1,721,066 research outputs found
Influence of repeated exposure to caffeine on dopamine transmission: preclinical evidence and potential consequences of caffeine consumption
No full textCaffeine is a most popular psychostimulant and is consumed worldwide. A large body of evidence
demonstrates the existence of striking differences between the effects of caffeine and those of psychostimulants bearing
abuse potential, like amphetamines and cocaine, a major one being that the reinforcing properties of caffeine are generally
modest. Nevertheless, preclinical research has suggested that caffeine, similar to addictive psychostimulants, is capable of
interacting with dopaminergic circuits in the brain and, accordingly, of influencing dopamine-mediated neurobehavioural
functions. Here evidence is reported from an experimental model of long-term caffeine administration in the rat which
demonstrates that caffeine can exert an enduring facilitatory influence on dopamine transmission in the corpus striatum.
Such an effect was found to be manifested as the development of sensitization to caffeine-induced motor stimulant
effects, and as the onset of modifications involving receptors and immediate early gene expression in the striatum.
Moreover, an increased responsiveness to the motor stimulation and striatal immediate early gene expression elicited by
D-amphetamine was observed in rats pre-exposed to caffeine, further supporting the ability of caffeine to induce a
hyperfunctionality of dopamine transmission. Taken together, these results lend support to the hypothesis that caffeine
consumption might represent a factor capable of amplifying certain behaviour
Rat ultrasonic vocalizations and behavioral neuropharmacology: from the screening of drugs to the study of disease
Full text linkSeveral lines of evidence indicate that rats emit ultrasonic vocalizations (USVs) in response to a wide range of stimuli that are capable of producing either euphoric (positive) or dysphoric (negative) emotional states. On these bases, recordings of USVs are extensively used in preclinical studies of affect, motivation, and social behavior. Rat USVs are sensitive to the effects of certain classes of psychoactive drugs, suggesting that emission of rat USVs can have relevance not only to neurobiology, but also to neuropharmacology and psychopharmacology. This review summarizes three types of rat USVs, namely 40-kHz USVs emitted by pups, 22-kHz USVs and 50-kHz USVs emitted by young and adult animals, and relevance of these vocalizations to neuropharmacological studies. Attention will be focused on the issues of how rat USVs can be used to evaluate the pharmacological properties of different classes of drugs, and how rat USVs can be combined with other behavioral models used in neuropharmacology. The strengths and limitations of experimental paradigms based on the evaluation of rat USVs will also be discusse
Ultrasonic vocalizations in rats: a tool for the investigation of psychoactive drugs and neuropsychiatric conditions
No full textAcute and long-term effects elicited by psychoactive drugs on 50-kHz ultrasonic vocalizations in rats: development of a new experimental tool for the study of drug-mediated reward.
Full text linkUltrasonic vocalizations (USVs) have recently emerged as an indicator of the emotional state of
rats, and the evaluation of the USVs in the 50-kHz range has been proposed as a tool to investigate the affective
properties of drugs of abuse. To clarify the relevance of 50-kHz USVs to drug-induced reward, the acute and
long-term effects elicited by different psychoactive drugs
[
amphetamine, 3,4-methylenedioxymethamphetamine
(MDMA, ecstasy), methylphenidate, morphine, and nicotine
]
were characterized in adult male rats.
Amphetamine and methylphenidate were the only drugs that stimulated the emission of 50-kHz USVs by rats
after their acute administration. Moreover, amphetamine was the only drug that elicited a significant emission
of 50-kHz USVs after repeated administration. However, rats in all the treatment groups emitted 50-kHz USVs
when later re-exposed to the environment previously paired with repeated drug administration, likely indicative
of drug-mediated environmental conditioning. Taken together, these results demonstrate the existence of major
differences in the acute and long-term effects of different psychoactive drugs on the emission of 50-kHz USVs
by rats. Moreover, these results provide a better understanding of the usefulness of 50-kHz USVs as a new tool
for the assessment of drug-mediated reward, with implications for the preclinical study of addictive behavior
Repeated amphetamine administration and long-term effects on 50-kHz ultrasonic vocalizations: possible relevance to the motivational and dopamine-stimulating properties of the drug
No full textUltrasonic vocalizations (USVs) of 50kHz are thought to indicate positive affective states in rats, and are increasingly being used to investigate the motivational properties of drugs of abuse. However, previous studies have observed that only dopaminergic psychostimulants of abuse, but not other addictive drugs, stimulate 50-kHz USVs immediately after their administration. This would suggest that 50-kHz USVs induced by addictive dopaminergic psychostimulants might reflect rewarding dopaminergic effect, rather than motivational effect. To elucidate this issue, our study compared the effects of the psychostimulant of abuse amphetamine and the dopamine receptor agonist apomorphine on 50-kHz USVs. Rats that received five drug administrations on alternate days in a novel test-cage, were first re-exposed to the test-cage 7 days after treatment discontinuation to assess drug-conditioning, and then received a drug challenge. USVs were recorded throughout the experiments together with locomotor activity. To further clarify how amphetamine and apomorphine influenced 50-kHz USVs, rats were subdivided into “low” and “high” vocalizers, and time-dependence of drug effects was assessed. Amphetamine and apomorphine stimulated both 50-kHz USVs and locomotor activity, though they elicited dissimilar changes in these behaviors, depending on drug dose, rats’ individual predisposition to vocalize, and time. Moreover, only amphetamine-treated rats displayed both sensitized 50-kHz USVs emission and conditioned vocalizations on test-cage re-exposure. These results indicate that the effects of amphetamine on 50-kHz USVs are not mimicked by a dopaminergic agonist with a low abuse potential, and may further support the usefulness of 50-kHz USVs in the study of the motivational properties of psychoactive drugs
Rat 50-kHz ultrasonic vocalizations as a tool in studying neurochemical mechanisms that regulate positive emotional states
No full textBackground: Adolescent and adult rats emit 50-kHz ultrasonic vocalizations (USVs) to communicate the appetitive arousal and the presence of positive emotional states to conspecifics.
