美国医学专业作业-Plasma IKK NF-kB [3]
论文作者:www.51lunwen.org论文属性:作业 Assignment登出时间:2014-06-01编辑:lzm点击率:10777
论文字数:2840论文编号:org201406012014576248语种:英语 English地区:中国价格:免费论文
关键词:美国医学专业Plasma IKK NF-kB血浆游离脂肪酸free plasma fatty acidsreactive oxygen species
摘要:This study examines the effect of prolonged exposure to FFA on the NF-kB activated inflammatory pathway. In vivo, infusion of oleate impaired insulin secretion as measured by c-peptide, while olive oil did not impair insulin secretion but impaired insulin sensitivity.
the end of the experiment (4 hours). Plasma glucose levels were analyzed using Beckman Glucose Analyzer. Radioimmunoassay for c-peptide and insulin was used to determine plasma concentration.
Ex vivo and in vitro studies: After 48hr infusion pancreas, the rat were cut open at the abdominal section and infused with collagenase in the pancreas. Pancreas was then placed in a 50ml test tube and incubated at 37⁰C. The contents were subsequently centrifuged and islets were isolated by Histoplaque density gradient. After pre-incubation in KRBB, islets were incubated at 2.8mM, 6.5mM, 13mM, and 22mM of glucose. For in vitro study cells were cultured in RPMI1640. Oleate was added at 0.4mM in 0.5% BSA.
Results:
In-vivo clamp studies: After 48hr infusion a two-step hyperglycemic clamp was performed to evaluate insulin secretion. During the first step the glucose level was elevated to 13mmol/l the upper physiological concentration in rats. In the second phase glucose level was elevated to 22mmol/l to achieve maximal stimulatory response. After 48hr infusion plasma FFA were elevated 2 fold with either oleate or olive oil. Basal plasma glucose levels were similar in all rats prior to the first infusion period. The glucose infusion rate (GINF) need to maintain the target the glucose rate was lower in oleate and olive oil infusion compared to the control (Figure 1a, 1b). This is consistent with decreased insulin secretion caused by oleate and decreased insulin sensitivity caused by olive oil. Infusion of oleate with salicylate or olive oil with salicylate prevented the effect of lowered GNIF cause by either fat.
Figure 1: Effect of oleate or olive oil on glucose infusion rate (GINF) during a two step hyperglycemic clamp. A) Oleate infusion resulted in lower GNIF and is restored by co-infusion of salicylate. B) Infusion of olive oil resulted in lower GNIF and is restored by co-infusion of salicylate. (p<0.01)
Basal Insulin and C-peptide levels were similar in all groups. As expected plasma insulin rose in response to increasing glucose levels (Figure 2a, 2b). Plasma c-peptide, derived from cleavage or pro-insulin, also rose indicating that the rise in insulin content was due to increased secretion (Figure 3a, 3b). Plasma insulin was lower in oleate treated rats compared with saline treated rats. The effect of reduced insulin secretion caused by oleate can be prevented by the co-infusion of salicylate with oleate as shown by the oleate and salicylate treated rats. The co-infusion of salicylate completely restored insulin content at 13mmol/l of glucose and 22mmol/l of glucose. In contrast olive oil did not decrease plasma insulin content or c-peptide level when compared to saline treated rats. Co-infusion of salicylate with olive oil also had no effect when compared to the control.
Figure 2: Plasma insulin and c-peptide secretion during the hyperglycemic clamp in 12 week old normal female Wistar rats treated for 48h with an i.v. infusion of: A) 1) Saline alone (SAL n=12), 2) Oleate alone (OLE 1.3µEq·min-1 n=10), 3) Oleate + Salicylate (OLE+SLY, oleate-1.3µEq·min-1, SLY-0.117mg·kg-1min-1, n=8), 4) Salicylate alone, (SLY, n=9); B) 1) Saline alone (SAL n=12), 2) Olive oil alone (OLO 5µl·min-1 n=7), 3) Olive oil + Salicylate (OLO+SLY, olive oil-5µl·min-1, SLY-0.117mg·kg-1min-1, n=11), 4)
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