9.3 Characteristics of Drugs to Treat Nervous System Disorders
4 min read•june 18, 2024
Neurotransmitters are chemical messengers that allow our nervous system to function. They play crucial roles in everything from muscle movement to mood regulation. Understanding how these chemicals work is key to grasping how drugs affect our bodies and minds.
Drugs can interact with our nervous system in various ways. Some mimic or block neurotransmitters, while others affect their release or reuptake. This knowledge helps us comprehend how medications treat conditions like depression, anxiety, and .
Neurotransmitters and Nervous System Pharmacology
Neurotransmitters and their functions
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- (ACh)
- Serves as a neurotransmitter in both the central nervous system (CNS) and peripheral nervous system (PNS)
- Plays a crucial role in memory formation, learning processes, and muscle contraction (skeletal and smooth muscle)
- Involved in the regulation of autonomic functions such as heart rate, digestion, and secretion
- (NE)
- Acts as a neurotransmitter primarily in the sympathetic nervous system
- Increases heart rate, blood pressure, and blood glucose levels during stress or physical activity
- Plays a key role in the body's "fight or flight" response to prepare for action in emergency situations
- (DA)
- Functions as a neurotransmitter in the CNS, particularly in the brain's reward and motor control systems
- Regulates movement, emotional responses, motivation, and feelings of pleasure and reward
- Imbalances in dopamine levels are associated with neurological disorders such as Parkinson's disease and psychiatric conditions like
- (5-HT)
- Serves as a neurotransmitter in the CNS and gastrointestinal tract
- Regulates mood, sleep patterns, appetite, and pain perception
- Dysregulation of serotonin is linked to various psychiatric disorders, including depression and anxiety
- ###Gamma-aminobutyric_acid_()_0###
- Acts as the primary inhibitory neurotransmitter in the CNS
- Reduces neuronal excitability by hyperpolarizing the postsynaptic membrane
- Plays a crucial role in regulating anxiety levels and promoting relaxation
-
- Serves as the primary excitatory neurotransmitter in the CNS
- Involved in learning, memory formation, and synaptic plasticity (the ability of synapses to strengthen or weaken over time)
- Excessive glutamate activity can lead to excitotoxicity, which is associated with
Drug interactions with autonomic receptors
- Cholinergic receptors
- (M1-M5)
- Activated by ACh and targeted by drugs like and to block their effects
- Used to treat conditions such as motion sickness, overactive bladder, and chronic obstructive pulmonary disease (COPD)
- (NM, NN)
- Activated by ACh and targeted by drugs like and to stimulate or partially activate these receptors
- Used to treat conditions such as smoking cessation and by improving cognitive function
- (M1-M5)
-
- (α1)
- Activated by NE and targeted by drugs like and to block their effects
- Used to treat conditions such as hypertension and by relaxing smooth muscle
- (α2)
- Activated by NE and targeted by drugs like and to stimulate these receptors
- Used to treat conditions such as hypertension and attention deficit hyperactivity disorder () by reducing sympathetic activity
- (β1)
- Activated by NE and targeted by drugs like and to block their effects
- Used to treat conditions such as hypertension, angina, and heart failure by reducing heart rate and contractility
- (β2)
- Activated by NE and targeted by drugs like and to stimulate these receptors
- Used to treat conditions such as asthma and COPD by promoting bronchodilation
- (α1)
Sympathetic vs parasympathetic nervous system agents
- Sympathetic nervous system (SNS) stimulants
- Drugs that increase the activity of the SNS by mimicking or enhancing the effects of NE
- Examples include , norepinephrine, and
- Used to treat conditions such as , cardiac arrest, and by increasing alertness and cardiovascular function
- Sympathetic nervous system (SNS) blockers
- Drugs that decrease the activity of the SNS by blocking the effects of NE at
- Examples include alpha blockers (prazosin) and beta blockers ()
- Used to treat conditions such as hypertension, angina, and migraine by reducing peripheral resistance and heart rate
- Parasympathetic nervous system (PNS) stimulants
- Drugs that increase the activity of the PNS by mimicking or enhancing the effects of ACh
- Examples include and
- Used to treat conditions such as and urinary retention by promoting smooth muscle contraction and secretion
- Parasympathetic nervous system (PNS) blockers
- Drugs that decrease the activity of the PNS by blocking the effects of ACh at muscarinic receptors
- Examples include atropine, scopolamine, and
- Used to treat conditions such as bradycardia, overactive bladder, and COPD by reducing smooth muscle tone and secretion
Drug mechanisms and nervous system interactions
-
- Selective permeability barrier that separates the circulating blood from the brain extracellular fluid
- Influences drug delivery to the CNS and must be considered when developing CNS-active medications
-
- Process by which neurotransmitters are removed from the synaptic cleft
- Target of many antidepressants and other psychoactive drugs to prolong neurotransmitter effects
-
- Process of signal transmission between neurons at synapses
- Affected by various drugs to modulate nervous system function
- and antagonists
- Agonists: Drugs that activate specific receptors to mimic or enhance neurotransmitter effects
- Antagonists: Drugs that block specific receptors to inhibit neurotransmitter effects
-
- The brain's ability to form new neural connections and adapt in response to experiences or injury
- Influenced by certain medications and therapies to promote recovery or manage neurological conditions
Key Terms to Review (62)
Acetylcholine: Acetylcholine is a neurotransmitter that plays a crucial role in the functioning of the nervous system, including the transmission of signals between nerve cells and the activation of muscle contractions. It is a key component in understanding various neurological disorders and the mechanisms of drugs used to treat them.
