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Understanding CNS Stimulants in Neuropharmacology

Learn about CNS stimulant drugs affecting the nervous system's central and peripheral divisions, neuronal synapse, neurotransmitters, and lab work with mice. Discover the mechanisms of action, signs, symptoms, and adverse effects of amphetamines, picrotoxin, and strychnine.

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Understanding CNS Stimulants in Neuropharmacology

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  1. PHL. 322 Presented by Dr. Khairy M A Zoheir

  2. I- CNS Stimulants Drugs

  3. Nervous System • The nervous system can be classified into • The Central Nervous System (CNS) Brain and spinal cord • The Peripheral Nervous System (PNS(The nervous system outside of the brain and spinal cord

  4. Peripheral Nervous System PNS Can be divided into- 1- Sensory division(affrent) Conducts impulses from receptors to the CNS and Informs the CNS of the state of the body 2- Motor division(effrent) Conducts impulses from CNS to effectors organs.

  5. Motor Neurons • The motor division is also divided into • 1- The somatic nervous system : • VOLUNTARY (generally) Somatic nerve fibers that conduct impulses from the CNS to skeletal muscles • 2. The autonomic nervous system: INVOLUNTARY (generally) Conducts impulses from the CNS to smooth muscle, cardiac muscle, and glands

  6. Neurons • They are the basic functional unit of the nervous system. • They contain three major parts: • 1.cell body. • 2. dendrites. • 3. axon.

  7. Structure

  8. Neurotransmitters CNS • They can be classified into : • 1. Exitatory: • - Ach, glutamate, aspartate , serotonin and NE. • 2. Inhibitory:- • - GABA , glycin .

  9. CNS Stimulants • Defination “Stimulants are a substance which tends to increase behavioral activity when administered”

  10. Signs and symptoms: • 1- Elevate Mood • 2- Increase Motor Activity • 3- Increase Alertness • 4- Decrease need for Sleep • In case of overdose lead to convulsion and death.

  11. MOA of CNS Stimulants • 1- Block neurotransmitters reuptake (Most reuptake inhibitors affect either NE or 5-HT(Serotonin) : Cocaine • 2- Promote neurotransmitters release : Amphetamine • 3- Block Metabolism - MAO inhibitors (monoamine oxidase):ex. Phenelzine • 4. antagonize the effect of inhibitory neurotransmitter: Picrotoxin & Strychnine

  12. Neuronal Synapse

  13. Neuronal Synapse

  14. CNS Stimulants • - They can be divided based on their site of action: • 1.Cerebral stimulants (amphetamines) • 2.Medullary stimulants (picrotoxin) • 3.Spinal stimulants (strychnine)

  15. Lab Work • - Objectives: • 1- To demonstrate effects of some CNS stimulant on mice. • 2- After the lab, you should able to handle and inject the mice correctly. • 3- You should able to differentiate between amphetamine,picrotoxin and strychinine regarding the symptoms that induced by each of them.

  16. 1- Amphetamine • MOAs : • Block the reuptake of norepinephrine and dopamine into the presynaptic neuron and increase the release of these monoamines into the extraneuronal space. - Clinical use: • 1. Narcolepsy. • 2. Attention-deficit hyperactivity disorder

  17. Amphetamine • Adverse effects: • - Cardiovascular: Hypertension (7% to 22%, pediatric ) • - Endocrine metabolic: Weight loss (4% to 9%, pediatric; 11%, adults ) • - Gastrointestinal: Abdominal pain (11% to 14%, pediatrics ), Loss of appetite (22% to 36%), Xerostomia (35% ) • - Neurologic: Headache (26% ), Insomnia ارق (12% to 17%, pediatric; 27%, adults ) • - Psychiatric: Feeling nervous (6% )

  18. Amphetamine • After injecting, the mice with amphetamine you well notice:- Hair erection • - Licking, gnawing. • - Stereotype • - Sniffing

  19. Picrotoxin • MOA: • Non-competitive antagonist of GABA receptors. • After injecting the mice with picrotoxin you wellnotice:- Clonic convulsion characterized by : • 1. Asymmetric • 2. Intermittent • 3. Spontaneous • 4. Coordinated

  20. Strychinine • MOA: • Competitive antagonist of the glycin receptors. • After injecting the mice with Strychinine you well • notice:- Tonic convulsion characterizedby : • 1. Symmetric • 2. Reflex in origin • 3. Continuous • 4. Uncoordinated.

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