Antidepressant effect of taurine in diabetic rats

Mitigating diabetes-related complications: Empowering metformin with cholecalciferol and taurine supplementation in type 2 diabetic rats

BACKGROUND

Type 2 diabetes is one of the most prevalent chronic diseases worldwide, significantly impacting patients' quality of life. Current treatment options like metformin (MET) effectively counteract hyperglycemia but fail to alleviate diabetes-associated complications such as retinopathy, neuropathy, nephropathy, hepatopathy, and cardiovascular diseases.

AIM

To propose the supplementation of cholecalciferol (CHO) and taurine (TAU) to enhance MET efficacy in controlling diabetes while minimizing the risk of associated complications.

METHODS

The study involved sixty rats, including ten non-diabetic control rats and fifty experimental rats with type 2 diabetes induced by streptozotocin. The experimental rats were further subdivided into positive control and treatment subgroups. The four treatment groups were randomly allocated to a single MET treatment or MET combined with supplements either CHO, TAU, or both.

RESULTS

Diabetic rats exhibited elevated levels of glucose, insulin, Homeostasis Model Assessment of Insulin Resistance (HOMA-IR), glycated hemoglobin%, lipid markers, aspartate aminotransferase, and malondialdehyde, along with reduced levels of antioxidant enzymes (catalase and superoxide dismutase). The administration of CHO and TAU supplements alongside MET in diabetic rats led to a noticeable recovery of islet mass. The antioxidative, anti-inflammatory, and anti-apoptotic properties of the proposed combination therapy significantly ameliorated the aforementioned abnormalities.

CONCLUSION

The supplementation of CHO and TAU with MET showed the potential to significantly improve metabolic parameters and protect against diabetic complications through its antioxidative, anti-inflammatory, and anti-apoptotic effects.

Taurine rescues pancreatic β-cell stress by stimulating α-cell transdifferentiation

The semi-essential ubiquitous amino acid taurine has been shown to alleviate obesity and hyperglycemia in humans; however, the pathways underlying the antidiabetic actions have not been characterized. We explored the effect of chronic taurine exposure on cell biology of pancreatic islets, in degenerative type 1-like diabetes. The latter was modeled by small dose of streptozotocin (STZ) injection for 5 days in mice, followed by a 10-day administration of taurine (2% w/v, orally) in the drinking water. Taurine treatment opposed the detrimental changes in islet morphology and β-/α-cell ratio, induced by STZ diabetes, coincidentally with a significant 3.9 ± 0.7-fold enhancement of proliferation and 40 ± 5% reduction of apoptosis in β-cells. In line with these findings, the treatment counteracted an upregulation of antioxidant (Sod1, Sod2, Cat, Gpx1) and downregulation of islet expansion (Ngn3, Itgb1) genes induced by STZ, in a pancreatic β-cell line. At the same time, taurine enhanced the transdifferentiation of α-cells into β-cells by 2.3 ± 0.8-fold, echoed in strong non-metabolic elevation of cytosolic Ca²⁺ levels in pancreatic α-cells. Our data suggest a bimodal effect of dietary taurine on islet β-cell biology, which combines the augmentation of α-/β-cell transdifferentiation with downregulation of apoptosis. The dualism of action, stemming presumably from the intra- and extracellular modality of the signal, is likely to explain the antidiabetic potential of taurine supplementation.

Taurine Alleviates Chronic Social Defeat Stress-Induced Depression by Protecting Cortical Neurons from Dendritic Spine Loss

Abnormal amino acid metabolism in neural cells is involved in the occurrence and development of major depressive disorder. Taurine is an important amino acid required for brain development. Here, microdialysis combined with metabonomic analysis revealed that the level of taurine in the extracellular fluid of the cerebral medial prefrontal cortex (mPFC) was significantly reduced in mice with chronic social defeat stress (CSDS)-induced depression. Therefore, taurine supplementation may be usable an intervention for depression. We found that taurine supplementation effectively rescued immobility time during a tail suspension assay and improved social avoidance behaviors in CSDS mice. Moreover, taurine treatment protected CSDS mice from impairments in dendritic complexity, spine density, and the proportions of different types of spines. The expression of N-methyl D-aspartate receptor subunit 2A, an important synaptic receptor, was largely restored in the mPFC of these mice after taurine supplementation. These results demonstrated that taurine exerted an antidepressive effect by protecting cortical neurons from dendritic spine loss and synaptic protein deficits.

