Neuropharm

• Neuropharmacology


  The study of drugs that alter processes controlled by the nervous system
• Conditions treated by neuropharmacologic drugs

  • Depression
  • Epilepsy
  • Hypertension
  • Asthma
• Categories of neuropharmacologic agents

  • Peripheral nervous system drugs
  • Central nervous system drugs
• Processes modified by neuropharmacologic drugs

  • Skeletal muscle contraction
  • Cardiac output
  • Vascular tone
  • Respiration
  • Gastrointestinal function
  • Uterine motility
  • Glandular secretion
  • Ideation, mood, and perception of pain
• Axon Conduction

  Process of conducting an AP down the axon of the neurons
• Synaptic Transmission


  Information is carried across the gap between the neuron and the postsynaptic cell
• Postsynaptic Cell


  Another neuron, muscle, or cell within a secretory gland
• Steps in synaptic transmission

  1. Transmitter synthesis

  2. Transmitter storage

  3. Transmitter release

  4. Receptor Binding

  5. Termination of transmission
• Transmitter synthesis


  Molecules of transmitter must be present
• Transmitter storage


  • Transmitter synthesized → stored until time of release
  • Takes place in vesicles at axon terminal
• Transmitter release


  Arrival of AP → vesicles fuse with terminal → release transmitter into synaptic gap
• Receptor Binding


  Transmitter moles diffuse across synaptic gap → reversible binding postsynaptic cell receptors → initiates cascade of events in altered behavior of postsynaptic cell
• Termination of transmission


  • Dissociation of transmitter from receptors & removal of free transmitter from synaptic gap
  • Removed from synaptic gap by re-uptake, enzymatic degradation, and diffusion
• Effects of drugs on the steps of synaptic transmission

  • Type or types of receptors through drug acts
  • Normal responses to activation of receptors
  • Drug does to the receptor
• Selectivity


  • Most desirable quality a drug can have
  • Able to alter a disease process while leaving other physiologic processes largely unaffected
  • Increased selectivity → different receptor types
• Divisions of the nervous system

  • Central nervous system
  • Peripheral nervous system
• Components of the peripheral nervous system

  • Somatic motor system
  • Autonomic nervous system
• Divisions of the autonomic nervous system

  • Parasympathetic
  • Sympathetic
• Functions of the autonomic nervous system


  • Regulates the heart
  • Regulates secretory glands
  • Regulate the smooth muscle
• Functions of the parasympathetic nervous system

  • Decreases heart rate
  • Increases gastric secretions
  • Empties bladder and bowel
  • Focuses eye for near vision
  • Constricts the pupil
  • Contracts bronchial smooth muscle
• Effects of parasympathetic nervous system drugs

  • Digestion of food
  • Excretion of waste
  • Control of vision
  • Conservation of energy
• Functions of the sympathetic nervous system

  • Regulates the cardiovascular system
  • Regulation of body temperature
• Effects of sympathetic nervous system drugs

  • Heart and blood vessels
  • Lungs
• Dual innervation opposed


  Heart rate
• Dual innervation complementary


  Erection and ejaculation
• One division innervation


  Blood vessels
• Feedback regulation


  • Adjust itself by responding to incoming information
  • Sensor, effector, and neurons connecting the sensor to effector
  • Reflex - adjustment of a physiologic process by the CNS
• Baroreceptor Reflex


  Receptors near heart monitor BP changes → send info to brain → activates ANS → restore BP to normal
• Autonomic tone


  Basal control of over which the reflex regulation is super imposed

  steady day-to-day influence exerted by the ANS on a organ or system

  only one division provides basal control of the organ

  predominant tone - PNS

  vascular - SNS
• Neurons of the autonomic nervous system

  • Preganglionic neurons
  • Postganglionic neurons
• Medulla of the adrenal gland


  Functional equivalent of the postganglionic SNS neuron

  only feature of the SNS
• Sites of action of neuropharmacologic drugs

  • Synapses: Preganglionic/postganglionic
  • Junction: Postganglionic neurons/effector organs
• Somatic Motor System


  One neuron lies in the pathway from the spinal cord to the muscles innervated by the somatic motor nerves
• Neurotransmitters


  • Acetylcholine
  • Norepinephrine
  • Epinephrine
• Receptor types of the peripheral nervous system

  • Cholinergic
  • Adrenergic
• Cholinergic receptor subtypes


  • Nicotinic N
  • Nicotinic M
  • Muscarinic
• Adrenergic receptor subtypes


  • Alpha1
  • Alpha2
  • Beta1
  • Beta2
  • Dopamine
• Receptor subtype


  • Peripheral receptors that respond to acetylcholine
  • Receptors at ganglia, neuromuscular junctions, and organs regulated by parasympathetic nervous system
  • All cholinergic but sufficiently different to constitute distinct receptor subtypes
• Receptor subtype identification


  • Previous studies of skeletal muscle and ciliary muscle
  • Current technology: Cloning receptors with the use of DNA sequencing
• Receptor subtype selectivity


  Synthesizing chemicals structurally related to natural transmitters to produce more selective drugs for specific receptor subtypes