New Method: Based on its communicative function, emission of 50-kHz USVs is increasingly being evaluated in preclinical studies of affective behavior, motivation and social behavior.
Results: Emission of 50-kHz USVs is initiated by the activation of dopamine receptors in the shell subregion of the nucleus accumbens. However, several lines of evidence show that non-dopaminergic receptors may influence the numbers of 50-kHz USVs that are emitted, as well as the acoustic parameters of calls.
Comparison with Existing Methods: Emission of 50-kHz USVs is a non-invasive method that may be used to study reward and motivation without the need for extensive training and complex animal manipulations. Moreover, emission of 50-kHz USVs can be used alone or combined with other well-standardized behavioral paradigms (e.g., conditioned place preference, self-administration).
Conclusions: This review summarizes the current evidence concerning molecular mechanisms that regulate the emission of 50-kHz USVs. Moreover, the review discusses the usefulness of 50-kHz USVs as an experimental tool to investigate how different neurotransmitter systems regulate the manifestations of positive emotional states, and also use of this tool in preclinical modeling of psychiatric diseases
Dopaminergic Treatments for Parkinson’s Disease: Light and Shadows
No full textDopamine‐replacement therapy still stands as the most effective pharmacological strategy for the management of motor impairment associated with Parkinson’s disease. The present chapter aims to provide an overview of the pharmacology of dopamine‐replacement therapy in both preclinical experimental models of Parkinson’s disease and patients, and to present its light and shadows. The effect of dopamine‐replacement therapy on motor impairment, motor complications, non‐motor symptoms, and disease progression will be discussed, with a focus on future therapeutic directions
Effects of Psychostimulants on Rat Emotional States and Emission of Ultrasonic Vocalizations
No full textPsychostimulants are drugs consumed worldwide that may have a profound influence on the emotional state and that possess marked addictive properties. For these reasons, the pharmacological effects of psychostimulants are extensively studied at both the preclinical and clinical levels. With regard to preclinical research, it is noteworthy that ultrasonic vocalizations (USVs) are being increasingly used as a tool in investigating the influence of psychostimulants on motivational processes and in elucidating the interplay between modifications in the emotional states and psychostimulant-induced addiction. This chapter provides an overview of the effects of psychostimulants on the emission of USVs in rats, focusing on results obtained in adult animals. The most recent evidence is discussed in regard to the effects of psychostimulants on the emotional state and, when relevant, to the other central and peripheral effects of these drugs
Contribution of Caffeine to the Psychostimulant, Neuroinflammatory and Neurotoxic Effects of Amphetamine-Related Drugs
No full textAssociation of amphetamine-related drugs with beverages containing high levels of caffeine is becoming very popular among adolescents and young adults. This review by examining the psychostimulant properties and the neuroinflammatory and neurotoxic effects of this drug association provides a new vision of the risks correlated to multiple substances consumption. In preclinical studies, caffeine amplifies the effects of amphetamine-related drugs on behavioral parameters, such as locomotor activity, operant behavioral tests, and discriminative stimulus effects, and promotes long-term modifications in the brain. Preclinical data also demonstrate that caffeine contributes to increase the acute toxicity, seizures, hyperthermia, and tachycardia elicited by amphetamine-related drugs in rats. These effects, together with the results showing that caffeine potentiates the loss of central serotonin and dopamine and the induction of neuroinflammation by amphetamine-related drugs, emphasize that, depending on the conditions in which it is consumed, caffeine may amplify the effects of neurotoxic drug
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