The Role of Obesity in Obstructive Sleep Apnea (OSA)

Intermittent Hypoxia and Leptins

Scott Mesenger recently published a Master's Thesis that implicates compelling links between Leptin Signaling and OSA: http://ir.lib.uwo.ca/cgi/viewcontent.cgi?article=2487&context=etd. This work was done in the John Cirello Lab at University of Western Ontario. The study extensively uses our Ob-Rb Antibody to generate data.

There is a strong link between obesity and OSA. "Perhaps the single most important factor affecting OSA risk is body weight. Weight gain of 10% increases the risk of developing OSA by six-fold (Peppard et al., 2000a) and a 10% loss of body weight is estimated to decrease the apnea/hypopnea index (events/hour) by 26%  Within the obese population (BMI ≥ 30) (Wolk et al., 2003), approximately 40% experience significant OSA and approximately 70% of OSA patients are obese (Vgontzas et al., 1994), daunting numbers considering the obesity epidemic occurring in North America and estimates suggesting 41% of Americans will be obese by 2015 (Nejat et al., 2009)."

"Leptin can exert cardiovascular effects by acting centrally, as has been shown by studies introducing leptin directly into the CNS. Central administration serves to increase plasma catecholamines epinephrine and norepinephrine (Satoh et al., 1999). In other studies, leptin has been found to increase SNA, arterial pressure as well as heart rate and to inhibit the baroreflex (Arnold et al., 2009; Mark et al., 2009). Leptin may also have a role in modulating the peripheral chemoreflex at the level of the CNS as microinjection of leptin into caudal pressor areas of the NTS has been found to potentiate the sympathetic and blood pressure responses to chemoreflex activation (Ciriello & Moreau, 2012). These cardiovascular effects may not be debilitating under normal homeostatic conditions, however in conditions of increased circulating leptin, such as in OSA and obesity, the cardiovascular responses may be detrimental."

This study shows the increase in the expression of leptins like Ob-Rb in Carotid .

Images: Fluorescent (a-c) photomicrographs showing the effect of IH on Ob-Rb (a) and ERK 1/2 (b) expression in carotid body glomus cells. Note that Ob-Rb and ERK 1/2 are co-expressed in the same cells (c). Calibration mark in (a) represents 100 μm and applies to (a-c).

Images: Western blots showing the presence of Ob-Rb (a) and Ob-R100 (b) in carotid bodies after IH. Note that IH significantly (*) decreases the protein level of Ob-Rb (a), while significantly (*) increasing the protein level of Ob-R100 (b) compared to normoxic controls (b). p values are indicated. n=5-6.

This study will give the reader great insights on the molecular biology of OSA. Check it out: http://ir.lib.uwo.ca/cgi/viewcontent.cgi?article=2487&context=etd.

Leptins and Obesity

Our Leptin and Leptin Receptor Markers have proven effective for researchers studying root causes of obesity. In this reference the authors show an interesting twist regarding the impact of endothial vs neuronal leptin signaling: Weihong Pan, Hung Hsuchou, Germaine G. Cornelissen-Guillaume, Bhavvani Jayaram, Yuping Wang, Hong Tu, Franz Halberg, Xiaojun Wu, Streamson C. Chua Jr., and Abba J. Kastin. Endothelial leptin receptor mutation provides partial resistance to diet-induced obesity. Published online before print February 2012, doi: 10.​1152/​japplphysiol.​00590.​2011.
...chicken anti-ObRb (1:100, Neuromics)...

Highlights: Leptin, a polypeptide hormone produced mainly by adipocytes, has diverse effects in both the brain and peripheral organs, including suppression of feeding. Other than mediating leptin transport across the blood-brain barrier, the role of the endothelial leptin receptor remains unclear. We recently generated a mutant mouse strain lacking endothelial leptin receptor signaling, and showed that there is an increased uptake of leptin by brain parenchyma after its delivery by in-situ brain perfusion. Here, we tested the hypothesis that endothelial leptin receptor mutation confers partial resistance to diet-induced obesity. These ELKO mice had similar body weight and percent fat as their wildtype littermates when fed with rodent chow, but blood concentrations of leptin were significantly elevated. In response to a high fat diet, wildtype mice had a greater gain of body weight and fat than ELKO mice . As shown by metabolic chamber measurement, the ELKO mice had higher oxygen consumption, carbon dioxide production, and heat dissipation, although food intake was similar to that of the wildtype mice and locomotor activity was even reduced. This indicates that the partial resistance to diet-induced obesity was mediated by higher metabolic activity in the ELKO mice. Since neuronal leptin receptor knockout mice show obesity and diabetes, the results suggest that endothelial leptin signaling shows opposite effects from that of neuronal leptin signaling, with a facilitatory role in diet-induced obesity.


Obesity is a growing health problem and will continue to drive up costs. Research like this could help find effective and log term solutions for helping with weight loss.