Determination of D-serine and D-alanine Tissue Levels in the Prefrontal Cortex and Hippocampus of Rats After a Single Dose of Sodium Benzoate, a D-Amino Acid Oxidase Inhibitor, with Potential Antipsychotic and Antidepressant Properties.

The effects of the N-methyl-D-aspartate receptor activators D-serine, D-alanine, and sarcosine against schizophrenia and depression are promising. Nevertheless, high doses of D-serine and sarcosine are associated with undesirable nephrotoxicity or worsened prostatic cancer. Thus, alternatives are needed. DAAO inhibition can increase D-serine as well as D-alanine and protect against D-serine-induced nephrotoxicity. Although several DAAO inhibitors improve the symptoms of schizophrenia and depression, they can increase the plasma levels but not brain levels of D-serine. The mechanism of action of DAAO inhibitors remains unclear. We investigated the effects of the DAAO inhibitor sodium benzoate on the prefrontal cortex and hippocampal level of D-alanine as known another substrate with antipsychotic and antidepressant properties and other NMDAR-related amino acids, such as, L-alanine, D-serine, L-serine, D-glutamate, L-glutamate, and glycine levels. Our results indicate that sodium benzoate exerts antipsychotic and antidepressant-like effects without changing the D-serine levels in the brain prefrontal cortex (PFC) and hippocampus. Moreover, D-alanine levels in the PFC and hippocampus did not change. Despite these negative findings regarding the effects of D-amino acids in the PFC and hippocampus, sodium benzoate exhibited antipsychotic and antidepressant-like effects. Thus, the therapeutic effects of sodium benzoate are independent of D-serine or D-alanine levels. In conclusion, sodium benzoate may be effective among patients with schizophrenia or depression; however, the mechanisms of actions remain to be elucidated.

Risk of Mental Illnesses in Patients With Hypopituitarism: A Nationwide Population-Based Cohort Study.

OBJECTIVE: The associations of mental illnesses and hypopituitarism have been reported. But, pituitary disorders are rare. The epidemiological studies have rarely addressed these associations between pituitary disorder and mental illnesses. Until now, no cohort study has been conducted to investigate the association. METHODS: We performed a nationwide, retrospective cohort study using the Taiwanese National Health Insurance Program dataset to analyze this relationship. In total, 1,194 patients diagnosed with hypopituitarism between 2000 and 2013 were identified. For the control group, 4,776 individuals without hypopituitarism and psychotic diseases were matched (1:4) according to age, sex, and index date. A Cox proportional hazards model was used to determine the adjusted hazard ratio (aHR). RESULTS: Patients with hypopituitarism had a significantly higher risk of incident depression and anxiety disorders than those without hypopituitarism. The aHRs of depressive and anxiety disorders were 2.98 and 1.67, respectively, for the hypopituitarism cohort. Furthermore, the risk of both hypopituitarism-associated depressive and anxiety disorders was significantly high in female subjects and subjects aged ≥18 years. A statistically significant increase was not observed in the risk of bipolar disorders, dementia, or schizophrenia in the hypopituitarism group compared with the control group. CONCLUSION: Although psychiatric morbidities were uncommon for the hypopituitarism cohort, the risk of developing depressive and anxiety disorders was significantly higher in those with hypopituitarism than in those without hypopituitarism.

Echinacoside exhibits antidepressant-like effects through AMPAR-Akt/ERK-mTOR pathway stimulation and BDNF expression in mice.