Effect of taurine on glycaemic, lipid and inflammatory profile in individuals with type 2 diabetes: study protocol of a randomised trial

Type 2 diabetes mellitus (T2DM) is characterised by chronic hyperglycaemia. Despite the efficacy of conventional pharmacotherapy, some individuals do not reach glycaemic goals and require adjuvant therapies. Taurine, a semi-essential amino acid, decreases blood glucose and cholesterol levels in rodents and humans. However, glycated hemoglobin (HbA1c) has not been evaluated in randomised controlled trials after taurine treatment for more than 12 weeks. This study aims to evaluate the effect of taurine administration on glycaemic, lipid, inflammatory, anthropometric and dietary parameters in individuals with T2DM. A randomised, double-blind, placebo-controlled clinical trial will be conducted at the Clinical Research Center of a tertiary public hospital. Participants with T2DM (n 94) will be recruited and randomised to receive 3 g of taurine or placebo, twice/day, orally, for 12 weeks. Blood samples will be collected before and after 12 weeks of treatment, when HbA1c, fasting glucose, insulin, albuminuria, creatinine, total cholesterol and fractions, triglycerides, C-reactive protein, TNF-α, IL 1, 4, 5, 6, 10 and 13 will be evaluated. Anthropometric parameters and 24-hour food recall will also be evaluated. The study will evaluate the effect of taurine treatment on biochemical and anthropometric parameters in individuals with T2DM. These results will guide the decision-making to indicate taurine treatment as an adjunct in individuals with T2DM who have not reached their glycaemic goal.

Taurine Administration Counteracts Aging-Associated Impingement of Skeletal Muscle Regeneration by Reducing Inflammation and Oxidative Stress

Sarcopenia, which occurs during aging, is characterized by the gradual loss of skeletal muscle mass and function, resulting in a functional decline in physical abilities. Several factors contribute to the onset of sarcopenia, including reduced regenerative capacity, chronic low-grade inflammation, mitochondrial dysfunction, and increased oxidative stress, leading to the activation of catabolic pathways. Physical activity and adequate protein intake are considered effective strategies able to reduce the incidence and severity of sarcopenia by exerting beneficial effects in improving the muscular anabolic response during aging. Taurine is a non-essential amino acid that is highly expressed in mammalian tissues and, particularly, in skeletal muscle where it is involved in the regulation of biological processes and where it acts as an antioxidant and anti-inflammatory factor. Here, we evaluated whether taurine administration in old mice counteracts the physiopathological effects of aging in skeletal muscle. We showed that, in injured muscle, taurine enhances the regenerative process by downregulating the inflammatory response and preserving muscle fiber integrity. Moreover, taurine attenuates ROS production in aged muscles by maintaining a proper cellular redox balance, acting as an antioxidant molecule. Although further studies are needed to better elucidate the molecular mechanisms responsible for the beneficial effect of taurine on skeletal muscle homeostasis, these data demonstrate that taurine administration ameliorates the microenvironment allowing an efficient regenerative process and attenuation of the catabolic pathways related to the onset of sarcopenia.

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.

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.

Hemisphere-dependent Changes in mRNA Expression of GABAA Receptor Subunits and BDNF after Intra-prefrontal Cortex Allopregnanolone Infusion in Rats

Allopregnanolone is a neurosteroid implicated in mood disorders such as depression and anxiety. It acts as a GABA_A receptor (GABA_AR)-positive allosteric modulator and changes the expression of GABA_AR subunits and of brain-derived neurotrophic factor (BDNF) in different brain regions. It has been demonstrated that such neurochemical changes may have an asymmetrical pattern regarding brain hemispheres. The aim of this study was to verify the behavioral and hemisphere-specific neurochemical effects of the bilateral intra-prefrontal cortex (intra-PFC) infusion of allopregnanolone in rats. Rats were exposed to the forced swim test and to the grooming microstructure test, followed by the right and left hemisphere-specific quantification of mRNA expression by Real-Time PCR of δ and γ2 GABA_AR subunits and BDNF in the PFC and in the hippocampus. Though we did not observe any significant effects in the behavioral tests, intra-PFC allopregnanolone infusion bilaterally increased the mRNA expression of the δ subunit in the same area and of BDNF in the hippocampus. Both mRNA expressions of the γ2 subunit and BDNF were higher in the right than in the left PFC of control animals, and the hemisphere differences were not seen after allopregnanolone infusion. Overall hippocampal BDNF expression was also higher in the right hemisphere, but this asymmetry was not normalized by allopregnanolone. No asymmetries or changes were observed in the hippocampal mRNA expression of GABA_AR subunits. These results point to a hemisphere-dependent regulation of GABA_AR subunits and BDNF that can be modulated by intra-PFC allopregnanolone infusion, even in the absence of associated behavioral effects.

