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In the comments here, rosko points me to a study on the effects on MC4R, a gene implicated in natural variation in human weight, on pathways involved in sexual function. It’s well known, of course, that genetic pathways can be involved in multiple physiological processes–in particular, signaling pathway can generate many different phenotypes depending on what the downstream target of the signal is.
The effects of MC4R simulation in humans are, as rosko comments, kind of interesting:
Methods. Ten subjects were enrolled in a double-blind, placebo-controlled, crossover study. Melanotan II (0.025 mg/kg) and vehicle were each administered twice by subcutaneous injection; real-time RigiScan monitoring and a visual analog were used to quantify the erections during a 6-hour period. The level of sexual desire and side effects were recorded with a questionnaire.
Results. Melanotan II initiated subjectively reported erections in 12 of 19 injections versus only 1 of 21 doses of placebo. The mean rigidity score of the responders was 6.9 on a scale of 0 to 10. The mean duration of tip rigidity greater than 80% was 45.3 minutes with Melanotan II versus 1.9 for placebo (P = 0.047). The level of sexual desire after injection was significantly higher after Melanotan II administration than after placebo. Nausea and stretching/yawning occurred more frequently with Melanotan II, and 4 of 19 injections were associated with severe nausea.
I wondered what a “Rigiscan” is–find out here. Hypothetically, one could test whether natural variation in sexual behavior in humans is also affected by MC4R polymorphism, though I can’t imagine that being a particularly fun study to carry out (one for agnostic’s new series? 23andme + free time = association studies about erections).
This reminds of the MC1R story about increased pain sensitivity in redheads in the vague sense that both involve melanocortin receptors and pleiotropy.
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testosterone also can tweak around with melanin production….
stosterone+melanin+&hl=en&lr=&btnG=Search
http://scholar.google.com/scholar?q=te
wouldn’t be surprising if there was feedback in other directions.
You don’t see much pattern formation in human skin color, not like spots or stripes. But the region near and including your junk is darker, and that’s obviously not due to suntanning.
The naive guess is an activator-inhibitor system like what’s been proposed for animal coat patterns: testosterone and/or melanin being the activators, and something else that inhibits them and which diffuses over a wider range of the body than T or M. I clicked on that Google scholar link, but do people know much about the larger network that T and M are a part of?
And dude, that 23andme site is totally geared toward females — is that who the market is?
“What do your genes say about you?” — appealing to chick crack like palm reading and horoscopes, but at least it’s more real.
“Do you have your mother’s sense of taste?” — why is it the mother, and who cares about sense of taste?
And the website has the word “me” in it.
I wonder how long it took industry to figure out they should market it toward females. “Give us some simple information, and we’ll tell you all about yourself, your past, and what the future holds in store for you.”
“Do you have your mother’s sense of taste?” — why is it the mother, and who cares about sense of taste?
http://www.gnxp.com/MT2/archives/003665.html
You don’t see much pattern formation in human skin color, not like spots or stripes
True, but wouldn´t it be mighty fantastic? You have just given a great idea to sci fi writers, and I am sure The Next Generation will feature striped, spotted, etc. humanoids of many colors.
Once the molecular mechanism is known, it could be commercial success ! I for one want to be phosphorescent green !
Yeah, but I mean why did they pick a trait that would focus on mothers — why not something that related to fathers? And again, why taste instead of myostatin or something?
Is melanotan II generally safe? I’ve been considering trying it for a while now, being an mc1r mutant and outdoors lover.
You have just given a great idea to sci fi writers, and I am sure The Next Generation will feature striped, spotted, etc. humanoids of many colors.
A colleague of mine has considered how things might be if tyrosinase were encoded by a gene on the human X chromosome. Think pinto ponies.
More: http://dx.doi.org/10.1016/j.pharmthera.2005.06.022
Anecdotally I’ve found that redheads tend to have a higher incidence of asthma, though I haven’t been able to find any epidemiological studies looking for a connection. It makes sense though, given the role MSH plays in modulating inflammatory response.
Is melanotan II generally safe? I’ve been considering trying it for a while now, being an mc1r mutant and outdoors lover.
People experiment with it and discuss their results at melanotan.org.
I use sunless tanning lotion, and recommend Coppertone’s brand in dark. It doesn’t give sun protection, though.