Effects of dopamine- and serotonin-related compounds on methamphetamine-induced self-injurious behavior in mice

Pharmacological Treatments for Methamphetamine Use Disorder: Current Status and Future Targets

The illicit use of the psychostimulant methamphetamine (METH) is a major concern, with overdose deaths increasing substantially since the mid-2010s. One challenge to treating METH use disorder (MUD), as with other psychostimulant use disorders, is that there are no available pharmacotherapies that can reduce cravings and help individuals achieve abstinence. The purpose of the current review is to discuss the molecular targets that have been tested in assays measuring the physiological, the cognitive, and the reinforcing effects of METH in both animals and humans. Several drugs show promise as potential pharmacotherapies for MUD when tested in animals, but fail to produce long-term changes in METH use in dependent individuals (eg, modafinil, antipsychotic medications, baclofen). However, these drugs, plus medications like atomoxetine and varenicline, may be better served as treatments to ameliorate the psychotomimetic effects of METH or to reverse METH-induced cognitive deficits. Preclinical studies show that vesicular monoamine transporter 2 inhibitors, metabotropic glutamate receptor ligands, and trace amine-associated receptor agonists are efficacious in attenuating the reinforcing effects of METH; however, clinical studies are needed to determine if these drugs effectively treat MUD. In addition to screening these compounds in individuals with MUD, potential future directions include increased emphasis on sex differences in preclinical studies and utilization of pharmacogenetic approaches to determine if genetic variances are predictive of treatment outcomes. These future directions can help lead to better interventions for treating MUD.

Gender Differences of Antioxidant System and Thyroid Function in Depressed Adolescents with Non-Suicidal Self-Injury

Purpose

The aim of our study was to explore the relation between serum levels of non-enzymatic antioxidants, thyroid function with the risk of non-suicidal self-injury (NSSI) in depressed adolescents.

Patients and Methods

We retrospected the electronic records of 454 hospitalized patients aged 13-17 years old with a diagnosis of major depressive disorder (239 patients with NSSI and 215 subjects without NSSI), and collected their demographic and clinical information, including serum levels of total bilirubin (Tbil), uric acid (UA), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH).

Results

The incidence of NSSI was 52.6% among depressed adolescents aged 13-17, 57.1% in female and 38.5% in male. After using the propensity scoring method to exclude the influence of age between the two groups, it was found that patients with NSSI showed lower levels of Tbil (P=0.046) and UA (P=0.015) compared with those without NSSI. Logistic regression results showed that serum UA was associated with NSSI behavior in female patients (OR=0.995, 95% CI: 0.991-0.999, P=0.014), and TSH was associated with NSSI in male participants (OR=0.499, 95% CI: 0.267-0.932, P=0.029).

Conclusion

Female and male may have different pathological mechanisms of NSSI. NSSI is more likely to be related to antioxidant reaction in female adolescent patients, while more likely to be related to thyroid function in male depressed adolescent patients.

Self-injury as a predominant challenging behavior in epilepsy: A study in a residential facility for profoundly disabled patients

BACKGROUND

The association between challenging behavior (CB) and epilepsy in people with intellectual disability (ID) remains largely controversial.

AIM

To clarify the correlation between CB and epilepsy, we investigated the clinical characteristics of CB in both people with and without epilepsy among individuals with ID hospitalized in our residential facility.

METHODS AND PROCEDURES

A total of 63 individuals with CB was retrospectively investigated using the Behavior Problems Inventory, and the following items were collected from the medical records: sex, age, hospitalization period, etiology and risk factors, level of ID, type of CB, administration of psychotropic drugs, presence or absence of epilepsy and clinical features of epilepsy.

OUTCOMES AND RESULTS

Almost all individuals with CB showed profound ID. There was no significant difference in the rate of CB between people with and without epilepsy. A type analysis of CB revealed that self-injurious behavior was observed more frequently in epilepsy cases (66.7 %) than in cases without epilepsy (36.4 %) (p =  0.015), and self-injurious behavior was the predominant clinical form in people with epilepsy among the three subgroups of CB (self-injurious, aggressive and self-injurious and aggressive behavior).

