effect by attenuating alterations in the cerebral cortex; while Zn sulfate supplementation in diabetic animals showed an anxiolytic effect demonstrated by the results obtained in the open field test and the elevated plus maze test. Considering the set of results, supplementation with both zinc compounds showed neurobehavioral benefits in diabetic animals with different effects depending on the type of anion associated with Zn.

Protective Effects of Spirulina platensis, Voluntary Exercise and Environmental Interventions Against Adolescent Stress-Induced Anxiety and Depressive-Like Symptoms, Oxidative Stress and Alterations of BDNF and 5HT-3 Receptors of the Prefrontal Cortex in Female Rats

BACKGROUND AND PURPOSE

Ample evidence indicates that chronic adolescence stress is associated with an increased risk of developing neuropsychiatric disorders in adulthood. Given the importance of the effective therapeutic ways to overcome adolescent stress-related deficits, the present study investigated the effects of Spirulina platensis (SP), environmental enrichment (EE), and voluntary exercise (EX) and their combination on anxiety or depression-like behaviors, oxidative stress, and alterations of BDNF and 5HT-3 receptors in the prefrontal cortex (PFC) induced by adolescent stress in adult female rats.

METHODS

During the adolescent period (PNDs30-40), rats were subjected to restraint stress. Then, the animals were subjected to SP treatment (200 mg/kg/day), EX, EE, and the combined treatments (SP+EX, and SP+EE) for 15 days between PNDs41-55. Subsequently, anxiety or depression-like behaviors, BDNF levels, oxidative stress markers and mRNA expression of BDNF and 5HT₃ in the PFC were assessed.

RESULTS

Stressed rats demonstrated enhanced anxiety levels and depression-like behaviors in adulthood. Regarding the oxidative stress markers, stressed rats exhibited significantly higher levels of malondialdehyde, a lipid peroxidation product, higher activities of antioxidant enzymes (glutathione peroxidase and superoxide dismutase) and significantly lower total antioxidant reactivity capacity in the PFC. Additionally, adolescent stress significantly increased 5HT3 receptor mRNA expression and decreased BDNF content and its mRNA expression in the PFC. Treatments with SP, EX, EE, and the combined interventions alleviated these deficits.

CONCLUSION

Our findings indicate that appropriate interventions during the adolescent period can protect against adolescent stress-induced behavioral, and biochemical defects and oxidative stress damage in adulthood.

Responsivity of lateral septum-mPFC connections in alloxan-induced hyperglycemia

The lateral septal nucleus (LSN) is related to the actions of antidepressants, and the prelimbic cortex (PL) and infralimbic cortex (IL) modulate responses to fear. However, unknown is whether experimental diabetes that is induced by alloxan alters the responsivity of these regions. We used a method in which one forebrain region (LSN) was electrically stimulated while single-unit extracellular recordings were performed in another mPFC region (PL and IL). Several experimental groups were tested: (a) animals that were subjected to long-term (42-day) alloxan-hyperglycemia and protected with insulin, (b) healthy animals that received a low dose of insulin that does not produce changes in glycemia, and (c) animals that received long-term treatment with fluoxetine. Additional healthy groups of animals received insulin or fluoxetine and underwent the forced swim test. Biological measurements indicated the induction of diabetes in alloxan-treated rats. In this group, a shift toward an inhibitory response to LSN stimulation was observed in the PL and IL compared with the control group. A low dose of insulin or fluoxetine produced similar changes in LSN-PL and LSN-IL responsivity. Long-term hyperglycemia increased inhibitory responsivity in the LSN-PL and LSN-IL, but this action was less pronounced than the action that was exerted by insulin and fluoxetine, which produced similar actions. Such similar actions were confirmed in the forced swim test, in which the antidepressant-like effects of insulin partially resembled the effects of fluoxetine. The changes that were observed in the alloxan group appeared to be related to neuronal damage, and a low dose of insulin exerted some antidepressant-like actions.