BACKGROUND: Several natural products have been demonstrated to be effective in the treatment of depressive disorders. Echinacoside, a naturally occurring phenol extracted from Cistanche tubulosa, Echinacea angustifolia, and Cistanche spp, has a wide range of physiological effects, such as antioxidation, neuroprotection, anti-inflammatory, and immunoregulation, which are closely related to depression. In addition, echinacoside can activate protein kinase B (Akt), extracellular signal-regulated kinase (ERK), and brain-derived neurotrophic factor (BDNF) in the brain. A key downstream event of the Akt, ERK, and BDNF signaling pathways, namely mechanistic target of rapamycin (mTOR) signaling, plays a crucial role in generating an rapid antidepressant effect. Thus, echinacoside is a promising therapeutic agent for depression. However, research regarding the role of echinacoside in antidepressant effect and brain mTOR activation remains lacking. MATERIALS AND METHODS: The forced swimming test and Western blot analysis in C57BL/6 mice was used to investigate the antidepressant-like activities of echinacoside and the underlying mechanism involved inα-amino3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-Akt/ERK-mTOR pathway. RESULTS: We confirmed the suggestions by previous reports that echinacoside activates Akt/ERK signaling and further demonstrated that echinacoside could provide antidepressant-like effects in mice via the activation of AMPAR-Akt/ERK-mTOR pathway in the hippocampus. CONCLUSIONS: To the best of our knowledge, our study is the first to reveal that echinacoside is a potential treatment for depressive disorders. Moreover, the present study suggests a mechanism for the neuroprotective effect of echinacoside.

Decreased efficacy of the ketamine and scopolamine-induced sustained antidepressant-like effects in rats receiving metformin.

BACKGROUND: Metformin is the most widely used drug for treating type 2 diabetes mellitus (DM), which frequently co-occurs with depressive disorders. Thus, patients with depression are likely to receive metformin. Metformin activates AMP-activated kinase (AMPK), which inhibits mechanistic target of rapamycin complex 1 (mTORC1) signaling. mTORC1 activation is essential for the antidepressant effects of ketamine and scopolamine. Thus, we hypothesized that metformin may attenuate ketamine- or scopolamine-induced antidepressant efficacies by blocking their mTORC1 activation. METHODS: We assessed the acute and sustained antidepressant-like actions of ketamine and scopolamine in male Sprague-Dawley rats subjected to the forced swim test with or without metformin pretreatment. The expressions of AMPK, mTORC1, and brain-derived neurotrophic factor (BDNF) in their prefrontal cortex were assessed. RESULTS: Metformin (50 mg/kg) attenuated the sustained, but not acute, antidepressant-like effects of ketamine (10 mg/kg) and scopolamine (25 µg/kg). Although metformin reduced mTORC1 downstream activated P70S6K, it did not significantly alter mTORser2448 activation and even increased BDNF expression. Notably, ketamine, scopolamine, and metformin all exerted significant antidepressant-like actions, as evidenced by increased AMPK phosphorylation and BDNF expression. CONCLUSIONS: Metformin-induced attenuation of sustained antidepressant-like effects are not directly dependent on AMPK-deactivated mTORC1. Our results indicate the complexity of interactions between AMPK, BDNF, and mTORC1. Further research, including mechanistic studies, is warranted to comprehensively evaluate the application of metformin in patients receiving mTORC1-based antidepressants.

Roles of Akt and ERK in mTOR-Dependent Antidepressant Effects of Vanillic Acid.

Vanillic acid, an oxidized form of vanilla, is a flavoring agent with a creamy odor. Several studies have reported the neuroprotective effects of vanillic acid, which are predominantly associated with anti-inflammatory and antioxidative properties. The anti-inflammatory and antioxidative properties may result from Akt or ERK signaling activation. The activation of the mammalian target of rapamycin (mTOR), a key downstream target of Akt and ERK signaling, is a crucial therapeutic target for treating depression. However, the antidepressant effects of vanillic acid remain unknown. The present study applied the forced swim test (FST) to investigate the antidepressant effects of vanillic acid and its association with Akt, ERK, and mTOR signaling and upstream α-amino-3-hydroxy-5-methyl-4-isoxazolepropionaic acid receptor (AMPAR) in the prefrontal cortex (PFC) of mice. Vanillic acid demonstrated antidepressant effects by significantly reducing behavioral despair in the FST. None of the treatments changed locomotor activity. Additionally, vanillic acid increased AMPAR throughput, Akt, and mTOR signaling but not ERK signaling in the PFC. NBQX (an AMPAR blocker), MK 2206 (an Akt blocker), and rapamycin (an mTOR blocker) used in pretreatment attenuated the antidepressant effects of vanillic acid, but SL327 (an ERK inhibitor) did not. The immunochemical results indicated that the antidepressant effects of vanillic acid depend on the AMPAR-Akt-mTOR signaling transduction pathway. Our findings reveal an Akt-dependent, but ERK-independent, the mechanism underlying the antidepressant effects of vanillic acid, which may be beneficial for some patients with depression.

