Related Experiment Video
Updated: May 15, 2026
09:54
Comprehensive Profiling of Dopamine Regulation in Substantia Nigra and Ventral Tegmental Area
Published on: August 10, 2012
Dorsal raphe neuronal activities are modulated by methylphenidate
1Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, 6431 Fannin, MSB 7.208B, Houston, TX 77030, USA.
Journal of Neural Transmission (Vienna, Austria : 1996)
|December 28, 2012
Summary
Methylphenidate (MPH) alters dorsal raphe nucleus (DR) neuron activity. Acute MPH changed firing rates, while repetitive dosing led to neurophysiological sensitization or tolerance in DR neurons.
Area of Science:
- Neuroscience
- Pharmacology
- Electrophysiology
Background:
- The dorsal raphe nucleus (DR) plays a crucial role in regulating various brain functions.
- Methylphenidate (MPH) is a widely prescribed stimulant medication.
Purpose of the Study:
- To investigate the electrophysiological effects of acute and repetitive methylphenidate (MPH) administration on dorsal raphe nucleus (DR) neurons.
- To determine if MPH induces neurophysiological sensitization or tolerance in DR neurons.
Main Methods:
- Electrophysiological recordings of DR neuronal activity in freely behaving, non-anesthetized rats.
- Acute and daily administration of MPH over several days, followed by washout and rechallenge.
- Analysis of neuronal firing rates and changes in baseline activity.
Main Results:
- Acute MPH administration (2.5 mg/kg i.p.) significantly altered firing rates in 56% of DR units, with a majority showing increased activity.
- Repetitive daily MPH administration followed by a washout period resulted in significant baseline activity changes in 83% of DR units by day 10.
- Rechallenge with MPH on day 10 showed significant firing rate changes in 63% of units, with 76% exhibiting increased firing.
- Comparison of rechallenge to initial administration revealed neurophysiological sensitization (further increase in firing) or tolerance (decrease/no change) in 47% and 53% of DR units, respectively.
Conclusions:
- Acute methylphenidate administration modulates dorsal raphe nucleus neuronal activity.
- Repetitive MPH administration alters baseline DR neuronal activity and can induce neurophysiological sensitization or tolerance.
- These findings highlight the significant impact of MPH on DR neuronal function.
Related Concept Videos
01:21Drugs Affecting Neurotransmitter Release or Uptake
Certain drugs can affect how neurotransmitters called catecholamines, are released or taken back up in the adrenergic neuron. They can have different effects on the body's sympathetic transmission. Reserpine, a natural compound found in the Rauwolfia shrub, blocks a transporter called vesicular monoamine transporter (VMAT), which leads to a buildup of catecholamines in the cell and reduces sympathetic transmission. Another drug called guanethidine works in multiple ways, including blocking...
01:29Drugs Affecting Neurotransmitter Synthesis
Drugs affecting neurotransmitter synthesis can impact the adrenergic neuron and the synthesis of neurotransmitters. For example, α-methyltyrosine and carbidopa target specific enzymes involved in catecholamine synthesis. α-methyltyrosine inhibits the enzyme tyrosine hydroxylase, which converts tyrosine into dopamine. By blocking this enzyme, α-methyltyrosine reduces dopamine production and other catecholamines. Carbidopa, on the other hand, inhibits the enzyme dopa decarboxylase, which converts...
01:23Drugs Acting on Autonomic Ganglia: Stimulants
Ganglionic stimulants activate NM nicotinic receptors in autonomic ganglia, falling into two categories: nicotine mimetics [e.g., lobeline, dimethylpiperazine, tetramethylammonium] and muscarinic receptor agonists [e.g., muscarine, methacholine]. The first category's action is rapid and blocked by nicotinic receptor antagonists, while the second category's action is delayed and blocked by atropine-like agents. Nicotine, an alkaloid, affects the heart rate by stimulating sympathetic or...
01:25Adrenergic Agonists: Indirect-Acting Agents
Indirect-acting adrenergic agonists potentiate the effects of endogenous catecholamines through different mechanisms without directly binding to adrenoceptors.
One mechanism involves depleting stored catecholamines by displacing them from synaptic vesicles. These agents, known as "displacers," are transported into vesicles at the expense of noradrenaline. Examples include amphetamine and tyramine, which lack a catechol moiety, resulting in prolonged action, improved oral bioavailability, and...
One mechanism involves depleting stored catecholamines by displacing them from synaptic vesicles. These agents, known as "displacers," are transported into vesicles at the expense of noradrenaline. Examples include amphetamine and tyramine, which lack a catechol moiety, resulting in prolonged action, improved oral bioavailability, and...
01:30Attention-Deficit/Hyperactivity Disorder
Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by persistent inattention, hyperactivity, and impulsivity. It affects approximately 5-8% of children globally, with around 60-70% of cases persisting into adulthood. ADHD has significant implications for educational attainment, social interactions, and occupational success.
Diagnostic Criteria and Symptoms
To diagnose ADHD, symptoms must manifest before age 12 and be evident across multiple settings.
Diagnostic Criteria and Symptoms
To diagnose ADHD, symptoms must manifest before age 12 and be evident across multiple settings.
01:24CNS Stimulants: Cocaine, Amphetamines and Cannabinoids
CNS stimulants, such as cocaine, amphetamines, and cannabinoids, have varying structures and mechanisms of action that lead to different therapeutic effects and side effects. Cocaine, with its molecular formula C17H21NO4, is a tropane alkaloid and a tertiary amino compound. It has two chemical forms: the hydrochloride salt and the "freebase." The former is in powder form, while the latter involves removing the hydrochloride salt to create a form that can be smoked. Cocaine exerts its effects by...