Hymenolepis diminuta: The effects of infection on transepithelial ion transport and tight junctions in rat intestines

In this study, we examine the effect of Hymenolepis diminuta on ion transport in the ileum and on tight junctions in the ileum and colon of rats. We also evaluate the effect of H. diminuta on C-fiber endings in the ileum, the direct habitat of H. diminuta, before and after mechanical stimulation and pharmacological modification by capsaicin (C-fiber irritant).Wistar rats were orally infected with five cysticercoids of H. diminuta. Using a modified Ussing chamber, electrophysiological parameters of the ileum were measured (transepithelial electrical potential difference and transepithelial electrical resistance) as well as the deposition of occludin (a tight junction protein) in the ileum and colon of the rats 8, 16, 25, 35, 40 and 60 days post infection.We observed a significant reduction in transepithelial electrical potential difference in the ileum of rats infected with H. diminuta. In both the ileum and colon of rats infected with H. diminuta we also observed a decrease in occludin deposition, which indicates leakage of tight junctions, correlating with the decrease in transepithelial electrical resistance of these tissues. The application of capsaicin confirmed the hypothesis that H. diminuta in rats affects the C-fiber sensory receptors, causing changes in ion transport in the ileum.The results of the performed electrophysiological and immunohistochemical examinations indicate hymenolepidosis-related changes in the active transport of ions and the passive movement of ions.     

Hymenolepis diminuta: Activity of anti-oxidant enzymes in different parts of rat gastrointestinal tract

The aim of this study was to assess the intensity of oxidative stress by measuring levels of lipid peroxidation products in the duodenum, jejunum and colon of rats infected with Hymenolepis diminuta and evaluate the effectiveness of protection against oxidative stress by measuring the glutathione levels and activity of anti-oxidant enzymes: superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase.In exposed rats we observed a significant increase of lipid peroxidation products in the duodenum and jejunum. A significant decrease in superoxide dismutase activity in all the examined parts of the digestive tract was observed. Additionally, rats from 16 to 40 days post H. diminuta infection (dpi) had a decreased catalase activity in the colon, while at 60 dpi it increased. The glutathione peroxidase activity increased significantly in the colon at 60 dpi. The increase in glutathione reductase activity was observed in the colon in rats 60 dpi. There was a lack of changes in the levels of glutathione in the duodenum and a significant increase in its concentration in the jejunum and colon from 40 to 60 dpi and from 16 to 40 dpi, respectively. In this study we observed altered activity of anti-oxidant enzymes and glutathione level in experimental hymenolepidosis, as a consequence of oxidative stress. It may indicate a decrease in the efficiency of intestinal protection against oxidative stress induced by the presence of the parasite. The imbalance between oxidant and anti-oxidant processes may play a major role in pathology associated with hymenolepidosis.     

Quantifying horizontal transmission of Nosema lymantriae, a microsporidian pathogen of the gypsy moth, Lymantria dispar (Lep., Lymantriidae) in field cage studies

Nosema lymantriae is a microsporidian pathogen of the gypsy moth, Lymantria dispar that has been documented to be at least partially responsible for the collapse of L. dispar outbreak populations in Europe. To quantify horizontal transmission of this pathogen under field conditions we performed caged-tree experiments that varied (1) the density of the pathogen through the introduction of laboratory-infected larvae, and (2) the total time that susceptible (test) larvae were exposed to these infected larvae. The time frame of the experiments extended from the early phase of colonization of the target tissues by the microsporidium to the onset of pathogen-induced mortality or pupation of test larvae. Upon termination of each experiment, the prevalence of infection in test larvae was evaluated. In the experiments performed over a range of pathogen densities, infection of test larvae increased with increasing density of inoculated larvae, from 14.2 ± 3.5% at density of 10 inoculated per 100 larvae to 36.7 ± 5.7% at 30 inoculated per 100 larvae. At higher densities, percent infection in test larvae appeared to level off (35.7 ± 5.5% at 50 inoculated per 100 larvae). When larval exposure to the pathogen was varied, transmission of N. lymantriae did not occur within the first 15 d post-inoculation (dpi) (11 d post-exposure of test larvae to inoculated larvae). We found the first infected test larvae in samples taken 20 dpi (16 d post-exposure). Transmission increased over time; in the cages sampled 25 dpi (21 d post-exposure), Nosema prevalence in test larvae ranged from 20.6% to 39.2%.     

