Behavioral effects of ketamine and toxic interactions with psychostimulants

BACKGROUND: The anesthetic drug ketamine (KT) has been reported to be an abused drug and fatal cases have been observed in polydrug users. In the present study, considering the possibility of KT-enhanced toxic effects of other drugs, and KT-induced promotion of an overdose without making the subject aware of the danger due to the attenuation of several painful subjective symptoms, the intraperitoneal (i.p.) KT-induced alterations in behaviors and toxic interactions with popular co-abused drugs, the psychostimulants cocaine (COC) and methamphetamine (MA), were examined in ICR mice. RESULTS: A single dose of KT caused hyperlocomotion in a low (30 mg/kg, i.p.) dose group, and hypolocomotion followed by hyperlocomotion in a high (100 mg/kg, i.p.) dose group. However, no behavioral alterations derived from enhanced stress-related depression or anxiety were observed in the forced swimming or the elevated plus-maze test. A single non-fatal dose of COC (30 mg/kg, i.p.) or MA (4 mg/kg, i.p.) caused hyperlocomotion, stress-related depression in swimming behaviors in the forced swimming test, and anxiety-related behavioral changes (preference for closed arms) in the elevated plus-maze test. For the COC (30 mg/kg) or MA (4 mg/kg) groups of mice simultaneously co-treated with KT, the psychostimulant-induced hyperlocomotion was suppressed by the high dose KT, and the psychostimulant-induced behavioral alterations in the above tests were reversed by both low and high doses of KT. For the toxic dose COC (70 mg/kg, i.p.)- or MA (15 mg/kg, i.p.)-only group, mortality and severe seizures were observed in some animals. In the toxic dose psychostimulant-KT groups, KT attenuated the severity of seizures dose-dependently. Nevertheless, the mortality rate was significantly increased by co-treatment with the high dose KT. CONCLUSION: Our results demonstrated that, in spite of the absence of stress-related depressive and anxiety-related behavioral alterations following a single dose of KT treatment, and in spite of the KT-induced anticonvulsant effects and attenuation of stress- and anxiety-related behaviors caused by COC or MA, the lethal effects of these psychostimulants were increased by KT

Toxic cocaine- and convulsant-induced modification of forced swimming behaviors and their interaction with ethanol: comparison with immobilization stress

BACKGROUND: Swimming behaviors in the forced swimming test have been reported to be depressed by stressors. Since toxic convulsion-inducing drugs related to dopamine [cocaine (COC)], benzodiazepine [methyl 6,7-dimethoxy-4-ethyl-β-carboline-carboxylate (DMCM)], γ-aminobutyric acid (GABA) [bicuculline (BIC)], and glutamate [N-methyl-D-aspartate (NMDA)] receptors can function as stressors, the present study compared their effects on the forced swimming behaviors with the effects of immobilization stress (IM) in rats. Their interactions with ethanol (EtOH), the most frequently coabused drug with COC which also induces convulsions as withdrawal symptoms but interferes with the convulsions caused by other drugs, were also investigated. RESULTS: Similar to the IM (10 min) group, depressed swimming behaviors (attenuated time until immobility and activity counts) were observed in the BIC (5 mg/kg IP) and DMCM (10 mg/kg IP) groups at the 5 h time point, after which no toxic behavioral symptoms were observed. However, they were normalized to the control levels at the 12 h point, with or without EtOH (1.5 g/kg IP). In the COC (60 mg/kg IP) and NMDA (200 mg/kg IP) groups, the depression occurred late (12 h point), and was normalized by the EtOH cotreatment. At the 5 h point, the COC treatment enhanced the swimming behaviors above the control level. CONCLUSIONS: Although the physiological stress (IM), BIC, and DMCM also depressed the swimming behaviors, a delayed occurrence and EtOH-induced recovery of depressed swimming were observed only in the COC and NMDA groups. This might be correlated with the previously-reported delayed responses of DA and NMDA neurons rather than direct effects of the drugs, which could be suppressed by EtOH. Furthermore, the characteristic psychostimulant effects of COC seemed to be correlated with an early enhancement of swimming behaviors

