The young Göttingen minipig as a model of childhood and adolescent obesity: influence of diet and gender.

OBJECTIVE: Gender and sex hormones influence the development of obesity and metabolic syndrome in humans and Göttingen minipigs. The aim of this study was to investigate possible gender differences in the metabolic response to a high energy diet in young Göttingen minipigs as a model of childhood/adolescent obesity. DESIGN AND METHODS: Nine-week-old male and female Göttingen minipigs were fed restrictedly on either a low energy diet (LED) or a high energy diet (HED) for 4 months (n = 5-7). Parameters of interest were fat percentage, visceral fat mass, plasma lipids and glucose tolerance, insulin resistance, and ß-cell function measured by oral and intravenous glucose tolerance tests. RESULTS: At 11 to 12 weeks of age, after 2 weeks diet feeding, both genders on HED had increased fat percentage, glucose intolerance, decreased insulin sensitivity, and increased plasma levels of cholesterol and triglycerides (TGs). There was no gender difference in body weight (BW) or fat percentage, but males had lower glucose tolerance than females. After 3.5 to 4 months on the diets, the pigs on HED had increased BW, fat percentage, and visceral fat mass and were more glucose intolerant and insulin resistant than pigs on LED. Also increases in plasma cholesterol and TG levels were observed in the pigs on HED. Females had higher fat percentage and more visceral fat, were more insulin resistant, and had a more unfavorable lipid profile compared with males independent of diet. CONCLUSION: In conclusion, the young Göttingen minipig, and especially the female gender, seems to be a potential model for diet induced childhood/adolescent obesity and metabolic syndrome.

Influence of castration-induced testosterone and estradiol deficiency on obesity and glucose metabolism in male Göttingen minipigs.

Low testosterone and estradiol concentrations are predictive for the development of the metabolic syndrome in men and women, respectively. The aim of this study was to investigate the influence of sex hormone deficiency on food intake, body weight, body composition and glucose metabolism in male Göttingen minipigs. Five adult male Göttingen minipigs were studied before castration (pre-cast), 10-18 days (post-cast 1) and 10-11 weeks (post-cast 2) after castration. Parameters of interest were food intake, body weight, body fat percentage and sex hormone concentrations. Furthermore glucose tolerance, glucagon suppression, insulin resistance, beta cell function and disposition index were evaluated by oral and intravenous glucose tolerance tests. Castration led to almost complete disappearance of circulating testosterone and estradiol and secondarily to increased food intake, body weight and body fat percentage. Ten-eighteen days sex hormone deficiency (post-cast 1) did not significantly change any of the investigated metabolic parameters compared to pre-cast levels. Ten weeks after castration (post-cast 2) significant insulin resistance, glucose intolerance and hyperglucagonemia was found, and the beta cell function and the disposition index both were decreased. In conclusion, castration-induced sex hormone deficiency in male Göttingen minipigs results in hyperphagia, obesity and disturbed glucose metabolism, which are some of the features typical for the human metabolic syndrome.

Gender-associated differences in metabolic syndrome-related parameters in Göttingen minipigs.

Gender-associated differences in pathophysiology and treatment of disease are an evolving area in human medicine that should be addressed in animal models. The aim of this study was to characterize gender differences in metabolic parameters of Göttingen minipigs and to determine which gender has the metabolic profile that is most appropriate as a model for human metabolic syndrome. Blood samples were collected from fasted, lean male and female Göttingen minipigs at 8 wk and 8 mo of age. Samples were analyzed for glucose, fructosamine, insulin, C-peptide, glucagon, triglycerides, total cholesterol, high-density lipoprotein cholesterol (HDL-c), free fatty acids, leptin, testosterone, and 17beta-estradiol. Insulin sensitivity and beta cell function were estimated by homeostasis model assessment and degree of obesity by measuring the abdominal circumference. Male minipigs had higher concentrations of both testosterone and estradiol. Female minipigs had a larger abdominal circumference and higher concentrations of C-peptide, insulin, triglyceride, total cholesterol, HDL-c and leptin but a lower concentration of free fatty acids and lower HDL-c:total cholesterol ratio. Compared with male minipigs, female minipigs were more insulin-resistant and had a higher beta-cell function. No gender-associated differences were found in any of the other investigated parameters. In conclusion, female minipigs were more obese and insulin-resistant and had a more atherogenic plasma profile than did their male counterparts and therefore may be better models for metabolic syndrome. Their high concentrations of both testosterone and estradiol may protect male minipigs from obesity and metabolic disturbances.

