Influence of dehydroepiandrosterone (DHEA) on cholesterol metabolism in rats

Wistar rats were fed semipurified diets containing 0.5% of dehydroepiandrosterone (DHEA) for 14 days. DHEA feeding resulted in weight loss and slight liver enlargement. It did not affect serum triglyceride levels but increased serum cholesterol levels. Liver triglyceride levels of DHEA-fed rats were significantly lower than in controls. DHEA inhibited cholesterol absorption. Liver slices from DHEA-fed rats incorporated more acetate into cholesterol than controls; there were no differences in conversion of mevalonate.     

Effects of dehydroepiandrosterone on oleic acid accumulation in rat liver

The purpose of the present study was to determine whether dehydroepiandrosterone (DHEA) affects de novo fatty acid synthesis, oleic acid formation, fatty acid oxidation, and very low density lipoprotein (VLDL) secretion, in relation to the accumulation of lipid containing oleic acid, in rat liver. The rates of hepatic de novo synthesis of both fatty acid and monounsaturated fatty acid, determined by incorporation of 3H from 3H(2)O into fatty acid, were increased markedly when rats were fed a diet containing 0.5% (w/w) DHEA for 14 days. The treatment of rats with DHEA also enhanced the conversion of [14C]stearic acid into oleic acid in the liver in vivo. DHEA did not suppress fatty acid degradation in the liver. Namely, mitochondrial palmitic acid oxidation in liver homogenates and isolated hepatocytes was increased approximately 1.9- and 5-fold, respectively, in DHEA-treated rats. Peroxisomal palmitic acid oxidation in isolated hepatocytes from rats treated with DHEA, however, was not significantly different from that of the control, despite the fact that peroxisomal degradation of palmitic acid in the liver homogenates was increased markedly. The rate of hepatic VLDL secretion in DHEA-treated rats was decreased markedly. These results indicate that the elevation of the hepatic fatty acid content, especially oleic acid, by DHEA feeding is due to an increase in both de novo fatty acid synthesis and the formation of oleic acid and to a decrease in the rate of hepatic VLDL secretion. Mitochondrial and peroxisomal fatty acid degradation does not appear to play a significant role in the accumulation of hepatic lipids.     

脱氢表雄酮对衰老大鼠线粒体外周型苯二氮(艹卓)卓受体的影响

目的:观察脱氢表雄酮(DHEA)对衰老模型大鼠大脑皮质线粒体外周型苯二氮艹卓受体(PBRs)的影响,探讨PBRs在脑老化中的作用。方法:Sprague-Dawley大鼠随机分为溶媒对照组和药物治疗组。实验动物连续注射D-半乳糖(100 mg.kg-1,qd,共56次)制备衰老动物模型。溶媒对照组、药物治疗组动物分别同时注射二甲基亚砜或DHEA,隔日一次,共28次。利用Morris水迷宫测试学习记忆能力后动物断头,采用梯度离心法制备大脑皮质线粒体,应用放射配基结合试验测定PBRs最大结合容量(Bmax)和平衡解离常数(KD)。结果:与溶媒对照组比较,药物治疗组Bmax显著升高,KD无显著变化,动物学习记忆能力显著改善。大脑皮质线粒体PBRs特异结合活性与迷宫试验动物逃避潜伏期、平台象限游泳距离和时间显著相关(P<0.05)。结论:大脑皮质线粒体PBRs表达量与衰老动物学习记忆功能密切相关。DHEA可以增加脑组织PBRs的表达量,并改善衰老动物智能状态。     

Disposition and metabolic profile of the weak androgen Dehydroepiandrosterone (DHEA) following administration as part of a nutritional supplement to exercised horses