Activity Dependent Mammalian Target of Rapamycin Pathway and Brain Derived Neurotrophic Factor Release Is Required for the Rapid Antidepressant Effects of Puerarin.

Puerarin is a traditional Chinese medicine with beneficial effects of reduced depression-like behaviors in mice with stress. Previous studies also show that puerarin can produce neuroprotective effect via activating the Akt or increased brain-derived neurotrophic factor (BDNF) expression. Interestingly, BDNF and Akt downstream target, mammalian target of rapamycin (mTOR) mediate the fast-acting antidepressant properties of ketamine. Until now, the involvement of the mTOR signaling pathway or BDNF on puerarin-induced antidepressant effect remains unknown. We aimed to investigate whether the antidepressant-like effect induced by puerarin would associate mTOR signaling pathway and BDNF release. The antidepressant-like effects of puerarin were evaluated using the forced swim test. The activation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionaic acid receptor (AMPAR)-mTOR signaling pathway and release of BDNF in the prefrontal cortex were determined. We also investigated the effect of puerarin on AMPAR trafficking through measuring the PKA phosphorylation of AMPAR subunit GluR1. Our present results show that puerarin exerted antidepressant-like responses that was mediated by AMPAR-induced mTOR signaling pathway and associated with increased BDNF release. Moreover, a significant increase in the GluR1 phosphorylation at its PKA site was noted following puerarin treatment. Our findings are the first to demonstrate that the antidepressant-like actions of puerarin require AMPAR-mTOR signaling pathway activation, are associated with an increased BDNF level and facilitate AMPAR membrane insertion. These findings provide preclinical evidence that puerarin may possess antidepressant property which is mediated by the glutamatergic system.

Acute Amino Acid d-Serine Administration, Similar to Ketamine, Produces Antidepressant-like Effects through Identical Mechanisms.

d-Serine is an amino acid and can work as an agonist at the glycine sites of N-methyl-d-aspartate receptor (NMDAR). Interestingly, both types of glutamatergic modulators, NMDAR enhancers and blockers, can improve depression through common targets, namely alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionaic acid receptors (AMPARs) and mammalian target of rapamycin (mTOR). To elucidate the cellular signaling pathway underlying this counterintuitive observation, we activated NMDARs in rats by using d-serine. Saline, ketamine (NMDAR antagonist), and desipramine (tricyclic antidepressant) were used as controls. The antidepressant-like effects of all agents were evaluated using the forced swim test. The activation of the AMPAR-mTOR signaling pathway, release of brain-derived neurotrophic factor (BDNF), and alteration of AMPAR and NMDAR trafficking in the hippocampus of rats were examined. A single high dose of d-serine exerted an antidepressant-like effect that was mediated by rapid AMPAR-induced mTOR signaling pathway and increased BDNF proteins, identical to that of ketamine. Furthermore, in addition to the increased protein kinase A phosphorylation of the AMPAR subunit GluR1 (an indicator of AMPAR insertion in neurons), treatment with individual optimal doses of d-serine and ketamine also increased adaptin ß2-NMDAR association (an indicator of the intracellular endocytic machinery and subsequent internalization of NMDARs). Desipramine did not influence these processes. Our study is the first to demonstrate an association between d-serine and ketamine; following adaptative regulation of AMPAR and NMDAR may lead to common changes of them. These findings provide novel targets for safer antidepressant agents with mechanisms similar to those of ketamine.

Tourette syndrome increases risk of bone fractures: a population-based cohort study.