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.

Acute intraperitoneal administration of taurine decreases the glycemia and reduces food intake in type 1 diabetic rats

Taurine, an amino acid with antioxidant and osmoregulatory properties, has been studied for its possible antidiabetic properties in type 1 and type 2 diabetic animals. In type 2 diabetic mice, taurine decreases blood glucose through increased insulin secretion and insulin receptor sensitization. However, insulin is absent in type 1 diabetic individuals. The aim of this study was to evaluate the effects of taurine on parameters related to the energy balance that could explain the metabolic action of this amino acid in type 1 diabetic rats. Control and streptozotocin-induced diabetic rats received saline or taurine (100 mg/kg/day), intraperitoneally, for 30 days. Parameters such as palatable food intake, gastrointestinal transit rate, serum glucose, insulin, leptin, and glucagon levels were measured 60 min after the last taurine administration. Liver, kidneys, heart, and retroperitoneal fat were dissected and weighted. Glycogen levels were measured in the liver and soleus muscle. Our results showed that acute taurine administration decreased glycemia. It also decreased food intake in diabetic rats, without affecting other metabolic parameters. Altogether, our results suggest that in type 1 diabetic rats, taurine decreases blood glucose by a non-insulin-dependent mechanism. Due to the safety profile of taurine, and its effect on glycemia, this amino acid may help to design new drugs to add benefit to insulin therapy in type 1 diabetic individuals.

Study of the Role of Dopamine Receptors in Streptozotocin-Induced Depressive-Like Behavior Using the Forced Swim Test Model

Background:

Diabetes is one of the most common endocrine diseases characterized by hyperglycemia. It is caused by an absolute or relative insulin deficiency or an insulin function deficiency. It is one of the major risk factors of depression, with the rate of depression in diabetic patients amounting to as high as 30%. This study examined the role of dopamine receptors in streptozotocin (STZ)-induced depressive-like behavior using the forced swim test (FST).

Materials and Methods:

This study was performed on 56 Wistar male rats. STZ at doses of 30 and 60 mg/kg body weight was administered via intraperitoneal (IP) route to induce diabetes and depression in rats. Thereafter, by using halobenzazepine (SCH23390) (D1 dopamine receptor antagonist) and sulpiride (D2 receptor dopamine receptor antagonist), the role of dopamine receptors in STZ-induced depression was studied. The one-way analysis of variance technique, Tukey’s range test, and t-test were used to analyze the data. The P-value less than 0.05 was regarded as statistically significant.

Results:

Our study showed that STZ at doses of 30 and 60 mg/kg, two weeks after injection, caused prolonged immobility in FST, indicating depressive-like behavior (P<0.05 and P<0.01, respectively). SCH23390 (0.001 mg/mL/kg) and sulpiride (0.1 mg/mL/kg) did not change the variables of depression in animals that received STZ (at doses of 30 and 60 mg/mL/kg) two weeks before (P>0.05).

Conclusion:

According to our study, STZ has a depressive-like behavior two weeks after injection, and dopamine receptors do not play a role in depression associated with STZ use.

Prophylactic role of taurine and its derivatives against diabetes mellitus and its related complications

Taurine is a conditionally essential amino acid present in the body in free form. Mammalian taurine is synthesized in the pancreas via the cysteine sulfinic acid pathway. Anti-oxidation and anti-inflammation are two main properties through which it exerts its therapeutic effects. Many studies have shown its excellent therapeutic potential against diabetes mellitus and related complications like diabetic neuropathy, retinopathy, nephropathy, hematological dysfunctions, reproductive dysfunctions, liver and pancreas related complications etc. Not only taurine, a number of its derivatives have also been reported to be important in ameliorating diabetic complications. The present review has been aimed to describe the importance of taurine and its derivatives against diabetic metabolic syndrome and related complications.

A comparative study of the main constituents and antidepressant effects of raw and vinegar-baked Bupleuri Radix in rats subjected to chronic unpredictable mild stress

Bupleuri Radix (BR) is a traditional Chinese medicine (TCM) widely used in Asian nations, which originates fromBupleurum chinenseDC orBupleurum scorzonerifoliumWilld.