Analgesic and Antidepressant Effects of Oltipraz on Neuropathic Pain in Mice by Modulating Microglial Activation

Nerve injury provokes microglial activation, contributing to the sensory and emotional disorders associated with neuropathic pain that do not completely resolve with treatment. In C57BL/6J mice with neuropathic pain induced by chronic constriction of the sciatic nerve (CCI), we evaluated the effects of oltipraz, an antioxidant and anticancer compound, on (1) allodynia and hyperalgesia, (2) microglial activation and pain signaling pathways, (3) oxidative stress, and (4) depressive-like behaviors. Twenty-eight days after surgery, we assessed the effects of oltipraz on the expression of CD11b/c (a microglial marker), phosphoinositide 3-kinase (PI3K)/ phosphorylated protein kinase B (p-Akt), nuclear factor-κB (NF-κB) transcription factor, and mitogen activated protein kinases (MAPK) in the spinal cord, hippocampus, and prefrontal cortex. Our results show that oltipraz alleviates neuropathic pain by inhibiting microglial activation and PI3K/p-Akt, phosphorylated inhibitor of κBα (p-IκBα), and MAPK overexpression, and by normalizing and/or enhancing the expression of antioxidant proteins, nuclear factor erythroid derived-2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1), and NAD(P)H:quinone oxidoreductase-1 (NQO1) in the spinal cord. The inhibition of microglial activation and induction of the Nrf2/HO-1/NQO1 signaling pathway in the hippocampus and/or prefrontal cortex may explain the antidepressant effects of oltipraz during neuropathic pain. These data demonstrate the analgesic and antidepressant effects of oltipraz and reveal its protective and antioxidant properties during chronic pain.

Anxiolytic-Like and Antidepressant-Like Effects of Resveratrol in Streptozotocin-Induced Diabetic Rats

Introduction

Diabetes is associated with anxiety and depression. Resveratrol, one of the most potent natural polyphenols with antioxidant properties, has been demonstrated to have benefits against diabetes. In the current study, we investigated the effects of resveratrol on depression and anxiety-like behaviors in diabetic rats.

Methods

Adult male Wistar albino rats were assigned for control and diabetic groups, and these groups were divided into four subgroups as follows: Saline-treated, DMSO-treated, resveratrol-treated and imipramine-treated animals (n=10). Diabetes was induced by a single intraperitoneal injection of streptozotocin (STZ) (50 mg/kg), and 2 days after the STZ injection the rats having hyperglycemia (>300 mg/dl) were assigned to be diabetic. Rats in treatment groups were injected intraperitoneally with resveratrol (20 mg/kg) and imipramine (10 mg/kg) for 4 weeks. After 4-week-treatment period, tail suspension test (TST), forced swimming test (FST), elevated plus maze test (EPM) and locomotor activity test were performed. Blood samples were collected to estimate serum superoxide dismutase (SOD) and NADPH oxidase (Nox) levels.

Results

Diabetic rats displayed depressive-like behaviors in the FST and TST, and anxiety-like behaviors in the EPM. Resveratrol and imipramine decreased anxiety-like and depressive-like behaviors without affecting locomotor activity in diabetic rats. A significant reduction in SOD levels and a marked increase in Nox levels were observed in diabetic rats. Resveratrol treatment normalized these levels, while imipramine did not affect neither SOD nor Nox levels.

Conclusion

This study indicates that chronic resveratrol treatment may able to treat comorbid anxiety-and depressive-like behaviors in diabetes through inhibition of oxidative stress.

Ellagic acid protects against diabetes-associated behavioral deficits in rats: Possible involved mechanisms

AIMS

Diabetes mellitus (DM), a chronic metabolic disease, is associated with behavioral deficits. It has been suggested that ellagic acid (EA), a natural polyphenol compound, has potent anti-diabetic, anti-inflammatory, and neuroprotective properties. The present study was aimed to explore the potential protective effects of EA against diabetes-associated behavioral deficits and verified possible involved mechanisms.

