Masayuki Miyazaki

Behavioural and neurochemical features of olfactory bulbectomized rats resembling depression with comorbid anxiety.

In order to probe the nature and validity of olfactory bulbectomized (OB) rats as a model of depression, we reevaluated their behavioural and neurochemical deficits in relation to the symptoms and neurochemical abnormalities of depression using our protocols, which distinguish anhedonia-resembling behaviour in sexual behavioural test, the hippocampus (Hip)-dependent long-term memory and anxiety-resembling behaviour specially. Besides exploratory hyperactivity in response to a novel environmental stress resembling the psychomotor agitation, OB rats showed a decrease of libido, and a deficit of long-term explicit memory, resembling loss of interest and cognitive deficits in depressive patients, respectively. OB rats also exhibited the anxiety symptom-resembling behaviour in social interaction and plus-maze tests. In the OB rats, we found degenerated neurons in the piriform cortex, decreased protein expression of NMDA receptor subunit 1 (NR1), but not NR2A or NR2B, in the prefrontal cortex (PFC), Hip and amygdala (Amg), and decreased phosphorylation of cAMP-response element-binding protein (CREB) in the PFC and Hip, but not Amg. The behavioural and neurochemical abnormalities in OB rats, except for the performance in the plus-maze task and neuronal degeneration, were significantly attenuated by repeated treatment with desipramine (10 mg/kg), a typical antidepressant. The present study indicated that OB rats may be a model of depression with comorbid anxiety, characterized by agitation, sexual and cognitive dysfunction, neuronal degeneration, decreased protein expression of NR1, and decreased phosphorylation of CREB.

Molecular mechanisms in dizocilpine-induced attenuation of development of morphine dependence: an association with cortical Ca2+/calmodulin-dependent signal cascade.

We investigated how dizocilpine, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, affects the development of morphine dependence in mice. Co-administration of dizocilpine (0.25 mg/kg) and morphine (10 mg/kg) for 5 days attenuated the development of tolerance to the antinociceptive effects of morphine. The withdrawal manifestation induced by the naloxone-challenge (5 mg/kg) was significantly reduced in mice that were treated with a combination of dizocilpine and morphine, compared to the mice treated with morphine and saline. The present study revealed a significant increase in c-Fos protein expression in the cortex and thalamus of mice showing naloxone-precipitated withdrawal syndrome. The combination of dizocilpine and morphine prevented the increase of c-Fos protein expression in the cortex and thalamus. Interestingly, repeated co-administration of dizocilpine and morphine prevented the withdrawal-induced phosphorylation of Ca2+/calmodulin kinase II (p-CaMK II) in the cortex, but not in the thalamus. Acute dizocilpine treatment prior to the naloxone-challenge and repeated treatment with dizocilpine alone had no effect on analgesia, withdrawal manifestations, p-CaMK II levels or c-Fos protein levels. These results showed that co-administration of dizocilpine and morphine prevented the development of morphine tolerance and dependence and suggested that the preventive effect of dizocilpine results from the regulation of c-Fos protein expression, which is possibly involved in the activation of the Ca2+/calmodulin-dependent signal cascade in the cortex.

Role of N-Methyl-D-aspartate Receptors in Antidepressant-Like Effects of σ1 Receptor Agonist 1-(3,4-Dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine Dihydrochloride (SA-4503) in Olfactory Bulbectomized Rats

In the present study, we aimed to investigate the role of N-methyl-d-aspartate (NMDA) receptors in the antidepressant-like effects of a σ1 receptor agonist, 1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride (SA-4503), in the olfactory bulbectomized (OB) rat model of depression. A symptomatology-based behavioral investigation was made by reconstructing in OB rats the symptoms of depression, such as psychomotor agitation, loss of interest, and cognitive dysfunction, using a typical antidepressant, desipramine, as a positive control. Repeated treatment with SA-4503 ameliorated the behavioral deficits in OB rats resembling depression symptoms in the open-field test, sexual behavior test, and cued and contextual fear-conditioning test. SA-4503 displayed advantages over desipramine in the sexual behavior test. SA-4503 also reversed the decrease in the protein expression of NMDA receptor subunit (NR)1, but not NR2A or NR2B, in the prefrontal cortex, hippocampus, and amygdala of OB rats. The behavioral and neurochemical effects of SA-4503 were blocked by combined treatment with a specific σ1 receptor antagonist, N,N-dipropyl-2-(4-methoxy-3-(2-phenylethoxy)phenyl)ethylamine monohydrochloride (NE-100). Furthermore, the effects of SA-4503 on the performance of OB rats in the behavioral tests were abrogated by acute treatment with an NMDA receptor antagonist, (–)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801). The present study indicated for the first time that the σ1 receptor agonist SA-4503 may have effects on depressive symptoms such as agitation, loss of interest, and impaired cognition, which are mediated by NMDA receptors.