B-type natriuretic peptide and anthropometric measures in a Brazilian elderly population with a high prevalence of Trypanosoma cruzi infection

B-type natriuretic peptide (BNP) is a diagnostic and prognostic tool in heart failure and also in Chagas disease, which is caused by the protozoan Trypanosoma cruzi and has cardiomyopathy as a main feature. BNP lipolytic actions and T. cruzi infection in the adipose tissue have been recently described. We aim to investigate the relationship between BNP and anthropometric measures and whether it is influenced by T. cruzi infection. We measured BNP, body mass index (BMI), waist circumference (WC), triceps skin-fold thickness (TSF) and performed serological, biochemical and electrocardiographic exams in 1398 subjects (37.5% infected with T. cruzi) in a community-dwelling elderly population in Bambui city, Brazil. Linear multivariate regression analysis was performed to investigate determinants of BNP levels. BNP levels were significantly (p < 0.05) higher in T. cruzi-infected subjects than in the non-infected group (median = 121 and 64 pg/mL, respectively). BMI, WC and TSF in infected subjects were significantly lower than those in non-infected subjects (24.3 vs. 25.5 kg/m2; 89.2 vs. 92.4 cm; and 14.5 vs. 16.0 mm, respectively). There was an inverse relationship between BNP levels and BMI (b = −0.018), WC (b = −0.005) and TSF (b = −0.193) levels. Infected and non-infected groups showed similar inverse relationships between BNP and BMI (b = −0.021 and b = −0.015, respectively). In conclusion, there was an inverse relationship between BNP levels and the anthropometric measures. Despite the actions in the adipose tissue, T. cruzi infection did not modify the associations between BNP and BMI, suggesting that body mass does not modify the accuracy of BNP in Chagas disease.     

Transepithelial transport of hesperetin and hesperidin in intestinal Caco-2 cell monolayers

The cell permeability of hesperetin and hesperidin, anti-allergic compounds from citrus fruits, was measured using Caco-2 monolayers. In the presence of a proton gradient, hesperetin permeated cells in the apical-to-basolateral direction at the rate (J_ap → bl) of 10.43 ± 0.78 nmol/min/mg protein, which was more than 400-fold higher than that of hesperidin (0.023 ± 0.008 nmol/min/mg protein). The transepithelial flux of hesperidin, both in the presence or absence of a proton gradient, was nearly the same and was inversely correlated with the transepithelial electrical resistance (TER), indicating that the transport of hesperidin was mainly via paracellular diffusion. In contrast, the transepithelial flux of hesperetin was almost constant irrespective of the TER. Apically loaded NaN₃ or carbonyl cyanide m-chlorophenylhydrazone (CCCP) decreased the J_ap → bl of hesperetin, in the presence of proton gradient, by one-half. In the absence of a proton gradient, both J_ap → bl and J_bl → ap of hesperetin were almost the same (5.75 ± 0.40 and 5.16 ± 0.73 nmol/min/mg protein). J_bl → ap of hesperetin in the presence of a proton gradient was lower than J_bl → ap in the absence of a proton gradient. Furthermore, J_bl → ap in the presence of a proton gradient remarkably increased upon addition of NaN₃ specifically to the apical side. These results indicate that hesperetin is absorbed by transcellular transport, which occurs mainly via proton-coupled active transport, and passive diffusion. Thus, hesperetin is efficiently absorbed from the intestine, whereas hesperidin is poorly transported via the paracellular pathway and its transport is highly dependent on conversion to hesperetin via the hydrolytic action of microflora. We have given novel insight to the absorption characteristics of hesperetin, that is proton-coupled and energy-dependent polarized transport.     