CONCLUSIONS AND IMPLICATIONS

The high incidence of self-injurious behavior in epilepsy with profound disabilities may imply the presence of common pathological basis of self-injurious behavior and epilepsy.

Extensive tissue necrosis of the tongue in a methamphetamine user: A case report

AIMS

Methamphetamine (meth) is a powerful, highly addictive stimulant that affects the central nervous system, and its side effects may result in severe self-mutilation. This report describes a case of a meth user with severe oral injury that demonstrates the necessity for prompt treatment when severe tongue biting occurs.

METHODS AND RESULTS

A 43-year-old meth-using man with severe tongue biting was left untreated for more than 24 hours, resulting in extensive ischemic changes in the tongue and eventual extensive tissue necrosis. After debridement and deep suture repair in several layers, the wound healed. However, tongue dysfunction and a speech disorder remained because of tongue shortening.

CONCLUSION

Meth may induce or aggravate severe oral self-mutilation. Tongue biting with severe tissue damage may occur as oral self-mutilation in meth users; however, among self-mutilation behaviors, tongue biting is especially difficult to prevent. A withdrawal from meth and a behavioral approach may be necessary for fundamental prevention, but it is often difficult in high dependence users. When severe tongue biting occurs, prompt suture reconstruction must be performed before ischemic change occurs to prevent tissue necrosis.

Atomoxetine Induced Skin Picking: A Case Report

"Skin picking disorder," also known as "dermatillomania" or "psychogenic excoriation," is classified in the "Obsessive Compulsive and Related Disorders" category in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition and characterized by repetitive skin picking behaviors resulting in skin lesions. Atomoxetine (ATX) is a selective norepinephrine (noradrenaline) reuptake inhibitor commonly used in the management of attention-deficit/hyperactivity disorder. Atomoxetine is considered to increase levels of noradrenaline and dopamine by inhibiting norepinephrine transporters. In this case report, we present an 8-year-old male attention-deficit/hyperactivity disorder patient with skin picking behavior due to ATX treatment. We discussed possible explanations of skin picking behavior with ATX in the light of the current literature. To our knowledge, this is the first report of skin picking due to ATX in literature, and further studies are needed to investigate the frequency and mechanisms of skin picking with ATX.

A case of clozapine-induced skin picking behaviour

There is some evidence consistently linking the occurrence of de novo obsessive-compulsive disorder (OCD) with clozapine. This skin-picking disorder is also known as impulsive-compulsive disorder-unspecified which with an increasing convergence with OCD has been placed in the current Diagnostic and statistical manual of mental disorders-fifth edition by American Psychiatric Association (DSM-5), in the category of the obsessive-compulsive and related disorders. To the best of our knowledge, there is no literature relating antipsychotics like clozapine with the occurrence of skin-picking behaviour. In this article, we present a case in whom skin-picking behaviour emerged during the upward dose titration of clozapine and was successfully treated with escitalopram.

Psychotomimetic-like behavioral effects of memantine in the mouse

A single administration of mice with memantine (1-amino-3,5-dimethyladamantane), a glutamatergic N-methyl-d-aspartate (NMDA) receptor antagonist, induced stereotyped behaviors in dose- and time-dependent manners. The predominant behavioral component of the stereotypy was a continuous, exaggerated sniffing which was accompanied by persistent locomotion. In contrast, a psychostimulant methamphetamine (METH) predominantly induced a stereotyped biting and other forms of intense stationary stereotypical behaviors. Memantine-induced stereotyped sniffing was attenuated by pretreatment with haloperidol, a dopamine D₂ receptor antagonist, in a dose-dependent manner. The memantine-induced stereotyped sniffing was also attenuated by pretreatment with betahistine (2-[2-(methylamino)ethyl]pyridine), an agent which increases histamine turnover and releases histamine in the brain. These observations suggest that memantine might induce stereotypies through neuronal mechanisms that are somewhat different from those of METH, but still overlap to a certain extent, since memantine-induced stereotypies can be attenuated by the mechanisms that also suppress METH-induced stereotypy. Importantly, these data suggests that the effects of memantine may be more limited to the ventral striatum including nucleus accumbens than those of METH, which is associated with dorsal striatal stimulation at high doses. In this respect memantine may also have pharmacological properties such as compartmentation (i.e. brain distribution) and neuronal mechanisms different from those of other NMDA receptor antagonists, such as ketamine, which may have important implications for therapeutic uses of these drugs.

