Is imidacloprid a cholinesterase inhibitor?

Is imidacloprid a cholinesterase inhibitor?

The simple answer to this is yes, and anyone familiar with biology can go ahead and read:

Wikipedia link

For those of you who have no idea what a cholinesterase is, let alone it’s inhibitor is or what imidacloprid is, I will break down the essential parts below.

Acetylcholine is in a group of chemicals called neurotransmitters. Other neurotransmitters include:

Epinephrine (Adrenaline)

Norepinephrine (simmilar to adrenaline, but with profound differences of effect)

Dopamine and Serotonin


Some Amino Acids, and some proteins

Some Cannabinoids

Acetylcholine is one of the most frequently used in nature, particularly in lower life forms, such as insects. The Primary one’s used in higher vertabrates bodies are Acetylcholine, and Epinephrine and Norepinephrine, but they all have simmilar effects of either initiating a new nerve impulse, carrying on one previously started, modifying the effect of a potential impulse, or inhibiting one.

Neurotransmitters aide in carrying a nerve impulse’s signal to another nerve cell. As an electrical signal (technically a salt signal, due to it’s very very low electrical activity, millivolts (a thousanth of a volt) or less) passes down the axon (the area of the nerve cell which extends to another area of the body) it reaches the synaptic cleft, the area where two nerve cells join. Here, saltatory conduction cannot occur, and the signal needs to be transduced (changed) into another form. When the impulse arrives at the end of the cell axon, vesicles (small storage units within cells) fuse with the outer membrane, and release the neurotransmitter. This diffuses across to the other cell, where it joins with a receptor molecule. This can have a variety of effects:

opening ion channels, which allow a transfer of salts across the cell membrane, and a new signal is started down the next cell

second messanger activating which causes the cell to react differently next time, or even forever/until a new message is received

This last one can have a very large volume of effects, and I will not go into the details of this, as I did it for a piece of coursework for university. And I can tell you it was not simple…. At all… I think I’ve still got the headache.

But the first is the main action which sends a signal from your brain, to other parts of your body. When the signal is received to open the ion channels, Calcium ions (charged calcium ions, ie. less two electrons) are allowed to enter the cell. This has two effects. Firstly it opens further ion channels, which allow the salts to move about creating the “charge” we are familiar with being a nerve impulse, and it also gives proteins used in resetting it back to square one (resting membrane potential) the green light. These prepare to shift the salts back to their origional position. So in one swift motion, an action potential (nerve impulse) is both started, and stopped.

Now back to (part of) the origional question. A cholinesterase is an enzyme which breaks down acetylcholine into acetic acid and choline. The acetic acid is bound to Co-Enzyme A and then degraded. Choline is taken back up (in the vesicles) so that Acetylcholine can be remanufactured. This is a very important enzyme, as without it’s use, nerve impulses would not stop, and a state of paralysis, and even death can occur. Therefore inhibitors of cholinesterase have been used in biological warefare, including (most prominently) nerve gases. Imidacloprid is an example of a cholinesterase inhibitor, and is used extensively as a pesticide, and has not been shown to effect larger vertabrates, although this does not mean they do not effect us. The quantities used in insecticides are low, and due to invertabrate’s high reliance on acytylcholine nerve impulse transmition, they are very effective. We as humans do not soley use Acetylcholine neurotransmitters, so are more immune to short term, low doeses. If Imidacloprid is being used in your area, and you are worried about it’s effects, you can contact your local authority for advice on the amounts used, and when spraying is occuring. If needed, avoid the area while spraying is going on, and for a day or two after, although it should not pose a health risk.