The Changes In Adipose Tissue And Blood Vessel Produced By Nicotine And Its Withdrawal

INTRODUCTIONRecently epidemiological study has showed that smoking cessation cause an increases in body weight gain while smoking decreases body weight. Nicotine is considered responsible for most of the effect on health consequent to the smoking habit. An increase in body weight is considered ,especially among women in western country, an obstacle to definitive smoking cessation. On the one hand,it show that rat that absorbed nicotine in pregnancy results in changing the effection on vascular and vascular adipose. The offspring increases the incidence of hypertension and obesity[1]. It shows that the effect on adipose and bood vessel is closely links with cardiovascular disease including hypertension and obesity. On the other hand,clinical research shows one of the most consistent adverse outcomes is reduced birth weight in the off-spring. Animal studies using chronic nicotine, the major psychoactive tobacco ingredient, have shown conflicting results, questioning the role of nicotine in growth retardation. It shows that body weight of their offspring increases slowly. To evaluate the direct effects of nicotine during a period equivalent to the human third trimester, Huang LZ[2] et al developed an oral gastric intubation model using neonatal rat pups. Nicotine (6 mg/kg/day) was dissolve in milk-formula and delivered during three feedings daily from postnatal day (P)1 to P7. Nicotine immediately and significantly decreased weight gain per day (WGD) after onset of treatment in both genders and throughout the treatment period. This resulted in significantly lower body weight at P4 and P5 in male and female pups, respectively. After nicotine withdrawal, WGD returned to control level within 1 day, whereas total body weight recovered by P18. There were no long-term consequences on body weight or growth pattern in either gender. The nicotinic acetylcholine receptor (nAChR) antagonist dihydro-beta-erythroidine (DHbetaE) reversed nicotine's effects on WGD suggesting an involvement of heteromeric alpha4beta2. The immediate decrease of growth in neonatal pups suggests that nicotine's effect on birth weight results from direct anorexic rather then indirect effects due to placental dysfunction or increased fetal hypoxia.In the past the special subjects are women and female animals in pregnancy about the effection of nicotine on adipose and vascular. YJ Gao[1] et al show that exposure to nicotine resulted in increased postnatal body weight and fat pad weight and an increased amount of PVAT in the offspring. Contraction of the aorta induced by phenylephrine was significantly attenuated in the presence of PVAT, whereas this effect was not observed in the aortic rings from the offspring of nicotine-exposed dams. Phenylephrine-induced contraction without PVAT was not different between saline- and nicotine-exposed rats. Transfer of solution incubated with PVAT-intact aorta to PVAT-free aorta induced a marked relaxation response in the rats from saline-exposed dams, but this relaxation response was significantly impaired in the rats from nicotine-exposed dams. Our results showed that prenatal nicotine exposure increased adiposity and caused an alteration in the modulatory function of PVAT on vascular relaxation response, thus providing insight into the mechanisms underlying the increased prevalence of obesity and hypertension in children exposed to cigarette smoke in utero.Above all we know that exposure to nicotine is harmful to vascular and adipose tissue function in pregnancy. How do nicotine treatment and cessation effect on the function of adipose tissue and aorta in normal object? What is the mechanism if their function change in them? Wether or not they increase the risk of cardiovascular system disease? We are not clear in these questions currently. Our study will answer these question. It not only provides a new clue of nicotine's effection on adipose and aorta in normal object, but also has an important significance in prevention of cardiovascular disease.METHODSFirstly, we mainly constructed four models of nicotine treatment and cessation in SD rat basing on different age, gender and dose. The male SD rats at the age of 6 weeks were divided into three groups including control group, nicotine group and nicotine withdrawal group. Control group was treated with saline 0.5ml/kg/d for 6 weeks. Nicotine group was treated with nicotine 3 mg/kg/d for 6 weeks . Nicotine withdrawl group was treated with nicotine 3 mg/kg/d for 2 weeks and following with saline for additional 4 weeks.The male SD rats at the age of 11 weeks were divided into three groups including control group, nicotine group and nicotine withdrawl group. Control group was treated with saline 0.5ml/kg/d for 6 weeks . Nicotine group was treated with nicotine 3 mg/kg/d for 6 weeks. Nicotine withdrawl group was treated with nicotine 3 mg/kg/d for 3 weeks and following with saline for additional 3 weeks. The female rats at the age of 10 weeks were divided into three groups including control group, nicotine group and nicotine withdrawal group. Control group was treated with saline 0.5ml/kg/d for 4-5 weeks. Nicotine group was treated with nicotine 0.8 mg/kg/d for 4-5 weeks. Nicotine withdrawl group was treated with nicotine 0.8 mg/kg/d for 2 weeks and following with saline for additional 2-3 weeks.The male rats at the age of 10 