Chronic benzylpiperazine (BZP) exposure produces behavioral sensitization and cross-sensitization to methamphetamine (MA)

Methamphetamine effects in zebrafish (Danio rerio) depend on behavioral endpoint, dose and test session duration

Research using zebrafish (Danio rerio) has begun to provide novel information in many fields, including the behavioral pharmacology of drug use and misuse. There have been limited studies on the effects of methamphetamine in adult zebrafish and the parameters of exposure (dose, test session length) have not been well-documented. Behavior following drug exposure is generally measured during relatively short sessions (6-10 min is common) in a novel tank environment. Many procedural variables (isolation, netting, novel tank) elicit anxiety-like behavior that is most apparent during the initial portion of a test session. This anxiety-like behavior might mask the initial effects of methamphetamine. During longer test sessions, these anxiety-like responses would be expected to habituate and drug effects should become more apparent. To test this idea, we measured several locomotor activity responses for 50-min following a range of methamphetamine doses (0.1-3.0 mg/L via immersion in methamphetamine solution). Methamphetamine failed to alter swimming velocity, distance travelled, or freezing time. In contrast, methamphetamine produced a dose-dependent decrease in time spent in the bottom of the tank, an increase in the number of visits to the top of the tank, and an increase in the number of transitions along the sides of the tank. The effects of methamphetamine were apparent 10-20 min following exposure and generally persisted throughout the session. These findings indicate that longer test sessions are required to measure methamphetamine-induced changes in behavior in zebrafish, as has been shown in other laboratory animals. The results also suggest that anxiety-like responses associated with various procedural aspects (netting, isolation, novel test apparatus) likely interfere with the ability to observe many behavioral effects of methamphetamine in zebrafish. Based on the current results, habituation to testing procedures to reduce anxiety-like behaviors is recommended in determining the effects of methamphetamine in zebrafish.

Roles of nucleus accumbens shell and core in footshock-induced stress altering behavioral sensitization by methamphetamine in acquisition and testing: Running head: stress, nucleus accumbens, and behavioral sensitization

How the subregions of the nucleus accumbens (NAc) shell and core and stress are involved in behavioral sensitization induced by psychostimulants remains unclear. The present study manipulated methamphetamine (MAMPH) injections, lesions of the NAc shell or core, and footshock-treatment-induced stress to address this issue. The present data showed that during the acquisition phase, MAMPH injections, lesions of the NAc shell, and footshock treatments induced hyperactivity for the NAc shell. For the NAc core, MAMPH injections induced hyperactivity; however, lesions of the NAc core did not affect locomotor activity. Footshock treatments disrupted hyperactivity of behavioral sensitization. During the testing phase, MAMPH injections, lesions of the NAc shell, and footshock-treatment-induced stress facilitated hyperactivity for the NAc shell. For the NAc core, MAMPH injections and footshock-treatment-induced stress increased hyperactivity. However, the lesion of the NAc core did not affect locomotor activity. In conclusion, MAMPH injections and footshock-treatment-induced stress play an excitatory role for the NAc shell in acquisition and testing. For the NAc core, footshock-treatment-induced stress plays an inhibitory role in acquisition but an excitatory role in testing. The NAc core was not involved in MAMPH-induced behavioral sensitization in acquisition and testing. The NAc shell plays an inhibitory role in acquisition and testing phases. The present data might provide some insights for drug addiction. The results should be discussed further.

Treatment with 1-benzylpiperazine (BZP) during adolescence of male and female hooded rats exposed to environmental enrichment: Subsequent behavioral outcomes

From 30 days after birth until the completion of the study, male and female rats were caged in same-sexed twos or threes either with (enriched cages, EC) or without several objects for them to explore (standard cages, SC). From 41 to 50 days of age (late adolescence), they received a daily intraperitoneal injection of saline, or 10 or 20 mg/kg of the monoaminergic agonist drug of abuse, 1-benzylpiperazine (BZP). Ten days later (PND60+), their behavior was observed over several days in an open field, an elevated plus maze, a light-dark box and (to assess short-term memory) a Y maze in which one of the arms had been changed in brightness between two trials. These tests were repeated from 40 days after PND60+, namely PND100+. While open-arm occupancy at PND100+ in the plus maze was lower following both doses of the drug for SC rats only, other examples of BZP-related heightened anxiety were confined to EC rats. This suggested that enrichment had enhanced rather than reduced any anxiogenic effects of the drug treatment. There was no plausible evidence of BZP-associated impaired spatial memory required to recognize the changed novel Y-maze arm. Instead, changes in novelty preferences or neophobia-related anxiety were most likely. While there were also some examples of sex and age differences in the later effects of BZP, in most cases these were evident at both ages following treatment with both BZP doses. A number of overall BZP, cage, sex and age differences, independent of enrichment effects, were also observed.