Acute angle-closure (narrow-angle) glaucoma: Acute angle-closure (narrow-angle) glaucoma is a type of glaucoma where the iris blocks the drainage angle in the eye, leading to a rapid increase in intraocular pressure. This condition is an ocular emergency requiring immediate treatment to prevent vision loss.
ADHD: ADHD, or Attention-Deficit/Hyperactivity Disorder, is a neurodevelopmental condition characterized by persistent inattention, hyperactivity, and impulsivity that can significantly impact an individual's daily functioning and quality of life. This term is particularly relevant in the context of understanding the characteristics of drugs used to treat nervous system disorders, as well as the classification and mechanisms of central nervous system (CNS) stimulants and nonstimulants.
Adrenergic receptors: Adrenergic receptors are a class of G protein-coupled receptors targeted by catecholamines like adrenaline and noradrenaline. They play a crucial role in the sympathetic nervous system by modulating physiological responses such as heart rate, blood pressure, and bronchodilation.
Adrenergic Receptors: Adrenergic receptors are a class of G protein-coupled receptors that bind to the neurotransmitters epinephrine (adrenaline) and norepinephrine (noradrenaline). These receptors play a crucial role in the body's sympathetic nervous system, mediating the physiological responses to these neurotransmitters.
Albuterol: Albuterol is a bronchodilator medication that works by relaxing and opening the airways in the lungs, making it easier to breathe. It is commonly used to treat and prevent symptoms of asthma, chronic obstructive pulmonary disease (COPD), and other respiratory conditions.
Alpha receptors: Alpha receptors are a type of adrenergic receptor found in various tissues of the body, including blood vessels and smooth muscles. They play a crucial role in the body's sympathetic nervous system response.
Alpha-1 Receptors: Alpha-1 receptors are a type of adrenergic receptor found primarily in smooth muscle cells, particularly in the blood vessels, bladder, and gastrointestinal tract. These receptors play a crucial role in the regulation of various physiological processes related to the nervous system disorders discussed in Chapter 9.3.
Alpha-2 Receptors: Alpha-2 receptors are a class of G protein-coupled receptors that are involved in the regulation of the sympathetic nervous system. They play a crucial role in the modulation of various physiological processes, including blood pressure, heart rate, and pain perception, making them an important target for drugs used to treat nervous system disorders.
Alzheimer's disease: Alzheimer's disease is a progressive neurodegenerative disorder that primarily affects the brain, leading to cognitive decline, memory loss, and impairment of daily functioning. It is the most common form of dementia, characterized by the accumulation of proteins that disrupt normal brain function and cause the death of brain cells over time.
Amphetamines: Amphetamines are a class of central nervous system (CNS) stimulant drugs that increase the levels of certain neurotransmitters, primarily dopamine and norepinephrine, in the brain. They are known for their ability to enhance focus, energy, and wakefulness, making them commonly used for the treatment of attention-deficit/hyperactivity disorder (ADHD) and narcolepsy, as well as for their potential for abuse and addiction.
Anaphylaxis: Anaphylaxis is a severe, life-threatening allergic reaction that can occur rapidly and requires immediate medical attention. It involves multiple organ systems and can lead to shock and death if not treated promptly.
Anaphylaxis: Anaphylaxis is a severe, whole-body allergic reaction that can be life-threatening. It occurs when the immune system overreacts to an allergen, triggering the rapid release of chemicals that cause widespread inflammation and impair breathing and blood circulation.
