Serotonin1A-receptor antagonism blocks psychostimulant properties of diethylpropion in marmosets (Callithrix penicillata)

Anxiolytic-Like Effects of Chrysanthemum indicum Aqueous Extract in Mice: Possible Involvement of GABAA Receptors and 5-HT1A Receptors

Chrysanthemum indicum Linne is an ancient herbal medicine used to treat bone and muscle deterioration, ocular infl ammation, headache, and anxiety in Korea, China, and Japan. Furthermore, tea derived from Chrysanthemum indicum Linne has been used to treat anxiety by facilitating relaxation and curing insomnia. However, no reports exist on the anxiolytic-like effects of Chrysanthemum indicum Linne water extract (CWE) in mice. In the present study, we investigated the anxiolytic-like effects of CWE using the elevated plus-maze (EPM) test in mice. CWE, at a dose of 500 mg/kg (p.o.), signifi cantly increased the time spent in the open arms of the EPM compared to a vehicle-injected control group. Moreover, the effect of CWE (500 mg/kg) was blocked by bicuculline (a selective GABA_A receptor antagonist) and WAY 100635 (a selective 5-HT_1A receptor antagonist). Taken together, these fi ndings suggest that the anxiolytic-like effects of CWE might be mediated by the GABA_A receptor and the 5-HT_1A receptor.

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.

Maternal fluoxetine treatment decreases behavioral response to dopaminergic drugs in female pups

Since serotonin (5-HT) acts as neurotrophic factor, the use of fluoxetine (FLX) by mothers during pregnancy and/or lactation could disrupt brain development of the progeny. To unveil if maternal FLX exposure could compromise the functional integrity of monoaminergic and GABA-ergic neurotransmission, the behavioral responses of male and female mouse pups to diethylpropion, apomorphine, 8-OH-DPAT and diazepam were evaluated. Swiss dams were gavaged daily with FLX (7.5 mg/kg) or tap water during pregnancy day zero to weaning (postnatal day 21). Pups were evaluated on postnatal day 40. The behavioral response to diethylpropion was assessed in the open-field and drug-induced stereotyped behavior; to apomorphine in the drug-induced stereotyped behavior; to diazepam, in the elevated plus maze test and to 8-OH-DPAT in the open-field and forced swimming tests. Exposure to FLX did not influence any drug-induced behavioral response in males. Conversely, in females, FLX exposure significantly prevented diethylpropion-induced hyperactivity in the open-field and reduced stereotyped behavior induced by diethylpropion and apomorphine. In conclusion, the results showed that maternal exposure to FLX induced in female pups long-lasting decreased dopaminergic-mediated behaviors, suggesting altered development of the dopaminergic system. If this alteration also occurs in humans, female children of women who use FLX during pregnancy and lactation may express dopaminergic behavioral alterations and/or altered responsiveness to psychotropic medications later in life.

Serotonin and psychostimulant addiction: Focus on 5-HT1A-receptors

Serotonin(1A)-receptors (5-HT(1A)-Rs) are important components of the 5-HT system in the brain. As somatodendritic autoreceptors they control the activity of 5-HT neurons, and, as postsynaptic receptors, the activity in terminal areas. Cocaine (COC), amphetamine (AMPH), methamphetamine (METH) and 3,4-methylenedioxymethamphetamine ("Ecstasy", MDMA) are psychostimulant drugs that can lead to addiction-related behavior in humans and in animals. At the neurochemical level, these psychostimulant drugs interact with monoamine transporters and increase extracellular 5-HT, dopamine and noradrenalin activity in the brain. The increase in 5-HT, which, in addition to dopamine, is a core mechanism of action for drug addiction, hyperactivates 5-HT(1A)-Rs. Here, we first review the role of the various 5-HT(1A)-R populations in spontaneous behavior to provide a background to elucidate the contribution of the 5-HT(1A)-Rs to the organization of psychostimulant-induced addiction behavior. The progress achieved in this field shows the fundamental contribution of brain 5-HT(1A)-Rs to virtually all behaviors associated with psychostimulant addiction. Importantly, the contribution of pre- and postsynaptic 5-HT(1A)-Rs can be dissociated and frequently act in opposite directions. We conclude that 5-HT(1A)-autoreceptors mainly facilitate psychostimulant addiction-related behaviors by a limitation of the 5-HT response in terminal areas. Postsynaptic 5-HT(1A)-Rs, in contrast, predominantly inhibit the expression of various addiction-related behaviors directly. In addition, they may also influence the local 5-HT response by feedback mechanisms. The reviewed findings do not only show a crucial role of 5-HT(1A)-Rs in the control of brain 5-HT activity and spontaneous behavior, but also their complex role in the regulation of the psychostimulant-induced 5-HT response and subsequent addiction-related behaviors.

