A tumorigenic cell line derived from a hamster cholangiocarcinoma associated with Opisthorchis felineus liver fluke infection.

AIMS: The food-born trematode Opisthorchis felineus colonizes bile ducts of the liver of fish-eating mammals including humans. There is growing evidence that this liver fluke is a risk factor for cholangiocarcinoma (CCA). Cancer cell lines are necessary for drug screening and for identifying protein markers of CCA. The aim was to establish a cell line derived from cholangiocarcinoma associated with opisthorchiasis felinea. MAIN METHODS: Allotransplantation, immunohistochemistry, karyotype analysis, cell culture techniques, immunocytochemistry and real-time PCR. KEY FINDINGS: Here we repot the establishment of first CCA cell line, CCA-OF, from a primary tumor of an experimental CCA in Syrian hamsters treated with low doses of dimethyl nitrosamine and associated with O. felineus infection. The cell line was found to be allotransplantable. Expression of epithelial and mesenchymal markers (cytokeratin 7, glycosyltransferase exostosin 1, Ca2+-dependent phospholipid-binding protein annexin A1 and vimentin) was demonstrated by immunostaining of the primary tumors, CCA-OF cells, and allotransplants. CCA-OF cells were found to express presumed CCA biomarkers previously detected in both human and experimental tumors associated with the liver fluke infection. The cells were diploid-like (2n = 42-46) with complex chromosomal rearrangements and have morphological features of epithelial-like cells. The usefulness of the CCA-OF cell model for antitumor activity testing was demonstrated by an analysis of effects of resveratrol treatment. It was shown that resveratrol treatment inhibited the proliferation and the migration ability of CCA-OF cells. SIGNIFICANCE: Thus, the allotransplantable CCA-OF cell line can be used in studies on helminth-associated cholangiocarcinogenesis and for the testing of antitumor drugs.

Acrosin is essential for sperm penetration through the zona pellucida in hamsters.

During natural fertilization, mammalian spermatozoa must pass through the zona pellucida before reaching the plasma membrane of the oocyte. It is assumed that this step involves partial lysis of the zona by sperm acrosomal enzymes, but there has been no unequivocal evidence to support this view. Here we present evidence that acrosin, an acrosomal serine protease, plays an essential role in sperm penetration of the zona. We generated acrosin-knockout (KO) hamsters, using an in vivo transfection CRISPR/Cas9 system. Homozygous mutant males were completely sterile. Acrosin-KO spermatozoa ascended the female genital tract and reached ovulated oocytes in the oviduct ampulla, but never fertilized them. In vitro fertilization (IVF) experiments revealed that mutant spermatozoa attached to the zona, but failed to penetrate it. When the zona pellucida was removed before IVF, all oocytes were fertilized. This indicates that in hamsters, acrosin plays an indispensable role in allowing fertilizing spermatozoa to penetrate the zona. This study also suggests that the KO hamster system would be a useful model for identifying new gene functions or analyzing human and animal disorders because of its technical facility and reproducibility.

Dietary fatty acid profile influences circulating and tissue fatty acid ethanolamide concentrations in a tissue-specific manner in male Syrian hamsters.