This study assesses the risk of fractures among children with Tourette syndrome (TS), and identifies the effects of comorbidities and antipsychotics. We randomly sampled the claims data of 1 million enrollees in the National Health Insurance program of Taiwan, and identified 1258 children with TS diagnosed between 2000 and 2010. Additionally, 12,580 children without TS who were frequency matched for sex, age, residential area, parental occupation, and index year were identified for comparison. The children's cases were followed until December 31, 2010, or censored to ascertain incident fractures cases and associations with comorbidities of attention-deficit/hyperactivity disorder (ADHD) or obsessive-compulsive disorder (OCD) and treatments with antipsychotics, antidepressants, or clonidine. The TS cohort had a 1.27-fold higher incidence of fractures than did the comparison cohort (190.37 vs. 149.94 per 10,000 person-years), with an adjusted hazard ratio (HR) of 1.28 [95% confidence interval (CI) 1.06-1.55] based on multivariable Cox regression analysis. This increased risk of fractures was apparent for fractures of the skull, neck, and spine. Comorbid ADHD and OCD did not result in an additional risk of fractures. The children without both ADHD and OCD were also at a higher risk of fractures, indicating that TS alone increases the risk of fractures. The children taking antipsychotics had a reduced risk of fractures, and the adjusted HR decreased to 1.17 (95% CI 0.90-1.52). Children with TS have an increased risk of fractures. ADHD and OCD do not increase the risk further.

Antidepressant-like effects of long-term sarcosine treatment in rats with or without chronic unpredictable stress.

Sarcosine, an N-methyl-d-aspartate receptor enhancer, can improve depression-like behavior in rodent models and depression in humans. We found that a single dose of sarcosine exerted antidepressant-like effects with rapid concomitant increases in the mammalian target of rapamycin (mTOR) signaling pathway activation and enhancement of α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor (AMPAR) membrane insertion. Sarcosine may play a crucial role in developing novel therapy for depression. For a detailed understanding of sarcosine, this study examined the effects of long-term sarcosine treatment on the forced swim test (FST), mTOR signaling, and AMPAR membrane insertion in rats. The effects of long-term sarcosine treatment were examined in naive rats and rats exposed to chronic unpredictable stress (CUS). Long-term sarcosine treatment (560mg/kg/d for 21 d) significantly ameliorated the increased immobility induced by CUS in the FST, reaffirming the potential role of sarcosine as an antidepressant for depressed patients. The same long-term treatment exhibited no such effect in naive rats despite increased mTOR activation and AMPAR membrane insertion in both groups. Our findings clearly show CUS-exposed rats are sensitive to long-term sarcosine treatment in FST and the response at the same dose is absent in naïve rats. Nevertheless, the distinct sensitivity to long-term sarcosine treatment in rats with or without CUS is not associated with the activated mTOR signaling pathway or increased AMPAR membrane insertion. Additionally, understanding the behavioral and molecular basis of distinct responses is vital important for developing personalized treatment programs to increase the probability of success when treating depression.

Effects of melatonin on the nitric oxide system and protein nitration in the hypobaric hypoxic rat hippocampus.

BACKGROUND: It is well documented that the nitric oxide (NO) might be directly involved in brain response to hypobaric hypoxia, and could contribute to memory deficiencies. Recent studies have shown that melatonin could attenuate hypoxia or ischemia-induced nerve injuries by decreasing the production of free radicals. The present study, using immunohistochemical and immunoblot methods, aimed to explore whether melatonin treatment may affect the expression of nitric oxide system and protein nitration, and provide neuroprotection in the rat hippocampus injured by hypobaric hypoxia. Prior to hypoxic treatment, adult rats were pretreated with melatonin (100 mg/kg, i.p.) before they were exposed to the altitude chamber with 48 Torr of the partial oxygen concentration (pO2) for 7 h to mimic the ambience of being at 9000 m in height. They were then sacrificed after 0 h, 1, and 3 days of reoxygenation. RESULTS: The results obtained from the immunohistochemical and immunoblotting analyses showed that the expressions of neuronal nitric oxide synthase (nNOS), endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), nitrotyrosine (Ntyr) and Caspase 3 in the hypoxic hippocampus were increased from 0 h to 3 days of reoxygenation. Interestingly, the hypoxia-induced increase of nNOS, eNOS, iNOS, Ntyr and Caspase 3 protein expression was significantly depressed in the hypoxic rats treated with melatonin. CONCLUSIONS: Activation of the nitric oxide system and protein nitration constitutes a hippocampal response to hypobaric hypoxia and administration of melatonin could provide new therapeutic avenues to prevent and/or treat the symptoms produced by hypobaric hypoxia.

