The hormone is best known as the key to energy balance and satiety. She finds with this study of Johns Hopkins Medicine a new possible indication: its nasal release could also alleviate respiratory disorders during sleep. The proof of concept is provided here on sleeping mice, and documented in the American Journal of Respiratory and Critical Care Medicine.
Leptin, a hormone created by fat cells, first identified in 1994, targets the appetite center in the brain, and helps regulate appetite. While its potential in treating obesity and controlling overeating has yet to be realized, this new role in the respiratory system could further expand its therapeutic promise, points out Dr. Vsevolod Polotsky, professor of pulmonary and critical care medicine at Johns Hopkins University School of Medicine. His laboratory has been studying the famous hormone for more than 20 years.
His latest experiments, conducted in mice, show that leptin can be effective in alleviating breathing problems during sleep, when administered nasally. In concrete terms, research is considering it in the treatment of apnea or obstructive sleep apnea syndrome (OSAS), a serious, even fatal condition which affects around 30% of adults and which is too rarely treated - in particular due to poor acceptance of standard treatment*. The prevalence of apnea can reach up to 50% in obese patients. The disease is characterized by frequent and brief periods when breathing ceases during sleep, due to closure of the upper airways. The result is oxygen deprivation which can lead, in obese patients to the syndrome of
*The most common effective treatment is regular wearing of a mask and a Continuous Positive Airway Pressure (CPAP) machine, which mechanically increases air pressure in the throat and thus keeps the airways open during breathing. sleep. But because CPAP devices must be worn constantly while sleeping, and some patients find them bulky, uncomfortable and noisy, a considerable number of patients discontinue treatment.
Leptin already documented as essential for the regulation of respiration: the researchers cite preliminary evidence for this key role of leptin but also recall that mice suffering from diet-induced obesity are resistant to the hormone leptin and do not do not respond to treatment with leptin by injection…Indeed, in this case, leptin cannot cross the blood-brain barrier and reach the target brain cells. The team therefore looked to see whether nasal administration could overcome this resistance to leptin.
Nasal spray in obese mice: The researchers first assessed the effect of a single dose (0.4 milligrams per kilogram of body weight) nasal spray in male mice made obese by a high-fat diet for 16 weeks. The researchers assessed the amount of air inhaled and the number of oxygen deficiencies during sleep, and blood oxygen levels. Experiments show that only mice given leptin through the nose exhibit more than 40% increased ventilation during sleep, which alleviates upper airway obstruction and reduces the number of episodes of respiratory illness by more than half. oxygen deficiency.
Nasal spray brings leptin to the brain: Labeling of neurons in the brains of mice that received leptin through the nose shows that the leptin receptor on the surface of the neurons detected the hormone, meaning that this method of administration is well able to bypass the blood-brain barrier and bring the hormone to the brain.
Additionally, mice treated with leptin through the nose exhibit reduced food intake and weight loss. They lose nearly 3% of their body weight. The study therefore confirms the already well-documented "satiety" effect of the hormone but suggests a second beneficial effect against respiratory disorders during sleep.
There is still a long way to go to identify the key molecules that regulate breathing and how these molecules could be used to treat diseases such as sleep apnea, but the discovery paves the way for new treatment options. It will obviously be necessary to verify the absence of side effects, including allergic reactions, and to be able to replicate these results in humans…