[Underlying Mechanisms of Methamphetamine-Induced Self-Injurious Behavior and Lethal Effects in Mice]

Relatively high doses of psychostimulants induce neurotoxicity on the dopaminergic system and self-injurious behavior (SIB) in rodents. However the underlying neuronal mechanisms of SIB remains unclear. Dopamine receptor antagonists, N-methyl-D-aspartic acid (NMDA) receptor antagonists, Nitric Oxide Synthase (NOS) inhibitors and free radical scavengers significantly attenuate methamphetamine-induced SIB. These findings indicate that activation of dopamine as well as NMDA receptors followed by radical formation and oxidative stress, especially when mediated by NOS activation, is associated with methamphetamine-induced SIB. On the other hand, an increase in the incidence of polydrug abuse is a major problem worldwide. Coadministered methamphetamine and morphine induced lethality in more than 80% in mice, accompanied by an increase in the number of poly (ADP-ribose) polymerase (PARP)-immunoreactive cells in the heart, kidney and liver. The lethal effect and the increase in the incidence of rupture or PARP-immunoreactive cells induced by the coadministration of methamphetamine and morphine were significantly attenuated by pretreatment with a phospholipase A2 inhibitor or a radical scavenger, or by cooling of body from 30 to 90 min after drug administration. These results suggest that free radicals play an important role in the increased lethality induced by the coadministration of methamphetamine and morphine. Therefore, free radical scavengers and cooling are beneficial for preventing death that is induced by the coadministration of methamphetamine and morphine. These findings may help us better understand for masochistic behavior, which is a clinical phenomenon on SIB, as well as polydrug-abuse-induced acute toxicity.

Dissecting the Influence of Two Structural Substituents on the Differential Neurotoxic Effects of Acute Methamphetamine and Mephedrone Treatment on Dopamine Nerve Endings with the Use of 4-Methylmethamphetamine and Methcathinone

Mephedrone (MEPH) is a β-ketoamphetamine stimulant drug of abuse that is often a constituent of illicit bath salts formulations. Although MEPH bears remarkable similarities to methamphetamine (METH) in terms of chemical structure, as well as its neurochemical and behavioral effects, it has been shown to have a reduced neurotoxic profile compared with METH. The addition of a β-keto moiety and a 4-methyl ring substituent to METH yields MEPH, and a loss of direct neurotoxic potential. In the present study, two analogs of METH, methcathinone (MeCa) and 4-methylmethamphetamine (4MM), were assessed for their effects on mouse dopamine (DA) nerve endings to determine the relative contribution of each individual moiety to the loss of direct neurotoxicity in MEPH. Both MeCa and 4MM caused significant alterations in core body temperature as well as locomotor activity and stereotypy, but 4MM was found to elicit minimal dopaminergic toxicity only at the highest dose. By contrast, MeCa caused significant reductions in all markers of DA nerve-ending damage over a range of doses. These results lead to the conclusion that ring substitution at the 4-position profoundly reduces the neurotoxicity of METH, whereas the β-keto group has much less influence on this property. Although the mechanism(s) by which the 4-methyl substituent reduces METH-induced neurotoxicity remains unclear, it is speculated that this effect is mediated by a loss of DA-releasing action in MEPH and 4MM at the synaptic vesicle monoamine transporter, an effect that is thought to be critical for METH-induced neurotoxicity.