AMPA Receptor-mTOR Activation is Required for the Antidepressant-Like Effects of Sarcosine during the Forced Swim Test in Rats: Insertion of AMPA Receptor may Play a Role.

Sarcosine, an endogenous amino acid, is a competitive inhibitor of the type I glycine transporter and an N-methyl-d-aspartate receptor (NMDAR) coagonist. Recently, we found that sarcosine, an NMDAR enhancer, can improve depression-related behaviors in rodents and humans. This result differs from previous studies, which have reported antidepressant effects of NMDAR antagonists. The mechanisms underlying the therapeutic response of sarcosine remain unknown. This study examines the role of mammalian target of rapamycin (mTOR) signaling and α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor (AMPAR) activation, which are involved in the antidepressant-like effects of several glutamatergic system modulators. The effects of sarcosine in a forced swim test (FST) and the expression levels of phosphorylated mTOR signaling proteins were examined in the absence or presence of mTOR and AMPAR inhibitors. In addition, the influence of sarcosine on AMPAR trafficking was determined by analyzing the phosphorylation of AMPAR subunit GluR1 at the PKA site (often considered an indicator for GluR1 membrane insertion in neurons). A single injection of sarcosine exhibited antidepressant-like effects in rats in the FST and rapidly activated the mTOR signaling pathway, which were significantly blocked by mTOR inhibitor rapamycin or the AMPAR inhibitor 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(f)quinoxaline (NBQX) pretreatment. Moreover, NBQX pretreatment eliminated the ability of sarcosine to stimulate the phosphorylated mTOR signaling proteins. Furthermore, GluR1 phosphorylation at its PKA site was significantly increased after an acute in vivo sarcosine treatment. The results demonstrated that sarcosine exerts antidepressant-like effects by enhancing AMPAR-mTOR signaling pathway activity and facilitating AMPAR membrane insertion. Highlights-A single injection of sarcosine rapidly exerted antidepressant-like effects with a concomitant increase in the activation of the mammalian target of rapamycin mTOR signaling pathway.-The antidepressant-like effects of sarcosine occur through the activated AMPAR-mTOR signaling pathway.-Sarcosine could enhance AMPAR membrane insertion via an AMPAR throughput.

CD200 in growing rat lungs: developmental expression and control by dexamethasone.

CD200 belongs to cell adhesion molecules of the immunoglobulin superfamily. It lacks intracellular signaling motifs and exerts immunosuppressive effect in various tissues. We have reported previously that CD200 is predominantly associated with the capillary network in the alveolar septum of adult rats. The alveolar endothelial cells express CD200, which is confined to their luminal cell membrane facing the blood-air barrier. Our present results show that lung CD200 protein increases gradually with advancing age, being maximally expressed in the early postnatal (P) period. CD200 protein expression, however, declines at P5 but increases again after P7, reaching the adult level at P21. In developing lungs in fetal and neonatal stages, double-immunofluorescence staining has confirmed intense CD200 immunoreactivity delineating the vascular profiles in the double layers of the alveolar capillaries; this staining becomes diffuse and patchy with time. Unlike in adult lungs, immunoelectron microscopy has revealed that CD200 expression in fetal and early postnatal lungs is localized over the entire luminal cell membrane and in the cytoplasm of the endothelia. CD200 expression is progressively redistributed to a specific luminal domain of alveolar endothelia during pulmonary microvascular maturation. In neonatal rats treated with dexamethasone, the amount of lung CD200 significantly increases and is also elevated with time. Upregulation of endothelial CD200 has further been confirmed in isolated pulmonary microvascular endothelial cells treated with dexamethasone. Thus, lung CD200 is developmentally regulated, possibly under hormonal influence.

Inhibition of glycine transporter-I as a novel mechanism for the treatment of depression.

