Click here to load reader

A Small Dose of ™ Neurotoxicity

  • View
    40

  • Download
    0

Embed Size (px)

DESCRIPTION

A Small Dose of ™ Neurotoxicity. An Introduction to Toxicology of the Nervous System. “You cannot reach your full genetic potential with a damaged nervous system.” S.G. Gilbert. Introduction. What is Neurotoxicity?. - PowerPoint PPT Presentation

Text of A Small Dose of ™ Neurotoxicity

PowerPoint PresentationAn Introduction to Toxicology of the Nervous System
A Small Dose of Toxicology - Overview
Intro Neurotoxicity – 5/7/04
Introduction
“You cannot reach your full genetic potential with a damaged nervous system.”
S.G. Gilbert
Intro Neurotoxicity – 5/7/04
A Small Dose of Toxicology
An adverse change in the chemistry, structure or function of the nervous system during development or at maturity, following exposure to a chemical or physical agent.
What is Neurotoxicity?
Intro Neurotoxicity – 5/7/04
A Small Dose of Toxicology
Even minor changes in the structure or function of the nervous system may have profound consequences for neurological, behavioral, and related body functions.
Nervous System Sensitivity
Intro Neurotoxicity – 5/7/04
Ancient Awareness
Dioscorides - GREEK 2ND BC
Intro Neurotoxicity – 5/7/04
A Small Dose of Toxicology
“The upsurge of interest in recent years in academia, industry, and government on the effects of toxic chemicals on the nervous system has created a new discipline of neurotoxicology.”
Peter S. Spencer & Herbert H. Schaumberg, in Experimental and Clinical Neurotoxicology, 1980
Current Awareness
Intro Neurotoxicity – 5/7/04
1930’s – Ginger-Jake Syndrome
During prohibition, an alcohol beverage was contaminated with TOCP (triorthocresyl phosphate) causing paralysis in 5,000 with 20,000 to 100,000 affected.
1950’s – Mercury poisoning
Methylmercury in fish cause death and sever nervous system damage in infants and adults.
Historical Events
Intro Neurotoxicity – 5/7/04
Case Studies
Intro Neurotoxicity – 5/7/04
Lead In Homes
Intro Neurotoxicity – 5/7/04
Nervous Systems Effects
Intro Neurotoxicity – 5/7/04
Alcohol (ethanol)
Intro Neurotoxicity – 5/7/04
FAS – Fetal Alcohol Syndrome
FAE – Fetal Alcohol Effects
Alcohol
Intro Neurotoxicity – 5/7/04
Effects of Prenatal Alcohol
FAS Child
MPTP
1-methyl-4-phenyl-1,2,3,6-tetrahydrophyridine
N
CH3
Intro Neurotoxicity – 5/7/04
1980s – Designer Drug
Damaged neurons that secrete dopamine
MPTP Effects
Intro Neurotoxicity – 5/7/04
CNS – Central Nervous System
PNS – Peripheral Nervous System
Nervous System Biology
Intro Neurotoxicity – 5/7/04
Nervous System – CNS & PNS
Central Nervous System (CNS)
A Small Dose of Toxicology - Overview
Intro Neurotoxicity – 5/7/04
Nervous System
Nervous System
Central Nervous System
Efferent (motor) Nerves
Intro Neurotoxicity – 5/7/04
Peripheral Nervous System
Somatic Nervous System
Stimulates Skeletal muscles
Autonomic Nervous System
Sympathetic
Intro Neurotoxicity – 5/7/04
Neurons
Oligodendrocytes (CNS – link cells)
A Small Dose of Toxicology - Overview
Intro Neurotoxicity – 5/7/04
Blood-brain Barrier
Anatomic Characteristics
Capillary endothelial cells are tightly joined – no pores between cells
Capillaries in CNS surrounded by astrocytes
Low protein concentration in CNS fluid
Active ATP-dependent transporter – moves chemicals into the blood
A Small Dose of Toxicology - Overview
Intro Neurotoxicity – 5/7/04
Neuronal Cells
Intro Neurotoxicity – 5/7/04
Dopamine
Neuronal Transmission
Intro Neurotoxicity – 5/7/04
Inhalation (e.g. solvents, nicotine)
Ingestions (e.g. lead, alcohol)
Skin (e.g. pesticides, nicotine)
Physical (e.g. load noise)
Intro Neurotoxicity – 5/7/04
What causes neurotoxicity?
A Small Dose of Toxicology - Overview
Intro Neurotoxicity – 5/7/04
Types Of Neurotoxicity
MPTP, Trimethytin
Lead, Hexachlorophene
Transmission Toxicity
Intro Neurotoxicity – 5/7/04
Neurotoxic Injury
Intro Neurotoxicity – 5/7/04
Examples of Neurotoxicology
Cognitive Effects
Classification of neurotoxicants by mechanism of action
Temporary inhibition of nerve function
Agents which alter membrane function
Agents with interfere with synaptic transmission
Intro Neurotoxicity – 5/7/04
Dependence on oxygen
Little anaerobic capacity
Dependence on glucose
Sole energy source
High metabolic rate
Intro Neurotoxicity – 5/7/04
Structure
Blood-Brain Barrier
Developmental stage
Intro Neurotoxicity – 5/7/04
Neurons CANNOT divide and replace themselves
Neurons CAN repair limited axonal damage
Most Recovery
Intro Neurotoxicity – 5/7/04
Classification of neurotoxicants by mechanism of action
Permanent inhibition of nerve function
Agents which cause Anoxia
Oligodendroglia (CNS)
Agents which damage nerve cell body
Agents which cause localized CNS lesions
Intro Neurotoxicity – 5/7/04
Neurological and Behavioral Effects of Exposure to Toxic Substances
Motor Effects - Convulsions, weakness, tremor, twitching, lack of coordination, unsteadiness, paralysis, reflex abnormalities, activity changes
Sensory Effects - Equilibrium changes, vision disorders, pain disorders, tactile disorders, auditory disorders
Cognitive Effects - Memory problems, confusion, speech impairment, learning impairment
Mood and personality effects - Sleep disturbances, excitability, depression, irritability, restlessness, nervousness, tension, delirium, hallucinations
General effects - Loss of appetite, depression of neuronal activity, narcosis stupor, fatigue, nerve damage
Intro Neurotoxicity – 5/7/04
Receptor
Ligand
Toxicant
1
Toxicant
inactivates
receptor
Intro Neurotoxicity – 5/7/04
Toxicant
1
Who Is Vulnerable?
Young or Old
Male or Female
Genetics - Individual Diff.
Intro Neurotoxicity – 5/7/04
Fetal Nervous System
Developing Nervous System
Mature Nervous System
Aging Nervous System
Intro Neurotoxicity – 5/7/04
A Small Dose of Toxicology - Overview
Intro Neurotoxicity – 5/7/04
Additional Information
Web Sites
Natural Resources Defense Council (NRDC). Online. Available HTTP: <http://www.nrdc.org/health/kids/cfqpa0599.asp> (accessed: 10 April 2003). NRDC site provides information on children’s health and neurotoxicology.
Other Chapters
Intro Neurotoxicity – 5/7/04
Authorship Information
E-mail: [email protected]
Web: www.asmalldoseof.org
A Small Dose of Toxicology - Overview