In order to ensure the welfare of performance horses and riders as well as the integrity of the sport, the use of both therapeutic and illegal agents in horse racing is tightly regulated. While Dehydroepiandrosterone (DHEA) is not specifically banned from administration to racehorses in the United States and no screening limit or threshold concentration exists, the metabolic conversion of DHEA to testosterone make its presence in nutritional supplements a regulatory concern. The recommended regulatory threshold for total testosterone in urine is 55 and 20 ng/mL for mares and geldings, respectively. In plasma, screening and confirmation limits for free testosterone (mares and geldings), of no greater than 0.1 and 0.025 ng/mL, respectively are recommended. DHEA was administered orally, as part of a nutritional supplement, to 8 exercised female thoroughbred horses and plasma and urine samples collected at pre‐determined times post administration. Using liquid chromatography‐mass spectrometry (LC‐MS), plasma and urine samples were analyzed for DHEA, DHEA‐sulfate, testosterone, testosterone‐sulfate, pregnenolone, androstenedione, and androstenediol. DHEA was rapidly absorbed with maximal plasma concentrations reaching 52.0 ± 43.8 ng/mL and 32.1 ± 12.9 ng/mL for DHEA and DHEA sulfate, respectively. Free testosterone was not detected in plasma or urine samples at any time. Maximum sulfate conjugated testosterone plasma concentrations were 0.98 ± 1.09 ng/mL. Plasma testosterone‐sulfate concentrations did not fall below 0.1 ng/mL and urine testosterone‐sulfate below 55 ng/mL until 24–36 h post DHEA administration. Urine testosterone sulfate concentrations remained slightly above baseline levels at 48 h for most of the horses studied. Copyright © 2014 John Wiley & Sons, Ltd.     

高效液相色谱串联质谱法同时定量测定人血清中脱氢表雄酮、睾酮及雄酮

目的:建立一种快速、灵敏地同时测定人血清中脱氢表雄酮、睾酮及雄酮的高效液相色谱串联质谱(电喷雾电离模式)定量方法。方法:血清样品选用甲基叔丁基醚(MTBE)萃取后,取上清液用盐酸羟胺对3种激素进行柱前衍生化后进样测定。色谱柱为Waters YMC ODS-AQ(2.0 mm×150 mm,3.0μm),流动相为70%乙腈和30%醋酸(0.02%)溶液,流速为0.2 mL·min-1,柱温为50℃。本文采用电喷雾离子源进行正离子离子化,使用MRM检测模式选择性监测脱氢表雄酮(m/z 304.2/253.2)、睾酮(m/z 304.2/124.0)、雄酮(m/z 306.2/255.2)及内标炔诺酮(m/z 314.1/124.2)。结果:脱氢表雄酮、睾酮与雄酮的最低定量限(LLOQ)分别为0.10,0.05,0.10 ng·mL-1;标准曲线相关系数(r)均大于0.99;3种激素的日间及日内方法回收率均在±115%之内,日内及日间精密度(RSD)均小于15%。结论:实现在ESI电离模式下,用HPLC-MS/MS同时测定脱氢表雄酮、睾酮与雄酮3种甾体激素;本方法具有良好的特异性、灵敏度、准确度及精密度,能满足人血清样品定量分析需要。     

Effects of subcutaneous and intracerebroventricular injection of physostigmine on the acute corneal nociception in rats

The present study investigated the effects of subcutaneous (sc) and intracerebroventricular (icv) injections of physostigmine (a cholinesterase inhibitor), atropine (an antagonist of muscarinic cholinergic receptors) and hexamethonium (an antagonist of nicotinic cholinergic receptors) on the acute corneal nociception in rats. Local application of 5 M NaCl solution on the corneal surface of the eye produced a significant nociceptive behavior, characterized by eye wiping. The number of eye wipes was counted during the first 30 s. The sc (0.25, 0.5 and 1 mg/kg) and icv (1.25, 2.5, 5 and 10 μg) injections of physostigmine significantly (p < 0.05) decreased the number of eye wipes. Atropine and hexamethonium at (2 mg/kg, sc and 20 μg, icv) had no effects when used alone, however, atropine, but not hexamethonium prevented the antinociception induced by physostigmine (sc and icv). The results of this study indicate that the central muscarinic, but not nicotinic receptors might be involved in the antinociceptive effect of physostigmine in the acute corneal model of pain in rats.     

Effects of dehydroepiandrosterone (DHEA) on ubiquinone and catalase in the livers of male F-344 rats

The adrenal steroid, dehydroepiandrosterone (DHEA) acts as a peroxisome proliferator in the rodents. The present study examined the effects on cellular antioxidants ubiquinone and catalase in the liver of DHEA-treated rats. When administered to male F-344 rats for 8 weeks, DHEA produced a significant increase in hepatic ubiquinone-9 and lipid peroxide levels while no change was observed after 2 weeks. Activity of catalase, in contrast, followed an inverse pattern, being significantly induced at 2 weeks with a return to normal levels after 8 weeks. A marked reduction of ubiquinone-10 in DHEA-treated rat livers was only observed after 2 weeks. These findings indicate the potentials of high dose DHEA to modulate ubiquinone in rat hepatic tissue.     