BACKGROUND: The discovery of N­acylethanolamines (NAEs) has prompted an increase in research aimed at understanding their biological roles including regulation of appetite and energy metabolism. However, a knowledge gap remains to understand the effect of dietary components on NAE levels, in particular, heterogeneity in dietary fatty acid (DFA) profile, on NAE levels across various organs. OBJECTIVE: To identify and elucidate the impact of diet on NAE levels in seven different tissues/organs of male hamsters, with the hypothesis that DFA will act as precursors for NAE synthesis in golden Syrian male hamsters. METHOD: A two-month feeding trial was performed, wherein hamsters were fed various dietary oil blends with different composition of 18-C fatty acid (FA). RESULTS: DFA directly influences tissue FA and NAE levels. After C18:1n9-enriched dietary treatments, marked increases were observed in duodenal C18:1n9 and oleoylethanolamide (OEA) concentrations. Among all tissues; adipose tissue brown, adipose tissue white, brain, heart, intestine-duodenum, intestine-jejunum, and liver, a negative correlation was observed between gut-brain OEA concentrations and body weight. CONCLUSION: DFA composition influences FA and NAE levels across all tissues, leading to significant shifts in intestinal-brain OEA concentrations. The endogenously synthesized increased OEA levels in these tissues enable the gut-brain-interrelationship. Henceforth, we summarize that the brain transmits anorexic properties mediated via neuronal signalling, which may contribute to the maintenance of healthy body weight. Thus, the benefits of OEA can be enhanced by the inclusion of C18:1n9-enriched diets, pointing to the possible nutritional use of this naturally occurring bioactive lipid-amide in the management of obesity.

Tetrahydropalmatine Prevents High-Fat Diet-Induced Hyperlipidemia in Golden Hamsters (Mesocricetus Auratus).

BACKGROUND Hyperlipidemia is a major cause of atherosclerotic cardiovascular disease. Tetrahydropalmatine (THP) can exhibit hepatoprotective, anti-arrhythmic, and anti-inflammatory activities. The mechanism of THP on the hyperlipidemia remains unknown; therefore, the present study explored the role of THP in hyperlipidemia. MATERIAL AND METHODS We established an animal model of hyperlipidemia by high-fat diet (HFD) feeding. Blood samples were obtained for determination of serum cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), pro-inflammatory cytokines, and CYP7A1 expression. Histology was performed and inflammation was detected in the liver using hematoxylin-eosin (HE) staining and enzyme-linked immunosorbent assay (ELISA), respectively. The mRNA and protein levels of TLR4 and TRAF-6 were determined by quantitative real-time PCR (qPCR) and Western blot, respectively. RESULTS THP suppressed hepatic lipid accumulation and reduced serum levels of TC, TG, LDL-c, and HDL-c in HFD-fed golden hamsters. THP increased cholesterol 7 a-hydroxylase (CYP7A1) expression and prevented inflammation by the limited reduction in interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) expressions in serum and liver. THP slightly increased the ratio of the body/liver weight. THP inhibited the mRNA and protein levels of Toll-like receptor 4 (TLR4) and TNF-receptor associated factor-6 (TRAF-6). CONCLUSIONS These results suggest that THP attenuates hyperlipidemia by multiple effects, including hepatoprotective and anti-inflammatory effects. Moreover, THP also suppressed the expressions of TLR4 and TRAF-6 in golden hamsters.

Maintenance of a fully functional digestive system during hibernation in the European hamster, a food-storing hibernator.

Some small mammals limit energy expenditure during winter conditions through torpor bouts, which are characterized by a decrease in body temperature and metabolic rate. Individuals arise periodically from torpor to restore critical functions requiring euthermia. Although most of the species involved do not feed during hibernation and rely on body reserves to fulfil energy requirements (fat-storing species), others hoard food in a burrow (food-storing species) and can feed during interbout euthermy. Whereas fat-storing species undergo a marked atrophy of the digestive tract, food-storing species have to maintain a functional digestive system during hibernation. Our study aimed to evaluate the absorption capacities of a food-storing species, the European hamster, throughout the annual cycle. In vivo intestinal perfusions were conducted in different groups of hamsters (n=5) during the different life periods, namely before hibernation, in torpor, during interbout euthermy, and during summer rest. The triglyceride, non-esterified free fatty acid, starch, glucose and protein composition of the perfusate was evaluated before and after the 1h perfusion of a closed intestinal loop. Triglyceride, starch and protein hydrolysis rates were similar in hibernating (torpid and euthermic) and non-hibernating hamsters. Intestinal absorption of free fatty acid was also similar in all groups. However, glucose uptake rate was higher during hibernation than during the summer. In contrast with fat-storing species, the intestinal absorption capacities of food-storing species are fully maintained during hibernation to optimize nutrient assimilation during short interbout euthermy. In particular, glucose uptake rate is increased during hibernation to restore glycaemia and ensure glucose-dependent pathways.