Distribution of soil algae at the monitoring sites in the vicinity of Syowa Station between austral summers of 1992/1993 and 1997/1998

Distribution of soil algae was studied in the vicinity of Syowa Station in Lutzow-Holm Bay, Antarctica between the austral summers of 1992/1993 (JARE-33) and 1997/1998 (JARE-38) from the viewpoint of environmental monitoring. Soils were collected from 10 monitoring sites. Sites 1-4 were within Syowa Station. Sites 1-3 were close to a urinal tank. Six sites (sites 5-10) were several km from the station. Site 10 was in a penguin rookery. Twenty-one soil algae were identified : eight of Cyanophyceae, eight of Chlorophyceae, three of Xanthophyceae and two of Bacillariophyceae. Leptolyngbya cf. battersii, Phormidium autumnale, Navicula muticopsis, Xanthonema spp., Botrydiopsis spp. and Macrochloris multinucleata were common. An ornithocoprophilous alga, Prasiola crispa, was found in cultures of soils from sites 1-3 and at site 10. Total carbon contents (TC), total nitrogen (TN) and total phosphorus (TP) in soils ranged from 0.04 to 0.991%, 0.002-0.401% and 0.161-0.809%, respectively. Maximum TC, TN and TP were observed at site 10. Relatively high values of TC (0.301%) and TN (0.016%) were detected at site 2. Presence of P. crispa at sites 1-3 and higher values of TC and TN at site 2 indicated that eutrophication of surface soils occurred near the urinal tank. The results of cluster analysis showed that most soil algal assemblages at sites 1-3 were grouped together. No clear changes in soil algal communities were observed during the study period at any of the monitoring sites

Haemodynamic Changes in the Superior Mesenteric Artery Induced by Acupuncture Stimulation on the Lower Limbs

Acupuncture is commonly performed on acupoints. A comparison of quantitative physiological alterations induced by stimulation on different acupoints has never been performed in the superior mesenteric artery (SMA) in humans. Therefore, we investigated changes in blood flow volume (BFV) in the SMA as an indicator of physiological effects induced by stimulation on 3 points. Thirty healthy participants aged 29 ± 10 years (mean ± SD) were enrolled. All participants underwent stimulations on 3 points located in the lower legs: ST36, LR3, and a non-acupoint. Control pertains to a condition with no-stimulation. Stimulation was performed bilaterally with manual rotation of the needles. BFV was measured by ultrasonography before insertion and 10, 20, 30, and 60 minutes after stimulation. Following acupuncture on ST36, BFV increased significantly 20 and 30 minutes after stimulation, compared to BFV before insertion (P < 0.05). Following stimulation on LR3 and the non-acupoint, no significant differences in BFV could be found. Relative to the no-stimulation group, stimulation on LR3, and the non-acupoint, stimulation on ST36 elicited a significant increase in BFV (P < 0.05). The results suggest that stimulation on the different points causes distinct physiological effects in BFV in the SMA

High Prevalence of Sinusitis in Children with Henoch-Schönlein Purpura

We evaluated the prevalence and the types of infectious foci in oral as well as ear, nose, and throat diseases, and we examined incidence of renal involvement with active treatment for focal infection in children with Henoch-Schönlein Purpura. A total of 96 children who presented at Aichi Children's Health and Medical Center and were diagnosed as having HSP were evaluated for infectious foci in the ear, nose, throat, and oral cavities. Seventy-one of 96 children (74.0%) had some type of infectious lesion, such as sinusitis or tonsillitis, and the prevalence of sinusitis was the highest (51 cases, 53.7%). In 44 HSP patients without renal involvement at the first examination, the incidence of nephritis was lower (13.6%) than in previous reports (17–54%) due to our aggressive intervention for infectious foci