Benzylpiperazine: "A messy drug"

Designer drugs are synthetic structural analogues/congeners of controlled substances with slightly modified chemical structures intended to mimic the pharmacological effects of known drugs of abuse so as to evade drug classification. Benzylpiperazine (BZP), a piperazine derivative, elevates synaptic dopamine and serotonin levels producing stimulatory and hallucinogenic effects, respectively, similar to the well-known drug of abuse, methylenedioxymethamphetamine (MDMA). Furthermore, BZP augments the release of norepinephrine by inhibiting presynaptic autoreceptors, therefore, BZP is a "messy drug" due to its multifaceted regulation of synaptic monoamine neurotransmitters. Initially, pharmaceutical companies used BZP as a therapeutic drug for the treatment of various disease states, but due to its contraindications and abuse potential it was withdrawn from the market. BZP imparts predominately sympathomimetic effects accompanied by serious cardiovascular implications. Addictive properties of BZP include behavioral sensitization, cross sensitization, conditioned place preference and repeated self-administration. Additional testing of piperazine derived drugs is needed due to a scarcity of toxicological data and widely abuse worldwide.

"Legal Highs"--An Emerging Epidemic of Novel Psychoactive Substances

During the last decade, there has been an increase in the availability and use of novel psychoactive substances (NPS), also known as "legal highs," across the world. They include a wide range of products, from natural plant-originated substances to synthetic compounds, that can be purchased both online and from high street retailers. "Legal highs" mimic psychoactive effects of illicit drugs of abuse. However, they are claimed to consist of compounds that are legal to sell, possess, and use, often labeled as "not for human consumption" to circumvent drug abuse legislation. Based on the spectrum of their actions on cognitive processes, mood, and behavior, "legal highs" can be classified into four basis categories: amphetamine- and ecstasy-like stimulants, synthetic cannabinoids (SCs), hallucinogenic/dissociative, and opioid-like compounds. NPS may, however, exhibit a combination of these actions due to their designed chemical structure. Although the prevalence and pattern of NPS use differ between various countries, the most popular groups are SCs and psychostimulants, described in this chapter. Currently, there is limited information available on the potential acute toxicity (harms) associated with the use of these substances. However, the number of intoxicated people presenting with emergencies is constantly increasing, providing evidence that negative health and social consequences may indeed seriously affect recreational and chronic users.

The impact of the prohibition of benzylpiperazine (BZP) "legal highs" on the availability, price and strength of BZP in New Zealand

BACKGROUND

Legal highs containing benzylpiperazine (BZP) were widely sold in New Zealand until BZP was prohibited in 2008. We examined the impact the prohibition had on the availability and price of BZP over following years.

METHODS

Two national population surveys of BZP use were conducted in 2006 and 2009. Four annual targeted surveys of frequent drug users (FDU) were conducted from 2007-2010. Availability and price measures were obtained. Inflation-adjusted real retail prices were calculated. Other drug markets were monitored as quasi-controls.

RESULTS

The proportion of BZP users from the general population who considered the availability of BZP to be 'very easy' declined from 76% in 2006 to 21% in 2009. The proportion who thought BZP had become 'harder' to obtain increased from 5% in 2006 to 71% in 2009. The proportion who reported the price of BZP was 'higher' increased from 27% in 2006 to 51% in 2009. FDU who considered the availability of BZP to be 'very easy' declined from 98% in 2007 to 15% in 2008, and then increased to 42% by 2010. The real retail price of a BZP tablet increased from $9.86 in 2007 to $15.83 in 2010. The proportion who considered the price of BZP to be 'increasing' rose from 3% in 2007 to 47% in 2010.

CONCLUSIONS

The availability of BZP declined immediately following its prohibition. Availability recovered in subsequent years, but not to the pre-prohibition legal level. The price of BZP increased slowly over a number of years following the prohibition.

Benzylpiperazine-induced acute delirium in a patient with schizophrenia and an incidental temporal meningioma

Benzylpiperazine is a psychotropic compound that has been widely available until recently from licensed premises such as ‘head shops’. This report describes a case of a 48 year old man with schizophrenia who developed an acute delirium secondary to benzylpiperazine use, although he initially presented as a diagnostic conundrum. Investigation of his delirium unearthed a temporal meningioma which appears to be an incidental finding. This is the first documented case of delirium due to benzylpiperazine use. Benzylpiperazine has significant abuse potential and psychiatric complications. Its sale and possession have recently been made illegal in Ireland, which may limit its abuse in the future.

Piperazine compounds as drugs of abuse

Synthetic drugs are among the most commonly abused drugs in the world. This abuse is widespread among young people, especially in the dance club and rave scenes. Over the last several years, piperazine derived drugs have appeared, mainly available via the internet, and sold as ecstasy pills or under the names of "Frenzy", "Bliss", "Charge", "Herbal ecstasy", "A2", "Legal X" and "Legal E". Although in the market piperazine designer drugs have the reputation of being safe, several experimental and epidemiological studies indicate risks for humans. Piperazine designer drugs can be divided into two classes, the benzylpiperazines such as N-benzylpiperazine (BZP) and its methylenedioxy analogue 1-(3,4-methylenedioxybenzyl)piperazine (MDBP), and the phenylpiperazines such as 1-(3-chlorophenyl)piperazine (mCPP), 1-(3-trifluoromethylphenyl)piperazine (TFMPP), and 1-(4-methoxyphenyl)piperazine (MeOPP). Toxicokinetic properties, including metabolic pathways, actions and effects in animals and humans, with some hypothesis of mechanism of action, and analytical approaches for the identification of these drugs are summarized in this review.