Atenolol: Atenolol is a cardioselective beta-blocker medication primarily used to treat high blood pressure, angina, and certain heart rhythm disorders. It works by selectively blocking beta-1 adrenergic receptors, which are predominantly found in the heart, reducing the heart's workload and oxygen demand.
Atropine: Atropine is a potent anticholinergic medication that blocks the action of the neurotransmitter acetylcholine at muscarinic receptors in the body. This pharmacological property of atropine allows it to have diverse therapeutic applications in the treatment of nervous system disorders, cholinergic conditions, and cardiac emergencies.
Benign Prostatic Hyperplasia: Benign prostatic hyperplasia (BPH) is a noncancerous enlargement of the prostate gland, a common condition in older men that can lead to urinary symptoms. This term is relevant in the context of understanding drugs that treat nervous system disorders, antihistamines and decongestants, phosphodiesterase 5 inhibitors, the male reproductive system, and alpha blockers and 5-alpha-reductase inhibitors.
Benign prostatic hyperplasia (BPH): Benign prostatic hyperplasia (BPH) is a non-cancerous enlargement of the prostate gland that commonly affects older men. It can lead to urinary symptoms such as difficulty starting urination and weak urine flow.
Beta receptors: Beta receptors are a type of adrenergic receptor located on cells in various tissues that respond to the hormone adrenaline and neurotransmitter noradrenaline. They play a key role in the regulation of cardiovascular, pulmonary, and other systems.
Beta-1 Receptors: Beta-1 receptors are a type of adrenergic receptor found primarily in the heart and kidneys. They play a crucial role in regulating various physiological processes, including heart rate, contractility, and blood pressure, making them an important target for drugs used to treat nervous system disorders and cardiovascular conditions.
Beta-2 Receptors: Beta-2 receptors are a subtype of beta-adrenergic receptors that are primarily located in the smooth muscle cells of the lungs, blood vessels, and other organs. They play a crucial role in the regulation of various physiological processes, particularly in the context of nervous system disorders, beta-adrenergic blockers, and the interplay between adrenergics and anticholinergics.
Bethanechol: Bethanechol is a cholinergic drug that acts as a parasympathomimetic agent, stimulating muscarinic acetylcholine receptors in the parasympathetic nervous system. It is primarily used to treat urinary retention and to improve bladder function in patients with neurogenic bladder disorders.
Bethanechol chloride: Bethanechol chloride is a cholinergic agonist used primarily to treat urinary retention by stimulating bladder muscle contractions. It mimics the action of acetylcholine, enhancing parasympathetic activity.
Blood-Brain Barrier: The blood-brain barrier is a highly selective semipermeable membrane that separates the circulating blood from the brain and central nervous system (CNS). It acts as a gatekeeper, controlling the movement of substances between the bloodstream and the brain to protect the delicate neural tissue from harmful substances while allowing the passage of essential nutrients, oxygen, and other molecules required for proper brain function.
Cholinergic nerves: Cholinergic nerves are nerve fibers that release the neurotransmitter acetylcholine, which plays a crucial role in transmitting signals in both the central and peripheral nervous systems. These nerves are involved in various functions, including muscle contraction and modulation of autonomic activities.
Clonidine: Clonidine is a medication primarily used to treat high blood pressure, attention-deficit/hyperactivity disorder (ADHD), and certain types of pain. It is classified as an alpha-2 adrenergic agonist, which means it acts on specific receptors in the brain and body to produce its effects on the nervous system.
Dopamine: Dopamine is a neurotransmitter that plays a crucial role in the brain's reward and pleasure centers, as well as in the regulation of various physiological processes. It is involved in a wide range of functions, from motor control and cognition to emotional and behavioral responses, making it a key player in understanding and treating numerous nervous system disorders.
Epinephrine: Epinephrine, also known as adrenaline, is a hormone and medication that plays a critical role in the body's fight-or-flight response. It is used in medical emergencies to treat conditions like cardiac arrest, anaphylaxis, and severe asthma attacks.
Epinephrine: Epinephrine, also known as adrenaline, is a hormone and neurotransmitter produced by the adrenal glands. It plays a crucial role in the body's fight-or-flight response, preparing the body to handle stressful or dangerous situations. This key term is particularly relevant in the context of various nervous system and cardiovascular drug topics.
GABA: GABA (Gamma-Aminobutyric Acid) is the primary inhibitory neurotransmitter in the central nervous system. It plays a crucial role in regulating neuronal excitability and has been associated with various neurological and psychiatric disorders, including Parkinson's disease, epilepsy, mood disorders, and alcohol use disorder.