The effect of taurine and enriched environment on behaviour, memory and hippocampus of diabetic rats

Diabetes mellitus (DM) has been studied recently as a major cause of cognitive deficits, memory and neurodegenerative damage. Taurine and enriched environment have stood out for presenting neuroprotective and stimulating effects that deserve further study. In this paper, we examined the effects of taurine and enriched environment in the context of diabetes, evaluating effects on behaviour, memory, death and cellular activity. Eighty-eight Wistar rats were divided into 2 groups (E=enriched environment; C=standard housing). Some animals (24/group) underwent induction of diabetes, and within each group, some animals (half of diabetics (D) and half of non-diabetics (ND)/group) were treated for 30days with taurine (T). Untreated animals received saline (S). In total, there were eight subgroups: DTC, DSC, NDTC, NDSC, DTE, DSE, NDTE and NDSE. During the experiment, short-term memory was evaluated. After 30th day of experiment, the animals were euthanized and was made removal of brains used to immunohistochemistry procedures for GFAP and cleaved caspase-3. As a result, we observed that animals treated with taurine showed better performance in behavioural and memory tasks, and the enriched environment had positive effects, especially in non-diabetic animals. Furthermore, taurine and enriched environment seemed to be able to interfere with neuronal apoptosis and loss of glial cells, and in some instances, these two factors seemed to have synergistic effects. From these data, taurine and enriched environment may have important neurostimulant and neuroprotective effects.

CHRONIC CAFFEINE'S EFFECTS ON BEHAVIOURAL CHANGES IN STREPTOZOTOCIN-INDUCED DIABETIC RATS

Context

Memory deficits, anxiety and depression are often associated with diabetes, worsening diabetic patients' prognosis. Caffeine, a worldwide used psychoactive substance, is a candidate for improving these conditions.

Objective

The aim of this study was to assess the behaviour in streptozotocin-induced diabetic Wistar rats and to evaluate the behavioural effects of caffeine administration.

Materials and methods

Diabetes was induced by a single intraperitoneal injection of 50 mg/kg BW streptozotocin (n=10), while control rats received the vehicle (n=9). After six weeks, behavioural tests for anxiety, memory and depression were performed: elevated plus maze (EPM) test, novel object recognition (NOR) test and forced swimming test (FST), respectively. The tests were repeated after further 2 weeks of continuous caffeine administration (20 mg/kg BW/day in drinking water).

Results

Diabetic rats manifested a high anxiety level, showed by a reduced exploratory activity compared to control rats (p<0.05) and long-term memory impairment, spending more time near the old object in NOR test. Caffeine administered for 2 weeks did not modify glycemic values in either group, and attenuated the behavioural changes observed in the EPM test. Also, in NOR test for long-term memory, caffeine administration induced an increased time spent with the novel object than with the old one in both groups.

Conclusions

Our data suggest that chronic caffeine administration has an anxiolytic effect in diabetic rats and improves long-term memory in both diabetic and control rats.

Antidepressant-like effects of quercetin in diabetic rats are independent of hypothalamic-pituitary-adrenal axis

OBJECTIVE

Quercetin, one of the most potent flavonol in the family of flavonoids, has been shown to have benefits against diabetes and its complications. In the present study, we investigated effects of quercetin on depression-like behaviours and hypothalamic-pituitary-adrenal (HPA) axis in diabetic rats.

METHODS

Experimental diabetes was induced by using streptozotocin, and either 50 or 100 mg/kg quercetin was intraperitoneally administered for 21 days. Following the last treatment, animals were subjected to the forced swim test, and subsequently, the blood was obtained by cardiac puncture to measure plasma adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels.

RESULTS

A significant increase of the total immobile time, accompanied by a decrease in the immobility latency, which suggests a depressive status, was observed in diabetic animals that was reversed by the treatment of 50 mg/kg quercetin. However, the higher dose of quercetin (100 mg/kg) was ineffective in alleviating depression-like behaviours. The plasma concentrations of ACTH, and total- and free-CORT were not affected by both doses of quercetin.

CONCLUSION

Therefore, we concluded that the antidepressant-like effects of quercetin in diabetes are independent of the HPA axis.

Antidepressant dose of taurine increases mRNA expression of GABAA receptor α2 subunit and BDNF in the hippocampus of diabetic rats

Diabetes mellitus is a metabolic disorder associated with higher risk for depression. Diabetic rats present depressive-like behaviors and taurine, one of the most abundant free amino acids in the brain, reverses this depressive behaviors. Because taurine is a GABAA agonist modulator, we hypothesize that its antidepressant effect results from the interaction on this system by changing α2 GABAA receptor subunit expression, beside changes on BDNF mRNA, and memory in diabetic rats. Streptozotocin-diabetic and non-diabetic Wistar rats were daily injected with 100mg/kg of taurine or saline, intraperitoneally, for 30 days. At the end of the experiment, rats were exposed to the novel object recognition memory. Later they were euthanized, the brains were weighed, and the hippocampus was dissected for α2 GABAA subunit and BDNF mRNA expression. Real-time quantitative PCR (qPCR) showed that diabetic rats presented lower α2 GABAA subunit and BDNF mRNA expression than non-diabetic rats and taurine increased both parameters in these sick rats. Taurine also reversed the lower brain weight and improved the short-term memory in diabetic rats. Thus, the taurine antidepressant effect may be explained by interference with the GABA system, in line to its neuroprotective effect showed here by preventing brain weight loss and improving memory in diabetic rats.

