Tamaki Hayase

Behavioral effects of ketamine and toxic interactions with psychostimulants

BackgroundThe 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.ResultsA 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.ConclusionOur 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.

Protective effects of cannabinoid receptor agonists against cocaine and other convulsant‐induced toxic behavioural symptoms

Based on the previously reported co‐localization and relationship between cannabinoid and dopamine receptors, the effects of cannabinoid receptor agonists against cocaine‐induced toxic behavioural symptoms, including convulsive seizures, were examined in mice. The anticonvulsant effect of several cannabimimetics against seizures induced by other convulsants was also compared. The cannabinoid receptor agonists CP 55940 ((‐)‐cis‐3‐[2‐hydroxy‐4‐(1,1‐dimethylheptyl)phenyl]‐trans‐4‐(3‐hydroxypropyl)‐cyclohexanol) and WIN 55212–2 ((R)‐(+)‐[2.3‐dihydro‐5‐methyl‐3‐(4‐morpholinylmethyl)pyrrolo[1,2,3‐de]‐1,4‐benzoxazin‐6‐yl]‐1‐naphthalenylmethanone), and the endogenous cannabinoid anandamide were co‐administered intraperitoneally with cocaine (75 mg kg−1) or other convulsants such as bicuculline, methyl 6,7‐dimethoxy‐4‐ethyl‐β‐carboline‐carboxylate (DMCM), l‐glutamic acid and N‐methyl‐d‐aspartate (NMDA). CP 55940 (2.5 mg kg−1) and anandamide (15 mg kg−1) significantly antagonized cocaine‐induced lethality, and CP 55940 and WIN 55212–2 (2.5 mg kg−1) significantly attenuated the severity of cocaine‐induced convulsive seizures. Furthermore, ataxic hyperactivity, which was observed only in the cocaine‐treated group of mice and could be evaluated by their activity counts, was also depressed in the groups of mice co‐treated with each of the three cannabinoid agonists. However, none of these agonists protected against bicuculline‐ or DMCM‐induced lethality or convulsive seizures. In contrast, all of the cannabinoid agonists, most notably anandamide, antagonized both l‐glutamic acid (2 g kg−1)‐ and NMDA (200 mg kg−1)‐induced convulsive seizures. These data support the previously reported close correlation between dopamine and cannabinoid receptors, and between cannabinoid agonists, especially anandamide, and glutamate (NMDA) receptors. Furthermore, these results suggest a potential therapeutic role for cannabinoid agonists against cocaine‐ and other‐convulsant‐induced toxicities.

Chronologically overlapping occurrences of nicotine-induced anxiety- and depression-related behavioral symptoms: effects of anxiolytic and cannabinoid drugs

BackgroundAnxiety and depression are among the most frequently-observed psychiatric symptoms associated with nicotine (NC). In addition to the similarity to other addictive drugs, these NC-induced symptoms are characteristic in that the opposite behavioral effects, i.e. anxiolytic and antidepressant effects, which may reinforce the habitual use of NC, have also been reported. In the present study, the time course of anxiety- and depression-related behavioral alterations was examined in mice. Furthermore, based on the reported similarity in the mechanisms responsible for NC-induced anxiety- and depression-related symptoms, as well as the contribution of brain cannabinoid (CB) receptors to these behavioral symptoms, the effects of anxiolytics and CB receptor ligands (CBs) against these behavioral symptoms were investigated.ResultsRepeated subcutaneous NC treatments (0.3 mg/kg, 4 days), compared with a single treatment (0.5 mg/kg), caused both prolonged anxiogenic effects in the elevated plus-maze test, and prolonged depressive effects in the forced swimming test, even at 120 min time point after the last NC treatment. A transient anxiolytic preference for open arms was also observed in the elevated plus-maze test. Among the anxiolytics and CBs, the serotonin 1A (5-HT1A) antagonist WAY 100135 and the endogenous mixed CB agonist/antagonist virodhamine (VD), when administered intraperitoneally before each NC treatment, provided the strongest antagonistic effects against the anxiety-related symptoms. However, against the depression-related symptoms, only VD provided significant antagonistic effects in both single and repeated treatment groups.ConclusionThe present results support the presence of a chronological overlap of NC-induced anxiety- and depression-related behavioral symptoms, and the contribution of brain CB receptors to these behavioral symptoms. The repeated NC-induced prolongation of these behavioral symptoms and the early transient anxiolytic behavioral alterations support an increased possibility of the habitual use of NC. Furthermore, based on the antagonistic effects of VD, one can predict that the characteristic effects on brain CB receptors as a mixed CB agonist/antagonist contributed to its therapeutic effects as both an anxiolytic and an antidepressant.