Foot-and-mouth disease virus nonstructural protein 2C interacts with Beclin1, modulating virus replication.

Foot-and-mouth disease virus (FMDV), the causative agent of foot-and-mouth disease, is an Apthovirus within the Picornaviridae family. Replication of the virus occurs in association with replication complexes that are formed by host cell membrane rearrangements. The largest viral protein in the replication complex, 2C, is thought to have multiple roles during virus replication. However, studies examining the function of FMDV 2C have been rather limited. To better understand the role of 2C in the process of virus replication, we used a yeast two-hybrid approach to identify host proteins that interact with 2C. We report here that cellular Beclin1 is a specific host binding partner for 2C. Beclin1 is a regulator of the autophagy pathway, a metabolic pathway required for efficient FMDV replication. The 2C-Beclin1 interaction was further confirmed by coimmunoprecipitation and confocal microscopy to actually occur in FMDV-infected cells. Overexpression of either Beclin1 or Bcl-2, another important autophagy factor, strongly affects virus yield in cell culture. The fusion of lysosomes to autophagosomes containing viral proteins is not seen during FMDV infection, a process that is stimulated by Beclin1; however, in FMDV-infected cells overexpressing Beclin1 this fusion occurs, suggesting that 2C would bind to Beclin1 to prevent the fusion of lysosomes to autophagosomes, allowing for virus survival. Using reverse genetics, we demonstrate here that modifications to the amino acids in 2C that are critical for interaction with Beclin1 are also critical for virus growth. These results suggest that interaction between FMDV 2C and host protein Beclin1 could be essential for virus replication.

Efeito de duas variedades de feijão (Phaseolus vulgaris) no metabolismo lipídico de hamsters / Effect of two beans varieties (Phaseolus vulgaris) in hamster lipid metabolism

Introdução Os feijões comuns, da espécie Phaseolus vulgaris, são amplamente produzidos e consumidos no Brasil. As variedades, carioca e preto ganham destaque na região Sudeste do país. Encontra-se descrita na literatura a ação hipocolesterolemizante de algumas leguminosas, tais como, soja, tremoço e feijão caupi, que podem estar associados à redução do risco de doenças cardiovasculares. Objetivo Avaliar o potencial efeito da adição de farinhas de feijões carioca e preto (Phaseolus vulgaris) no metabolismo lipídico de hamsters alimentados com dieta contendo gordura saturada e colesterol. Métodos A produção das farinhas dos feijões envolveu as etapas de autoclavagem, congelamento, liofilização e moagem. As propriedades hipocolesterolemizantes destas farinhas foram avaliadas por meio de dois ensaios biológicos. Foram utilizados hamsters Golden Syrian, machos com 21 dias, pesando 60 ± 4g, que receberam as dietas experimentais ad libitum. No Ensaio A, os animais foram separados em 3 grupos, diferenciados pela dieta. Todas as dietas eram hipercolesterolemizantes [13.5 por cento de gordura de coco e 0.1 por cento colesterol] e tinham as mesmas quantidades de proteínas, carboidratos, fibras, vitaminas e minerais. O Grupo Controle (C) tinha como fonte protéica a caseína; no Grupo Feijão Carioca (FC) a farinha de feijão carioca representou 15 por cento do peso total da dieta e no Grupo Feijão Preto a farinha de feijão preto representou 15 por cento do peso total da dieta. No Ensaio B, os animais foram separados em três grupos novamente. Desta vez, a única diferença entre os grupos foi quanto a fonte protéica, para o grupo controle (C) somente caseína, para o grupo feijão carioca (FC), 67 por cento de feijão e 7,5 por cento de caseína e para o grupo feijão preto (FP), 62 por cento de feijão e 7,5 por cento de caseína. Nos dois ensaios, após 21 dias de experimento, foi realizada coleta de materiais biológicos (plasma, fígado e fezes). Resultados O processo de produção d...