脱氢表雄酮对大鼠骨关节炎影响的实验研究

目的：研究脱氢表雄酮(DHEA)对大鼠实验性骨关节炎(OA)的影响。方法：40只大鼠随机分4组：正常对照组、模型对照组、DHEA大、小剂量组。除正常对照组外，其余3组右膝木瓜蛋白酶关节腔注射法建立OA模型。然后DHEA大、小剂量组两组右膝分别关节腔注射50μmmol·L~(-1)和100μmol·L~(-1)的DHEA溶液150μl，正常对照组、模型对照组两组右膝均注入生理盐水150μl，每周2次，注射5周。6周后处死大鼠，大体形态学、组织学、生化及免疫组化的方法评价关节软骨情况。结果：手术显微镜下观察，见DHEA大、小剂量组两组软骨损害均较模型对照组明显减轻。DHEA大、小剂量组Mankin’s评分、关节腔冲洗液一氧化氮含量、滑膜丙二醛含量及关节软骨基质金属蛋白酶-1和9的表达均较模型对照组显著降低，DHEA大剂量组上述指标均较DHEA小剂量组显著降低。且两组关节腔冲洗液和血清超氧化物歧化酶活性均较模型对照组显著升高，DHEA大剂量组上述指标升高均较DHEA小剂量组更明显。结论：DHEA对OA软骨有保护作用，且存在剂量依赖性，保护机制可能是抑制关节软骨基质金属蛋白酶表达、减少一氧化氮释放和增强抗氧化作用。     

Sex differences in the pharmacokinetics of dehydroepiandrosterone (DHEA) after single- and multiple-dose administration in healthy older adults

The pharmacokinetics of exogenously administered DHEA have not been well characterized despite its increasing use in therapeutic and research investigations. The purpose of this study was to evaluate the pharmacokinetics of DHEA and its sulfated metabolite (DHEA-S) after single- and multiple-dose oral administration of DHEA 200 mg. Healthy older adult volunteers (7 women, 6 men) ages 65 to 79 years were studied on five visits separated by 1 week. Subjects received daily administration of placebo (days 1 to 7), DHEA 200 mg (days 8 to 22), and placebo (days 23 to 29). Blood samples were collected over 24 hours on days 1, 8, 15, 22, and 29 for DHEA and DHEA-S determinations by RIA. Pharmacokinetic parameter estimates were calculated by noncompartmental methods. Administration of DHEA 200 mg resulted in higher DHEA Cmax, AUC, and overall concentrations in women than in men (p < 0.03); DHEA-S parameter estimates were similar between men and women. Following a single dose of DHEA 200 mg, DHEA concentrations increased 5- to 6-fold in both men and women, and DHEA-S concentrations increased 5-fold in men and 21-fold in women relative to endogenous concentrations. The results of this study indicate that the pharmacokinetics of DHEA differ between older men and women.     

酒精依赖和戒断时大鼠奖赏回路不同脑区脱氢表雄酮及其硫酸酯水平的变化

目的：采用大鼠酒精依赖模型，观察酒精依赖及戒断对大鼠伏隔核、前额叶皮质、杏仁核、海马中神经甾体脱氢表雄酮（DHEA）、脱氢表雄酮硫酸酯（DHEAS）水平的影响。方法：大鼠通过自由饮含6％的乙醇溶液连续42d形成酒精依赖，并撤除酒精使自然戒断。断头取脑分离取出伏隔核、前额叶皮质、杏仁核、海马脑区。使用液一液萃取和固相萃取两步法提取脑组织中的DHEA、DHEAS，以高效液相色谱一质谱联用法测定神经甾体含量。结果：与对照组相比，酒精依赖大鼠伏隔核DHEA、DHEAS的水平显著降低（P〈0．05），海马DHEAS的水平显著升高（P〈0．05）；酒精戒断6h大鼠伏隔核DHEA、DHEAS、额叶皮质DHEAS的水平均显著降低（P〈0．05）；酒精戒断24h大鼠杏仁核DHEA、额叶皮质DHEAS水平显著上升（P〈0．05），伏隔核、杏仁核DHEAS的水平显著下降（P〈0．01）。结论：酒精依赖形成和戒断对伏隔核、前额叶皮质、杏仁核、海马中的神经甾体水平具有不同影响。     

