Evolution and the cannabinoid receptor

[Deleted member 170540]

Most receptors that are found in humans are also known to be found in other animals, including even insects. For example, insects have a lot of cholinergic(nicotinic/muscarinic) receptors and are therefore especially sensitive to cholinesterase inhibitors like parathion, allowing the use of these compounds as insecticides.

However, the following study claims that cannabinoid receptors are not found in insects:

http://www.ncbi.nlm.nih.gov/pubmed/11447587

Cannabinoid receptors are absent in insects.

Abstract
The endocannabinoid system exerts an important neuromodulatory role in mammals. Knockout mice lacking cannabinoid (CB) receptors exhibit significant morbidity. The endocannabinoid system also appears to be phylogenetically ancient--it occurs in mammals, birds, amphibians, fish, sea urchins, leeches, mussels, and even the most primitive animal with a nerve network, the Hydra. The presence of CB receptors, however, has not been examined in terrestrial invertebrates (or any member of the Ecdysozoa). Surprisingly, we found no specific binding of the synthetic CB ligands [(3)H]CP55,940 and [(3)H]SR141716A in a panel of insects: Apis mellifera, Drosophila melanogaster, Gerris marginatus, Spodoptera frugiperda, and Zophobas atratus. A lack of functional CB receptors was confirmed by the inability of tetrahydrocannabinol (THC) and HU210 to activate G-proteins in insect tissues, utilizing a guanosine-5'-O-(3-[(35)]thio)-triphosphate (GTP gamma S) assay. No orthologs of human CB receptors were located in the Drosophila genome, nor did we find orthologs of fatty acid amide hydrolase. This loss of CB receptors appears to be unique in the field of comparative neurobiology. No other known mammalian neuroreceptor is understood to be missing in insects. We hypothesized that CB receptors were lost in insects because of a dearth of ligands; endogenous CB ligands are metabolites of arachidonic acid, and insects produce little or no arachidonic acid or endocannabinoid ligands, such as anandamide

According to this, it seems that the CB receptor is a very unique receptor... Anyone want to speculate about the reason for this? Why does the hemp plant produce a cannabinoid agonist (THC) if it's not to repel insects?

 

[23536]

There was a discussion of the evolutionary role of THC in http://www.bluelight.ru/vb/threads/520238-Evolution-of-drugs-in-plants

From having seen marijuana grow in woods and fields, it seems to me that a lot of animals are attracted to the plants (we had to piss on them to keep the deer away, for instance). If any of these animals are insectivores, the plant may benefit.

 

[Nagelfar]

According to this, it seems that the CB receptor is a very unique receptor... Anyone want to speculate about the reason for this? Why does the hemp plant produce a cannabinoid agonist (THC) if it's not to repel insects?

It only showed a panel of 5 insects in which the THC receptors were evolutionarily 'knocked out'. I'm sure it's use may still very well have been to repel insects. Family Hydridae after all, is more simplistic than & precursive to, insect types.

 

[Deleted member 170540]

The only other article I could find on the subject was this: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1088434/pdf/TB010381.pdf (full text).

It's surprising that there's no more research on this... It's interesting that the CB receptor is somehow 'special' in this respect.

 

[Chainer]

tagged... been interested in this since I first thought about it's evolutionary need to produce THC.

I have seen insects caught and die in the sticky tris of high THC% genetics. Much of the cannabis being studied now is high grade, which is not how it appears in nature at all, but is more engineered and tailored to turn out that way. Just thought that was some food for thought behind the studies.

The CB receptors we have interest me so much more since I learned we have naturally occurring action potential that binds... I wish I knew more about the neurochem that occurred, but thats off topic.

 

[Epsilon Alpha]

I had one prof's that argued that THC and all the associated phytochemicals were more for UV resistance, and another that argued that "if a deer ate a ounce no way in hell it can get away from a wolf".

Personally I think the truth is somewhere in the middle depending on the strain.

 

[Nagelfar]

It's surprising that there's no more research on this... It's interesting that the CB receptor is somehow 'special' in this respect.

Honestly, it may be more the 'insects' that are special than the CB receptor. In all likelihood, the insects lost the receptor as a way of overcoming cannabinoids effects on said insect varieties. That seems the most logical to me.