Experimental concurrent infection of Afar breed goats with Oestrus ovis (L1) and Haemonchus contortus (L3): interaction between parasite populations, changes in parasitological and basic haematological parameters

The study was conducted to examine the occurrence and interaction between Oestrus ovis and Haemonchus contortus in experimentally infected Ethiopian Afar breed of goats. Twenty goats were divided into four groups (O, OH, H, and C) of five animals each. Each animal of groups O and OH received weekly infections for 5 weeks with 66 first instar larvae (L₁) of O. ovis. Then animals of groups OH and H were infected with a single dose of 5000 third stage larvae (L₃) of H. contortus. Goats of group C were kept free of any infection as non-infected control. Faecal egg count (FEC), blood cell count, total serum protein level and body weight were recorded weekly throughout the study period. At necropsy worm burden, female worm length, fecundity and larval burden of O. ovis in the nasal-sinus cavities of infected animals were assessed. The results showed that the presence of H. contortus in the abomasum of goats of group OH had no influence on the development of O. ovis. On the contrary, a significant reduction (P < 0.05) in FEC, worm burden, fecundity and female worm length was revealed in group OH animals compared to the mono-infected animals (group H). This was associated with eosinophilia and reduced packed cell volume.     

A preliminary study on the responses to experimental Haemonchus contortus infection in indigenous goat genotypes

A preliminary study on the responses of different goat genotypes to experimental haemonchosis was assessed in 48 castrated 6-months old Boer, Xhosa-Boer, Nguni and Xhosa goats randomly assigned to four balanced groups: non-infected and non-supplemented (NINS); infected, non-supplemented (INS); infected, supplemented (IS) and non-infected, supplemented (NIS). Each goat in the infected groups received a dose of 7200 L3 H. contortus larvae and kept for 90 days. Of the infected groups, the IS Xhosa goats had the lowest faecal larval counts (FLC) and maintained the highest PCV values throughout the study. The INS Xhosa and Nguni goats maintained body weight, but INS Boer goats lost body weight markedly. In all the treatments, the Xhosa goats also maintained high PCV values throughout the study. In conclusion, the Xhosa and Nguni genotypes performed better in terms of tolerance to haemonchosis. With protein supplementation, the Xhosa and Nguni genotypes also appeared to be much more capable of increasing PCV and eosinophil counts as worm counts increased, unlike the Boer and Xhosa-Boer genotypes.     

Differentiated structure and function of primary cultures of monkey oviductal epithelium

Summary We have established well-differentiated, polarized cultures of monkey oviductal epithelium. Oviductal epithelial cells were isolated by protease digestion and plated on collagen-coated, porous cell culture inserts. About 5 d after plating, cells developed detectable transepithelial electrical resistance of up to 2000 Ω.cm² (an index of tight junction formation) and transepithelial voltages of up to 20 mV (an index of vectorial transepithelial ion transport). Measurements of short-circuit current in Ussing chambers indicated that active secretion of Cl was the major transepithelial active ion transport process, and that this was stimulated by elevation of either cAMP or Ca. Furthermore, estimates of the volume of mucosal liquid were consistent with Cl secretion mediating fluid secretion. Various microscopical methods showed that the cultures were densely ciliated and contained mature secretory cells. Transport across the oviductal epithelium determines the composition of the oviductal fluid, and the study of the relevant transport processes will be greatly enhanced by well-differentiated cultures of oviductal epithelium of the kind established here.     