Nociception after intraperitoneal injection of a sodium pentobarbitone formulation with and without lidocaine in rats quantified by expression of neuronal c-fos in the spinal cord--a preliminary study.

After a search on Medline, it appears that intraperitoneal injection of sodium pentobarbitone is often used for anaesthesia and euthanasia of rodents. In the present pilot study in rats, spinal nociception after intraperitoneal injection of sodium pentobarbitone, with and without lidocaine, was examined by estimation of the number of c-fos-expressing neurones in the spinal dorsal horn. One group of rats received an intraperitoneal injection of 0.4 mL/kg sodium pentobarbitone (100 mg/mL; n=4). Another group of rats received a similar intraperitoneal injection of sodium pentobarbitone formulated with lidocaine 10 mg/mL (n=4); a control group received a similar intraperitoneal injection of 0.9% saline (n=4). After 3 h, the animals were re-anaesthetized and perfused with 4% formaldehyde, and the spinal cord was collected and processed by immunohistochemistry for stereological quantification of the number of neurones with c-fos-like immunoreactivity (FLI). Intraperitoneal injection of the sodium pentobarbitone formulation caused a significantly increased number of neurones with FLI in the spinal cord (3930+/-247; mean+/-SEM; P<0.001) compared with the saline control group (765+/-131). The lidocaine added to the sodium pentobarbitone formulation significantly reduced the number to 2716+/-393 (P<0.05). In conclusion, intraperitoneal injection of sodium pentobarbitone caused a significant increase in nociception which was lowered by adding lidocaine to the formulation, although it was still significantly higher than the control level. Further studies are needed with the aim of optimizing the lidocaine concentration and also to examine the effect of the combination of lidocaine with a long-acting local anaesthetic agent, e.g. bupivacaine.

Capsaicin-sensitive sensory fibers in the islets of Langerhans contribute to defective insulin secretion in Zucker diabetic rat, an animal model for some aspects of human type 2 diabetes.

The system that regulates insulin secretion from beta-cells in the islet of Langerhans has a capsaicin-sensitive inhibitory component. As calcitonin gene-related peptide (CGRP)-expressing primary sensory fibers innervate the islets, and a major proportion of the CGRP-containing primary sensory neurons is sensitive to capsaicin, the islet-innervating sensory fibers may represent the capsaicin-sensitive inhibitory component. Here, we examined the expression of the capsaicin receptor, vanilloid type 1 transient receptor potential receptor (TRPV1) in CGRP-expressing fibers in the pancreatic islets, and the effect of selective elimination of capsaicin-sensitive primary afferents on the decline of glucose homeostasis and insulin secretion in Zucker diabetic fatty (ZDF) rats, which are used to study various aspects of human type 2 diabetes mellitus. We found that CGRP-expressing fibers in the pancreatic islets also express TRPV1. Furthermore, we also found that systemic capsaicin application before the development of hyperglycemia prevents the increase of fasting, non-fasting, and mean 24-h plasma glucose levels, and the deterioration of glucose tolerance assessed on the fifth week following the injection. These effects were accompanied by enhanced insulin secretion and a virtually complete loss of CGRP- and TRPV1-coexpressing islet-innervating fibers. These data indicate that CGRP-containing fibers in the islets are capsaicin sensitive, and that elimination of these fibers contributes to the prevention of the deterioration of glucose homeostasis through increased insulin secretion in ZDF rats. Based on these data we propose that the activity of islet-innervating capsaicin-sensitive fibers may have a role in the development of reduced insulin secretion in human type 2 diabetes mellitus.

Oxidants and antioxidants in disease: oxidative stress in farm animals.