Brain Histamine N-Methyltransferase As a Possible Target of Treatment for Methamphetamine Overdose

Stereotypical behaviors induced by methamphetamine (METH) overdose are one of the overt symptoms of METH abuse, which can be easily assessed in animal models. Currently, there is no successful treatment for METH overdose. There is increasing evidence that elevated levels of brain histamine can attenuate METH-induced behavioral abnormalities, which might therefore constitute a novel therapeutic treatment for METH abuse and METH overdose. In mammals, histamine N-methyltransferase (HMT) is the sole enzyme responsible for degrading histamine in the brain. Metoprine, one of the most potent HMT inhibitors, can cross the blood-brain barrier and increase brain histamine levels by inhibiting HMT. Consequently, this compound can be a candidate for a prototype of drugs for the treatment of METH overdose.

Multidisciplinary assessment and treatment of self-injurious behavior in autism spectrum disorder and intellectual disability: integration of psychological and biological theory and approach

The objective of this review is to consider the psychological (largely behavioral) and biological [neurochemical, medical (including genetic), and pharmacological] theories and approaches that contribute to current thinking about the etiology and treatment of self-injurious behavior (SIB) in individuals with autism spectrum disorder and/or intellectual disability. Algorithms for the assessment and treatment of SIB in this context, respectively, from a multidisciplinary, integrative perspective are proposed and challenges and opportunities that exist in clinical and research settings are discussed.

Pretreatment with l-histidine produces a shift from methamphetamine-induced stereotypical biting to persistent locomotion in mice

The administration of methamphetamine (METH; 10mg/kg, i.p.) to male ICR mice induced bizarre behaviors including persistent locomotion and stereotypical behaviors, which were classified into four categories: stereotypical head-bobbing, circling, sniffing, and biting. Pretreatment with l-histidine (750 mg/kg, i.p.) significantly decreased the stereotypical biting induced by METH and significantly increased persistent locomotion. This effect of l-histidine on behavior was completely abolished by simultaneous administration of pyrilamine or ketotifen (brain-penetrating histamine H(1) receptor antagonists; 10mg/kg each, i.p.), but not by the administration of fexofenadine (a non-sedating histamine H(1) receptor antagonist that does not cross the blood-brain barrier; 20mg/kg), zolantidine (a brain-penetrating histamine H(2) receptor antagonist; 10mg/kg), thioperamide, or clobenpropit (brain-penetrating histamine H(3) receptor antagonists; 10mg/kg each). The histamine content of the hypothalamus was significantly increased by l-histidine treatment. These data suggest that l-histidine modifies the effects of METH through central histamine H(1) receptors.

Sigma1 receptor antagonists determine the behavioral pattern of the methamphetamine-induced stereotypy in mice

OBJECTIVE

The effects of sigma receptor antagonists on methamphetamine (METH)-induced stereotypy have not been examined. We examined the effects of sigma antagonists on METH-induced stereotypy in mice.

RESULTS

The administration of METH (10 mg/kg) to male ddY mice induced stereotyped behavior consisting of biting (90.1%), sniffing (4.2%), head bobbing (4.1%), and circling (1.7%) during an observation period of 1 h. Pretreatment of the mice with BMY 14802 (alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazinebutanol; 1, 5, and 10 mg/kg), a non-specific sigma receptor antagonist, significantly increased METH-induced sniffing (19.2%, 30.5%, and 43.8% of total stereotypical behavior) but decreased biting (76.6%, 66.9%, and 49.3% of total stereotypical behavior) in a dose-dependent manner. This response was completely abolished by (+)-SKF 10,047 ([2S-(2alpha,6alpha,11R)]-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2,6-methano-3-benzazocin-8-ol; 4 and 10 mg/kg), a putative sigma(1) receptor agonist, and partially by PB 28 (1-cyclohexyl-4-[3-(1,2,3,4-tetrahydro-5-methoxy-1-naphthalen-1-yl)-n-propyl]piperazine; 1 and 10 mg/kg), a putative sigma(2) receptor agonist. The BMY 14802 action on METH-induced stereotypy was mimicked by BD 1047 (N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine; 10 mg/kg), a putative sigma(1) receptor antagonist, but not by SM-21 ((+/-)-tropanyl 2-(4-chlorophenoxy)butanoate; 1 mg/kg), a putative sigma(2) receptor antagonist. The BD 1047 effect on METH-induced stereotypy was also abolished completely by (+)-SKF 10,047 and partially by PB 28. The overall frequency of METH-induced stereotypical behavior was unchanged with these sigma receptor ligands, despite the alteration in particular behavioral patterns. The BMY 14802 action on METH-induced stereotypy was unaffected by pretreatment with centrally acting histamine H(1) receptor antagonists (pyrilamine or ketotifen, 10 mg/kg), suggesting that these effects are independent of histamine H(1) receptor signaling systems.

