Why Does Weed Make You Hungry?

If you’ve ever smoked weed, chances are you've felt pretty hungry afterwards. Maybe you even said, “I’m starving” as you plowed through a Nachos BellGrande, a Quesarito Combo, and a Crunchwrap Supreme.

Well, you were right—you were starving. Or at least, your body thought you were. And that's because of tetrahydrocannabinol, also known as THC, which is the main psychoactive component in marijuana.

A 2015 study conducted on mice by researchers at the Yale School of Medicine found that THC flipped a switch in the rodents' brain circuitry, making them feel hungry rather than full.

“By observing how the appetite center of the brain responds to marijuana, we were able to see what drives the hunger brought about by cannabis and how that same mechanism that normally turns off feeding becomes a driver of eating,” said Tamas Horvath, the study's lead author.

“It’s like pressing a car’s brakes and accelerating instead,” Horvath explained. “We were surprised to find that the neurons we thought were responsible for shutting down eating, were suddenly being activated and promoting hunger, even when you are full. It fools the brain’s central feeding system.”

Assuming that THC has a similar effect on humans, it's easy to understand how smoking weed would produce insatiable cravings for anything and everything.

But that’s not the only science at work when it comes to getting the munchies: THC also binds to cannabinoid receptors known as CB1s in the brain's olfactory bulb, making food aromas more intense, which increases your perception of flavor. So not only are you convinced that you’re ravenous, but things smell and taste better than they do when you’re not high, which is kind of a double whammy.

While this all may be a little annoying if you’re trying to cut back on your fast-food intake, the link between hunger and THC is potentially great news for people who have trouble eating due to illness or other medical reasons. For instance, marijuana has been shown to be an effective appetite stimulant in cancer patients. If researchers know exactly what causes that appetite surge, they may be able to use the munchies to benefit those who need it.

A Simple Skin Swab Could Soon Identify People at Risk for Parkinson's

iStock.com/stevanovicigor
iStock.com/stevanovicigor

More than 200 years have passed since physician James Parkinson first identified the degenerative neurological disorder that bears his name. Over five million people worldwide suffer from Parkinson’s disease, a neurological condition characterized by muscle tremors and other symptoms. Diagnosis is based on those symptoms rather than blood tests, brain imaging, or any other laboratory evidence.

Now, science may be close to a simple and non-invasive method for diagnosing the disease based on a waxy substance called sebum, which people secrete through their skin. And it’s thanks to a woman with the unique ability to sniff out differences in the sebum of those with Parkinson's—years before a diagnosis can be made.

The Guardian describes how researchers at the University of Manchester partnered with a nurse named Joy Milne, a "super smeller" who can detect a unique odor emanating from Parkinson's patients that is unnoticeable to most people. Working with Tilo Kunath, a neurobiologist at Edinburgh University, Milne and the researchers pinpointed the strongest odor coming from the patients' upper backs, where sebum-emitting pores are concentrated.

For a new study in the journal ACS Central Science, the researchers analyzed skin swabs from 64 Parkinson's and non-Parkinson's subjects and found that three substances—eicosane, hippuric acid, and octadecanal—were present in higher concentrations in the Parkinson’s patients. One substance, perillic aldehyde, was lower. Milne confirmed that these swabs bore the distinct, musky odor associated with Parkinson’s patients.

Researchers also found no difference between patients who took drugs to control symptoms and those who did not, meaning that drug metabolites had no influence on the odor or compounds.

The next step will be to swab a a much larger cohort of Parkinson’s patients and healthy volunteers to see if the results are consistent and reliable. If these compounds are able to accurately identify Parkinson’s, researchers are optimistic that it could lead to earlier diagnosis and more effective interventions.

[h/t The Guardian]

World’s Oldest Stored Sperm Has Produced Some Healthy Baby Sheep

A stock photo of a lamb
A stock photo of a lamb
iStock.com/ananaline

It’s not every day that you stumble across a 50-year-old batch of frozen sheep sperm. So when Australian researchers rediscovered a wriggly little time capsule that had been left behind by an earlier researcher, they did the obvious: they tried to create some lambs. As Smithsonian reports, they pulled it off, too.

The semen, which came from several prize rams, had been frozen in 1968 by Dr. Steve Salamon, a sheep researcher from the University of Sydney. After bringing the sample out of storage, researchers thawed it out and conducted a few lab tests. They determined that its viability and DNA integrity were still intact, so they decided to put it to the ultimate test: Would it get a sheep pregnant? The sperm was artificially inseminated into 56 Merino ewes, and lo and behold, 34 of them became pregnant and gave birth to healthy lambs.

Of course, this experiment wasn’t just for fun. They wanted to test whether decades-old sperm—frozen in liquid nitrogen at -320°F—would still be viable for breeding purposes. Remarkably, the older sperm had a slightly higher pregnancy rate (61 percent) than sheep sperm that had been frozen for 12 months and used to impregnate ewes in a different experiment (in that case, the success rate was 59 percent).

“We believe this is the oldest viable stored semen of any species in the world and definitely the oldest sperm used to produce offspring,” researcher Dr. Jessica Rickard said in a statement.

Researchers say this experiment also lets them assess the genetic progress of selective breeding over the last five decades. “In that time, we’ve been trying to make better, more productive sheep [for the wool industry],” associate professor Simon de Graaf said. “This gives us a resource to benchmark and compare.”

[h/t Smithsonian]

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