Interaction of the tachykinin NK3 receptor agonist senktide with behavioral effects of cocaine in marmosets (Callithrix penicillata)

Brain neuropeptide transmitters of the tachykinin family are involved in the organization of many behaviors. However, little is known about their contribution to the behavioral effects of drugs of abuse. Recently, antagonism of the tachykinin NK3-receptor (NK3-R), one of the three tachykinin receptors in the brain, was shown to attenuate the acute and chronic behavioral effects of cocaine in rats and the acute effects in non-human primates. In order to expand these findings we investigated the effects of the NK3-R agonist, succinyl-[Asp6, Me-Phe8]SP(6-11) (senktide), on the acute behavioral effects of cocaine in marmoset monkeys (Callithrix penicillata) using a figure-eight maze procedure. Animals were pretreated with senktide (0, 0.1, 0.2, 0.4 mg/kg, s.c.), and received either a treatment with cocaine (10 mg/kg) or saline (i.p.). Cocaine increased locomotor activity and the duration of aerial scanning behavior, but reduced exploratory activity, bodycare activity, the frequency of aerial scanning, and terrestrial glance behavior. Senktide blocked the effects of cocaine on locomotor activity, but enhanced the cocaine effects on exploratory activity, aerial scanning frequency, and terrestrial glance behavior. Senktide alone did not significantly influence monkey behavior in this study. These data expand previous findings suggesting a complex role of the NK3-R in the acute behavioral effects of cocaine in non-human primates.

The tachykinin NK3 receptor antagonist SR142801 blocks the behavioral effects of cocaine in marmoset monkeys

Brain neuropeptide transmitters of the tachykinin family are involved in the organization of many behaviors. However, little is known about their contribution to the behavioral effects of drugs of abuse. Recently, the tachykinin NK3 receptor, one of the three tachykinin receptors in the brain, was shown to attenuate the acute and chronic behavioral effects of cocaine in rats. In order to test if these findings can be generalized to primates we investigated the role of the tachykinin NK3 receptor in the acute behavioral effects of cocaine in marmoset monkeys (Callithrix penicillata) using a figure-eight maze procedure. Animals were pretreated with the tachykinin NK3 receptor antagonist, (R)-(N)-[1-[3-[1-benzoyl-3-(3,4-dichlorophenyl)piperidin-3-yl]propyl]-4-phenylpiperidin-4-yl]-N-methylacetamide (SR142801; 0, 0.02, 0.2, 2.0 mg/kg, i.p.), and received either a treatment with cocaine (10 mg/kg, i.p) or saline (i.p.). Cocaine increased locomotor activity and aerial glance behavior, but reduced exploratory and bodycare activities, scent marking and terrestrial scanning behavior. A sensitivity analysis revealed that two responder types can be differentiated in relation to the occurrence of a hyperlocomotor response to cocaine. SR142801 blocked the actions of cocaine on several behaviors dose-dependently for each responder type, respectively. There was no effect of SR142801 alone on any behavior measured. These data suggest that the tachykinin NK3 receptor contributes to the individual behavioral response to cocaine in marmoset monkeys. Having no behavioral effects on its own, but blocking the cocaine effects, might suggest the tachykinin NK3 receptor antagonist, SR142801, as a potential treatment of cocaine addiction in humans.