Oxytocin and vasopressin immunoreactive staining in the brains of Brandt's voles (Lasiopodomys brandtii) and greater long-tailed hamsters (Tscherskia triton).

Immunoreactive (ir) staining of the neuropeptides oxytocin (OT) and vasopressin (AVP) was performed in the brains of Brandt's voles (Lasiopodomys brandtii) and greater long-tailed hamsters (Tscherskia triton)-two species that differ remarkably in social behaviors. Social Brandt's voles had higher densities of OT-ir cells in the medial preoptic area (MPOA) and medial amygdala (MeA) as well as higher densities of AVP-ir cells in the lateral hypothalamus (LH) compared to solitary greater long-tailed hamsters. In contrast, the hamsters had higher densities of OT-ir cells in the anterior hypothalamus (AH) and LH and higher densities of AVP-ir cells in the MPOA than the voles. OT-ir and AVP-ir fibers were also found in many forebrain areas with subtle species differences. Given the roles of OT and AVP in the regulation of social behaviors in other rodent species, our data support the hypothesis that species-specific patterns of central OT and AVP pathways may underlie species differences in social behaviors. However, despite a higher density of OT-ir cells in the paraventricular nucleus of the hypothalamus (PVN) in females than in males in both species, no other sex differences were found in OT-ir or AVP-ir staining. These data failed to support our prediction that a sexually dimorphic pattern of neuropeptide staining in the brain is more apparent in Brandt's voles than in greater long-tailed hamsters.

Sex differences in the excretion of fecal glucocorticoid metabolites in the Syrian hamster.

We verified the relevance of measuring fecal glucocorticoid metabolites (FGM) to assess the stress response of the Syrian hamster. Male and female hamsters (n = 10 each) were submitted to an adrenocorticotropic hormone (ACTH) challenge test, whereas animals in the control group received 0.5 mL of sterile isotonic saline solution. All feces voided by each animal were collected at 4 h intervals from 24 h before (baseline) until 48 h after injections. FGM were quantified using an 11-oxoetiocholanolone enzyme immunoassay (EIA). Basal concentrations of FGM were almost four times higher in males than in females. Following ACTH administration, FGM levels started rising from 8 h onwards, reaching peak concentrations 20 or 28 h post injection in males and females, respectively. Despite the much higher absolute concentrations present in males, the relative increase (500%) in response to the ACTH stimulation was similar in both sexes. Sex differences in FGM levels are in accordance with results reported by others regarding the hamster adrenal physiology. The comparison of the adrenocortical response of males and females to an ACTH challenge provided new information about the amplitude and the timing of such a response and the excretion of glucocorticoids in both sexes. We demonstrated for the first time in the Syrian hamster that adrenocortical activity can be monitored in fecal samples in a noninvasive way. Our study provides a humane, practical, and noninvasive alternative to blood removal and therefore a powerful tool for stress-related studies in a species frequently used as an animal model in medical research.

Transcriptome and proteome analysis of Chinese hamster ovary cells under low temperature and butyrate treatment.

Recombinant Chinese hamster ovary (CHO) cells selected for high productivity are capable of secreting immunoglobulin G (IgG) molecules at a level that rivals plasma cells in vivo. Following butyrate treatment at 33 degrees C, further increases in productivity are observed. To better understand the mechanisms by which this increased productivity is incurred, the transcriptional response of an antibody-producing cell line undergoing these treatments was investigated using oligo-DNA microarrays. Using distance calculations, more than 900 genes were identified as kinetically differentially expressed between the butyrate-treated 33 degrees C culture and the untreated culture. Furthermore, transcript levels of the heavy and light chain IgG genes increased following treatment. Using stable isotope labeling (SILAC), the secretion rate of IgG was investigated by tracking the decay of the isotope label upon switching to unlabeled medium. Both treated and untreated cultures exhibited very similar IgG secretion kinetics. In contrast, the intracellular IgG content was found to be elevated following treatment. This result suggests that increased productivity under treatment is attributable to elevated cellular secretory capacity, rather than shorter holding times in the secretory pathway. This hypothesis is further supported by the results of gene set enrichment analysis (GSEA), which revealed that elements of the secretory pathway, including Golgi apparatus, cytoskeleton protein binding and small GTPase-mediated signal transduction are enriched and thus may play a role in the increased recombinant protein production observed under butyrate treatment at 33 degrees C.