MAIN METHODS

Fifty adult male Wistar rats were randomly divided into five groups: i.e., CON: normal rats treated with vehicle (5 ml/kg/day; P.O.), EA: normal rats treated with EA (50 mg/kg/day; P.O.), STZ: diabetic rats treated with vehicle (5 ml/kg/day; P.O.), STZ + INS: diabetic rats treated with insulin (6 IU/rat/day; S.C.), STZ + EA: diabetic rats treated with EA (50 mg/kg/day; P.O.). All the groups were under treatment for eight consecutive weeks. During the seventh and eighth weeks, behavioral functions of the rats were assessed by commonly used behavioral tests. Subsequently, pro- and anti-inflammatory cytokines, neurotrophic factors, and also histological changes were evaluated in both cerebral cortex and hippocampus of the rats.

KEY FINDINGS

Chronic EA treatment attenuated anxiety/depression-like behaviors, improved exploratory/locomotor activities, and ameliorated cognitive deficits in diabetic rats. These results were accompanied by decreased blood glucose levels, modulation of inflammation status, improved neurotrophic support, and amelioration of neuronal loss in diabetic rats. In some aspects, treatment with EA was even more effective than insulin therapy.

SIGNIFICANCE

The current work's data confirms that EA could potentially serve as a novel, promising, and accessible protective agent against diabetes-associated behavioral deficits, owing to its anti-hyperglycemic, anti-inflammatory, and neurotrophic properties.

Coenzyme Q10 Alleviated Behavioral Dysfunction and Bioenergetic Function in an Animal Model of Depression

Coenzyme Q₁₀ (CoQ₁₀) is a natural compound, is involved in the mitochondrial electron transfer chain (ETC) and plays an important pattern in adenosine triphosphate (ATP) production. Amelioration of ATP is related to abnormalities in cognitive function and psychiatric diseases. Previous studies have shown that depression is accompanied by the induction of inflammatory and oxidative stress pathways and amelioration of antioxidant status. In a recent study, we investigated the beneficial effects of CoQ₁₀ on behavioral dysfunction and CoQ₁₀ level in the rat brain. Therefore, intracerebroventricular (ICV) infusion of a single dose of streptozotocin (STZ, 0.2 mg/mouse) was used in adult male mice to induce depression. The behavioral data revealed a significant difference between the depression and control groups regarding the forced swim test (FST) and splash test results at 24 h following STZ treatment. Also, the validated and accurate high-performance liquid chromatography (HPLC) technique showed decreased CoQ₁₀ level in the brain samples of the STZ group, compared to the controls. Our findings revealed that behavioral abnormalities due to STZ target mitochondria and affect energy metabolism and hemostasis, resulting in the initiation of oxidative damage in the brain. Besides, 4-week administration of CoQ₁₀ could reverse the depressive like behavior and bioenergetic effects of STZ in the treated groups.

Hydrogen sulfide modulates SIRT1 and suppresses oxidative stress in diabetic nephropathy

DN is recognized as not only a leading cause of end stage renal disease (ESRD) but also an independent risk factor for cardiovascular disease (CVD). Novel therapeutic approaches to diabetic nephropathy (DN) are needed, or else, healthcare resources will be overwhelmed by the expected worldwide increase in associated cases of ESRD and CVD. Reactive oxygen species (ROS) and advanced glycation end product (AGE) are implicated in the development of DN. Hydrogen sulfide (H₂S) is known for its antioxidant and antiapoptotic characteristics. Simultaneously diabetics have lower H₂S levels. Thus, it is worth investigating the use of H₂S in treatment of DN. To investigate the potential therapeutic role of H₂S in DN. Sixty male rats were divided into four groups: control, DN, DN+NaHS30 µmol/kg/day and DN+NaHS100 µmol/kg/day. Fasting blood sugar (FBS), kidney function tests, SIRT1 activity, superoxide dismutase activity (SOD), malondialdehyde (MDA) and expression of caspase3 and p53 in renal tissues were assessed. Kidney was examined histopathologically. DN rats had higher FBS, renal dysfunction, decreased SIRT1 and SOD activity levels, increased caspase3 and p53 relative expression and increased MDA in renal tissues. NaHS increased SIRT1 and reversed biochemical, apoptotic, oxidant and pathologic parameters characteristic of DN, with better results using a dose of 100 µmol/kg/day. H₂S has a protective role against DN through decreasing FBS, ROS, apoptosis and upregulating SIRT1, thus preserving renal cells from further damage caused by DM.

