Low-Dose 5-FU and the Heart's Nervous System: Unseen Effects

5-Fluorouracil, or 5-FU, is a common medicine used to fight solid tumors. But like many strong drugs, it has side effects. One of them is cardiotoxicity, which affects your heart. Scientists wanted to look into how low doses of 5-FU might change the intrinsic cardiac nervous system (ICNS)—a key part of the heart that's not often studied. To do this, they used Wistar rats, splitting them into two groups. One group got small amounts of 5-FU, while the other just got saline (like saltwater). The 5-FU was given in three stages: 15 mg/kg for four days, then 6 mg/kg for four days with breaks in between, and finally one more 15 mg/kg dose on day 14.

On day 15, all the rats were awakened to their fate. The scientists looked at the heart's white parts (atria) for cell structures and the larger parts (ventricles) for chemical changes. Results? The neuron density went up, but their size and area decreased. There were also signs of inflammation, like more proinflammatory factors and active enzymes. The heart's antioxidant defenses dropped, showing oxidative stress. Plus, there was some heart muscle shrinkage and scarring. So what does this mean? Low doses of 5-FU can cause some serious heart problems, affecting how nerves work in the heart. This isn't something to ignore!

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