Characteristics of 263K scrapie agent in multiple hamster species.

Transmissible spongiform encephalopathy (TSE) diseases are known to cross species barriers, but the pathologic and biochemical changes that occur during transmission are not well understood. To better understand these changes, we infected 6 hamster species with 263K hamster scrapie strain and, after each of 3 successive passages in the new species, analyzed abnormal proteinase K (PK)-resistant prion protein (PrPres) glycoform ratios, PrPres PK sensitivity, incubation periods, and lesion profiles. Unique 263K molecular and biochemical profiles evolved in each of the infected hamster species. Characteristics of 263K in the new hamster species seemed to correlate best with host factors rather than agent strain. Furthermore, 2 polymorphic regions of the prion protein amino acid sequence correlated with profile differences in these TSE-infected hamster species.

Seasonal changes in cortisol and progesterone secretion in Common hamsters.

In this study, we investigated endocrine factors and behaviour in free-living Common hamsters (Cricetus cricetus) during reproductive and non-reproductive periods of the annual cycle. We applied a non-invasive method to gain information on seasonal changes in adrenocortical activity in male and female hamsters by analysing faecal glucocorticoid metabolite concentrations (FCM). In addition, plasma progesterone concentrations were monitored in females throughout the non-hibernation season. The animals were live-trapped from spring emergence until the onset of hibernation in autumn. Reproductive status was determined at capture and blood and faecal samples were collected. During behavioural observations, agonistic and sexual interactions were recorded. FCM concentrations were significantly higher in males than in females during the reproductive period. In males, a pronounced increase in FCM during the reproductive period coincided with high frequencies of intrasexual aggression. In females, FCM levels remained relatively constant. Aggressive behaviour in females increased during the reproductive period, but was much less frequent than in males. Females, which successfully raised a second litter after a postpartum oestrus and concurrent lactation and gestation had lower FCM levels than individuals, which lost their second litter after parturition. As expected, plasma progesterone concentrations were low before and after the reproductive period. During gestation, levels peaked and remained elevated during lactation. The results of this field study provide insight in critical periods associated with reproduction in male and female Common hamsters.

Brain antioxidant levels in hamsters during hibernation, arousal and cenothermia.

Warming from hibernation to cenothermia involves intense metabolic activity coincident with large fluxes in blood flow and is considered to be a period of oxidative stress during which utilization of endogenous antioxidants prevents pathology. Very slow flow brain microdialysis enabled temperature independent sampling of the brain striatal extracellular fluid (ECF) during hibernation, arousal and cenothermia in Syrian hamsters (Mesocricetus auratus). Brain tissue and dialysates were analyzed to provide the first profile of changes in ECF levels of ascorbate (AA), glutathione (GSH) and urate during hibernation and the transition to cenothermia. Brain tissue content of AA and GSH was unchanged between hibernation and cenothermia; however, arousal was associated with substantial oxidation of AA from the brain ECF and plasma compartments. ECF GSH increased during arousal. Brain tissue urate content was decreased 50% during hibernation. ECF urate levels were unchanged in hibernation and cenothermia but transiently increased 100% during arousal. These experiments demonstrate that arousal from hibernation is a suitable experimental model for examination of the mechanisms by which non-pathological tissue integrity is maintained in the face of the generation of free radicals during increasing metabolism, temperature and cerebral reperfusion.

