A simple method for determining the rate of gastrointestinal transit in the rat

A Rat Immobilization Model Based on Cage Volume Reduction: A Physiological Model for Bed Rest?

Bed rest has been an established treatment in the past prescribed for critically illness or convalescing patients, in order to preserve their body metabolic resource, to prevent serious complications and to support their rapid path to recovery. However, it has been reported that prolonged bed rest can have detrimental consequences that may delay or prevent the recovery from clinical illness. In order to study disuse-induced changes in muscle and bone, as observed during prolonged bed rest in humans, an innovative new model of muscle disuse for rodents is presented. Basically, the animals are confined to a reduced space designed to restrict their locomotion movements and allow them to drink and eat easily, without generating physical stress. The animals were immobilized for either 7, 14, or 28 days. The immobilization procedure induced a significant decrease of food intake, both at 14 and 28 days of immobilization. The reduced food intake was not a consequence of a stress condition induced by the model since plasma corticosterone levels –an indicator of a stress response– were not altered following the immobilization period. The animals showed a significant decrease in soleus muscle mass, grip force and cross-sectional area (a measure of fiber size), together with a decrease in bone mineral density. The present model may potentially serve to investigate the effects of bed-rest in pathological states characterized by a catabolic condition, such as diabetes or cancer.

Evaluation of hepatobiliary excretion and enterobiliary reflux in rats with biliary obstruction submitted to bilioduodenal or biliojejunal anastomosis

Bilioduodenal and biliojejunal anastomoses are effective for the treatment of biliary obstruction. The objective of this study was to compare the effects of these anastomoses on hepatobiliary excretion and enterobiliary reflux. Enterobiliary reflux and biliary excretion were evaluated respectively after oral administration of technetium ((99m)Tc) in combination with sodium phytate and intravenous infusion of (99m)Tc with diisopropyl-iminodiacetic acid. Enterobiliary reflux occurred to an equal degree in the bilioduodenal and biliojejunal groups. Maximum hepatic activity time (T(max)) and radiotracer clearance half-time (T(1/2)) were similar in both groups. However, when compared with that found for the sham-operated group, T(max), and T(1/2) were higher in the biliojejunal group (P = 0.02 and P = 0.01, respectively). Histopathological analysis showed marked reduction in ductal proliferation in both groups. These data undermine the theoretical advantages attributed to biliojejunal anastomosis and further the understanding of the pathophysiology of cholangitis that occurs even with patent anastomosis.

Ethnopharmacology, phytochemistry and pharmacology: a successful combination in the study of Croton cajucara

Phytochemical and pharmacological studies of Croton cajucara were oriented by traditional medicine. The stem bark of the mature plant is a rich source of clerodane-type diterpenes: trans-dehydrocrotonin (DCTN), trans-crotonin (CTN), cis-cajucarin B, cajucarin A, cajucarinolide and two novel clerodanes, trans-cajucarin B and sacacarin. In young (18-month-old) plants, the triterpene acetyl aleuritolic acid (AAA) was the major stem bark component and in these the diterpene DCTN was not present. The highest concentration of DCTN (1.4% of dry bark) was detected in 4-6 year-old plants, while 3-year-old plants contained only 0.26% of this diterpene. Three steroids (beta-sitosterol, stigmasterol and sitosterol-3-O-beta-glucoside), two flavonoids (kaempferol 3,4', 7-trimethyl ether and 3,7-dimethyl ether) and one diterpene (cajucarinolide) were isolated from the leaves of this Croton. The main pharmacological activity was correlated with DCTN. This clerodane produced anti-inflammatory and antinociceptive effects and a significant hypoglycemia in alloxan-induced diabetic rats. The compound also reduced the index of gastric lesions induced by restraint-in-cold. Dose-related DCTN and CTN inhibited in vivo the basal acid secretion in pylorus-ligature rats and oxyntic glands isolated from rabbit gastric mucosa, DCTN, CTN or AAA decreased in vitro uptake basal acid secretion induced by histamine and measured with the 14C-aminopyrine uptake method. Uniquely DCTN inhibited 14C-AP uptake induced by bethanechol. The terpenoids, DCTN and AAA, and the chloroform extract of 6-month-old plants reduced gastrointestinal transit in mice. The effects of DCTN and CTN on the survival of mice bearing Sarcoma 180 and Ehrlich carcinoma ascitic tumors, on the proliferation of cultured cells and TNFalpha were determined. DCTN was also evaluated for a possible antioestrogenic activity using the immature rat as a model system for bioassay of oestrogen and for an anti-implantation effect in regularly cycling rats. The biological experiments, using the plant extracts and the terpenoids DCTN, CTN and AAA, are herein discussed.