Working memory- and anxiety-related behavioral effects of repeated nicotine as a stressor: the role of cannabinoid receptors

BackgroundLike emotional symptoms such as anxiety, modulations in working memory are among the frequently-reported but controversial psychiatric symptoms associated with nicotine (NC) administration. In the present study, repeated NC-induced modulations in working memory, along with concurrently-observed anxiety-related behavioral alterations, were investigated in mice, and compared with the effects of a typical cognition-impairing stressor, immobilization stress (IM). Furthermore, considering the structural and functional contributions of brain cannabinoid (CB) receptors in NC-induced psychiatric symptoms including emotional symptoms, the interactive effects of brain CB receptor ligands (CB ligands) and NC and/or IM on the working memory- and anxiety-related behaviors were examined.ResultsStatistically significant working memory impairment-like behavioral alterations in the Y-maze test and anxiety-like behavioral alterations in the elevated plus-maze (EPM) test were observed in the groups of mice treated with 0.8 mg/kg NC (subcutaneous (s.c.) 0.8 mg/kg treatment, 4 days) and/or IM (10 min treatment, 4 days). In the group of mice treated with NC plus IM (NC-IM group), an enhancement of the behavioral alterations was observed. Among the CB type 1 (CB1) antagonist AM 251 (AM), the non-selective CB agonist CP 55,940 (CP), and the CB1 partial agonist/antagonist virodhamine (VD), significant recovering effects were provided by AM (0.2-2.5 mg/kg) and VD (5 mg/kg) against the working memory impairment-like behaviors, whereas significant anxiolytic-like effects (recoveries from both attenuated percentage of entries into open arms and attenuated percentage of time spent on open arms) were provided by VD (1–10 mg/kg) and CP (2 mg/kg) against the anxiety-like behaviors.ConclusionsAlthough working memory impairment- and anxiety-like behavioral alterations were commonly induced in the NC, IM, and NC-IM groups and the therapeutic involvement of CB receptors was shown, there were discrepancies in the types of effective CB ligands between the working memory- and anxiety-related behaviors. The differential involvements of CB receptor subtypes and indirectly activated neurotransmitter systems may contribute to these discrepancies.

Effect of Methamphetamine on Male Mice Fertility

The effect of methamphetamine (MAMP) on the ability of males to mate with females and to impregnate them was examined in 8‐week‐old ICR mice. Male mice that had been administered an intraperitoneal injection of MAMP (15 mg/kg, 7.5 mg/kg, or 3.75 mg/kg) or saline were housed with females 24 or 48 hours later. The vaginal plugs were checked, and the number of births was counted. The effect of MAMP on sperm motility and the serum testosterone (TS) concentration was also examined.

Stressor-like effects of cocaine on heat shock protein and stress- activated protein kinase expression in the rat hippocampus: interaction with ethanol and anti-toxicity drugs

The present study examined the stressor-like effects of repeated (4 days) administration of cocaine hydrochloride(COC) (35 mg/kg, i.p.) on the expression of heat shock proteins (HSPs) (HSP27, HSP60, HSP70, HSC70) and stress-activated protein kinases (SAPKs) (SAPKalpha, SAPKbeta, SAPKgamma) in the rat hippocampus. The interactions with intraperitoneal ethanol and drugs known as antidotes against COC toxicity were also examined. Similar to the effects of a 10 min immobilization stress (IM) over 4 days, an early increase (5 h time point) in nerve cells immunoreactive for HSPs (HSP27, HSP60, HSP70, HSC70) and SAPKs (SAPKbeta, SAPKgamma) was observed in the COC group. At the 24 h time point, a recovery was observed only for SAPKs, which have been suggested to control the HSP levels. Before the 48 h time point, alterations in the number of HSP+cells as compared to the control group (increase for HSP27 and HSP70+cells, and attenuation for HSP60 and HSC70+cells) could still be observed. Stress-related, attenuated swimming behaviors in the forced swimming test were also the most severe at the 5 h time point. Ethanol (1.5 g/kg) cotreatment on each administration day, even at non-toxic and/or euphoric doses, enhanced these stressor-like alterations. On the other hand, the protective effects of daily coadministered drugs related to benzodiazepine (5 mg/kg Ro 15-4513), dopamine (0.5 mg/kg SCH 23390), muscarinic (0.25 mg/kg pirenzepine) and serotonin (5 mg/kg ketanserin) receptors could be observed on the number of HSP-immunoreactive (24 h) and SAPK-immunoreactive cells (5 h). Against the stressor-altered swimming behaviors, Ro 15-4513 and SCH 23390 were more effective as compared to pirenzepine and ketanserin.

Effects of amphetamine on rat embryos developing in vitro

Wistar rat embryos were explanted on Day 10.5 of gestation and exposed in vitro to amphetamine (AMP) at concentrations of 0.1, 0.4, 0.8, 1.2, or 1.6 mM for 24 h, and the direct dysmorphogenic effects of the drug on the embryos were examined by comparisons with a control group. The viability of the cultured embryos was not affected by the AMP treatment. The yolk sac diameter was reduced at AMP concentrations of 1.2 and 1.6 mM. The crown-rump length, the somite number, and the protein content of the embryos were decreased significantly at these two doses, as was the developmental score. The frequency of malformed embryos was increased significantly at the two highest concentrations. The malformations induced in treated embryos included microcephaly, neural tube defects, incomplete rotation of the body axis, and tortuous spinal cord. Abnormal histologic changes, such as derangement and necrosis of the neuroepithelial tissue, were observed in the embryos exposed to the two highest concentrations of the drug. The observed embryotoxic effects appeared to depend on the AMP concentration. Our results demonstrated the direct embryotoxic effects of AMP on rats. The direct dysmorphogenic effect of AMP might be weaker than that of methamphetamine.

