Increased systemic low-grade inflammation in high altitude native rats mediated by adrenergic receptors

To compare the serum levels of inflammatory mediators in high altitude [HA] native rats, and to search for the possible underlying mechanism[s]. The study was carried out between January and April 2013. Fifty male rats from the same genetic pool were bred at either a HA or low altitude [LA] area. The study was carried out in 2 stages. In the first stage, serum levels of inflammatory markers, adhesive molecules, lipid profiles, catecholamines, magnesium [Mg[+2]], and lipid peroxidation were compared between theses 2 groups. In the second stages, inflammatory response and lipid peroxidation were analyzed in HA native rats after treatment with either alpha [Prazosin] or beta [propranolol] adrenergic blockage. The HA native rats showed significant increases in the serum levels of inflammatory cytokines, lipid profiles, as well as a significant increase in the urinary norepinephrine with a concomitant decrease in the serum levels of Mg[+2] and increased lipid peroxidation. Blockage of the beta and alpha adrenergic receptors of the HA rats caused partial or complete decreases in both inflammatory and oxidative stress mediators. Living under HA conditions results in an increased systemic inflammatory reaction; an effect that is mediated through the sympathetic nervous system mainly via alpha-adrenergic receptors and could be attributed to low Mg[+2] levels

Inhibited thyroid function, impaired lipid metabolism and increased tissue oxidative stress in rats native to high altitude

To evaluate the effect of high altitude on markers of thyroid function, serum lipid profile and tissues oxidative stress in male Wistar rats native to high altitude [HA] with male rats native to low altitude [LA]. Randomized experimental animal study. Physiology laboratory, Medical School of King Khalid University. Male rats aged six months, weighing 250 gm were bred and maintained at low altitude [LA, 600 m above sea level, n=6] or high altitude [HA, 2800 m, n=6], under the same laboratory conditions and fed the same diet. Blood samples were obtained for thyroid hormones and lipid profile analysis. Livers, kidneys, lungs and testes were collected and used for determination levels of thiobarbituric acid reactive substances [TBARS], reduced glutathione [GSH], Superoxide Dismutase [SOD] and Catalase Activity [CAT]. HA rats had significantly [P<0.05] lower serum T3 [17.14%], T4 [13.75%], TSH [39.29%] and total cholesterol [15.84%] and LDL [60.90%].There were no significant differences in TAG or HDL. All tissues from HA rats showed significant decreases in SOD and CAT activities compared to LA rats. These rats showed significantly higher oxidative stress in the lungs and the liver, but lower oxidative stress in the kidney and no difference in the testes. Living at high altitude environment results in impaired thyroid function and lipid metabolism and causes increased tissue oxidative stress

Chronic exposure of rats to native high altitude increases in blood pressure via activation of the renin-angiotensinaldosterone system

To study the effect of chronic exposure to native high altitude [HA] on blood pressure, and to investigate the underlying mechanism of action. This study was carried out between February and April 2011. A total of 20 male rats were divided into 2 groups [n=10 rats]. The low altitude [LA] group were rats born and lived in an LA environment at King Saud University, College of Pharmacy, Riyadh, Kingdom of Saudi Arabia [KSA], and the HA group were rats born in the same LA area, then acclimatized to HA area in Physiology Department, King Khalid University, College of Medicine, Abha, KSA for 90 days. At the end of day 90, hematocrit, plasma renin activity, aldosterone, norepinephrine and vasopressin levels were determined in both groups. Invasive arterial blood pressure was also measured, and fractional excretion of sodium [FENa], and potassium [FE[K]] were calculated. The quantitative real time-polymerase chain reaction of renin was carried out in the kidneys of both rat groups. When compared to LA native rats, HA rats exhibited a significant increase in systolic and diastolic blood pressure with a significant increase in renin plasma activity as well as an increase in the levels of aldosterone, norepinephrine, and vasopressin. Furthermore, HA rats showed a significant increase in renin expression in their kidneys, as well as decreased FENa. Data shows that prolonged exposure to HA results in elevated blood pressure precipitated by the activation of the renin-angiotensin-aldosterone system