Antioxidant and antidepressant-like effects of Eugenia catharinensis D. Legrand in an animal model of depression induced by corticosterone

This work investigated the antioxidant and antidepressant-like effects of ethyl acetate extract from Eugenia catharinensis in mice treated with corticosterone (20 mg/Kg). The animals received saline or corticosterone (21 days) and, in the last 7 days, they were treated with the extract (50, 125, 200 or 250 mg/Kg) or vehicle. After 24 h, the mice were submitted to the open field and forced swimming tests, after which the hippocampus and cerebral cortex were removed. Our results showed that the extract decreased the immobility time of mice in the forced swimming test and that the extract was able to reverse the effect caused by corticosterone. Corticosterone pre-treatment generated oxidative stress, altering antioxidant enzymes in the nervous tissue. The extract increased the catalase and superoxide dismutase activities and reversed the effects of corticosterone. In the hippocampus, the extract increased superoxide dismutase activity and reversed the increase in catalase activity elicited by corticosterone. We propose that the effects elicited by the Eugenia catharinensis are dependent on the presence of phenolic compounds (gallic acid, protocatechuic acid, syringic acid, 4-hydroxy methylbenzoic acid, chlorogenic acid, salicylic acid, caffeic acid, vanillic acid, p-coumaric acid, isoquercetin, rutin, ferulic acid, aromadendrin, galangin and apigenin) in this extract, as demonstrated by HPLC-ESI-MS/MS.

Ascorbic acid therapy: A potential strategy against comorbid depression-like behavior in streptozotocin-nicotinamide-induced diabetic rats

This study examined the potency and efficacy of ascorbic acid (AA) in the management of depression-like behavior in diabetic rats. Diabetes mellitus was induced by single intraperitoneal injections of nicotinamide (120 mg/kg) and streptozotocin (65 mg/kg) administered 15 min apart. Diabetic (blood glucose ≥250 mg/dL) rats were subjected to intermittent foot-shocks to induce comorbid depression. Seven groups of diabetes comorbid depressed rats received vehicle (1 mL/kg) or AA (10, 25, 50, 100, 200, or 400 mg/kg) orally for eleven days. Three control groups namely- nondiabetic, diabetic, and depressed rats received the vehicles only. The potency (ED₅₀) and efficacy (E_max) of AA against immobility period, hypercorticosteronemia, adrenal hyperplasia, hyperglycemia, hypoinsulinemia, oxidative stress, and inflammatory response were estimated. AA administration caused a dose-dependent decrease (P < 0.05) in immobility period with maximum inhibition of 69% (efficacy) at 200 mg/kg and ED₅₀ of 14 mg/kg (potency). AA at 200 mg/kg produced the maximal reduction in hypercorticosteronemia (55.1%) and adrenal hyperplasia (52.6%) with ED₅₀ of 9.8 and 14.4 mg/kg, respectively. AA at 400 mg/kg produced the maximal reduction in hyperglycemia (35.5%), hypoinsulinemia (32.7%), and lipid peroxidation (82%) with ED₅₀ of 18.6, 13.7, and 20.7 mg/kg, respectively. Moreover, AA at 400 mg/kg produced the maximal increase in SOD content (83%), CAT activity (77.9%), and IL-10 level (63%) with ED₅₀ of 21.5, 21, and 21 mg/kg, respectively. In conclusion, the present results suggest that AA has therapeutic potential against diabetes comorbid depression but better regulation of hyperglycemia and hypoinsulinemia is required to achieve maximal benefits.