CONCLUSION

In summary, modulation of central sigma(1) receptors alters the pattern of METH-induced stereotypy, producing a shift from stereotypical biting to stereotypical sniffing, without affecting the overall frequency of stereotypical behavior.

Brief exposure to methamphetamine (METH) and phencyclidine (PCP) during late development leads to long-term learning deficits in rats

Exposure to methamphetamine (METH) and phencyclidine (PCP) during early development is thought to produce later behavioral deficits. We postulated that exposure to METH and PCP during later development would produce similar behavioral deficits, particularly learning deficits in adulthood. Wistar rats were treated with METH (9 mg/kg), PCP (9 mg/kg), or saline during later development, postnatal days (PD) 50-51, and subsequent behavioral changes were examined including: locomotor activity during the acute drug state (PD 50-51) and the post-drug phase (PD 50-80); social interaction on PD 54-80; and spatial discrimination and reversal in adulthood (after PD 90). METH and PCP differentially affected locomotion during the acute state, but not during the post-drug phase. METH decreased social interaction throughout tests two weeks after drug treatment, whereas PCP decreased social interaction only during the first 8 min of tests. Neither METH nor PCP impaired initial acquisition of spatial discrimination. However, reversal was significantly impaired by PCP, whereas METH produced a mild deficit, compared to controls. Our data provide evidence that exposure to PCP and METH during later development lead to enduring cognitive deficits in adulthood. Selective impairment of reversal may reflect neurological damage in the prefrontal cortex due to early exposure to drugs.

Complicated interaction between psychostimulants and morphine in expression of phenotype of behavior in the dopaminergic system of BALB/c mice

It is believed that BALB/c mice appear to be less sensitive to the locomotor effects of abused drugs compared to other strains, and several behaviors induced by abused drugs depend on genetic factors. The present study was designed to investigate the effects of the interaction between psychostimulants and morphine on behavior in BALB/c mice. Morphine and cocaine induced hyperlocomotion and hypolocomotion, respectively, while methamphetamine did not affect locomotor activity and high doses of methamphetamine significantly increased self-injurious behavior. Cocaine or methamphetamine increased the effects of morphine on locomotor behavior. Haloperidol (a dopamine-receptor antagonist) attenuated the hyperlocomotion induced by the combination of cocaine or methamphetamine plus morphine. These results indicate that the synergistic effects of methamphetamine or cocaine and morphine on locomotor activity are mediated through enhancement of the dopaminergic system and that combinations of psychostimulants and morphine enhance the locomotor activity in BALB/c mice. On the other hand, morphine completely attenuated methamphetamine-induced self-injurious behavior. Furthermore, a low dose (0.01 mg/kg) of haloperidol significantly increased the effects of methamphetamine and morphine on the locomotor activity. Hyperlocomotion induced by psychostimulants is mediated by the mesolimbic dopaminergic system, whereas stereotyped behaviors is mediated by the nigrostriatal dopaminergic system. Our findings suggest that balances of the activation of dopaminergic neurons (between mesolimbic and nigrostriatal systems) may play an important role to engender corresponding behavioral outcomes in BALB/c mice.