Important infectious diseases in farm animals, such as pneumonia and enteritis, are thought to be associated with the so-called oxidative stress, i.e. a chemical phenomenon involving an imbalance in the redox status of the individual animal. The specifics of oxidative stress and how it may result in disease or be prevented are complex questions with no simple answers. However, the considerable literature on the subject suggests that many researchers consider oxidative stress-related mechanisms to be important early events in disease development. A particularly intriguing aspect is that, at least theoretically, oxidative stress should be easily prevented with antioxidants yet the use of antioxidants as therapy remains controversial. The present knowledge on oxidative stress in farm animals is the topic of this review.

Spinal nociception induced by intramuscular injection of oxytetracycline preparations in rats and pigs.

Some drug formulations for intramuscular use may cause damage, which potentially can be associated with pain. In animals, spinal nociception can be assessed by stereological quantification of number of regional dorsal horn neurones containing intranuclear Fos-protein as a consequence of expression of the c-fos gene. The aim of the present study was to use c-fos gene expression as a measure of nociceptive input after intramuscular injection of different oxytetracycline formulations. Rats were given a 0.3 ml intramuscular injection in the thigh of one of two 100 mg/ml oxytetracycline preparations (Maxicyklin Vet., Boehringer-Ingelheim or Engemycin Vet., Intervet; n=6 for both), 0.9% saline (n=4) or 4% formalin (n=2). In addition, five pigs were given an intramuscular injection of Aquacykline Vet. (Rosco) in a dose of 1.0 ml/10 kg. After three hours the animals were anaesthetised and perfusion fixed and their spinal cords were taken out. Cryostate sections of the spinal cords were stained immunohistochemically for Fos-protein in dorsal horn neurones and then subjected to stereological quantification of Fos-positive neurones. Rats receiving a saline injection had 905+/-586 (mean+/-S.D.) Fos-positive neurones, whereas formalin injection increased this number to 11,091+/-4,825. Rats receiving an injection of Engemycin had 1,932+/-893 Fos-positive neurones, which was not significantly different from the saline group. In contrast, injection with Maxicyklin increased the number of Fos-positive neurones to 5,488+/-3,116, which was higher than after injection of saline (P<0.05). In pigs receiving an Aquacyklin injection, the number of Fos-positive neurones was 3,493+/-2,027, which was not significantly higher than the previously determined basal level. The increased neuronal activation after intramuscular injection of Maxicyklin Vet. may suggest that injection of this drug may be more painful than injection with saline. In contrast, no significant difference in neuronal activation caused by saline and Engemycin Vet. was found.

The minipig in toxicology.

The use of pigs (Sus scrofa) in biomedical research is well established in particular in surgical and physiological research. For years both pigs and minipigs have been used in pharmacology and toxicology to answer specific questions when the more conventional species have been found unsuitable. The development of minipigs has resulted in strains of more manageable size than the domestic pig. Because of their well-accepted physiological and other similarities to humans, minipigs are becoming increasingly attractive toxicological and pharmacological models. There are several strains of minipigs (Göttingen, Yucatan, Sinclair, Hanford and other). This presentation is based on experience primarily with the Göttingen minipigs. In toxicology in Europe minipigs have become very popular for pharmaceutical studies in place of dogs and primates. Minipigs have been shown to be sensitive to a wide variety of drugs and chemicals. It has become obvious that minipigs can be used for all routes of administration, and in many cases are preferable to dogs or primates for metabolic or pharmacological reasons. There are advantages over the traditional non-rodent species in relation to specific responses to particular drug classes. Their use in general toxicology testing employing the continuous intravenous infusion, dermal or inhalation route has been described in detail in the literature. Background data on toxicological endpoints (ophthalmology, clinical pathology, ECG, organ weight, histopathology and reproduction parameters) have been well-established allowing studies to be interpreted. In the context of this conference, histopathology and toxicopathology data of spontaneous or drug-induced origin are available in the scientific literature. Now there is good supply of high-quality minipigs of known disease status. There are advantages over the traditional non-rodent species in relation to the ethical difficulties of use of animals in biomedical research. Consequently, there are scientific, economic and sociological reasons that make minipigs good toxicological and pharmacological models. The principal disadvantage is that toxicity testing in minipigs may require more test compound than the traditional species.

Pharmacokinetics of amoxicillin administered in drinking water to recently weaned 3- to 4-week-old pigs with diarrhea experimentally induced by Escherichia coli O149:F4.