The effect of levamisole and levamisole + vitamin C on oxidative damage in rats naturally infected with Syphacia muris

This study was performed to determine the effects of levamisole and levamisole + vitamin C against Syphacia muris naturally infection in rats and to detect its effect on the oxidative parameters in blood and tissues of host. For this purpose, natural infection was diagnosed using the cellophane tape method on the perianal region of rats. Infected rats (total 18) were divided into three groups. On the other hand six without helminth rats were used in this study as negative control group. Group 2 was given an orally levamisole HCl treatment with gastric gavage at a dose level of 20 mg/kg body weight in distilled water, every alternate day. Group 3 was given levamisole HCl via gastric gavage at a dose level of 20 mg/kg and vitamin C was given 1 g/L added to the drinking water. All the treatments continued for a period of 7 days. As a result; levamisole administered to rats at dose of 20 mg/kg orally 98.34% was found to be effective against adult S. muris in the rats. In addition to levamisole + vitamin C is effective to alleviate the oxidative damage in rats infected with S. muris.     

Transmission of MdSGHV among adult house flies, Musca domestica (Diptera: Muscidae), occurs via oral secretions and excreta

The MdSGHV is a double-stranded DNA virus that replicates in the salivary glands of infected adult house flies. Transmission of this non-occluded, enveloped virus is believed to be mediated orally via deposition and consumption of oral secretions composed of salivary gland secretions and crop contents. In this study, transmission electron micrographs of crops from infected flies showed numerous enveloped virions in the crop lumen adjacent to the cuticular intima, as well as on the hemocoel side in close vicinity to muscle cells. Oral treatments of newly emerged flies with viremic salivary gland homogenates, crop homogenates, or gradient-purified virus resulted in an average 44% infection. Virus released via oral secretion was infectious when ingested by newly emerged adult flies, resulting in an average 66% infection. Using quantitative real-time PCR, MdSGHV DNA was quantified in oral secretions and excreta obtained from viremic flies. Between 2 and 4 days post-infection (dpi), viral copy numbers in oral secretions increased exponentially and from 5 to 21 dpi each infected fly released an average 10⁶ MdSGHV copies per feeding event. Excreta samples collected overnight from individual infected flies at 5 dpi contained an average 6.5 × 10⁵ viral copies. Low but detectable infection rates were produced when newly emerged flies were challenged with excreta samples. In summary, evaluation of the quantity and infectivity of MdSGHV released by individual infected house flies clearly showed that deposition of oral secretions and excreta onto a shared food substrate is the main route of natural MdSGHV transmission among adult house flies.     

Trichinella spiralis: Rapid,immunologically influenced reduction of intestinal,sodium-coupled sugar transport in the rat

Epithelium of isolated small intestinal segments were studied in Ussing-type chambers to detect physiological changes associated with rapid, immune rejection of Trichinella spiralis infective larvae. Electrophysiological parameters associated with Na⁺-coupled hexose transport were measured. Changes in transepithelial electrical potential difference (PD), resistance, and short circuit current (I_sc) due to the addition of actively absorbed β-methyl-d-glucoside (BMG) to the mucosal solution were determined. Measurements were made prior to and 30 min after primary and secondary infections. Animals were infected by intraduodenal inoculation. As the infective larval dose in primarily infected (nonimmunized) rats increased from 50 to 2000 larvae the magnitude of the rise in I_sc elicited by BMG decreased in a dose-dependent fashion, with 50 larvae per rat having no effect. In previously infected (immunized) rats challenged with a secondary inoculum, all doses, ranging from 50 to 2000 larvae per rat, decreased the BMG-stimulated change in I_sc by approximately 50%. The effect of 50 worms per rat in immunized hosts was equivalent to that produced by ~1600 worms in nonimmunized animals. Measurements of ¹⁴C-BMG mucosa-to-serosa flux confirmed that Na⁺-BMG cotransport was responsible for observed changes in I_sc. Results support the conclusion that changes in intestinal epithelial function are associated with larval challenge of immune rats.     