Dynamic analysis of the endogenous metabolites in depressed patients treated with TCM formula Xiaoyaosan using urinary (1)H NMR-based metabolomics

ETHNOPHAMACOLOGICAL RELEVANCE

Xiaoyaosan (XYS), one of the best-known traditional Chinese medicine prescriptions with a long history of use, is composed of Bupleurum chinense DC., Paeonia lactiflora Pall., Poria cocos (Schw.) Wolf, Angelica sinensis (Oliv.) Diels, Zingiber officinale Rosc., Atractylodes macrocephala Koidz., Glycyrrhiza uralensis Fisch., and Mentha haplocalyx Briq. For centuries, XYS has been widely used in China for the treatment of mental disorders such as depression. However, the complicated mechanism underlying the antidepressant activity of XYS is not yet well-understood. This understanding is complicated by the sophisticated pathophysiology of depression and by the complexity of XYS, which has multiple constituents acting on different metabolic pathways. The variations of endogenous metabolites in depressed patients after administration of XYS may help elucidate the anti-depressant effect and mechanism of action of XYS. The aim of this study is to establish the metabolic profile of depressive disorder and to investigate the changes of endogenous metabolites in the depressed patients before and after the treatment of Xiaoyaosan using the dynamic analysis of urine metabolomics profiles based on (1)H NMR.

MATERIALS AND METHODS

Twenty-one depressed patients were recruited from the Traditional Chinese Medicine Department of the First Affiliated Hospital of Shanxi Medical University. Small endogenous metabolites present in urine samples were measured by nuclear magnetic resonance (NMR) and analyzed by multivariate statistical methods. The patients then received XYS treatment for six weeks, after which their Hamilton Depression Scale (HAMD) scores were significantly decreased compared with their baseline scores (p≤0.01). Eight components in urine specimens were identified that enabled discrimination between the pre- and post-XYS-treated samples.

RESULTS

Urinary of creatinine, taurine, 2-oxoglutarate and xanthurenic acid increased significantly after XYS treatment (p≤0.05), while the urinary levels of citrate, lactate, alanine and dimethylamine decreased significantly (p≤0.05) compared with pre-treatment urine samples. These statistically significant perturbations are involved in energy metabolism, gut microbes, tryptophan metabolism and taurine metabolism.

CONCLUSIONS

The symptoms of depression had been improved after 6 weeks׳ treatment of XYS according to evaluation of HAMD scores. The dynamic tendency of the 8 metabolites that changed significantly during the treatment of XYS is consistent with the improvement in symptoms of depression. These metabolites may be used as biomarkers for the diagnosis of depressive disorders or the evaluation of the antidepressant as well as the exploration of the mechanism of depression.

Diabetic encephalopathy-related depression: experimental evidence that insulin and clonazepam restore antioxidant status in rat brain

There is increasing evidence suggesting that oxidative stress plays an important role in the development of many chronic and degenerative conditions such as diabetic encephalopathy and depression. Considering that diabetic rats and mice present higher depressive-like behaviour when submitted to the forced swimming test and that treatment with insulin and/or clonazepam is able to reverse the behavioural changes of the diabetic rats, the present work investigated the antioxidant status, specifically total antioxidant reactivity and antioxidant potential of insulin and clonazepam, as well as the effect of this drugs upon protein oxidative damage and reactive species formation in cortex, hippocampus and striatum from diabetic rats submitted to forced swimming test. It was verified that longer immobility time in diabetic rats and insulin plus clonazepam treatment reversed this depressive-like behaviour. Moreover, data obtained in this study allowed to demonstrate through different parameters such as protein carbonyl content, 2'7'-dichlorofluorescein oxidation, catalase, superoxide dismutase, glutathione peroxidase assay, total radical-trapping antioxidant potential and total antioxidant reactivity that there is oxidative stress in cortex, hippocampus and striatum from diabetic rats under depressive-like behaviour and highlight the insulin and/or clonazepam effect in these different brain areas, restoring antioxidant status and protein damage.