Deprenyl treatment attenuates long-term pre- and post-synaptic changes evoked by chronic methamphetamine

Deprenyl, used clinically in Parkinson's disease, has multiple pharmacological effects which make it a good candidate to treat neurotoxicity. Thus, we investigated deprenyl's ability to attenuate methamphetamine-induced dopamine neurotoxicity. We also examined deprenyl's effect in changing markers associated with psychostimulant sensitization. A potential therapeutic effect on either pathological domain would be a boon in developing novel treatments for methamphetamine abuse. Adult male Sprague-Dawley rats were split into 6 groups. Three groups received a 7-day saline minipump with saline, 0.05 or 0.25 mg/kg SC deprenyl injections given for 10 days before, during and 5 days after the 7-day saline minipump implant. Similarly, 3 groups received methamphetamine pumps (25 mg/kg/day) with escalating daily injections of methamphetamine (0-6 mg/kg) in addition to the minipump treatment. These rats also received saline, 0.05 or 0.25 mg/kg deprenyl injections given before, during and the 7-day minipump treatment. Rats were killed on day 28 of withdrawal and brain samples taken. HPLC analysis for dopamine and 3,4-Dihydroxy-Phenylacetic Acid (DOPAC) revealed a loss of dopamine in the caudate and accumbens which was partially reversed by high dose deprenyl. Tyrosine hydroxylase immunostaining in the midbrain was unaffected by methamphetamine, suggesting that dopamine neurotoxicity was localized to the caudate. Western blot analysis of the caudate after methamphetamine revealed little change in Alpha-Amino-3-Hydroxy-5-Methyl-4-Isoxazole Propionic Acid (AMPA) GluR1 or N-Methyl-d-Aspartate (NMDA) NR2B subunits, or their phosphorylation state. However, methamphetamine increased levels of GluR1 and its phosphorylation state in the prefrontal cortex (PFC), and these increases were attenuated by deprenyl. Methamphetamine also increased levels of PFC NR2B subunit, but these increases were not attenuated by deprenyl. We suggest that deprenyl may be effective in reducing the neurotoxic effects of methamphetamine and may also attenuate changes in prefrontal AMPA receptor function, presumably more associated with addiction rather than neurotoxicity.

Differential effects of the ascorbyl and tocopheryl derivative on the methamphetamine-induced toxic behavior and toxicity

A previous study showed that high doses of methamphetamine induce self-injurious behavior (SIB) in rodents. Furthermore, the combination of methamphetamine and morphine increased lethality in mice. We recently surmised that the rise in SIB and mortality induced by methamphetamine and/or morphine may be related to oxidative stress. The present study was designed to determine whether an antioxidant could inhibit SIB or mortality directly induced by methamphetamine and/or morphine. The SIB induced by 20mg/kg of methamphetamine was abolished by the administration of Na L-ascorbyl-2-phosphate (APS: 300 mg/kg), but not Na DL-alpha-tocopheryl phosphate (TPNa: 200mg/kg). In contrast, APS (300 mg/kg) and TPNa (200mg/kg) each significantly attenuated the lethality induced by methamphetamine and morphine. The present study showed that the signal intensity of superoxide adduct was increased by 20mg/kg of methamphetamine in the heart and lungs, and methamphetamine plus morphine tended to increase superoxide adduct in all of the tissues measured by ESR spin trap methods. Adduct signal induced in brain by methamphetamine administration increased in significance, but in mouse administrated methamphetamine plus morphine. There are differential effects of administration of methamphetamine and coadministration of methamphetamine plus morphine on adduct signal. These results suggest that APS and TPNa are effective for reducing methamphetamine-induced toxicity and/or toxicological behavior. While APS and TPNa each affected methamphetamine- and/or morphine-induced toxicology and/or toxicological behavior, indicating that both drugs have antioxidative effects, their effects differed.

