Correlation Study Between Endocannabinoid System And Obstructive Sleep Apnea-hyponea Syndrome

Background:Obstructive sleep apnea hypopnea syndrome (OSA) is a highly prevalent sleep disorder and its evidence is up to 3-4%in the population. The current knowledges on the OSA suggests that it is an independent risk factor for many kinds of diseases, such as hypertension, coronary heart disease, stroke, metabolize dysfunction, sexual dysfunction and so on. It is said that OSA would affect every physiological mechanism that correlation with oxygen metabolism. Main pathological damages of OSA include sleep structure damage, chest abnormal pressure change and chronic hypoxia, where the key factors in pathological damage is the existence of the long-term chronicintermittenthypoxia(CIH) environment and the inflammatory response pathway inside oxidatie stress signal channel network, causing damage to multiple target organs. The endocannabinoid (EC) system is an endogenous signaling system which is involved in numerous physiological functions, both in the central and peripheral nervous systems and in peripheral organs. It is composed of the cannabinoid receptors, endocannabinoids and the molecular machinery required for their synthesis and degradation. The EC system has been implicated in a wide range of pathological conditions ranging from mood and anxiety disorders, movement disorders, hypertension to the metabolize dysfunction. Now, EC system is belived to be a neuroactive lipid signaling system that functions to gate homeostasis maintainence. OSA may interfere with endocannabinoids system, and affect its steady-state function. Disorder of endocannabinoids system and other signal network influenced by OSA will constitute the pathological basis for the development of OSA complications. In the following study, we will examine the relationship between endocannabinoids system and OSA and its complications.Objective:(1) The expression of endocannabinoids system component in peripheral mononuclear cells of normal and diabetic population were tested, to confirmâ‘ peripheral mononuclear cells have complete functional components of endogenous cannabinoid system;â‘¡endogenous cannabinoid system has changed in diabetes;â‘¢the activity of endocannabinoids system on peripheral mononuclear cells can reflect the overall pathological physiological changes. (2) detected the expression of endogenous cannabinoids and its relationship with clinical manifestations in OSA patients, to confirmâ‘£endocannabinoids system changes in OSA patients;â‘¡endocannabinoids system is associated with OSA complications; (3) Through exploring the expression changes of endocannabinoid system in patients before and after sleep to further evidence the influence of OSA pathophysiology on endocannabinoid system.Methods:Cast-control studies were adopted to do the following research.â‘ Real-time quantitative PCR was used to detect the difference of endocannabinoid system in type 2 diabetes and normal controls groups;â‘¡The differences of endocannabinoid system in OSA and normal controls groups were detected and the correlation between endocannabinoids system component changes and the clinical manifestations in OSA patients were also analysised.â‘¢Mononuclear cells were extracted from peripheral blood samples of 24 cases of OSA patients and 18 healthy volunteers before and after sleep, and changing of endocannabinoid system were also detected to explore the influence of the pathological physiology change of OSA on it.Results:1. Clear amplification curves of the two kinds of endocannabinoid receptors CB1, CB2, and FAAH, MGL, DAGL and Nape, the key-synthesis and degradation enzymes of the two main ligands endocannabinoid AEA and 2-AG, were detected from peripheral blood mononuclear cells. Indicating that mononuclear cells might have the total functional compositions of endocannabinoid system. Compared with the normal control, in diabetic group, mRNA of CB1 increased noticeable(t=1.54, P=0.05), and CB2 decreased significantly(t=2.76, P=0.01)2. Results from immunohistochemistry and flow cytometry showed that, compared with the normal group, CB2 receptor protein expression was significantly higher in OSA (t=0.95,1.82; P=0.008,0.049). In OSA group, mRNA of CB2 increased significantly(t=1.97, P=0.05); NAP, key synthase of AEA, increased significantly(t=1.99, P=0.05); MGL, main 2-AG-degrading enzyme, decreased significantly(t=2.06, P=0.04).3. Correlation analysis showed that CB2 and NAP were correlation with the longest apnea time(Tmax) and the average oxygen saturation(SaO2min). MGL was correlation with Tmax, SaO2min and the average oxygen saturation (SaO2). Multiple linear regression analysis showed that multiple regression models of CB2 and NAP were established, micro-arousal index into the CB2 regression model, standardized regression coefficient 0.26, t=2.69, P=0.01; micro-arousal index and the SaO2 into the NAP model, standardized regression coefficient respectively,0.27 and 0.24, t=2.86,2.58 and P=0.01,0.01.4. In the group of OSA patients with cognitive impairment, mRNA of NAP was significantly higher, t=2.48,P=0.02; SaO2min and arousal index between the two groups have more significant difference, t=1.79,1.69; P=0.05,0.05.5. In the group of OSA patients with impaired sexual function, mRNA of MGL was significantly reduced, t=1.68, P=0.05; micro-arousal index between the two groups were significantly different, t=1.46, P=0.05.6. In OSA patients with hypertension, mRNA of FAAH, main AEA-degrading enzyme was significantly lower, t=0.77, P=0.01. Micro-arousal index between the two groups were significantly different, t=1.68; P=0.04.7. MGL was influenced by OSA and nocturnal sleep, the treatment main effect (OSA) (F=3.996,P=0.035) and time main effect (nocturnal sleep) (F=4.131, P=0.025) were statistically significant, the interaction between treatment effect and time effect has no statistical significance (F=0.956, P=0.338).Conclusion:1. Human peripheral blood mononuclear cells expresses the full biochemical substances to bind and metabolize AEA and 2-AG The finding that human mononuclear cells show a functional "endocannabinoid system" indicates that peripheral actions of the endocannabinoids may have a role in mononuclear cells. Expression level of endocannabinoids system components changes with glucose metabolism disorder, indicating mononuclear cells may respond to physiological and pathological conditions as a whole. This section provided a theoretical and experimental basis for the following research.2. In OSA group, changes of the endocannabinoids system component correlated with PSG, especially with nocturnal arousal index and SaO2. The endocannabinoids system of OSA patients enhance overall performance of activity. Through its regulatory role in a wide range of negative, endocannabinoids system would prompt the body to regain balance. It would lower blood pressure, inhibit the activity of peripheral sympathetic nervous system, in order to cope with stress, but may also promote inhibition of cognitive and sexual function.3. Like other acute stress in the literature, nocturnal pathological state of OSA may lead to the enhanced role of 2-AG and participate in the termination of the stress response and restore the body balance. This section further supports the results of the second part.