GABA structural analogs: GABA structural analogs are compounds that mimic the structure of gamma-aminobutyric acid (GABA), a neurotransmitter. These analogs are used to modulate neural activity and are often employed in the treatment of neurological conditions such as multiple sclerosis.
Gamma-aminobutyric acid (GABA): Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the central nervous system. It helps regulate neuronal excitability and muscle tone.
Glaucoma: Glaucoma is a group of eye conditions that can damage the optic nerve, often due to increased pressure within the eye. It is a leading cause of irreversible blindness worldwide and can affect various aspects of the nervous system, eyes, and fluid regulation in the body.
Glutamate: Glutamate is the principal excitatory neurotransmitter in the mammalian central nervous system, playing a crucial role in various neurological processes and disorders affecting the brain and nervous system.
Glycopyrrolate: Glycopyrrolate is a synthetic anticholinergic medication that is primarily used to reduce excessive secretions, such as saliva, sweat, and gastrointestinal fluids. It acts by blocking the action of the neurotransmitter acetylcholine, which is responsible for stimulating these secretions, making it a valuable tool in the management of various nervous system disorders, cholinergic effects, and urinary tract conditions.
Guanfacine: Guanfacine is a centrally-acting alpha-2 adrenergic agonist medication primarily used to treat attention-deficit/hyperactivity disorder (ADHD) and hypertension. It works by stimulating alpha-2 receptors in the brain, which helps to reduce the activity of the sympathetic nervous system and promote calmness and focus.
Metoprolol: Metoprolol is a beta-adrenergic blocking agent, commonly known as a beta-blocker, that is primarily used to treat various cardiovascular conditions, including hypertension, angina, and certain types of arrhythmias. It works by selectively blocking the beta-1 receptors in the heart, reducing the heart's workload and oxygen demand.
Muscarinic Receptors: Muscarinic receptors are a type of acetylcholine receptor that are primarily found in the parasympathetic nervous system and are responsible for mediating the effects of the neurotransmitter acetylcholine. These receptors play a crucial role in regulating various physiological processes, including cardiac function, gastrointestinal motility, and bladder control, and are the target of both therapeutic drugs and toxins.
Narcolepsy: Narcolepsy is a chronic sleep disorder characterized by overwhelming daytime drowsiness and sudden, uncontrollable episodes of sleep. It is a neurological condition that affects the brain's ability to regulate the sleep-wake cycle, leading to disruptions in normal sleeping patterns.
Neurodegenerative Disorders: Neurodegenerative disorders are a group of progressive, incurable conditions that affect the structure and function of the nervous system, leading to the gradual deterioration and death of nerve cells. These disorders are characterized by the accumulation of abnormal proteins and the destruction of neural pathways, which can impair cognitive, motor, and sensory abilities.
Neuroplasticity: Neuroplasticity is the brain's ability to reorganize itself by forming new neural connections throughout life. It allows neurons in the brain to compensate for injury and disease, and to adjust their activities in response to new situations or changes in their environment.
Neuroplasticity: Neuroplasticity refers to the brain's ability to adapt, change, and reorganize itself in response to new experiences, learning, and environmental demands. It is a fundamental property of the nervous system that allows the brain to modify its structure and function throughout an individual's lifetime.
Neurotransmitter Reuptake: Neurotransmitter reuptake is the process by which neurotransmitters, such as serotonin, dopamine, and norepinephrine, are removed from the synaptic cleft and transported back into the presynaptic neuron or surrounding glial cells. This mechanism helps regulate the duration and intensity of neurotransmitter signaling in the nervous system, which is crucial for maintaining proper neurological function.
Nicotine: Nicotine is a highly addictive chemical compound found in tobacco plants. It is a central nervous system stimulant that acts on nicotinic acetylcholine receptors, producing various physiological and psychological effects in the body. Nicotine is a key consideration in the context of drugs used to treat nervous system disorders.
Nicotinic Receptors: Nicotinic receptors are a type of cholinergic receptor that respond to the neurotransmitter acetylcholine. They are found in the central and peripheral nervous systems, as well as in the neuromuscular junctions, and play a crucial role in the regulation of various physiological processes, including nervous system disorders and urinary tract function.
Norepinephrine: Norepinephrine is a neurotransmitter and hormone produced by the adrenal glands and certain neurons in the brain. It plays a crucial role in the body's sympathetic nervous system, responsible for the 'fight-or-flight' response, and is involved in a variety of physiological and psychological processes.