Oxidative stress in methamphetamine-induced self-injurious behavior in mice

Previous studies have shown that N-methyl-D-aspartate, the formation of free radicals and poly(ADP-ribose) polymerase are related to methamphetamine-induced neurotoxicity. This study was designed to investigate the involvement of oxidative stress in methamphetamine-induced self-injurious behavior in mice. In this study, methamphetamine (20 mg/kg) induced continuous self-injurious behavior in six of seven mice. N-methyl-D-aspartate-receptor antagonists (MK801 and 3-((R)-2-carboxypiperazin-4-yl) propyl-1-phosphonic acid) significantly attenuated this methamphetamine-induced self-injurious behavior. These results suggest that the activation of N-methyl-D-aspartate receptors is involved in methamphetamine-induced self-injurious behavior. Furthermore, we found that the nonselective nitric oxide synthase inhibitor l-N-nitro-L-arginine methyl ester hydrochloride and the neuronal nitric oxide synthase inhibitor 7-nitroindazole, but not the inducible nitric oxide synthase inhibitor aminoguanidine, the free-radical inhibitors fullerene and 3-methyl-1-phenyl-2-pyrazolin-5-one-186, or the poly(ADP-ribose) polymerase inhibitor benzamide, significantly attenuated methamphetamine-induced self-injurious behavior. The present results show that oxidative stress, which is mediated by the activation of neuronal nitric oxide synthase, is associated with methamphetamine-induced self-injurious behavior. These findings may help us to better understand the clinical phenomenon of self-injurious behavior.

Methamphetamine modulates DC-SIGN expression by mature dendritic cells

We report that methamphetamine (meth) may act as cofactor in human immunodeficiency virus (HIV)-1 pathogenesis by increasing dendritic cell (DC)-specific intercellular adhesion molecule-3 (ICAM-3) grabbing non-integrin (DC-SIGN) expression on DCs. Mature DCs (MDCs), obtained from normal subjects, cultured with meth show an up-regulation of DC-SIGN gene and protein expression as analyzed by real-time quantitative polymerase chain reaction and fluorescence-activated cell-sorting analyses, respectively. Furthermore, these meth-induced effects were reversed by a dopamine D1 receptor antagonist (SCH 23390) and small interfering RNA specific to the D1 receptor (D1R) demonstrating that meth-induced effects are mediated through these receptors. Furthermore, meth in synergy with the HIV-1 peptide gp120 up-regulates DC-SIGN gene expression by MDCs. These data are the first evidence that meth up-regulates the expression of DC-SIGN on MDCs. A better understanding of the role of DC-SIGN in HIV-1 infection may help to design novel therapeutic strategies against the progression of HIV-1 disease in the drug-using population.

Methamphetamine reward in mice as assessed by conditioned place preference test with Supermex sensors: effect of subchronic clorgyline pretreatment

Recent studies in our laboratory have shown that methamphetamine (METH)-induced hyperlocomotion and behavioral sensitization in mice were inhibited by clorgyline, an irreversible monoamine oxidase inhibitor. In this study, the effect of clorgyline pretreatment on METH-induced rewarding effect was assessed by a conditioned place preference (CPP) test, using an apparatus developed with Supermex sensors (infrared pyroelectric sensors). Although intact male ICR mice showed significant CPP for METH (0.5 mg/kg, i.p.), pretreatment with subchronic clorgyline (0.1 and 10 mg/kg, s.c.) did not affect the magnitude of CPP. At a dose of 1 mg/kg, pretreatment of the mice with clorgyline showed a similar CPP index in both saline/saline and METH/saline pairing groups. During the conditioning session, the mice did not express behavioral sensitization to METH. Pretreatment with clorgyline (0.1, 1, and 10 mg/kg) decreased striatal apparent monoamine turnover in a dose-dependent manner. These results indicated that clorgyline pretreatment (0.1 and 10 mg/kg) did not influence the METH-induced rewarding effect in mice, although pretreatment of the mice with clorgyline at a dose of 1 mg/kg appeared to influence the CPP for METH.