Effects of (R)-(-)-1-(benzofuran-2-yl)-2-propylaminopentane hydrochloride [(-)-BPAP] in animal models of mood disorders

(R)-(-)-1-(Benzofuran-2-yl)-2-propylaminopentane hydrochloride [(-)-BPAP] is a highly potent enhancer of impulse propagation-mediated monoamine release and an inhibitor of monoamine uptake. We evaluated the efficacy of (-)-BPAP as a drug for mood disorders by using two animal models. (1) Acute, but not chronic, administration of (-)-BPAP and imipramine significantly attenuated immobility in mice induced by forced swimming. Chronic, but not acute, administration of (-)-BPAP ameliorated the impairment of social interaction (SI) behavior following forced swimming, without affecting locomotor activity. The ameliorating effect of (-)-BPAP on the impairment of SI behavior was suppressed by dopamine receptor antagonists, which suggests that the effect was mediated through the activation of the dopaminergic system. Chronic administration of imipramine tended to attenuate the impairment of SI behavior in stressed mice, but not significantly. (2) In the olfactory bulbectomized (OB) rat, chronic (-)-BPAP treatment significantly ameliorated the impairment of SI behavior, prepulse inhibition, and tone-cue fear learning, without affecting locomotor activity in an open field and circadian activity pattern. Furthermore, (-)-BPAP tended to improve sexual dysfunction in OB rats, but imipramine had no such effect. These findings suggest that (-)-BPAP may be clinically effective in treating mood disorders, including comorbid anxiety and depression that are poorly responsive to imipramine.

Genotype frequencies for polymorphisms related to chemotherapy-induced nausea and vomiting in a Japanese population

BackgroundGenotype frequencies for chemotherapy-induced nausea and vomiting (CINV)-related polymorphisms have not yet been reported for Japanese subjects.MethodsWe analyzed 10 genotype frequencies for following polymorphisms associated with the development of CINV: serotonin 5-HT3 receptors (HTR3); neurokinin-1 receptors (Tachykinin-1 receptors, TACR1); dopamine D2 receptors (DRD2); and catechol-O-methyltransferase (COMT).ResultsAll polymorphisms were successfully genotyped in 200 Japanese subjects and were in Hardy-Weinberg equilibrium. Almost all genotype frequencies were similar to those in the HapMap database or in the previous reports, while frequencies for the Y192H polymorphism in TACR1 were different in Japanese subjects from those in a previous report.ConclusionsThe present study revealed genotype frequencies for polymorphisms, which were related to the appearance of CINV in Japanese subjects. Individual therapy based on genotype variations for each race is needed to allow cancer patients to undergo chemotherapy more safely and to understand etiology of CINV.

Efficacy of Prophylactic Treatment for Oxycodone‐Induced Nausea and Vomiting Among Patients with Cancer Pain (POINT): A Randomized, Placebo‐Controlled, Double‐Blind Trial

BACKGROUND Although opioid-induced nausea and vomiting (OINV) often result in analgesic undertreatment in patients with cancer, no randomized controlled trials have evaluated the efficacy of prophylactic antiemetics for preventing OINV. We conducted this randomized, placebo-controlled, double-blind trial to evaluate the efficacy and safety of prophylactic treatment with prochlorperazine for preventing OINV. MATERIALS AND METHODS Cancer patients who started to receive oral oxycodone were randomly assigned in a 1:1 ratio to receive either prochlorperazine 5 mg or placebo prophylactically, given three times daily for 5 days. The primary endpoint was the proportion of patients who had a complete response (CR) during the 120 hours of oxycodone treatment. CR was defined as no emetic episode and no use of rescue medication for nausea and vomiting during 5 days. Key secondary endpoints were the proportion of patients with emetic episodes, proportion of patients with moderate or severe nausea, quality of life, and proportion of treatment withdrawal. RESULTS From November 2013 through February 2016, a total of 120 patients were assigned to receive prochlorperazine (n = 60) or placebo (n = 60). There was no significant difference in CR rates (69.5% vs. 63.3%; p = .47) or any secondary endpoint between the groups. Patients who received prochlorperazine were more likely to experience severe somnolence (p = .048). CONCLUSION Routine use of prochlorperazine as a prophylactic antiemetic at the initiation of treatment with opioids is not recommended. Further research is needed to evaluate whether other antiemetics would be effective in preventing OINV in specific patient populations. IMPLICATIONS FOR PRACTICE Prophylactic prochlorperazine seems to be ineffective in preventing opioid-induced nausea and vomiting (OINV) and may cause adverse events such as somnolence. Routine use of prophylactic prochlorperazine at the initiation of treatment with opioids is not recommended. Further research is needed to evaluate whether other antiemetics would be effective in preventing OINV in specific patient populations.