Chih-Chia Huang

Add-on Treatment of Benzoate for Schizophrenia: A Randomized, Double-blind, Placebo-Controlled Trial of d-Amino Acid Oxidase Inhibitor

IMPORTANCE In addition to dopaminergic hyperactivity, hypofunction of the N-methyl-d-aspartate receptor (NMDAR) has an important role in the pathophysiology of schizophrenia. Enhancing NMDAR-mediated neurotransmission is considered a novel treatment approach. To date, several trials on adjuvant NMDA-enhancing agents have revealed beneficial, but limited, efficacy for positive and negative symptoms and cognition. Another method to enhance NMDA function is to raise the levels of d-amino acids by blocking their metabolism. Sodium benzoate is a d-amino acid oxidase inhibitor. OBJECTIVE To examine the clinical and cognitive efficacy and safety of add-on treatment of sodium benzoate for schizophrenia. DESIGN, SETTING, AND PARTICIPANTS A randomized, double-blind, placebo-controlled trial in 2 major medical centers in Taiwan composed of 52 patients with chronic schizophrenia who had been stabilized with antipsychotic medications for 3 months or longer. INTERVENTIONS Six weeks of add-on treatment of 1 g/d of sodium benzoate or placebo. MAIN OUTCOMES AND MEASURES The primary outcome measure was the Positive and Negative Syndrome Scale (PANSS) total score. Clinical efficacy and adverse effects were assessed biweekly. Cognitive functions were measured before and after the add-on treatment. RESULTS Benzoate produced a 21% improvement in PANSS total score and large effect sizes (range, 1.16-1.69) in the PANSS total and subscales, Scales for the Assessment of Negative Symptoms-20 items, Global Assessment of Function, Quality of Life Scale and Clinical Global Impression and improvement in the neurocognition subtests as recommended by the National Institute of Mental Healths Measurement and Treatment Research to Improve Cognition in Schizophrenia initiative, including the domains of processing speed and visual learning. Benzoate was well tolerated without significant adverse effects. CONCLUSIONS AND RELEVANCE Benzoate adjunctive therapy significantly improved a variety of symptom domains and neurocognition in patients with chronic schizophrenia. The preliminary results show promise for d-amino acid oxidase inhibition as a novel approach for new drug development for schizophrenia.

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.

Effect of age, gender, menopausal status, and ovarian hormonal level on rTMS in treatment-resistant depression

This study examines how gender and menopausal status contribute to age effect on the antidepressant efficacy of repetitive transcranial stimulation (rTMS). Thirty-one women (17 premenopausal, 14 postmenopausal), and 16 men with treatment-refractory bipolar/major depression underwent 10 consecutive sessions of rTMS. Mood symptoms and female hormones were measured. ANOVA-R revealed a significant gender (p<0.05) and time effect (p<0.001) on the Hamilton Depression Rating Scale (HAM-D) score. Percentage reduction of the rating correlated negatively with age in women (p<0.001). While no difference in the rTMS response was observed between male and premenopausal female patients (68.8% and 70.6%, respectively), postmenopausal women responded least (0%). We also found that greater improvement of depression score was associated with a higher estradiol/progesterone ratio in premenopausal women (p<0.05), suggesting an important role of female hormones in the therapeutic response. Regression analysis revealed that menopausal status and ovarian steroid levels, but not age, were the main determinants of antidepressant efficacy of rTMS in females. This is the first study to specifically investigate the effect of female hormones on rTMS therapeutic effect. Our data support changes in menopausal status and ovarian steroid levels as effectors of mood and the CNS neural substrate response to rTMS in refractory depression. However, the restricted number of patients and the shorter duration of rTMS treatment and follow-up might influence its generalization. Further study examining the interactions between mood, ovarian hormones, and rTMS treatment is warranted.

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

BackgroundOxidative 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.ResultsIn 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.ConclusionsThe present evidence indicated that EGCG can reduce NADPH-d/nNOS reactivity and thus may enhance motor neuron survival time following peripheral nerve injury.

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.

Unexpected interaction between quetiapine and valproate in patients with bipolar disorder.