Comparison of implantation and cytotoxicity testing for initially toxic biomaterials.

To evaluate the predictive value of cytotoxicity testing, the present study compares the in vivo tissue responses to in vitro cytotoxicity before and after implantation. Material toxicity was caused by addition of the toxic substance Zincdiethyldithiocarbamate (ZDEC) that is used as a standard for in vitro cytotoxicity testing. Polyurethane discs with the addition of 0.5% or 1% ZDEC as well as nontoxic discs were inserted in the abdominal wall of rats for 1 day up to 6 weeks. After explantation the foreign body response was analyzed immunohistochemically. An in vitro reanalysis of the explanted reference materials (RMs) revealed remaining high concentrations of toxic compounds after 1-week implantation, whereas no toxicity was seen after 6 weeks implantation. This was reflected in the foreign body response where a significantly thicker capsule and more inflammatory cells were seen at 1 week for the toxic implants. Over time, with decreasing toxicity, these differences disappeared. Test samples that only were subjected to in vitro extraction with water did not elute toxic compounds to the same extent as the in vivo conditions. It is concluded that many clinically useful implant materials may be unnecessarily rejected due to the results of in vitro tests.

Serine protease activity, bovine sperm protease, 66 kDa (BSp66), is present in hamster sperm and is involved in sperm-zona interaction.

Bovine sperm protease, 66 kDa (BSp66) is a serine protease previously characterized in bovine spermatozoa. Like other proteases, it may be present in sperm from other mammalian species different from bovine, playing a role in the fertilization process. In this study, we looked for BSp66 in hamster spermatozoa using heterologous antibodies against bovine BSp66. An immunoreactive protein was detected by Western blotting in mature and immature sperm. The detected protein had two isoforms similar to the ones reported in bovine sperm. Furthermore, indirect immune detection by fluorescence and electron microscopy assays, showed BSp66 signal at the acrosomal region similar to bovine sperm. As it was determined in bovine sperm, the acrosomal reaction displays the antigen within the acrosomal content. When live hamster sperm was incubated with polyclonal antibody against bovine BSp66 a decrease in the number of sperm bound to zona pellucida in homologous IVF and an impairment of head-head agglutination, were observed. These results suggest that a protease homologous to bovine BSp66 is present in golden hamster spermatozoa, with a conserved molecular mass and cellular location. Moreover, hamster BSp66 is probably involved in zona pellucida recognition.

Molecular cloning, functional expression, and gene silencing of two Drosophila receptors for the Drosophila neuropeptide pyrokinin-2.

The database of the Drosophila Genome Project contains the sequences of two genes, CG8784 and CG8795, predicted to code for two structurally related G protein-coupled receptors. We have cloned these genes and expressed their coding parts in Chinese hamster ovary cells. We found that both receptors can be activated by low concentrations of the Drosophila neuropeptide pyrokinin-2 (CG8784, EC(50) for pyrokinin-2, 1x10(-9)M; CG8795, EC(50) for pyrokinin-2, 5 x 10(-10)M). The precise role of Drosophila pyrokinin-2 (SVPFKPRLamide) in Drosophila is unknown, but in other insects, pyrokinins have diverse myotropic actions and are also initiating sex pheromone biosynthesis and embryonic diapause. Gene silencing, using the RNA-mediated interference technique, showed that CG8784 gene silencing caused lethality in embryos, whereas CG8795 gene silencing resulted in strongly reduced viability for both embryos and first instar larvae. In addition to the two Drosophila receptors, we also identified two probable pyrokinin receptors in the genomic database from the malaria mosquito Anopheles gambiae. The two Drosophila pyrokinin receptors are, to our knowledge, the first invertebrate pyrokinin receptors to be identified.

Expression of drug-metabolizing enzymes in the pancreas of hamster, mouse, and rat, responding differently to the pancreatic carcinogenicity of BOP.

