Fructose vs Glucose - Octopus Intelligence - Pigeons & Variety - Acetaminophen Safety

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6:14 AM (8 hours ago) 6:14 AM

https://www.thetransmitter.org/metabolism/fructose-silences-hunger-driving-neurons-less-than-glucose-does/

Fructose silences hunger-driving neurons less than glucose does

By Sarah Thau

Hunger pangs build with activity in Agouti-related protein (AgRP) neurons, and when we eat, these cells fall silent, signaling to the body that it’s full. Until recently, researchers thought these neurons responded to calorie intake alone, but a new study shows fructose quiets them less effectively than glucose does, even though both simple monomeric sugars carry the same number of calories.

“We were really surprised when we tested these different sugars and found that fructose looks much different than glucose,” says study investigator Amber Alhadeff, a member of the Monell Chemical Senses Center and adjunct assistant professor of neuroscience at the University of Pennsylvania.

Fiber photometry recordings of individual AgRP neurons in mice consuming fructose or glucose solutions first tipped the lab off to the fact that fructose is the weaker inhibitor. The same difference surfaced when the team infused the solutions directly into the animals’ guts, controlling for the fact that the mice tended to take more licks of the glucose than fructose. Glucose does not require the vagus nerve to inhibit AgRP neurons, according to previous work from Alhadeff’s group, but fructose does, the new study demonstrates.

This study is the first to show “that the brain is responding to these things in different ways, and with a real mechanistic underpinning,” says Martin Myers, professor of diabetes research at the University of Michigan Medical School, who was not involved in the research. “This is an absolutely fabulous lab that is doing things that few, if any, other people in the world can do.”

Once the team discovered that fructose acts through the vagus nerve, Alhadeff’s graduate student Aaron McKnight hit the mechanistic ground running. He worked for five years, according to Alhadeff, to show that fructose activates the vagus nerve, releasing a hormone called PYY that signals Y2 receptor-expressing vagal afferent neurons and then inhibits AgRP neurons. Glucose does not lead to increased PYY levels, acting through gut-spinal afferent signaling—a separate peripheral pathway.

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https://www.sciencenews.org/article/octopus-hunt-crabs-with-mirror

Crabs can’t hide from an octopus with a mirror

By Nora Bradford

Mirrors are tricky. Even humans aren’t born with an intuitive understanding of them; we have to learn how they work. Now, scientists have discovered that the California two-spot octopus (Octopus bimaculoides) can also learn to use mirrors, researchers report June 3 in Current Biology.

When brainstorming octopus experiments, Mary Kieseler, a neuroscientist at the University of Fribourg in Switzerland, had wondered whether the famously smart creatures could pass the mirror test, which evaluates if an animal can identify itself in a mirror. Because of the challenging logistics the mirror self-recognition test would entail underwater, Kieseler and her team decided to first study whether octopuses could use mirrors as a tool to do something they’re already great at. And octopuses are great at hunting prey.

The team began by habituating three wild-caught octopuses to a mirror covering half their tank. They let the octopuses hide from the mirror and even explore the other half of the tank behind it. After the octopuses became comfortable with seeing their reflection and eating in front of the mirror, the team gave them a task: Find a hidden jar with a tasty crab inside, placed where the snack could be found using only its reflection in the mirror.

Initially, the octopuses approached the mirror, then turned around to find their prey. But after about 10 to 12 trials, each animal learned to crawl directly to the crab without the mirror pit stop.

When using real crabs, there was no way to know whether the octopuses might have been relying on smell or another nonvisual sense to hunt, so Kieseler and her team came up with one final test. Rather than using real crabs, the team used virtual ones.

https://www.scientificamerican.com/article/chaotic-pigeons-are-helping-redefine-what-we-know-about-learning/

Chaotic pigeons are helping redefine what we know about learning

By K. R. Callaway

Strutting and fluttering around cities, pigeons have adapted to an ever-shifting environment. But their environment isn’t the only thing that’s constantly changing. New research suggests the birds themselves avoid stability in their decision-making, instead choosing to live “at the edge of chaos.” As model species for learning and behavior, these birds are helping researchers test a century-old law about how humans and other creatures learn.

When learning something new, people and animals alike tend to repeat behaviors that are rewarded. First proposed by Edward Thorndike in 1898, this principle is so well established in psychology that it's become known as the law of effect. But the law implies that beyond making a behavior more frequent, rewards also make it more consistent: reducing variability in the specific way behaviors are performed over time.

Although scientists have repeatedly tested whether rewards increase the frequency of behaviors, their effect on consistency is less well studied. University of Iowa experimental psychologist Edward A. Wasserman and his colleagues decided to put it to the test in pigeons—a species that has been integral to the study of learning at the university’s Comparative Cognition Laboratory for more than 50 years. And the study’s results, published in the Journal of Experimental Psychology: Animal Learning and Cognition, suggest these birds experience variability as the spice of life.

To see how rewarded behaviors vary, the researchers gave pigeons a series of five colorful buttons to peck. They could peck any buttons in any order, but as long as they pecked five times, a treat would appear. Based on previous theories of learning, the scientists expected the pigeons might eventually slip into a routine—perhaps choosing to repeat patterns they know work or simply pecking the button nearest to them five times. Instead they continued pecking in a variety of patterns.

https://www.sciencenews.org/article/acetaminophen-pregnancy-autism-adhd

Acetaminophen in pregnancy shows no link to autism or ADHD, again

By Aimee Cunningham

Reassuring evidence on acetaminophen’s safety during pregnancy keeps growing.

A large, two-decade study in Hong Kong is the latest to find no link between use of the drug — known as Tylenol in the United States — and a risk of autism or attention-deficit/hyperactivity disorder in children. The lack of an association persisted no matter the trimester the drug was prescribed, the dose or the recommended frequency, researchers report June 29 in JAMA Internal Medicine.

Joining several other analyses, including ones conducted in Sweden and Japan, the research adds to the body of evidence reporting no association between acetaminophen use in pregnancy and long-term neurodevelopmental disorders in children.

All the studies compared siblings born to mothers who had taken the drug at some point, such that some siblings were exposed to the drug in utero and others weren’t. This approach accounts for the fact that both ADHD and autism are largely influenced by genetics. If acetaminophen were also a factor, researchers would expect a difference between siblings exposed to the drug and those not. None of the studies have found one.

For the new study, the researchers pored over electronic health records from 2001 to 2023 for more than 700,000 pairs of mothers and children. Around 43 percent of the kids encountered acetaminophen in utero. The team focused on pairs of siblings that differed in exposure and used their records to follow the children for at least two years for autism diagnoses and at least five for ADHD. The autism analysis included more than 124,000 children, while the ADHD component had more than 97,000. Going a step further, the analysis also looked at the timing and amount of acetaminophen that was prescribed.

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