OBJECTIVE: To measure effects of Escherichia coli O149:F4-induced diarrhea on water consumption and pharmacokinetics of amoxicillin after administration in drinking water. ANIMALS: 24 recently weaned 24- to 28-day-old crossbred pigs. PROCEDURE: 10 pigs were inoculated with E. coli O149:F4; all 10 pigs subsequently developed diarrhea. Pigs were medicated by administration of amoxicillin in the drinking water (0.75 mg/mL) for a 4-hour period on 2 consecutive days. Fourteen age-matched noninfected healthy pigs (control group) were medicated in a similar manner. Blood samples were obtained from both groups daily, and plasma concentrations of amoxicillin were analyzed by use of high-performance liquid chromatography. RESULTS: Diarrhea reduced the area under the plasma concentration-versus-time curve (AUC) and maximum plasma concentration (C(max)) of amoxicillin on the first day of medication by 56% and 63%, respectively. The AUC of amoxicillin on the second day of medication for diarrheic pigs did not differ significantly from that of control pigs on the first day of medication. CONCLUSIONS AND CLINICAL RELEVANCE: E. coli-induced diarrhea reduced the AUC of amoxicillin and time that plasma concentration of amoxicillin was > 0.025 microg/mL and, hence, less likely to have a therapeutic effect on the first day of administration in drinking water. On the assumption that plasma concentrations may indirectly reflect concentrations at the site of infection, analysis of our results suggests that higher doses of amoxicillin may be appropriate for administration in drinking water during a 4-hour period on the first day that pigs have diarrhea attributable to E. coli O149:F4.

Experimental infection with Escherichia coli O149:F4ac in weaned piglets.

The outcome of experimental intestinal infections with enterotoxigenic Escherichia coli (ETEC) is dependent on several factors. An important factor is adhesion of the challenge strain to the intestinal mucosa. The test for susceptibility towards ETEC adhesion has so far been made by an intestinal adhesion test made after slaughter of piglets. However, in an experimental infection study with the purpose to obtain diarrhoeic piglets, it would be an advantage to test for susceptibility prior to experimentation. The Mucin 4 gene on porcine chromosome 13 has been proposed as a candidate gene for the production of the specific ETEC F4ab/ac receptor, and a DNA marker-based test has been developed to allow genotyping for ETEC F4ab/ac resistance/susceptibility [Jørgensen, C.B., Cirera, S., Archibald, A.L., Anderson, L., Fredholm, M., Edfors-Lilja, I., 2004. Porcine polymorphisms and methods for detecting them. International application published under the patent cooperation treaty (PCT). PCT/DK2003/000807 or WO2004/048606-A2]. The aim of this study was to test an experimental model for ETEC O149:F4ac-induced diarrhoea in piglets, selected for susceptibility towards ETEC O149:F4ac adhesion prior to experimentation using a DNA marker-based test. Sixty-two healthy 25-32 days old recently weaned Danish crossbred piglets were used. All piglets were tested prior to experimentation for susceptibility or resistance towards ETEC O149:F4ac adhesion. Thirty-nine piglets, both susceptible and resistant, were oro-gastric intubated with 10(9)CFU of ETEC O149:F4ac and 23 age-matched piglets, both susceptible and resistant, were used as non-infected controls. Of susceptible piglets, challenged with ETEC O149:F4ac, 74% had ETEC O149:F4ac-associated diarrhoea first day after first challenge, which were significantly higher relatively to the resistant and challenged piglets where 20% had diarrhoea (p=0.04). This study suggests a model for experimental ETEC induced diarrhoea.

Plasma calcitonin gene-related peptide is increased prior to obesity, and sensory nerve desensitization by capsaicin improves oral glucose tolerance in obese Zucker rats.