Toxicology and toxicokinetics of acute and subchronic administration of histamine dihydrochloride in rats

Histamine dihydrochloride is currently being evaluated as an adjuvant to immunotherapy regimens in neoplastic and infectious diseases. The no-observed-effect-level (NOEL), no-observable-adverse-effect-level (NOAEL), and pharmacokinetics of subcutaneously administered histamine dihydrochloride were determined via 5 and 28 day repeated dose studies in Sprague-Dawley rats. In the five day study, male rats received 0 (vehicle), 5, 30, 500, or 1000 mg/kg BID. Acute tissue damage was observed at one or more injection sites in the two highest dose groups after 24 h. At five days, animals in these groups displayed indications of pathological inflammation at the injection sites. In the 28 day study, male and female rats received 0 (vehicle), 0.5, 5, or 100 mg/kg BID. The most significant treatment-related pathological findings were signs of inflammation at the injection sites for animals in the 100 mg/kg BID group. Hematology and clinical chemistry changes in the highest dose groups in both studies were consistent with inflammation and anemia but were found to be reversible following a 14-day recovery. Plasma histamine levels were quantified from male and female animals receiving 0.5, 5, and 100 mg/kg injections on Day 1 and 28 of the twenty-eight day study. Cmax was achieved within 0.25 h and was dose-proportional. The elimination half-life and tmax were longer at the 100 mg/kg dose than the lower doses. No marked differences between genders or between Day 1 and 28 were found. Based on these findings, the NOEL and NOAEL were established at 0.5 mg/kg BID and 5 mg/kg BID, respectively. When converted to human equivalent dose, the NOAEL is 0.81 mg/kg which is 54 times the intended human dose. These studies support a wide safety margin for histamine dihydrochloride.     

Stimulation of Sigma-1 receptor signaling by dehydroepiandrosterone ameliorates pressure overload-induced hypertrophy and dysfunctions in ovariectomized rats

Objective: Decreased dehydroepiandrosterone (DHEA) levels are associated with endothelial dysfunction and increased cardiovascular mortality in postmenopausal women. We investigated the role of DHEA, also known as sigma-1 receptor (Sig-1R) agonist, in myocardial hypertrophy, cardiac functional recovery and defined mechanisms of cardioprotective action. Methods: Wistar rats subjected to bilateral ovariectomy (OVX) were further treated with abdominal aortic stenosis. DHEA (15 and 30 mg/kg) was administered orally once a day for 14 days starting from 2 weeks after aortic banding. Results: Time course study indicated that left ventricle (LV) weight:body weight (BW) ratio increased time-dependently from 1 to 4 weeks after pressure-overload (PO) with significant inversed regulation of Sig-1R expression. Treatment with the Sig-1R agonist, DHEA, significantly attenuated PO-induced myocardial hypertrophy with increased expression of Sig-1R in the LV. DHEA also attenuated hypertrophy-induced impaired LV end diastolic pressure, LV developed pressure and LV contractility (± dp/dt_max). DHEA treatment significantly restored PO-induced impaired eNOS and Akt activity in the LV. Conclusion: We report, for the first time to our knowledge, the potential role of Sig-1R expression in the heart to attenuate PO-induced hypertrophy in ovariectomized rats. DHEA treatment protects against PO-induced cardiac injury via upregulation of Sig-1R and stimulation of Sig-1R-mediated Akt-eNOS signaling.     