Effects of grazing willow fodder blocks upon methane production and blood composition in young sheep

A 79-day rotational grazing experiment was conducted over the summer and autumn of 2007 to compare effects of grazing willow (Salix spp.) fodder blocks, a combination of small trees (i.e., 1.0 m) and herbage, or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) control pasture on breath methane (CH₄) emissions, concentrations and solubility of CH₄ and sulphur hexafluoride (SF₆) tracer gas in blood, and haematology variables in young growing female sheep (i.e., hoggets). Measurements of gases in blood followed a double equilibration technique with two (n = 20) replicate per treatment. Ten ewe hoggets in each replicate were dosed on day 22 with intraruminal slow release SF₆ capsules, an inorganic tracer gas used to calculate CH₄ emissions. Breath samples were collected over 5-day periods in weeks 5 (period 1) and 11 (period 2). Total condensed tannin (CT) concentrations calculated in the diet selected by the willow fodder block sheep was 12 g CT kg/dry matter intake, with negligible amounts in control pasture hoggets. Compared to control pasture, grazing willow fodder blocks reduced CH₄ emission/kg metabolic body weight (BW^0.75) by 20% in period 1 (P<0.01), but not in period 2. Blood CH₄ concentrations (ng/mL blood) were similar for both groups on day 36, but higher (P<0.001) on day 76 for hoggets grazing willow fodder blocks, while a different trend was observed for SF₆ blood concentration being higher (P<0.01) on day 36 in hoggets grazing willow fodder blocks, but similar in both groups on day 76. Repeatability of blood CH₄ concentration was 75% in period versus 84% in period 2. Methane and SF₆ Ostwald solubility coefficients in blood were similar in both periods for sheep grazing willow fodder blocks and the control pasture. Hoggets grazing willow fodder blocks had lower BW gain (65 g/day), carcass weight (16.1 kg) and carcass fatness (9.2 mm) than hoggets grazing control pasture (102 g; 18.3 kg; 11 mm). Hoggets dosed with SF₆ capsules had lower (P<0.05) red blood cells, haemoglobin and haematocrit concentrations when grazing either willow fodder blocks or control pasture, while neutrophil (P=0.063), platelet (P=0.073) and monocyte (P=0.072), white blood cell and total lymphocyte counts (P<0.05) were higher for willow fodder block-fed hoggets than those fed the control pasture. Differences in the reduction in CH₄ emission between periods from grazing willow fodder blocks may be due to more willow leaf being eaten during the CH₄ measurement period in period 1 than in period 2.     

Stimulus (polyphenol, IFN-gamma, LPS)-dependent nitric oxide production and antileishmanial effects in RAW 264.7 macrophages

The effects of interferon (IFN-γ), lipopolysaccharide (LPS), and some polyphenols as individual stimuli, as well as in various combinations on NO production in non-infected and infected macrophage-like RAW 264.7 cells were investigated, with emphasis on the NO/parasite kill relationship. In non-infected and in Leishmania parasitized cells, gallic acid significantly inhibited the IFN-γ and LPS-induced NO detected in the supernatant. This effect was less prominent in IFN-γ- than in LPS-stimulated cells. Interestingly, and in contrast to non-infected cells, gallic acid inhibited NO production only when added within 3 h after IFN-γ + LPS. Addition of gallic acid following prolonged incubation with IFN-γ + LPS periods (24 h) no longer inhibited, sometimes even enhanced NO release. Notably, an excellent NO/parasite kill relationship was evident from all the experiments. This study was extended to a series of polyphenols (3-O-shikimic acid, its 3,5-digalloylated analogue, catechin, EGCG, and a procyanidin hexamer) with proven immunostimulatory activities. Although these compounds themselves were found to be weak NO-inducers, the viability of intracellular Leishmania parasites was considerably reduced. Furthermore, their dose-dependent effects on macrophage NO release was determined in the presence of IFN-γ and/or LPS. Again, non-infected and infected cells differed significantly in the NO response, while inhibition of IFN-γ and/or LPS-induced NO production by the tested polyphenols strongly depended on the given time of exposure and the sequence of immunological stimuli. A strong inverse correlation between NO levels and intracellular survival rates of Leishmania parasites supported the assumption that the observed inhibition of NO was not simply due to interference with the Griess assay used for detection.     