Quetiapine, a second-generation antipsychotic originally used in the treatment of schizophrenia, was also found to be effective as monotherapy or as an adjunctive therapy for acute mania. Delirium in patients treated with quetiapine seems to be a rare phenomenon; however, we report two patients with bipolar disorder who developed delirium when prescribed quetiapine as an adjunct to valproate for acute mania. Both had previously developed mild renal insufficiency after an episode of lithium intoxication. The delirium resolved after quetiapine was discontinued. Unexpected interactions may occur when medications are combined without being subject to controlled clinical trials.

Mild hypoxic preconditioning attenuates injury-induced NADPH-d/nNOS expression in brainstem motor neurons of adult rats

Excessive production of nitric oxide (NO) might have detrimental effects on the hypoxia-related neuropathology. This study aimed to test if mild hypoxic preconditioning (MHPC) would attenuate the pathological changes in the brainstem motoneurons having a different functional component after peripheral nerve crush injury (PNCI). Prior to PNCI treatment, young adult rats were caged in the mild hypoxic altitude chamber with 79Torr of the partial oxygen concentration ( pO(2)) (i.e., 0.5atm at 5500m in height) for 4 weeks to adapt the environmental changes. After that, all the animals having successfully crushed both the hypoglossal and vagus nerves (left-side) were allowed to survive for 3, 7, 14, 30 and 60 successive days in normoxic condition. Nicotinamine adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry and neuronal nitric oxide synthase (nNOS) immunohistochemistry revealed that MHPC reduces NADPH-d/nNOS expression in the hypoglossal nucleus (HN) and the dorsal motor nucleus of the vagus (DMN) at different time points after PNCI. The morphological findings were further ascertained by Western blot analysis of nNOS and nitrite assay for NO production. Both the morphological and quantitative results peaked at 7 days in HN, whereas for those in DMN were progressively increased up to 60 days following PNCI. The staining intensity of NADPH-d/nNOS(+) neurons, expression of nNOS protein, NO production levels as well as the neuronal loss in HN and DMN of MHPC rats following PNCI were attenuated, especially for those having a longer survival period over 14 days. The MHPC treatment might induce minute amounts of NO to alter the state of milieu of the experimental animals to protect against the PNCI.

Neuronal NADPH-d/NOS expression in the nodose ganglion of severe hypoxic rats with or without mild hypoxic preconditioning

This study aimed to test the hypothesis that mild hypoxic preconditioning (MHPC)-induced NOS expression would attenuate the neuropathological changes in the nodose ganglion (NG) of severe hypoxic exposure (SHE) rats. Thus, the young adult rats were caged in the altitude chamber for 4 weeks prior to SHE for 4 h to gain hypoxic preconditioning. The altitude chamber was used to set the height at the level from 5500 m (0.50 atm; pO2=79 Torr) to 10,000 m (0.27 atm; pO2=43 Torr) for MHPC and SHE, respectively. The experimental animals were allowed to survive for 0, 7, 14, 30 and 60 successive days, respectively. Nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry and neuronal nitric oxide synthase (nNOS) immunohistochemistry were used to detect NADPH-d/nNOS reactivity in the NG at various time points following hypoxic exposure. The present results showed that about 38% of the neurons in the NG displayed NADPH-d/nNOS positive [NADPH-d/nNOS(+)] in normoxic rats. In SHE rats, a peak in the percentage (71%) and staining intensity (230%) of NADPH-d/nNOS(+) nodose neurons at 0 day, which then gradually decreased at 7-60 days. About 25% of the nodose neurons died 60 days after SHE. However, in MHPC rats subjected to SHE, NADPH-d/nNOS(+) neurons peaked in the percentage (51%) and staining intensity (171%) at 0 day, which then decreased at 7-60 days. In addition, neuronal survival was markedly increased by MHPC. These results suggested that MHPC might have a neuroprotective effect that reduces the susceptibility of the nodose neurons to NOS mediated neuropathy subsequent to SHE.

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.

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

HighlightsLong‐term sarcosine treatment exerts antidepressant‐like effects in the forced swim test in chronic unpredictable stress (CUS)‐exposed rats but not in naive rats.Long‐term sarcosine treatment increases the expression of the mTOR signaling‐related proteins and increases AMPAR membrane insertion in the hippocampus in both naive rats and CUS‐exposed rats.The distinct sensitivity to long‐term sarcosine treatment in rats with or without CUS is found after long‐term sarcosine treatment, which is not associated with the activated mTOR signaling pathway or increased AMPAR membrane insertion. ABSTRACT 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 &agr;‐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 (560 mg/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.