Neurobehavioural study of subchronic administration of oxydemeton-methyl (insecticide and acaricide) in rats

Oxydemeton-methyl, an organophosphate insecticide and acaricide produced decrease in the exploratory behaviour and prolongation of barbitone sodium induced hypnosis in rats after intermittent aerosol spray inhalational exposure, for 1/2 hour daily for 7 consecutive days, compared to the saline control group. Further, ED50 +/- SEM value for haloperidol induced catalepsy, CD50 +/- SEM value for pentylenetetrazole induced seizure and CI50 +/- SEM value for electroshock (i.e. the dose of haloperidol, PTZ and intensity of electroshock producing catalepsy or positive seizure response in 50% of rats) were significantly decreased after 7 days exposure to oxydemeton-methyl compared to that of saline control group. The study has established the central nervous system depressant effect, extrapyramidal effect and proconvulsant potential of oxydemeton-methyl which is widely used by the agricultural workers in the form of field spray.     

Dose-independent pharmacokinetics of torasemide after intravenous and oral administration to rats

After intravenous (at doses of 1, 2, 5, and 10 mg/kg) and oral (at doses of 1, 5, and 10 mg/kg) administration of torasemide, the pharmacokinetic parameters were dose-independent. Hence, the extent of absolute oral bioavailability (F) was also independent of oral doses; the values were 95.6, 98.8, and 97.3% for oral doses of 1, 5, and 10 mg/kg, respectively. The high F values indicated that the first-pass (gastric, intestinal, and hepatic) effects of torasemide in rats could be almost negligible. After intravenous administration, the total body clearances of torasemide were extensively slower than the reported cardiac output in rats and hepatic extraction ratio was only 3-4% suggesting almost negligible first-pass effects of torasemide in the heart, lung, and liver in rats. Based on in vitro rat tissue homogenate studies, the tissues studied also showed negligible metabolic activities for torasemide. Equilibrium of torasemide between plasma and blood cells of rat blood reached fast and plasma-to-blood cells concentration ratio was independent of initial blood concentrations of torasemide, 1, 5, and 10 microg/ml; the mean value was 0.279. Protein binding of torasemide to fresh rat plasma was 93.9 +/- 1.53% using an equilibrium dialysis technique.     

Oral opioid administration and hyperalgesia in patients with cancer or chronic nonmalignant pain

AIMS: Previous research has reported on reduced paw withdrawal latencies to heat and mechanical stimuli after parenteral administration of opioids in animals and on increased pain sensitivity in humans subsequent to postoperative infusions of short-acting opioids or in drug addicts. The aim of the present study was to explore the possibility that oral opioid treated patients with cancer-related or chronic nonmalignant pain differ in their pain sensitivity from patients treated with non-opioid analgesics. METHODS: The study population consisted of 224 patients, including 142 in the opioid-treated group and 82 in the non-opioid-treated group. Pain thresholds for punctuate measured by von Frey filaments (g), mechanical pressure measured by pressure algometer (mmHg), heat stimuli measured by quantitative sensory testing (degrees C), as well as suprathreshold tonic heat pain intensity (46.5 degrees C for 1 min) measured by 0-10 numerical pain scale (NPS) were obtained at a nonpainful site (thenar eminence) in all patients. RESULTS: No differences between the groups were found for gender, age, duration of pain, or duration of treatment (independent variables). No significant differences between the groups were found in punctuate (difference = 17.0 g (95% CI -8.8, 42.8), P = 0.19), pressure (2.2 mmHg (-28.7, 33.2), P = 0.89) and heat (-0.3 degrees C (-1.5, 0.9), P = 0.70) pain thresholds, or in suprathreshold heat pain intensity (difference between maximal pain intensities -0.4 NPS units (95% CI -1.2, 0.4), P = 0.31). Pearson correlations within the opioid-treated group failed to show significant relationships between any of the independent variables and the outcome measures. A further comparison of the outcomes between the 'weak' opioid-treated subgroup and the 'strong' opioid-treated subgroup again revealed insignificant results. CONCLUSIONS: These results suggest that the administration of 'commonly used' dosages of oral opioids does not result in abnormal pain sensitivity beyond that of patients receiving non-opioid analgesia.     