OBJECTIVE: It has earlier been demonstrated that capsaicin-induced desensitization improves insulin sensitivity in normal rats. However, whether increased capsaicin-sensitive nerve activity precedes the onset of insulin resistance in diet-induced obesity--and therefore might be involved in the pathophysiology--is not known. Further, it is of relevance to investigate whether capsaicin desensitization improves glycaemic control even in obese individuals and we therefore chose the obese Zucker rats to test this. DESIGN AND METHODS: Plasma levels of calcitonin gene-related peptide (CGRP; a marker of sensory nerve activity) was assessed in 8-week-old Zucker rats. To investigate whether capsaicin desensitization (100 mg/kg at 9 weeks of age) would also ameliorate glycaemia in this non-diabetic model, we assessed oral glucose tolerance at 7 weeks after capsaicin. RESULTS: It was found that plasma CGRP levels were elevated in obese Zucker rats prior to the onset of obesity (16.1+/-3.4 pmol/l in pre-obese Zucker rats vs 6.9+/-1.1 pmol/l in lean littermates; P = 0.015) despite similar body weights. Furthermore, capsaicin desensitization reduced both fasting blood glucose (4.3+/-0.2 mmol/l vs 5.1+/-0.2 mmol/l in controls; P = 0.050) as well as the mean blood glucose level during an oral glucose tolerance test (OGTT) (6.8+/-0.3 mmol/l vs 8.6+/-0.5 mmol/l in control obese rats; P = 0.024) whereas the plasma insulin levels during the OGTT were unchanged. However this did not lead to an improvement in insulin resistance or to a reduction of tissue triglyceride accumulation in muscle or liver. CONCLUSION: We concluded that capsaicin-induced sensory nerve desensitization improves glucose tolerance in Zucker rats. Since, in this study, plasma CGRP levels, a marker of sensory nerve activity, were increased in the pre-obese rats, our data support the hypothesis that increased activity of sensory nerves precedes the development of obesity and insulin resistance in Zucker rats.

Intramuscular injection of hypertonic saline: in vitro and in vivo muscle tissue toxicity and spinal neurone c-fos expression.

Intramuscular injection of hypertonic saline (4-6% NaCl) is widely used to induce muscle pain in volunteers. The quality of the pain is comparable to clinical muscle pain with localised and referred pain. The objective was to evaluate the muscle toxicity of hypertonic saline by characterisation of 1) cytotoxicity in vitro, 2) local muscle toxicity in rabbits and 3) number of spinal dorsal horn neurones expressing c-fos after intramuscular injection in pigs as an indicator of nociception. Rat myocyte cultures and erythrocyte suspensions were treated with hypertonic NaCl solutions. The creatine kinase activity remaining in the myocytes and haemolysis were measured. Groups of six rabbits were given an intramuscular injection of 0.5 ml of 0.9, 3 or 6% NaCl. Three days later, creatine kinase activity was determined in injection site muscle tissue and normal contralateral muscle. The amount of injection site muscle tissue totally depleted of creatine kinase was calculated. Groups of two pigs were given an intramuscular injection of 3.0 ml of 6% NaCl. The spinal cord was sampled 1, 2 or 3 hr later and processed for stereological quantification of the number of dorsal horn neurones expressing c-fos. Saline was not toxic in vitro at 0.9-6%, but toxic to erythrocytes at 7% or higher and rat myocytes at 15% or higher. No muscle toxicity was seen in rabbits. The number of dorsal horn neurones expressing c-fos was not above basal level. In conclusion, 6% saline caused no in vitro or in vivo toxicity in sensitive models. Consequently, the pain caused by intramuscular injection of hypertonic saline is most likely not related to tissue damage. Consistently, intramuscular injection of 6% NaCl did not activate dorsal horn neurones in pigs to express c-fos beyond basal level.

Sensory nerve inactivation by resiniferatoxin improves insulin sensitivity in male obese Zucker rats.

Recent studies have suggested that sensory nerves may influence insulin secretion and action. The present study investigated the effects of resiniferatoxin (RTX) inactivation of sensory nerves (desensitization) on oral glucose tolerance, insulin secretion and whole body insulin sensitivity in the glucose intolerant, hyperinsulinemic, and insulin-resistant obese Zucker rat. After RTX treatment (0.05 mg/kg RTX sc given at ages 8, 10, and 12 wk), fasting plasma insulin was reduced (P < 0.0005), and oral glucose tolerance was improved (P < 0.005). Pancreas perfusion showed that baseline insulin secretion (7 mM glucose) was lower in RTX-treated rats (P = 0.01). Insulin secretory responsiveness to 20 mM glucose was enhanced in the perfused pancreas of RTX-treated rats (P < 0.005) but unaffected in stimulated, isolated pancreatic islets. At the peak of spontaneous insulin resistance in the obese Zucker rat, insulin sensitivity was substantially improved after RTX treatment, as evidenced by higher glucose infusion rates (GIR) required to maintain euglycemia during a hyperinsulinemic euglycemic (5 mU.kg(-1).min(-1)) clamp (GIR(60-120min): 5.97 +/- 0.62 vs. 11.65 +/- 0.83 mg.kg(-1).min(-1) in RTX-treated rats, P = 0.003). In conclusion, RTX treatment and, hence, sensory nerve desensitization of adult male obese Zucker rats improved oral glucose tolerance by enhancing insulin secretion, and, in particular, by improving insulin sensitivity.