Protection against cocaine and combined cocaine-ethanol toxicities in mice by imidazobenzodiazepine Ro 15-4513

The effects of Ro 15-4513 in preventing cocaine and combined cocaine-ethanol toxicities were examined in mice. Ro 15-4513 is a partial inverse agonist of benzodiazepine receptors, which has been implicated in ethanol lethality and cocaine-induced seizures. Ro 15-4513 (5 mg/kg, 10 mg/kg, or 15 mg/kg) was administered intraperitoneally 10 min before the administration of saline and cocaine (75 mg/kg) in the cocaine groups, or before ethanol (3 g/kg) and cocaine (75 mg/kg) in the cocaine-ethanol groups. In both cocaine and cocaine-ethanol groups, two distinct groups of dead animals meeting the same criteria, the IL (immediate lethal) and DL (delayed lethal) groups, could be differentiated, depending on their survival times, observed disorders, and drug levels at the time of death. Differences in the seizure scores further subdivided the two groups. Ro 15-4513 protected mainly against the immediate lethality in the cocaine groups and mainly against the delayed lethality in the cocaine-ethanol groups. The dose of Ro 15-4513 providing the maximal protection against the lethal effects of these drugs was 10 mg/kg in the cocaine groups, and 5 mg/kg in the cocaine-ethanol groups. The sum of the lethalities was still higher with the maximal effective dose of Ro 15-4513 in the cocaine-ethanol groups than in the cocaine groups. In the cocaine-ethanol groups, 5 mg/kg of Ro 15-4513 attenuated both brain and liver cocaethylene levels. Cocaine-induced seizures were also attenuated by any dose of Ro 15-4513 used in the cocaine groups. Although some discrepancies were observed in the protective properties, some validity for the use of Ro 15-4513, a drug with more than one mode of protective action, was demonstrated in this study.

An autopsy case of osteogenesis imperfecta initially suspected as child abuse

Osteogenesis imperfecta (OI) is an uncommon congenital disease of collagen synthesis. It has a wide range of phenotypic expressions, but it is classically characterized by varying degrees of bone fragility. Consequently, individuals with OI frequently suffer repeated severe bone injuries from otherwise innocuous traumatic events. In the evaluation of suspected child abuse cases with suspicious fractures, clinicians are taught to rule out the possibility of OI. However, because OI is quite rare, this possible diagnosis may be overlooked in situations where the child seems to have clearly suffered non-accidental trauma. OI may potentially be mistaken for child abuse by an inexperienced examiner. An autopsy case of osteogenesis imperfecta that was initially diagnosed as child abuse is presented.

Brain β-Endorphin Immunoreactivity as an Index of Cocaine and Combined Cocaine–Ethanol Toxicities

The present study examines alterations in the cytoplasmic immunoreactivity of brain beta-endorphin, an endogenous opioid peptide regarded as the mediator of both euphoria and antinociceptive systems, in relation to toxicities due to cocaine and combined cocaine-ethanol. Beta-endorphin-immunoreactive cells were visualized and counted in adjacent sections from male rat brains at the level of the arcuate nucleus. In this region, cytoplasmic beta-endorphin immunoreactivity is prevalent. An intraperitoneal injection of cocaine (75 or 15 mg/kg) was given 15 min after an intraperitoneal injection of 3 g/kg ethanol or vehicle. With a fatally toxic dose (75 mg/kg) of cocaine, the number of neurons exhibiting cytoplasmic beta-endorphin immunoreactivity (immunoreactive nerve cells) was significantly increased immediately after the drug administration. Ethanol further enhanced the effects of both 15 and 75 mg/kg of cocaine. When the immunoreactivity was visually estimated by computer imaging analysis, lightly stained, weakly immunoreactive cells with photographic light absorption values greater than 50% were enhanced in the cocaine-ethanol groups compared to the cocaine only groups. Fatal toxicities were only observed in the groups treated with the high cocaine doses (75 mg/kg), with or without ethanol. In these groups, the number of strongly immunoreactive cells had increased significantly compared to the other groups. In the group treated with the high cocaine dose (75 mg/kg) plus ethanol, an increased frequency of late deaths that occurred over 1 h after the drug administration was observed, together with a decreased severity of cocaine-induced seizures and an early enhancement of weakly immunoreactive cells. Unlike the strongly immunoreactive cells, the weakly immunoreactive cells appeared to be continuously enhanced, based on an experiment examining beta-endorphin immunoreactivity at 24 h after an injection of 50 mg/kg cocaine.