Evaluation of the effects of subchronic oral administration of n-butyl maleate in Sprague-Dawley rats

n-Butyl maleate, also referred to as monobutyl maleate, is an ester of maleic acid, which is used as a counterion in the pharmaceutical industry. While substantial published data exist on short-term treatment, maleic acid-induced renal toxicity in the rat, no toxicity data are available on the monobutyl ester. This study evaluated the oral subchronic nephrotoxicity potential of n-butyl maleate administered to Sprague-Dawley rats (10/males and females/group) at doses of 0 (vehicle control), 10, 30, or 60 mg/kg/d for 2 wk. Statistically significant elevations in organ weights were noted in males at 60 mg/kg/d and included: (a) increases in absolute heart, kidney, and liver weights; (b) increased liver to body weight ratios; and (c) increased heart, kidney, liver, spleen, and epididymides to brain weight ratios. In females, statistically significant increases in organ weights were limited to increases in adrenal to brain weights at > or = 10 mg/kg/d, kidney to brain weights at > or = 30 mg/kg/d, and kidney to body weight and liver to brain weight ratios at 60 mg/kg/d. There were no macroscopic or microscopic pathology changes observed in any of the tissues examined. Importantly, light microscopic examination of the kidney was unremarkable at the end of the 2-wk dosing period with n-butyl maleate. Although lacking a histopathological correlate, resultant increases in organ weights at 60 mg/kg/d might be considered indicative of an adverse effect. However, renal perturbation induced by n-butyl maleate was mild in comparison to maleic acid-induced renal toxicity, which manifested as impaired tubular resorption and necrosis of the proximal tubules at doses > or = 60 mg/kg/d. The no-observed-adverse-effect level (NOAEL) for the study was 30 mg/kg/d.     

Enhancement of oral bioavailability of paclitaxel after oral administration of Schisandrol B in rats

Paclitaxel is a substrate of the efflux transporters such as P‐glycoprotein, and is mainly metabolized by the liver. Schisandrol B (Sch B), one of the active components in Schisandra, has been reported to be able to inhibit the activity of P‐gp and CYP3A. It might be possible that Sch B would alter the pharmacokinetic behavior of paclitaxel. Therefore, the purpose of this study was to investigate the effect of Sch B on the pharmacokinetics of paclitaxel administered orally and intravenously in rats. Paclitaxel were administered to rats orally (30 mg/kg) or intravenously (0.5 mg/kg) with or without the concomitant administration of Sch B (10 or 25 mg/kg). Oral pharmacokinetic parameters of paclitaxel were significantly altered when pretreated with Sch B. There were significant increases in AUC_0‐24h (from 297.7±110.3 to 838.9±302.1 h*ng/ml; p<0.05) and C_max (from 51.7±20.1 to 136.4±35.5 ng/ml; p<0.05) in the presence of Sch B (25 mg/kg). The pharmacokinetic parameters for i.v. paclitaxel were not significantly affected by Sch B in contrast to that of oral administration. Since the presence of Sch B enhanced the systemic exposure of paclitaxel, their pharmacokinetic interaction should be taken into consideration. As the oral bioavailability of paclitaxel was increased about 3‐fold in the presence of Sch B, the concomitant use of Sch B may provide a benefit in the oral delivery of paclitaxel. Copyright © 2010 John Wiley & Sons, Ltd.     

Pharmacokinetics and pharmacodynamics of furosemide after intravenous and oral administration to spontaneously hypertensive rats and DOCA-salt-induced hypertensive rats

