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Lecture

NEUR 2600 Lecture Notes - Tight Junction, Latrodectus, Pineal Gland

by

Department
Neuroscience
Course Code
NEUR 2600
Professor
Ian Whishaw

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Drugs can act as agonists, or antagonists (decreases)
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5 classes of drugs based on behavioural effects
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There is no one-to-one action of a drug as most have effects at many different kinds of synapses and these
diverse effects often account for the side effects of their actions.
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The route of administration
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Administration/elimination
Injecting a drug directlyi nto the brain allow it to act quickly in low doses because there are no barrier.
1.
2.
Drugs that are weak acids pass from the stomach into the bloodstream
3.
Drugs that are weak bases pass from the intestines to the bloodstream
4.
Drugs injected into muscle encounter more barriers than do drugs inhaled
5.
Drugs inhaled into the lungs encounter few barriers en route to the brain
6.
Drugs injected into the bloodstream encounter the fewest barrier to the brain but must be hydrophilic
7.
Drugs contained in adhesive patches are absorbed through the skin
8.
Trace amounts of common anti-anciesty drugs in rivers is altering the behaviors of unsuspecting fish
Ecoestrogens - feminizing males
Absence of lead in gas - reduced violent crime
Oral 1000 micograms
1.
Intraveneous 100
2.
CSF 10
3.
Neuron 1
4.
Amphetamine: route of administration determines dose required
The BBB tightly controls what is allowed into the brain and so resists many chemicals, drugs, etc
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The Blood-Brain Barrier
Capillaries in the body are leaky and have few tight junctions. Materials can move in and out relatively
easy
Capillaries in the brain are not leaky, have tight junction and are covered with astrocyte feet. These properties
prevent materials from moving in and out easily -> Basis of BBB
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Small uncharged molecules are able to pass through
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Certain other molecules are carried across the membrane by active transport
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Large and electrically charged molecules are unable to pass out of the capillary
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How it Works
Pineal gland: allows entry of chemicals that affect day-night cycles
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Pituitary: allows entry of chemicals that influence pituitary hormones
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Postrema (area): allows entry of toxic substances that induce vomiting
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3 Locations at which there is no BBB
The most useful classification system uses behavioral effects of drugs
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Drug Classification
Synthesis
1.
Storage
2.
Release
3.
Some can block release
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Receptor Interaction
4.
Some can block the receptor
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Inactivation
5.
Acetylcholine gets torn apart into acetyl and choline, but some drugs block that
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Reuptake
6.
Some can block reuptake
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Degradation
7.
Agonist or Antagonist
Agonist (+)
Antagonist (-)
Agonist: black widow spider venom promotes release of ACh
Antagonist: bolutin (food poisoning) toxin blocks release of ACh
Agonist: nicotine stimulates ACh receptors
Antagonist: curare (poisons animals) blocks ACh receptors
Agonist: Physostigmine and organophosphates block the inactivation of ACh
Choline-rich diet increases available acetylcholine (ACh)
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ACh - synapse (muscle-nicotinic)
General Anesthesia
Sleep
Sedation
Disinhibition
Relief from anxiety
Normal
Synapses - the site of drug action
February-15-13
11:00 AM
Brain and Behavior Page 1
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