Effects of mu-, delta- and kappa-opioid receptor agonists on methamphetamine-induced self-injurious behavior in mice

Opioid receptor agonists can differentially modify the behavioral effects of direct/indirect dopamine receptor agonists, such as methamphetamine, cocaine and apomorphine. However, the effects of opioid receptor agonists on high-dose methamphetamine-induced behavior have not yet been clarified. Therefore, the present study was undertaken to investigate the effects of mu (morphine)-, delta (SNC80)- and kappa (U50,488H)-opioid receptor agonists on methamphetamine-induced self-injurious behavior and locomotor activity in mice. Methamphetamine (20 mg/kg) induced severe self-injurious behavior. In a combination test, some opioid receptor agonists significantly attenuated methamphetamine-induced self-injurious behavior, with potencies in the order morphine>buprenorphine (mu-opioid and kappa-opioid receptor agonist/antagonist) >U50,488H, as maximum effects. These results suggest that the stimulation of mu- and kappa-opioid receptors plays an inhibitory role in high-dose methamphetamine-induced stereotypic self-injurious behavior in mice, without affecting locomotor activity.

2-Phenylethylamine in combination with l-deprenyl lowers the striatal level of dopamine and prolongs the duration of the stereotypy in mice

2-Phenylethylamine (PEA)-induced stereotypy in rodents is suggested to model psychotic symptoms of schizophrenia. It is reported that PEA induces dopamine release in the striatum in vivo and in vitro. The present study analyzed the PEA-induced stereotypy and possible associated brain dopamine metabolism in mice. Using male ICR mice treated with a combination of PEA (100 mg/kg, i.p.) and increasing doses of l-deprenyl (0-10 mg/kg, s.c.), we examined (1) the behavioral profile of stereotypy (rating the scores), and (2) the tissue levels of dopamine and its metabolites by high-performance liquid chromatography. The stereotypic scores reached a plateau level at 10 min which lasted until 30 min after a single administration of 100 mg/kg PEA. The stereotyped behavior completely disappeared 45 min after PEA administration. Pretreatment with l-deprenyl (0.1, 1, and 10 mg/kg, s.c.) dose-dependently prolonged the duration of PEA-induced stereotypy. Notably, pretreatment with l-deprenyl dose-dependently increased the continuous sniffing. Treatment with PEA in combination of l-deprenyl (1 and 10 mg/kg) significantly reduced the level of dopamine in the region of the striatum and nucleus accumbens, compared with control animals. These results suggest that PEA in combination with l-deprenyl prolonged the duration of the stereotypy (particularly, continuous sniffing) while reducing the striatal level of dopamine.

Underlying mechanism of combined effect of methamphetamine and morphine on lethality in mice and therapeutic potential of cooling

An increase in polydrug abuse is a major problem worldwide. A previous study showed that coadministration of methamphetamine and morphine induced lethality in rodents and humans. However, the underlying mechanisms by which the lethality is increased by the coadministration of methamphetamine and morphine have not been fully understood. Therefore, the present study was designed to determine the mechanism of increased lethality induced by methamphetamine and morphine. Coadministered methamphetamine and morphine increased the lethality by more than 70% in BALB/c mice. Pretreatment with NMDA-receptor antagonists, such as MK-801 and 3-((R)-2-carboxypiperazin-4-yl) propyl-1-phosphonic acid (CPP), and benzamide [poly(ADP-ribose) polymerase (PARP) inhibitor] significantly attenuated the increased lethality induced by methamphetamine and morphine. Furthermore, the lethal effect induced by methamphetamine and morphine was completely attenuated by immediate cooling after the coadministration of methamphetamine and morphine. It has been reported that methamphetamine-induced neurotoxicity can be blocked by lowering the temperature, and this effect might be mediated by a reduction of release of free radicals. These results suggest that activation of NMDA receptors and PARP play an important role in the increased lethality induced by methamphetamine and morphine.