Effects of heparin-binding protein (CAP37/azurocidin) in a porcine model of Actinobacillus pleuropneumoniae-induced pneumonia.

Heparin-binding protein (HBP; CAP37/azurocidin) is secreted from neutrophil leukocytes early during inflammation and plays a central role in early capillary leakage and extravasation of neutrophils. Furthermore, HBP is chemotactic towards monocytes and lymphocytes and protects against stress-induced apoptosis, e.g. induced by oxygen radicals released during inflammation. Thus, administration of HBP as an adjunct to antibiotics increased survival of mice with peritonitis. In the present study, the effects of recombinant HBP as an adjunct to standard antibiotics were examined in a porcine model of Actinobacillus pleuropneumoniae-induced pneumonia. Beneficial and possible adverse effects of HBP were evaluated clinically and pathologically as well as by measurement of clinical chemical variables and markers of inflammation (interleukin-6 and C-reactive protein) and oxidative stress (ascorbic acid and alpha-tocopherol). Pigs receiving HBP (0.55 mgkg-1, n=11) as a 6-hourly subcutaneous infusion starting 1-h post-infection had a faster decrease in rectal temperature compared to control animals receiving a carrier-infusion (n=11), with a significant lower temperature at 32 h post-infection (p<0.05). This difference was, however, transient and the temperature curves had a similar course from 38 h and onwards. The transient effect of HBP might be explained by the dosage regimen that was used. No signs of adverse effects of the HBP-infusion were observed. More studies are needed to elucidate of the effects of HBP further and to optimise the dosage regimen for further improvement the efficacy and safety.

Effect of local anaesthesia on neuronal c-fos expression in the spinal dorsal horn and hypothalamic paraventricular nucleus after surgery in rats.

The surgical stress response is the neurophysiologic reflex response to surgery, which involves activation of the hypothalamic-pituitary-adrenal axis and is regulated by the hypothalamic paraventricular nucleus. The effect of pre-operative use of local anaesthetics on activation of neurones in the paraventricular nucleus during surgery was studied by quantification of the neuronal expression of the c-fos-gene after a standardized plantar incision in rats. Furthermore, c-fos expression in the spinal dorsal horn was used as a measure of spinal nociception. Six halothane-anaesthetized animals underwent surgery following infiltration with lidocaine and bupivacaine, six animals were operated without local anaesthetics, and six control animals were subjected to the anaesthetic procedures. After two hours, the animals were perfused with 4% formaldehyde and the spinal cords and brains were collected and processed by immunohistochemistry for stereological quantification of the number of neurones with Fos-like immunoreactivity. Furthermore, brain and spinal cord were sampled from nine control animals right after induction of halothane anaesthesia. Surgery without local anaesthetics caused a significant increased number of neurones with Fos-like immunoreactivity in the spinal cord (4258+/-1710; mean+/-S.D.; P<0.01) compared to the anaesthesia control group (1204+/-436). Local anaesthetics reduced this number to 2029+/-919 (P<0.05), which was not significantly different from the anaesthesia control group. After surgery, the number of neurones with Fos-like immunoreactivity in paraventricular nucleus increased from 2948+/-1365 in the anaesthetized control group to 5550+/-3875 and 5191+/-1558 in the surgery and local anaesthetics plus surgery group, respectively, although significance was only reached for the group receiving local anaesthetics (P<0.05). In conclusion, preoperative local anaesthetic infiltration did not reduce the surgery-induced c-fos expression in paraventricular nucleus after paw surgery in rats, although spinal nociception was reduced.

