neurotoxicants Flashcards
Pyrethrins/Pyrethroids
Pyrethrins are derived from Chrysanthemum flowers
Pyrethroids are synthetic analogues
Na+ causes neurons to depolarize (fire) > neuronal excitation >
Type I vs type II pyrethrin toxicity
type I: nervous system stimulation
* Tremor syndrome
type II: Suppression of action potential and reduced ability of the nerve to fire
* Choreoathetosis/salivation syndrome
Which animals are sensitive to pyrethrins?
Cats are very sensitive to concentrated pyrethrin products > permethrin
fish and reptiles
Organophosphate and carbamate mechanism of action
insecticides inhibit the enzyme acetylcholinesterase
excessive stimulation of muscarinic, nicotinic and CNS cholinergic receptors
* Parasympathetic pathway overstimulation
* Sympathetic pathway stimulation
* CNS
organophosphate and carbamate toxicity signs
“SLUDDE” Signs (parasympathetic MUSCARINIC overstimulation)
S alivation
L acrimation
U rination
D efecation (GI hypermotility, diarrhea)
D yspnea (Bronchial secretions and constriction)
E mesis
Nicotinic Acetylcholine Receptor Overstimulation:
* Stimulatory Phase: Muscle fasciculations & tremors initially, Muscle stiffness
* After Stimulatory Phase: Followed by flaccid paralysis > weakness due to muscle fatigue
ANTIDOTE for organophosphate and carbamate toxicity
MUSCARINIC SIGNS =Atropine Sulfate (Antidote!)
Non-competitive antagonist that blocks muscarinic receptors from acetylcholine overstimulation
No effect on nicotinic acetycholine receptors
Selective Serotonin Reuptake Inhibitors (SSRIs) mechanism
Block reuptake of serotonin > build-up of serotonin at presynaptic membrane
Clinical Signs of “Serotonin Syndrome”
Agitation, tremors, seizures, hyperactive
Hyperthermia
Mydriasis
Vomiting/diarrhea
Hypersalivation
Tachycardia, hypertension
Hyperventilation
antidote for “serotonin syndrome”
Acepromazine/Chlorpromazine
* Blocks serotonin and dopamine receptors
Cyproheptadine
* Serotonin antagonist
Sources of Tremorigenic Mycotoxins
Ingestion of moldy food or decomposing organic matter
Dairy foods, walnuts/peanuts, spaghetti, compost
2 most common mycotoxins
Penitrem A – produced by Penicillium crustosum
Roquefortine – produced by Penicillium roqueforti
clinical signs of Tremorigenic Mycotoxins
30 minutes to 3 hours post-ingestion
- Tremors, seizures
- Ataxia
- Tachycardia
- Vomiting
- Hyperthermia
- Depression
- Hyperexcitability
- Hypersalivation
why medical edibles (“medibles”) and medical cannabis pose more of a risk for toxicity
higher concentrations of THC
how marijuana causes nervous system depression
Increases gamma-amino-butyric acid (GABA) causing CNS depression