The colon of Leucophaea maderae: fine structure and physiological features

The colon of L. maderae consists of a single columnar epithelium covered with a cuticle and of a musculo-connective sheath. The apical plasma membranes form a system of leaflets with numerous mitochondria inserted in association with microfilaments. Lateral plasma membranes are linked together by junctional complexes consisting of a zonula adherens and a long convoluted septate junction of the pleated type. In the basal region of the cell, numerous membrane infolds and scattered scalariform junctions with associated mitochondria are present. These cell specializations are typical of arthropod transporting organs, being distinctive features of ion and fluid transporting epithelia. The isolated colon exhibited a transepithelial electrical potential difference (PD) of about 100 mV, lumen side positive with respect to the haemolymph side. The PD was almost abolished by metabolic inhibitors, it was reduced by acetazolamide and SITS, and it was unaffected by ouabain. These effects suggest that HCO3- and Cl- are involved in the genesis of the PD, whereas Na+ is not directly responsible of the PD. Measurements of Na+ and Cl- fluxes across the colon wall confirm that Na+ moves following the PD across the tissue, while Cl- movement occurs against an electrochemical potential difference. The electrical profile of the epithelial cells is of the well type and it suggests that the primary or secondary active step for Cl- transport across the epithelium should be located at the mucosal border of the cell.     

The acute effects of single-dose orally administered doramectin, eprinomectin and selamectin on natural infections of Syphacia muris in rats

This study was designed to determine the acute effects of a single-dose of orally administered doramectin, eprinomectin and selamectin on Syphacia muris infection in rats. Rats, naturally infected with S. muris, were divided into four groups: three different treatment groups (n = 7) and one positive control (n = 7). Cellophane tape preparations were obtained from the treated rats on day 0 pre-treatment and on days 2, 4 and 6 post-treatment. Syphacia sp. eggs were counted. Eprinomectin was found to be 100% effective in eliminating eggs on two post-treatment. However when egg counts on day 6 post-treatment were compared with pre-treatment egg counts, doramectin and selamectin were found to be 99.32 and 98.77% effective in eliminating eggs, respectively. On day 7 post-treatment, blood samples were obtained from all groups, and then the rats were necropsied. Doramectin, eprinomectin and selamectin were found to be 100% effective in eliminating adult S. muris, when compared with the positive control group.     

Identification of a SLC19A2 nonsense mutation in Persian families with thiamine-responsive megaloblastic anemia

Thiamine-responsive megaloblastic anemia (TRMA) is an autosomal recessive syndrome characterized by early-onset anemia, diabetes, and hearing loss caused by mutations in the SLC19A2 gene. We studied the genetic cause and clinical features of this condition in patients from the Persian population. A clinical and molecular investigation was performed in four patients from three families and their healthy family members. All had the typical diagnostic criteria. The onset of hearing loss in three patients was at birth and one patient also had a stroke and seizure disorder. Thiamine treatment effectively corrected the anemia in all of our patients but did not prevent hearing loss. Diabetes was improved in one patient who presented at the age of 8 months with anemia and diabetes after 2 months of starting thiamine. The coding regions of SLC19A2 were sequenced in all patients. The identified mutation was tested in all members of the families. Molecular analyses identified a homozygous nonsense mutation c.697C > T (p.Gln233*) as the cause of the disease in all families. This mutation was previously reported in a Turkish patient with TRMA and is likely to be a founder mutation in the Persian population.     