Parasympathomimetic: Parasympathomimetic drugs mimic the effects of the parasympathetic nervous system by stimulating cholinergic receptors. These drugs are often used to treat conditions like myasthenia gravis and Alzheimer's disease.
Parkinson's Disease: Parkinson's disease is a chronic and progressive neurological disorder that primarily affects the motor system. It is characterized by the loss of dopamine-producing neurons in the brain, leading to a variety of symptoms that can significantly impact an individual's quality of life. This term is particularly relevant in the context of understanding the characteristics of drugs used to treat nervous system disorders, as well as the specific anti-parkinsonian drugs that are designed to manage the symptoms of this condition.
Pilocarpine: Pilocarpine is a cholinergic agonist that acts as a parasympathomimetic drug, primarily stimulating muscarinic acetylcholine receptors. It is used in the treatment of various conditions, including nervous system disorders and glaucoma.
Prazosin: Prazosin is a medication that belongs to the class of drugs known as alpha-1 adrenergic antagonists. It is primarily used to treat hypertension (high blood pressure) and certain types of prostate disorders by blocking the effects of the neurotransmitter norepinephrine in the body.
Propranolol: Propranolol is a beta-adrenergic blocking agent, commonly known as a beta-blocker, that is primarily used to treat a variety of cardiovascular and neurological conditions. It works by blocking the effects of the neurotransmitter norepinephrine, which is responsible for the body\'s fight-or-flight response, making it a versatile medication with applications in the nervous system, migraine treatment, and cardiac dysrhythmia management.
Receptor Agonists: Receptor agonists are substances that bind to and activate specific receptors in the body, mimicking the effects of the natural ligand or neurotransmitter. They are an important class of drugs used to treat various nervous system disorders by modulating receptor activity and signaling pathways.
Receptor Antagonists: Receptor antagonists are a class of pharmacological agents that block or inhibit the binding and activation of specific receptors, preventing the normal physiological response to the endogenous or exogenous agonist. They are an important consideration in the treatment of nervous system disorders, as they can modulate neurotransmission and receptor-mediated signaling pathways in the brain and peripheral nervous system.
Salmeterol: Salmeterol is a long-acting beta-2 adrenergic agonist medication used primarily in the management of asthma and chronic obstructive pulmonary disease (COPD). It works by relaxing and dilating the airways, improving airflow and reducing symptoms associated with these respiratory conditions.
Schizophrenia: Schizophrenia is a severe and chronic mental disorder characterized by distortions in perception, thinking, emotions, language, sense of self, and behavior. It is a complex neurological condition that affects how a person thinks, feels, and behaves, often leading to a distorted perception of reality.
Schizophrenia in children: Schizophrenia in children is a severe mental disorder characterized by distorted thinking, hallucinations, and impaired functioning. It typically presents before the age of 13 and can significantly impact a child's development.
Scopolamine: Scopolamine is a tropane alkaloid compound derived from plants of the nightshade family. It is known for its potent anticholinergic effects, making it a valuable medication for treating nervous system disorders and managing nausea and vomiting.
Selective serotonin receptor agonists: Selective serotonin receptor agonists are drugs that specifically target and activate serotonin receptors in the brain to alleviate migraine headaches. They primarily work by narrowing blood vessels and reducing inflammation.
Serotonin: Serotonin is a neurotransmitter that plays a crucial role in regulating various physiological and psychological processes in the body. It is involved in the functioning of the nervous system, the regulation of mood, sleep, appetite, and other important bodily functions.
Sympathomimetic: Sympathomimetics are drugs that mimic the effects of the sympathetic nervous system by stimulating adrenergic receptors. They are used to treat conditions like asthma, hypotension, and anaphylaxis.
Synaptic Transmission: Synaptic transmission is the process by which an electrical or chemical signal is transmitted from one neuron to another across the synaptic cleft, the small gap between the presynaptic and postsynaptic neurons. This process is essential for the communication and integration of information within the nervous system.
Tamsulosin: Tamsulosin is a medication that belongs to the class of alpha-1 adrenergic receptor antagonists, commonly referred to as alpha blockers. It is primarily used to treat the symptoms of benign prostatic hyperplasia (BPH), a condition characterized by an enlarged prostate gland, as well as to facilitate the passage of kidney stones.
Varenicline: Varenicline is a prescription medication used to help people quit smoking. It works by partially activating the nicotine receptors in the brain, reducing cravings and withdrawal symptoms associated with nicotine addiction.