BACKGROUND: Antidepressants, aiming at monoaminergic neurotransmission, exhibit delayed onset of action, limited efficacy, and poor compliance. Glutamatergic neurotransmission is involved in depression. However, it is unclear whether enhancement of the N-methyl-D-aspartate (NMDA) subtype glutamate receptor can be a treatment for depression. METHODS: We studied sarcosine, a glycine transporter-I inhibitor that potentiates NMDA function, in animal models and in depressed patients. We investigated its effects in forced swim test, tail suspension test, elevated plus maze test, novelty-suppressed feeding test, and chronic unpredictable stress test in rats and conducted a 6-week randomized, double-blinded, citalopram-controlled trial in 40 patients with major depressive disorder. Clinical efficacy and side effects were assessed biweekly, with the main outcomes of Hamilton Depression Rating Scale, Global Assessment of Function, and remission rate. The time course of response and dropout rates was also compared. RESULTS: Sarcosine decreased immobility in the forced swim test and tail suspension test, reduced the latency to feed in the novelty-suppressed feeding test, and reversed behavioral deficits caused by chronic unpredictable stress test, which are characteristics for an antidepressant. In the clinical study, sarcosine substantially improved scores of Hamilton Depression Rating Scale, Clinical Global Impression, and Global Assessment of Function more than citalopram treatment. Sarcosine-treated patients were much more likely and quicker to remit and less likely to drop out. Sarcosine was well tolerated without significant side effects. CONCLUSIONS: Our preliminary findings suggest that enhancing NMDA function can improve depression-like behaviors in rodent models and in human depression. Establishment of glycine transporter-I inhibition as a novel treatment for depression waits for confirmation by further proof-of-principle studies.

Dental health - a challenging problem for a patient with autism spectrum disorder.

Patients with autism spectrum disorders (ASDs) are at an increased risk for many diseases. However, little has been published about the dental health of patients with ASDs. Here, we describe the clinical presentations in a 28-year-old woman with autistic disorder. The most striking finding was the severe dental problems which had been neglected for several years. Our patient exhibited a combination of several factors that may have increased the risk of development of severe dental problem. The early recognition is still challenging to managing this unusual condition in patients with ASDs. From the experience of caring for this patient, a team of parents or caregivers, psychiatrist and dentist should be involved in maintaining oral health care of such patients with early intervention and long-term follow-up. Evidence-based behavioral management approaches for patients with ASD need to be developed to improve compliance with oral care procedures.

Berberine induces heme oxygenase-1 up-regulation through phosphatidylinositol 3-kinase/AKT and NF-E2-related factor-2 signaling pathway in astrocytes.

Our previous report has shown that berberine effectively inhibits LPS- and IFN-γ-induced neuroinflammation in microglia cells. Recently, we also reported that HO-1 (Heme oxygenase-1) may be a therapeutic target to regulate neuroinflammation in microglia cells. The present study examined the ability of berberine, the major constituents of Chinese herb Rhizoma coptidis, to induce expression of HO-1, and analyzed its signaling mechanism in rat brain astrocytes. HO-1 is known as an antioxidant enzyme which helps to protect against cellular damage and maintains tissue homeostasis. Here, we found that berberine increased HO-1 mRNA and protein expression concentration- and time-dependently. In addition, berberine-induced HO-1 expression was attenuated by PI 3-kinase (phosphatidylinositol 3-kinase) inhibitors LY294002 and wortmannin, and an AKT inhibitor. Treatment of astrocytes with berberine also induced p85 (PI 3-kinase) and AKT phospholation, and increased AKT kinase activity. Berberine also increased NF-E2-related factor-2 (Nrf2) accumulation in the nucleus and increased Nrf2-DNA binding activity as determined by the EMSA (electrophoretic mobility shift assay). Moreover, berberine-induced increase of Nrf2-DNA binding activity was reduced by PI 3-kinase and AKT inhibitors. Berberine-increased HO-1-luciferase activity was also inhibited by co-transfection with dominant-negative (DN) mutants of p85 and AKT. Moreover, berberine-mediated increase of HO-1 transcriptional activity and protein expression were reduced by transfection with siRNA againt Nrf2. These findings suggest that berberine-increased HO-1 expression is mediated by Nrf2 activation through the PI 3-kinase/AKT pathway in astrocytes. Thus, berberine may be useful as a therapeutic agent for the treatment of neuroinflammation-associated disorders.