weeks were divided into three groups including control group, nicotine group and nicotine withdrawl group. Control group was treated with saline 0.5ml/kg/d for 6 weeks. Nicotine group was treated with nicotine 0.8 mg/kg/d for 6 weeks. Nicotine withdrawl group was treated with nicotine 0.8 mg/kg/d for 3 weeks and following with saline for additional 3 weeks. In the proceed of preparing the model of nicotine cessation, we recorded body weight every day or every week. In the end we evaluate the model by body weight, serum biochemical indicator of correlation with of glucose and lipid and the adipose tissue weight in different location including subcutaneous fat, epididymal fat, perirenal and retroperitoneal fat, omental and mesenteric fat, periaortic fat et al.Secondly, the area of adpose in the aorta stained by hematoxylin and eosin toa is measured. Silver staining aorta is to observe Calcium deposition.The aorta effects on contraction and relaxation after nicotine withdrawl. Aorta was cut into 5-mm-wide rings. In some rings the endothelium was removed mechanically.Changes in some rings the ehdothelium or perivascular adipose was removed mechanically.Changes in isometric tension were recorded using a computerized system . We study that phenyllphrine inducing to contaction and Acetylcholine causing to relax depending on endothelium effect on aorta in three groups. The following experiments is that sodium nitroprusside causing to relax and Potassium Chloride inducing to contract effects on media of aorta.Thirdly, we observe that different adipose including epididymal fat, perirenal and retroperitoneal fat, omental and mesenteric fat, periaortic fat expresses visfatin protein by western-blot.RESULTSThe male SD rats at the age of 6 weeks and 11 weeks were treated with nicotine 3mg/kg/d.In these two nicotine cessation models, body weight in nicotine group decreased(P<0.01)obviously compared with in control group for 2-3 weeks after nicotine treatment while body weight in nicotine cessation group increased rapidly(P<0.01)compared with in nicotine group for 3 weeks after nicotine withdrawl. The female and male SD rats at the age of 10 weeks were treated with nicotine 0.8mg/kg/d . In the two latter, body weight in three group was not obviously difference.Serum biochemical indicator of correlation with of glucose and lipid at the dose of 3 mg/kg/d show that triglyeride reduced and insulin sensitivity increase in nicotine group while serum biochemical indicator at the dose of 0.8mg/kg/d models have not obvious difference in nicotine group and nicotine cessation group.Adipose tissue weight results show that fat weight of male SD rats at the age of 6 weeks and 11-weeks Which were treated nicotine 3mg/kg/d fat weight including subcutaneous fat, visceral fat and aorta fat decreased in nicotine group while increasedin nicotine cessation group. At the same time, adipose tissue weight of female an male rats which were treated with nicotine 0.8mg/kg/d have not obvious difference.We find that adipose area obviously decrease (P<0.01) in Nicotine group while increase in Nicotine withdrwal group compared with Nicotine group (P<0.05). Calcium deposition is observed in intima and adventitia of aorta in nicotine group while depositon only exists in intima of aorta in Nicotine withdrawal group and Saline Group.Contraction induced by Phenylephrine has not difference in three groups when endothelium exist adipose of aorta removed or not. Acetylcholine causing to relax depending on endothelium also have not difference in three groups.In aorta denuded adipose endothelium removed or not show that sodium nitroprusside causing to relax more increasing in nicotine group compared with control group. In additional experiment continuous added sodium nitroprusside induces to relax in the rings denuded adipose endothelium removed or not .We find that relaxation more increasing in nicotine group compared with contol group.The result of visfatin expression in different adipose tissue show that visftin expression have no difference in three groups. Visfatin protein of omental and mesenteric fat, periaortic fat more increasing in nicotine group compared with control group while visfatin expression more decreasing in nicotine withdrawal group compared with nicotine group.CONCLUSIONSThe male SD rats treated with nicotine 3mg/kg/d, body weight decreases obviously at 3 weeks while body weight increases at 3 weeks in nicotine withdrawl group. Serum biochemical indicator show that triglyeride reduced and insulin sensitivity increase in nicotine group. Adipose tissue weight show that subcutaneous fat,visceral fat and periaorta fat decrease in nicotine treatment while nicotine cessation increase. It shows that the male SD rats treated with nicotine 3mg/kg/d is suitable foe nicotine withdrawal model.The adipose of aorta decrease and form Calcium deposition of media aorta in Nicotine group.In nicotine treatment, the relaxation caused by sodium nitroprusside is more increasing in nicotine group .It show that smooth muscle cell in media vascular is involved in. It is also possible to involve in NO pathway.Visfatin expression of omental and mesenteric fat, periaortic fat increases in nicotine group while decrease in nicotine withdrawl group. It is possible to link with insulin sensitivity and adipose. It is also caused by that visfatin expression is more in omental and mesenteric fat, periaortic fat than other fat.