Current awareness of piperazines: pharmacology and toxicology

Although many piperazine derivatives exist, only a limited number have been studied, whereby they have been found to be generally stimulant in nature resulting from dopaminergic, noradrenergic, and predominantly serotoninergic effects in the brain. Reported toxic effects include agitation, anxiety, cardiac symptoms (e.g. tachycardia) and sometimes seizures. As for many drugs, they are primarily metabolized by cytochrome P450 with subsequent possible glucuronidation and/or sulfation. Their abuse has been relatively recently observed in the last decade with only a few identified in biological fluid (primarily 1-benzylpiperazine (BZP) and 1-(3-trifluoromethylphenyl)piperazine (3-TFMPP)) despite publications of a number of analytical methods. Even when detected, however, the toxicological significance of their presence is often difficult to ascertain as many cases involve other drugs as well as a wide and overlapping range of concentrations found in blood (both in life and after death). This paper reviews the current pharmacological and toxicological information for piperazine derivatives and also includes new ante-mortem and post-mortem blood data.

MDMA ("ecstasy") abuse as an example of dopamine neuroplasticity

A number of reviews have focused on the short- and long-term effects of MDMA and, in particular, on the persistent deficits in serotonin neurotransmission that accompany some exposure regimens. The mechanisms underlying the serotonin deficits and their relevance to various behavioral and cognitive consequences of MDMA use are still being debated. It has become clear, however, that some individuals develop compulsive and uncontrolled drug-taking that is consistent with abuse. For other drugs of abuse, this transition has been attributed to neuroadaptations in central dopamine mechanisms that occur as a function of repeated drug exposure. A question remains as to whether similar neuroadaptations occur as a function of exposure to MDMA and the impact of serotonin neurotoxicity in the transition from use to abuse. This review focuses specifically on this issue by first providing an overview of human studies and then reviewing the animal literature with specific emphasis on paradigms that measure subjective effects of drugs and self-administration as indices of abuse liability. It is suggested that serotonin deficits resulting from repeated exposure to MDMA self-administration lead to a sensitized dopaminergic response to the drug and that this sensitized response renders MDMA comparable to other drugs of abuse.

Methamphetamine self-administration and the effect of contingency on monoamine and metabolite tissue levels in the rat

A number of studies have shown that exposure to high doses of methamphetamine (MA) is toxic to central dopamine (DA) and serotonin (5-HT) neurons. In most of those studies, however, high doses of MA were experimenter-administered during a short exposure time. Because contingency is a determinant for many effects of drug exposure, the present objective was to investigate the effects of self-administered MA on tissue monoamine levels following a short (24 hours) or longer (7 days) withdrawal period. As previously reported, a noncontingent "binge" high-dose treatment regimen (4 injections of 10 mg/kg MA administered every 2 hours) produced persistent depletion of cortical 5-HT and striatal DA. Effects of self-administered MA (0.1 mg/kg/infusion) were then determined following a 20-day duration where a yoked design was employed such that some rats received MA contingent on an operant lever press and others received either MA or saline dependent on the responses of the contingent rat. Self-administered MA produced a transient striatal DA depletion with a more persistent increase in DA turnover, indicating the presence of some lasting adaptations. Furthermore, the yoked design revealed that there was no effect of contingency on these parameters.

Pharmacology of stimulants prohibited by the World Anti-Doping Agency (WADA)

This review examines the pharmacology of stimulants prohibited by the World Anti-Doping Agency (WADA). Stimulants that increase alertness/reduce fatigue or activate the cardiovascular system can include drugs like ephedrine available in many over-the-counter medicines. Others such as amphetamines, cocaine and hallucinogenic drugs, available on prescription or illegally, can modify mood. A total of 62 stimulants (61 chemical entities) are listed in the WADA List, prohibited in competition. Athletes may have stimulants in their body for one of three main reasons: inadvertent consumption in a propriety medicine; deliberate consumption for misuse as a recreational drug and deliberate consumption to enhance performance. The majority of stimulants on the list act on the monoaminergic systems: adrenergic (sympathetic, transmitter noradrenaline), dopaminergic (transmitter dopamine) and serotonergic (transmitter serotonin, 5-HT). Sympathomimetic describes agents, which mimic sympathetic responses, and dopaminomimetic and serotoninomimetic can be used to describe actions on the dopamine and serotonin systems. However, many agents act to mimic more than one of these monoamines, so that a collective term of monoaminomimetic may be useful. Monoaminomimietic actions of stimulants can include blockade of re-uptake of neurotransmitter, indirect release of neurotransmitter, direct activation of monoaminergic receptors. Many of the stimulants are amphetamines or amphetamine derivatives, including agents with abuse potential as recreational drugs. A number of agents are metabolized to amphetamine or metamphetamine. In addition to the monoaminomimetic agents, a small number of agents with different modes of action are on the list. A number of commonly used stimulants are not considered as Prohibited Substances.