(-)-Epigallocatechin gallate attenuates NADPH-d/nNOS expression in motor neurons of rats following peripheral nerve injury.

BACKGROUND: Oxidative stress and large amounts of nitric oxide (NO) have been implicated in the pathophysiology of neuronal injury and neurodegenerative disease. Recent studies have shown that (-)-epigallocatechin gallate (EGCG), one of the green tea polyphenols, has potent antioxidant effects against free radical-mediated lipid peroxidation in ischemia-induced neuronal damage. The purpose of this study was to examine whether EGCG would attenuate neuronal expression of NADPH-d/nNOS in the motor neurons of the lower brainstem following peripheral nerve crush. Thus, young adult rats were treated with EGCG (10, 25, or 50 mg/kg, i.p.) 30 min prior to crushing their hypoglossal and vagus nerves for 30 seconds (left side, at the cervical level). The treatment (pre-crush doses of EGCG) was continued from day 1 to day 6, and the animals were sacrificed on days 3, 7, 14 and 28. Nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry and neuronal nitric oxide synthase (nNOS) immunohistochemistry were used to assess neuronal NADPH-d/nNOS expression in the hypoglossal nucleus and dorsal motor nucleus of the vagus. RESULTS: In rats treated with high dosages of EGCG (25 or 50 mg/kg), NADPH-d/nNOS reactivity and cell death of the motor neurons were significantly decreased. CONCLUSIONS: The present evidence indicated that EGCG can reduce NADPH-d/nNOS reactivity and thus may enhance motor neuron survival time following peripheral nerve injury.

Transient ischemia/hypoxia enhances gentamicin ototoxicity via caspase-dependent cell death pathway.

Aminoglycoside ototoxicity is a common cause of drug-induced hearing loss. Toxicity is dose related, but some patients may still develop hearing loss even under safe dosage. Apart for genetic idiosyncrasy, indirect evidences imply that ischemia may increase the aminoglycoside ototoxic sensitivity because common clinical situations associated with cochlear ischemia such as noise, sepsis, and shock are known to augment the development of aminoglycoside ototoxicity. At present, a direct interaction of cochlear ischemia and aminoglycoside ototoxicity is still lacking. This study demonstrated a direct evidence of increased gentamicin (GM) ototoxic sensitivity in chronic guinea pig models of transient cochlear ischemia. No permanent auditory changes were observed after a single dose of GM (125 mg/kg) or after transient cochlear ischemia for 30 min. Persistent and significant auditory threshold shift was detected when GM was given after transient cochlear ischemia. Cochlear hair cells and spiral ganglion neurons are the major regions affected. Apoptosis contributes to hair cell death during acute interaction of ischemia and GM ototoxicity. Increased apoptotic cell death was also depicted when GM crossreacted with hypoxia in vitro, using cochlear cell lines. Generation of reactive oxygen species, loss of mitochondrial membrane potential, calcium release, and caspase-dependent apoptotic cell death were shown during the interaction of hypoxia and GM ototoxicity in vitro. This synergistic ototoxicity may be critical to aminoglycoside-induced hearing loss in clinical scenarios. The results should improve our understanding of the interacting mechanism and potential preventive strategy to aminoglycoside ototoxicity.

The real mechanism of VPA-induced hyperammonemia remains unknown.

Valproic acid (VPA) is a well-tolerated and effective agent for the treatment of epilepsy, bipolar disorder, and schizoaffective disorder. Several case reports have indicated that VPA may induce serious symptomatic hyperammonemia. Based on analysis of susceptible patients, several possible mechanisms and risk factors have been proposed to identify the patients at risk. Nevertheless, we report the case of a schizoaffective patient who developed severe hyperammonemia occurring after brief exposure to VPA, despite the absence of any known risk factors. Until now, early recognition of the signs and symptoms of hyperammonemia is crucial to managing this unusual adverse reaction.