Sensory nerve desensitization by resiniferatoxin improves glucose tolerance and increases insulin secretion in Zucker Diabetic Fatty rats and is associated with reduced plasma activity of dipeptidyl peptidase IV.

Sensory nerve desensitization by capsaicin has been shown to improve the diabetic condition in Zucker Diabetic Fatty rats. However, administration of capsaicin to adult rats is associated with an increased mortality. Therefore, in this experiment, we examined the influence of resiniferatoxin, a tolerable analogue of capsaicin suitable for in vivo use, on the diabetic condition of Zucker Diabetic Fatty rats. A single subcutaneous injection of resiniferatoxin (0.01 mg/kg) to these rats was tolerable, with no mortality. When administered to early diabetic rats at 15 weeks of age, the further deterioration of glucose homeostasis was prevented by resiniferatoxin. Further, when administered to overtly diabetic rats at 19 weeks of age, resiniferatoxin markedly improved glucose tolerance at two weeks after administration and this was accompanied by an increased insulin response to oral glucose as well as a reduction in the plasma levels of dipeptidyl peptidase IV. Therefore, resiniferatoxin is a safe alternative to capsaicin for further investigations of the role of the sensory nerves in experimental diabetes.

Pharmacokinetics of amoxicillin after oral administration in recently weaned piglets with experimentally induced Escherichia coli subtype O149:F4 diarrhea.

OBJECTIVE: To measure the effect of Escherichia coli subtype O149:F4-induced diarrhea on the pharmacokinetics of orally administered amoxicillin in affected piglets relative to that of uninfected piglets. ANIMALS: 22 healthy 4-week-old recently weaned Danish crossbred piglets. PROCEDURE: 12 piglets were orally inoculated through gastric intubation with 10(9) CFUs of an E. coli O149:F4 strain and responded by developing diarrhea 12 to 16 hours later. Piglets were dosed with amoxicillin trihydrate solution (20 mg/kg) by gastric intubation. A control group of 10 age-matched piglets without signs of diarrhea was dosed similarly. Blood samples were obtained before amoxicillin administration and at 0.5, 1, 1.5, 2, 3, 6, 12, and 24 hours after amoxicillin administration. The plasma concentration of amoxicillin was analyzed by high-performance liquid chromatography. RESULTS: A significant 39% decrease in the area under the plasma concentration versus time curve of amoxicillin was observed in piglets with diarrhea relative to that of control piglets. The maximum plasma concentration (Cmax) was significantly (52%) lower in piglets with diarrhea, compared with control piglets, while the elimination rate constant, time to reach Cmax, and elimination half-life were unchanged. CONCLUSIONS AND CLINICAL RELEVANCE: Escherichia coli-induced diarrhea may decrease systemic bioavailability of amoxicillin. Escherichia coli bacteria attach to the intestinal epithelial cells. Because it is assumed that the concentration of the antimicrobial at the site of infection reflects the systemic concentration, higher doses of amoxicillin in the treatment of piglets with E. coli O149:F4-induced diarrhea may be appropriate.

Increased manganese concentration in the liver after oral intake.

RATIONALE AND OBJECTIVES: Manganese is a well-known liver-specific agent used in magnetic resonance imaging. For this purpose, manganese is now administered intravenously. In theory it should be possible to increase the gastrointestinal uptake of manganese through the use of nutritional products as promoters. Such an agent has now been formulated. As part of a primary pharmacologic investigation, the uptake of manganese in the kidney, heart, and liver was studied. MATERIALS AND METHODS: One hundred two female Sprague Dawley rats fasted for 18 hours before the agent (CMC-001) was given orally by gavage. One hundred micromol/kg BW was given to all rats except six, who served as controls. Various concentrations of the promoters (vitamin D3 and the amino acid alanine) were also given. Three hours after administration the rats were killed and the heart, the liver and kidneys were removed. The manganese content was determined by atomic absorption. RESULTS: No systematic increased concentration of manganese was found in either the kidneys or the heart; whereas the manganese content of the liver (approximately 100%) increased significantly compared with the controls and the group receiving pure manganese. No side effects were observed. CONCLUSION: It is possible to increase the gastrointestinal uptake of manganese in fasting rats and thereby increase the concentration in the liver.