Toxins

Question 1

Hexachlorophene

Answer 1

Germicide

Spongy degeneration of WM

Question 2

Penitrem A and roquefortin

Answer 2

Mycotoxins produced by penicillium app

Ataxia, tremors, staring

Question 3

Thallium

Answer 3

Heavy metal found in rodenticides that are banned from use

Seizures, dementia, hyperesthesia, tremors, ataxia, paraparesis or plegia

Question 4

Pyridoxine

Answer 4

Massive dose of vitamin B6

Sensory neuropathy- ataxia, dysmetria, decreases GP

Question 5

Vincristine

Answer 5

Alkaloid antineoplastic agent
Impairment of axonal transport due to breakdown of neurotubules
LMN paraplegia

Question 6

Salinomycin

Answer 6

Cats
Chicken feed ionosphere coccidiostat
Paresis, dysphasia, suspense, muscle atrophy

Question 7

Anatoxin-a

Answer 7

Blue green algae

Potent cholinergic agonist at nACh receptors and at the NMJ

Question 8

Anatoxin-a(s)

Answer 8

Naturally produced OP

Potent irreversible inhibitor of ACh

Question 9

Charatoxin

Answer 9

Green algae
Competitive antagonist at nACh receptor at high concentrations
Enhances ACh binding at low concentrations

Question 10

Aminoglycosides

Answer 10

Acute, reversible NMJ blockade mediated via calcium antagonism at external cell membrane channel site on pre and post synaptic membrane
Neomycin>kanamycin>amikacin>gentamicin>tobramycin

Question 11

Polymyxins

Answer 11

Microorganism derives polypeptides that disrupt the structure of cell membranes and are effective for g- bacteria
primary effect on postsynaptic membrane in nondepolarizing non competitive manner

Question 12

Tetracyclines

Answer 12

Proposed mechanisms for NMJ blockade include:
Chelation of serum calcium
Calcium antagonizing effects of the magnesium in the diluent
Post NMJ depression of muscle to the effect of ACh

Question 13

Ionophores

Answer 13

Most of the toxic effect is thought to be mediated by disrupting the normal ion gradient of cells
Lasalocid May induce changes in the membrane potential by influencing the permeability of nerve cell membranes to cations

Question 14

A-latrotoxin

Answer 14

Potent activation of neurotransmitter release and loss of synaptic vesicles followed by depletion of neurotransmitter and conduction block

Black widow spider

Question 15

Botulism

Answer 15

One of the most potent known toxins
Dogs - type C1
Blocks the release of ACh at the level
of the NMJ and at cholinergic autonomic synapses
Cleaves the proteins required for neurotransmitter exocytosis

Question 16

Tetrodotoxin

Answer 16

Selectively blocks the voltage gated Na conductance mechanism common to both nerve and muscle and this inhibits propagation of action potentials

Question 17

Curare class of NMJ blocking agents - membrane stabilizing NMJ blocking agents

Answer 17

Post synaptic binding to nicotine cholinergic receptor and competitively blocking the action of ACh
Atracurium, vecuronium

Question 18

Depolarizing NMJ blocking agents

Answer 18

Succinylcholine and decamthonium
Open ion channels similarly to ACh but the resultant depolarization in the end plate and adjacent area of the sarcoplasmic reticulum is persistent

Question 19

Ganglion blocking agents

Answer 19

Block postsynaptic ion channel

Hexamethonium and trimethaphan camsylate

Question 20

OP

Answer 20

Cholinergic syndrome - competitive and irreversible AChE inhibitors by binding to the enzyme esthetic site
OP-induced delayed polyneuropathy
Chronic encephalopathy

Question 21

Carbamate insecticides

Answer 21

Target AChE at Ps autonomic junctions, all ganglia and NMJs

Reversible bind AChE which allows dissociation to occur more readily facilitating reactivation of AChE activity

Question 22

Mojave rattlesnakes

Answer 22

Venoms A and B
Venom A (mojave toxin) acts as non competitive Ca2+ channel blocker blocking the release of ACh and causing presynaptic block

Question 23

SA rattlesnake

Answer 23

Crotoxin A and B
Toxin A potentiates toxicity of B
Crotoxin B blocks synaptic transmission by inhibiting the release of ACh

Question 24

Coral snake envenomation

Answer 24

Alpha neurotoxins

Curate-like syndrome resulting in blockade of the postsynaptic neuromuscular transmission

Question 25

Tick bite paralysis

Answer 25

Salivary neurotoxin Interferes with ACh release at the NMJ and/or propagation of the impulse along motor axon terminals D variabilis or andersoni I holocyclus

Question 26

Amphetamines

Answer 26

Monoamine release - competitive substrate for NE reuptake transporter and dopamine reuptake transporter Induces impulse independent release of cytosolic catecholamines

Question 27

Methylphenidate

Answer 27

Inhibits noradrenaline and dopamine reuptake at nerve terminus

Question 28

Caffeine

Answer 28

Exact MOA unknown May include phosphodiesterase inhibition, enhances catecholamine release, adenosine antagonism, or increased Ca entry into the cell

Question 29

Permethrin

Answer 29

Interference with Na channels, enhanced Na ion conductance, and post synaptic GABA receptor chloride ionophore complex blockade

Question 30

Cycad

Answer 30

BMAA - excitatory toxic MOA Prolonged depolarization, changes in intracellular calcium concentrations, and activation of enzymatic and nuclear mechanisms of cell death

Question 31

Moxidectin

Answer 31

Macrocyclic lactone | Binding GABA and glutamate gated chloride channels

Question 32

Barbiturates

Answer 32

Inhibiting calcium accumulation in neural tissue, inhibition of neurotransmitter release, GABA mimetic action within the CNS

Question 33

Avermectins

Answer 33

Macrocyclic lactone Agonist effects at GABA chloride channel - in CNS of mammals and PNS of invertebrates Potentiates synaptic GABA effects by enhancing its presynaptic release and enhancing the binding of GABA to postsynaptic receptors Collie - ABCB1

Question 34

Nicotine

Answer 34

Cholinergic receptor agonist that exhibits stimulant (low dose) and depressant (high dose) effects in PNS and CNS May increase circulating levels of cortisol and catecholamines Imidacloprid is a nicotine analogue

Question 35

Bromethalin

Answer 35

Effective uncoupled of oxidative phosphorylation | Results in inadequate ATP synthesis leading to decreases sodium and potassium ion channel pump activity

Question 36

Metronidazole

Answer 36

Binds to nRNA and inhibits protein synthesis thereby causing axonal degeneration

Question 37

Selegiline

Answer 37

Selective, irreversible inhibitor of MAO-B and acts centrally to increase dopamine concentrations

Question 38

Fluoxetine

Answer 38

SSRI- Serotonin syndrome from excessive serotonergic agonist on CNS and peripheral receptor neuromuscular hyperactivity Autonomic hyperactivity Altered mental status Cyproheptadine May reduce adverse effects

Question 39

Venlafaxine

Answer 39

Bicyclic antidepressant that acts as serotonin, NE, and dopamine reuptake inhibitor

Question 40

TCAs

Answer 40

Atropine-like anticholinergic effects | Inhibit biogenic amine (serotonin, NE) reuptake

Question 41

Metaldehyde

Answer 41

Decreased brain serotonin, GABA, and noradrenaline Systemic acidosis Important cause of seizures