On 27 March, 1998, Sildenafil (compound UK-92,480) was approved for use in erectile dysfunction by the US Food and Drug Administration. You might giggle, but this drug, more commonly known as Viagra, serves a very important function which is not even mentioned in all the pharmaceutical spam.
Mammalian circadian rhythms are generated by a master clock located in the suprachiasmatic nuclei and entrained by light-activated signaling pathways. In hamsters, the mechanism responsible for light-induced phase advances involves the activation of guanylyl cyclase, cGMP and its related kinase (PKG). It is not completely known whether interference with this pathway affects entrainment of the clock, including adaptation to changing light schedules. Here we report that cGMP-specific phosphodiesterase 5 is present in the hamster suprachiasmatic nuclei, and administration of the inhibitor sildenafil (3.5 mg/kg, i.p.) enhances circadian responses to light and decreases the amount of time necessary for reentrainment after phase advances of the light–dark cycle. These results suggest that sildenafil may be useful for treatment of circadian adaptation to environmental changes, including transmeridian eastbound flight schedules.
What does this mean? Simply put, the study discovered that Viagra helps hamsters to recover from jet lag more easily. Isn’t that wonderful? And aren’t you glad that I’m around to find these things out for you?
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It’s easy to take part!
1) Take a photo on a Saturday and upload it to a site like Flickr or Fotonomy
2) Twitter the url for your photograph to @SatScenes
3) Watch for the next post on Saturday Scenes to see a fun set of all the photographs together.
I’m looking forward to seeing your scenes next Saturday!