More Bug Venom

Via Homely Scientist, I’m introduced to the shockingly large Vespa mandarinia (a.k.a. the Asian Giant Hornet, a.k.a. Japanese Hornet).

He quotes the wikipedia article on the species:

The venom contains 5% acetylcholine, a greater concentration than is present in bee or other wasp venoms. Acetylcholine stimulates the pain nerve fibres, intensifying the pain of the sting.

I haven’t seen anything anywhere that would corroborate that Acetylcholine stimulates pain receptors. Acetylcholine, like all the neurotransmitters, is used in a lot of different contexts, sometimes to contradictory effect (it’s not the transmitter; it’s the system), so it’s hard to pin down what it does. The only studies I’ve found suggest it actually increases pain thresholds, but that’s in a specific context. Interesting thing to me, though, is the further example of neurotransmitters appearing in venom.

Inflammation and Otherwise

Serotonin and dopamine are both found in the venoms of some scorpions and some centipedes.

Injected subcutaneously, as with a scorpion sting, the molecules are inflammatory.

Cannabinoids have an anti-inflammatory effect on the skin, as I cited in an earlier post.

Serotonin and dopamine are of course excitatory neurotransmitters.

Endocannabinoids serve to guide axons in the formation of new synapses.

I’m just saying.

Gut Flora, Mood, and Behavior

Speaking of things to eagerly await, in the first of a five-part series, Mike Johnson at Modern Dragons speculates about gut flora and their possible influence on human mood and behavior:

I think that’s probably the case and, getting further afield, what I’d like to do is attempt to look into whether the changes in gut ecosystems caused by changes in eating habits and food manufacturing trends- aggregated over the 300 million people who live in America- could contribute to a stochastic change in national character. Perhaps a significant contributing factor to some of our institutional ills is the food we eat, the corresponding imbalance in gut flora which arises from eating such food, and the subtle yet powerful-in-aggregate dysfunctional personality changes that e.g., biologically-active metabolites of such non-symbiotic gut flora might cause.

I sense some reader eyebrows being raised at this point– that bacteria could influence, let alone commonly influence, personality may seem quite a stretch. But consider the case of toxoplasma gondii (among other examples): it’s a protozoan parasite that spends part of its lifecycle in cats and part in other mammals, and shows clear signs of manipulating host behavior for its own ends. Infected rats, for instance, actually seek out the scent of cat urine, since when the rat gets eaten the toxoplasma can complete its lifecycle in the cat. What’s mind-boggling, though, is that humans who show tell-tale immunological signs of a past toxoplasma infection score statistically different on personality tests than do those who have not been infected (infected men tend to score higher in paranoia, whereas for women toxoplasmosis seems to lead to higher levels of social trust and sexual promiscuity).

Insects Share Some Neurotransmitters with Humans and Other Mammals

Kelley at Bugs for Thugs:

Do insects have the same kinds of neurotransmitters as humans do? A neurotransmitter is a chemical messenger that is released when a nerve impulse reaches the synapse. Yes insects have them and even more they have some of the same neurotransmitters as vertebrates do, such as serotonin, dopamine, and acetylcholine.

metabolic metaphor?

Just read an old post over at The Ethicurean about a talk given by Italian socialist food ethicist Carlo Petrini. I’m not going to weigh in on the larger issues covered by Mental Masala and Dairy Queen. I did want to comment on this idea:

Petrini used the metaphor of “metabolism” to explain the earth’s ecosystem: humans (and animals) eat food, digest it, transform it, make manure. The earth follows a reverse process, starting with manure and ending with food.

I agree with this characterization, save for one technical detail. It’s not a metaphor. It’s definitional. Plant and animal life evolved together and utilize one another. Elements are constantly cycling through the biosphere. The organisms which feast on our waste (and on our dead bodies, if we’d allow them to) return these elements to the soil, to be used by plants which we (or other animals, or plants) eat.

In pointing this out, I’m not trying to be pedantic. I think the distinction is important. “Metaphor” implies that metabolism is just one more way of looking at the issue, whereas it is the most accurate way.

VMAT2

Wikipedia:

The Vesicular Monoamine Transporter 2 or VMAT2 is an integral membrane protein that acts to transport monoamines—particularly neurotransmitters such as dopamine, norepinephrine and serotonin—from ceullular cytosol into synaptic vesicles.

Translation: The VMAT2 is permanently attached to the membrane of the neuron. It works to collect monoamine neurotransmitters from the interior fluid of the cell, concentrating them in the synaptic vesicles, where they await release into the synapse.

Whether or not the VMAT2 is an expression of the “God gene” (must I capitalize that?), and whether or not religious experiences have anything to do with adherence to bodies of faith, is something for others to discuss. I’m just putting this here for my later reference.

A Thought on Evolutionary Theory

One of the bad assumptions constantly made by people who theorize about the meaning of genetic traits is that this or that trait is “advantageous” in the abstract. Traits are advantageous in relation to a particular locality. If you carry an organism out of that locality, it may not fare as well. Likewise if the conditions to which the organism has adapted change. There is another assumption that if human beings (for example) have a particular trait, then the survivability of that trait has been decided. In other words, advantage is tied not only to a particular place, but a particular time within that place.

I’m a little spotty on how long, traditionally, evolution posits it takes for new traits to get selected out of a gene pool. I’m assuming that its different for different kinds of traits, ranging from single generations to millennia.

Weird

Attenuation of Allergic Contact Dermatitis Through the Endocannabinoid System

Allergic contact dermatitis affects about 5% of men and 11% of women in industrialized countries and is one of the leading causes for occupational diseases. In an animal model for cutaneous contact hypersensitivity, we show that mice lacking both known cannabinoid receptors display exacerbated allergic inflammation. In contrast, fatty acid amide hydrolase–deficient mice, which have increased levels of the endocannabinoid anandamide, displayed reduced allergic responses in the skin. Cannabinoid receptor antagonists exacerbated allergic inflammation, whereas receptor agonists attenuated inflammation. These results demonstrate a protective role of the endocannabinoid system in contact allergy in the skin and suggest a target for therapeutic intervention.

Viagra for Kids!

Just sounds so wrong. Undoubtedly, Pfizer will not be marketing sildenafil under the “Viagra” name for PHS.

Pesticides and Parkinson’s

I found this through The Michael J. Fox Foundation website.

Adjusted logistic regression analyses showed significantly increased odds ratios for Parkinson’s disease/parkinsonism with an exposure-response relationship for pesticides (low v no exposure, OR 1.13, 95% CI 0.82-1.57, high v no exposure, OR 1.41, 95% CI 1.06-1.88) and ever knocked unconscious (once v never, OR 1.35, 95% CI 1.09-1.68, more than once v never, OR 2.53, 95% CI 1.78-3.59). Hypnotic, anxiolytic or anti-depressant use for more than one year and a family history of Parkinson’s disease showed significantly increased odds ratios. Tobacco use was protective (OR 0.50, 95%CI 0.42-0.60). Analyses confined to subjects with Parkinson’s disease gave similar results. Conclusions The association of pesticide exposure with Parkinson’s disease suggests a causative role. Repeated traumatic loss of consciousness is associated with increased risk.

Emphasis mine.

It used to be the case that neurogenesis was assumed false. In reference to neurodegenerative diseases like Alzheimer’s and Parkinson’s, the question was “Why are the brain cells dying?” Now that neurogenesis is an established fact, we have to also ask, “Why aren’t these brain cells replenishing themselves?”