Presynaptic effects of toxins

Alan L. Harvey

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)


Toxins are natural products that have deleterious pharmacological actions. They come from plant, microbial, and animal sources and either are a byproduct of metabolism (e.g., many secondary plant metabolites) or have evolved for defense or predatory purposes (e.g., many snake-venom components). Neurotoxins are toxins that affect the nervous system. They include toxins that act on neurons directly and toxins that disturb communication between neurons and their target cells. Neurotoxins are very diverse chemically. They are among the most potent biologically active compounds known and are usually extremely specific in their actions. Hence, neurotoxins often find use as experimental tools. The nervous system controls many vital functions, and therefore its disturbance can have serious consequences. The majority of neurotoxins do not cross the blood–brain barrier but act on the peripheral nervous system. There are some notable exceptions, such as apamin and tetanus toxin, but usually special uptake mechanisms have to exist to allow neurotoxins to enter the brain or spinal cord. In the peripheral nervous system, toxins can affect the physiological functions of neurons themselves or interfere with the synaptic signaling processes. As the somatic nervous system is essential for the activation of respiratory muscles, most neurotoxins appear to affect its function rather than that of the autonomic nervous system, whose role is to modulate cardiovascular and digestive processes. Physiologically important targets for neurotoxins acting directly on neurons include the transmembrane ionic channels that are essential for action potential conduction and transmitter release. As synaptic transmission is a complex, energetically demanding process, it contains a large number of target sites on which neurotoxins might act. The prejunctional mechanisms include those controlling the synthesis, storage, and release of neurotransmitters. Toxins affecting presynaptic processes are discussed in the chapter.
Original languageEnglish
Pages (from-to)201-239
Number of pages39
JournalInternational Review of Neurobiology
Issue numberC
Publication statusPublished - 1 Jan 1990


  • alpha latrotoxin
  • botulinum toxin
  • bungarotoxin
  • calcium
  • fish venom
  • glycerotoxin
  • insect protein
  • ion channel
  • leptinotarsin protein
  • maitotoxin
  • neurotoxin
  • oxocin derivative
  • snake venom
  • spider venom
  • drug antagonism
  • drug effect
  • metabolism


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