Feasibility of Histological Scoring and Colony Count for Evaluating Infective Severity in Mouse Vaginal Candidiasis

Qualitative measurement of the infective level is relatively difficult in experimental vaginal candidiasis. Female BALB/c mice aged 8 to 10 weeks were randomly divided into E1, E2 and E0 groups, which received subcutaneous injection of 0.05 mg, 0.1 mg of estradiol benzoate or 0.1 ml soybean oil 3 days before vaginal inoculation, respectively, and hormone treatment continued every other day thereafter. Each group was further divided into infected and noninfected subgroups. The infected mice were inoculated intravaginally with 10 µl (5 × 10⁴ conidia) of Candida albicans suspension, while the noninfected mice were inoculated with 10 µl phosphate-buffered saline. Direct microscopic examination, colony count and vaginal histopathology including infection degree and inflammation extent were performed at 3, 7 and 14 days post inoculation. Estrogen treatment increased the vaginal fungal burden and extent of infection and inflammation compared with the control group, and 0.3 mg/week estrogen generally induced more severe infection and inflammation than 0.15 mg/week estrogen did. Colony count peaked on day 3 and decreased remarkably after 7 days. Infection score increased gradually during the first 7 days and decreased on day 14, while inflammation extent exacerbated progressively over the course of 14 days. This study demonstrates that the modified histological scoring system might be more feasible than colony count for evaluation of infectivity and dynamic change in experimental vaginal candidiasis.     

Transepithelial transport of artepillin C in intestinal Caco-2 cell monolayers

The absorption characteristics of artepillin C (AC), an active ingredient of Brazilian propolis, were examined by measuring permeation across Caco-2 cell monolayers. The permeation rate in the basolateral-to-apical direction, J_bl → ap, in the presence of proton gradient was 0.14 nmol/min/mg protein, whereas J_bl → ap in the absence of proton gradient was 1.14 nmol/min/mg protein. The latter value is nearly the same as the permeation rate in the apical-to-basolateral direction, J_ap → bl, both in the presence and absence of proton gradient. In the presence of proton gradient, J_ap → bl was almost constant, irrespective of NaN₃ or benzoic acid. However, J_bl → ap dramatically increased upon the addition of NaN₃ or benzoic acid specifically to the apical side. In both the presence and absence of proton gradient, J_ap → bl also appeared to be constant irrespective of the paracellular permeability of Caco-2 cells. After AC was loaded apically in the presence of proton gradient, the intracellular AC increased with time. This accumulation was inhibited by apically loaded NaN₃. These indicate that AC transport occurs mainly via transcellular passive diffusion, although a considerable amount of AC was taken up intracellularly by monocarboxylic acid transporter (MCT) on the apical side and not transported out across the basolateral membrane, suggesting that different subtypes of MCT are involved.     

Ambient temperature-dependent thermoregulatory role of REM sleep

Changes in ambient temperature produce complex effects on sleep–wakefulness. In order to find out the mechanisms involved in temperature-sensitive changes in sleep in rats, their thermal preference, body temperature and sleep were studied before and after the destruction of both peripheral and central warm receptors, by systemic administration of 375 mg/kg capsaicin. Though the pre-treated rats preferred to stay mostly at the ambient temperature of 27 °C, post-treated rats strayed freely into chambers having ambient temperature of 30 °C and 33 °C. Sleep and body temperature of these rats were studied for six hours each, when they were kept at an ambient temperature of 18–36 °C. Total sleep time, especially REM sleep, was maximum at 30 °C in pre-treated rats, but this REM sleep peak at 30 °C disappeared after capsaicin administration. Body temperature increased sharply in post-treated rats, at ambient temperatures above 30 °C. Apart from the ability to defend body temperature at high ambient temperature, avoidance of warm ambient temperature and increase in REM sleep are the behavioral measures which are lost in post-treated rats. Results of this study suggest that the ambient temperature-related increase in REM sleep at 30 °C could be part of the thermoregulatory measures.