The antioxidant gallic acid induces anxiolytic-, but not antidepressant-like effect, in streptozotocin-induced diabetes

The physiopathology of anxiety or depression related to diabetes is still poorly understood. The treatment with antidepressant drugs is a huge challenge due to theirs adherence low rate and many adverse effects. Thus, the seeking for a better treatment for these associated diseases is of utmost importance. Given that the oxidative stress in different tissues occurs in diabetes and anxiety or depression as well, the antioxidant gallic acid becomes an interesting compound to be investigated. Thus, the effects of long-term treatment with gallic acid (0, 10, 20 and 40 mg/kg; gavage) were evaluated in diabetic (DBT) animals submitted to the elevated plus-maze (EPM), the light-dark transition (LDT) tests and modified forced swim test (mFST). Also, indirect parameters of oxidative stress, lipid peroxidation (LPO) and reduced glutathione (GSH) levels were evaluated in the hippocampus (HIP) and prefrontal cortex (PFC). The results showed that DBT animals presented a decrease in the spent time in the open arms, in the end arm exploration and head dips when evaluated in the EPM test; moreover, a decrease in the spent time in the lit compartment of LDT test was observed, suggesting an anxiogenic-like behavior. During the mFST, an increase in the mean counts of immobility and a decrease in the mean counts of swimming and climbing were observed, indicating a depressive-like behavior. These aversive behaviors were more pronounced when compared to normoglycemic (NGL) animals and streptozotocin-treated animals that not become DBT. In addition, DBT rats showed an increase in the oxidative stress parameters in the HIP and PFC that was reversed by the gallic acid treatment (lowest dose - 10 mg/kg), i.e., the treatment decreased the elevated LPO levels and increased the reduced GSH in the HIP and PFC. Also, gallic acid treatment was able to produce an anxiolytic-like effect in the EPM and LDT tests, but not antidepressant-like effect in the FST. Taken together, the results suggest that the antioxidant/neuroprotective effect of gallic acid treatment in HIP and PFC of DBT animals may be essential to the anxiolytic-like effect.

Nonfunctional mutant Wrn protein leads to neurological deficits, neuronal stress, microglial alteration, and immune imbalance in a mouse model of Werner syndrome

Werner syndrome (WS) is a premature aging disorder caused by mutations in a RecQ-family DNA helicase, WRN. Mice lacking part of the helicase domain of the WRN orthologue exhibit many phenotypic features of WS, including metabolic abnormalities and a shorter lifespan. Yet, little is known about the impact of WRN mutations on the central nervous system in both humans and mouse models of WS. In the current study, we have performed a longitudinal behavioral assessment on mice bearing a Wrn helicase deletion. Behavioral tests demonstrated a loss of motor activity and coordination, reduction in perception, increase in repetitive behavior, and deficits in both spatial and social novelty memories in Wrn mutant mice compared to age-matched wild type mice. These neurological deficits were associated with biochemical and histological changes in the brain of aged Wrn mutant mice. Microglia, resident immune cells that regulate neuronal plasticity and function in the brain, were hyper-ramified in multiple regions involved with the behavioral deficits of Wrn mutant mice. Furthermore, western analyses indicated that Wrn mutant mice exhibited an increase of oxidative stress markers in the prefrontal cortex. Supporting these findings, electron microscopy studies revealed increased cellular aging and oxidative stress features, among microglia and neurons respectively, in the prefrontal cortex of aged Wrn mutant mice. In addition, multiplex immunoassay of serum identified significant changes in the expression levels of several pro- and anti-inflammatory cytokines. Taken together, these findings indicate that microglial dysfunction and neuronal oxidative stress, associated with peripheral immune system alterations, might be important driving forces leading to abnormal neurological symptoms in WS thus suggesting potential therapeutic targets for interventions.