Lactate IV infusion found to trick the body into releasing a hormone behind that post-workout brain boost

(Press-News.org) Science has confirmed what sports lovers have always known from experience: exercise is good for the brain. It increases blood flow, inhibits stress hormones, and stimulates the release of ‘feel good’ endorphins. One way by which exercise is thought to yield these benefits on the brain is through a chain of processes that ultimately results in the release of the hormone BDNF. Produced by the liver, brain, skeletal muscle, and fat tissue, BDNF is known to promote the growth, survival, and maintenance of nerve cells.

Previous studies have suggested that the starting signal for this physiological chain is a high level in the blood of lactate, a by-product of the conversion inside muscle, the liver, and the blood of carbohydrates into energy when oxygen is limited – for example during high-intensity exercise. Now, a study in Frontiers in Cellular Neuroscience has found that the physiological benefits of exercise may be partly mimicked by a simple IV infusion of lactate.

“Here we show for the first time that such an infusion leads to levels of lactate in the blood which are characteristic of medium to intense exercise. Ultimately, this boosts levels of the precursor molecule of BDNF, likely released by the skeletal muscle,” said lead author Dr Marcus Moberg, a senior lecturer at the Swedish School of Sport and Health Sciences in Stockholm.

Blood will out

The authors did a so-called ‘randomized crossover study’ on 12 healthy volunteers aged between 20 and 40 years old. After fasting overnight, these were invited to lie down while either receiving a one-hour long IV infusion of sodium lactate and then, seven to 30 days later, a one-hour long infusion of saline solution; or receiving these treatments in the reverse order. Blood was taken from each volunteer every 10 minutes during both treatments, as well as 15, 30, 45, 60, 90, and 120 minutes afterwards. A leg muscle biopsy was taken before and immediately after each infusion with lactate, as well as 60 and 120 minutes later.

A control group of six additional volunteers exclusively underwent a treatment with saline solution, and likewise donated blood samples and four muscle biopsies.

The researchers measured the lactate concentration in each blood or muscle tissue sample. They further quantified the levels of pro-BDNF, a biologically active precursor molecule of BDNF, in addition to its mature molecular form mBDNF, in blood plasma, serum, and platelet-poor plasma – that is, plasma from which most platelets have been removed.

As expected, the concentration of lactate in blood increased during infusion, peaking at values similar to those normally obtained after high-intensity exercise. Importantly, the concentration of the prohormone pro-BDNF increased 15 min after the end of lactate infusion and stayed high for two hours afterwards. In contrast, neither the level of pro-BDNF in muscle nor that of mBDNF in plasma or serum changed during or after lactate infusion.

The authors concluded that IV infusion with lactate is sufficient to boost the levels of pro-BDNF in the bloodstream, but without affecting those of mBDNF. In other words, lactate infusion alone is enough to mimic some, but not all, of the physiological effects of high-intensity exercise. It is expected that such an increase of pro-BDNF will have similar beneficial effects on brain health, irrespective of the mechanism behind it.

Continuing to exercise is a no-brainer

Is this good news for those among us who loathe exercise? Possibly one day, but for now the authors strongly caution against skipping the exercise step and relying on lactate infusion alone.

“We speculate rather that the intensity of exercise is important if brain health is the desired goal. High-intensity exercise a couple of times per week, thus exposing the brain to high levels of lactate, should be recommended for healthy neurological aging,” said Moberg.

“In the future, these findings can aid in the targeted, individualized prescription of exercise in clinical settings, especially for populations with compromised brain health.”

“Also, since lactate is known to exert hormonal-like effects, there is a potential for pharmacological interventions. This would require additional research to pinpoint the exact mechanism by which lactate controls BDNF metabolism in humans.”

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