The pharmacokinetics and pharmacodynamics of furosemide were investigated after intravenous (i.v.), 1 mg/100 g body weight, and oral administration, 2 mg per 100g body weight, to spontaneously hypertensive rats (SHRs) and deoxycorticosterone acetate-salt-induced hypertensive rats (DOCA-salt rats). After i.v. administration, the 8 h urinary excretion of furosemide/g kidney (397 versus 572 μg) was significantly lower and the non-renal clearance (5.78 versus 3·94 ml min^?1 kg^?1) was significantly faster in SHRs of 16 weeks of age than in age-matched control Wistar rats. This suggested that the nonrenal metabolism of furosemide could be faster in SHRs of 16 weeks of age than in age-matched control Wistar rats, and this could be supported by the significantly greater amount of 4-chloro-5-sulphamoyl anthranilic acid, a metabolite of furosemide, excreted in 8 h urine as expressed in terms of furosemide (11·1 versus 4·79% of the i.v. dose) in SHRs. It could also be supported at least in part by a study of liver homogenate; the amount of furosemide remaining per gram of liver after 30 min incubation of 50μg of furosemide with the 9000g supernatant fraction of liver homogenate was significantly smaller (40·4 versus 43·7μg) in SHRs of 16 weeks of age than in age-matched Wistar rats. The greater metabolic activity of furosemide in liver may also be supported by the result that the amount of hepatic cytochrome P-450 (0·7013 versus 0·5186 nmol/mg protein) and the weights of liver (3·52 versus 2·93% of body weight) were significantly greater in SHRs of 16 weeks of age than in age-matched Wistar rats. After i.v. administration of furosemide, the 8 h urine output (9·93 versus 16·5 ml) and 8 h urinary excretion of sodium (1·21 versus 2·05 mmol) and chloride (1·37 versus 2·17 mmol) per gram of kidney in SHRs of 16 weeks of age were lower than those in age-matched Wistar rats, this could be due to the significantly smaller amount of furosemide excreted in 8 h urine per gram of kidney. After oral administration, the pharmacokinetics and pharmacodynamics of furosemide were not significantly different between SHRs and the control Wistar rats of 16 weeks of age. After i.v. and oral administration of furosemide, there were no significant differences in the pharmacokinetics and pharmacodynamics between DOCA-salt rats and control SD rats of 16 weeks of age except for the significantly lower urinary excretion of potassium per gram of kidney in DOCA-salt rats. On the other hand, the 8 h urinary excretion of furosemide and non-renal clearance were not significantly different between SHRs of six weeks of age and age-matched control Wistar rats after i.v. administration of furosemide. Since the non-renal metabolism of furosemide was not faster in either DOCA-salt rats of 16 weeks of age or SHRs of six weeks of age than that in the respective age-matched control group, the faster non-renal metabolism of furosemide in SHRs of 16 weeks of age could be due to the physiological factor from the chronic phase of hypertension in SHRs, and could not be due solely to the heredity of SHRs or the hypertensive state itself.     

Assessing cortisol and dehydroepiandrosterone (DHEA) in saliva: effects of collection method

An increasing number of studies are utilizing saliva sampling as a method of assessing adrenal steroid secretion. Saliva samples have certain advantages over plasma, being non-invasive and easily collected. However, some methods of collection may compromise the accuracy of the assay, particularly those which employ aids to stimulate saliva production. We sought to compare the accuracy of cortisol and dehydroepiandrosterone (DHEA) measurement by examining the association between plasma levels, saliva and saliva collected using a citric acid-treated salivette device. Twenty six healthy male volunteers were recruited for the study. To increase the range of steroid levels in the samples collected, half the subjects were pre-treated with hydrocortisone (20mg, twice a day for 7 days) and half with placebo. Saliva samples were then collected from each subject using both a 'passive drool' method and a citric acid-treated salivette. A plasma sample was also collected. Cortisol and DHEA levels were measured by radioimmunoassay. For cortisol levels, both methods of saliva collection correlated highly with plasma levels and with each other (r 0.85; R(2) 0.72 for all). For DHEA levels, only saliva samples collected using the unstimulated collection method correlated with plasma levels. DHEA collected using the salivette device did not correlate significantly with either plasma or the unstimulated saliva (r 0.2;R(2) 0.04). It is crucial that future studies are aware of these issues and are cognizant of the effects of the method of collection when examining steroid levels in saliva.     

A subchronic oral toxicity study on pyrroloquinoline quinone (PQQ) disodium salt in rats

A subchronic oral toxicity study on pyrroloquinoline quinone (PQQ) disodium salt was performed in rats. Sprague-Dawley rats were randomly divided into four groups (10 rats/sex/group) and administered with PQQ disodium salt at doses of 0 (control), 100, 200 and 400 mg/kg bw/day by gavage for 13 weeks. Daily clinical observations and weekly measurement of body weights and food consumption were conducted. Blood samples were obtained on day 46 and day 91 for measurement of hematology and serum biochemical parameters. Animals were euthanized for necropsy, selected organs were weighted and recorded. Histological examination was performed on all tissues from animals in the control and PQQ disodium salt treatment groups. No mortality or toxicologically significant changes in clinical signs, body weight, food consumption, necropsy findings or organ weights was observed. Differences between treated and control groups in some hematological and serum biochemical examinations and histopathological examination were not considered treatment-related. The no-observed-adverse-effect-level (NOAEL) of PQQ disodium salt in rats was considered to be 400 mg/kg bw/day for both sexes, the highest dose tested.