BACKGROUND/METHODS: N-nitroso-bis(2-oxopropyl)amine (BOP) induces pancreatic ductal adenocarcinoma in Syrian golden hamsters, but not in rats or mice. To examine whether this difference is due to the diversity in the presence and distribution of enzymes involved in the metabolism of BOP, the cellular expression of nine cytochrome P-450 isozymes (CYP1A1, CYP1A2, CYP2B6, CYP2C8,9,19, CYP2D1, CYP2E1, CYP3A1, CYP3A2, and CYP3A4) and of three glutathione S-transferase isozymes (GST-pi, GST-alpha, and GST-mu) was investigated in the pancreas of hamsters, rats, and mice by immunohistochemistry. RESULTS: We found a wide species variation in the presence and cellular localization of the enzymes and a lack of several enzymes, including GST-alpha in islets, CYP2B6, CYP2C8,9,19, CYP3A1 in acinar cells, and CYP3A4 in ductal cells, in the rat as compared with hamster and mouse. CONCLUSION: Although the results could not clarify the reasons for the species differences in the pancreatic carcinogenicity of BOP, the presence of most of the cytochrome P-450 isozymes in pancreatic islets of all three species highlights the important role of the islets in drug metabolism.

Distribution of substance P and neurokinin-1 receptor immunoreactivity in the suprachiasmatic nuclei and intergeniculate leaflet of hamster, mouse, and rat.

The circadian pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) receives photic information directly via the retinohypothalamic tract (RHT) and indirectly from retinally innervated cells in the thalamic intergeniculate leaflet (IGL) that project to the SCN. Using standard immunohistochemical methods, we examined the presence and distribution of substance P (SP) and the neurokinin-1 receptor (NK-1) in the SCN and IGL of rat and determined whether the patterns of immunostaining generalized to the SCN and IGL of Syrian hamster, Siberian hamster, and mouse. Terminals immunoreactive for SP were sparse within the SCN of Siberian and Syrian hamsters and mouse but were intense in the ventral, retinally innervated portion of the rat SCN. Immunostaining for the NK-1 receptor was mainly absent from the SCN of hamster and mouse. In contrast, a plexus of NK-1-ir cells and processes that was in close proximity to SP-ir terminals was found in the ventral SCN of the rat. Substance P-ir terminals were observed in the IGL of all four species, as were NK-1-ir cells and fibres. Double-labelled IGL sections of hamster or rat revealed SP-ir terminals in close apposition to NK-1-immunostained cells and/or fibres. These data indicate that SP could be a neurotransmitter of the RHT in rat, but not in hamster or in mouse, and they highlight potential species differences in the role of SP within the SCN circadian pacemaker. Such species differences do not appear to exist at the level of the IGL, where SP-ir and NK-1-ir were similar in all species studied.

Cloning of the hamster androgen receptor gene.

Flank organs of male Golden Syrian hamsters contain sebaceous glands and hair follicles whose morphology and function are highly dependent on androgen, which makes these organs a useful model to study androgen action. In order to investigate molecular mechanisms of androgen action, we cloned a cDNA encoding the hamster androgen receptor (hamAR) by polymerase chain reaction (PCR) amplification of hamster testis cDNA. Nucleotide sequence analysis revealed that the cDNA has the capacity to encode a polypeptide of 900 amino acid. The deduced amino acid sequence was highly homologous to those of androgen receptors (AR) from other species. Western blot analysis of COS1 cells transfected with a vector expressing hamAR revealed that the recombinant ham AR was identical in size to that of endogeneous ham AR expressed in liver, sebaceous glands and testis. We further demonstrated that transfection of the hamAR expression vector into COS1 cells resulted in activation of a luciferase reporter gene containing multiple androgen responsive elements (ARE) in a testosterone-dependent manner. Availability of the recombinant hamAR clone along with the flank organ system should provide a more powerful tool than currently available to investigate androgen action at the molecular level.

Effect of carnosine administration on metabolic parameters in bilharzia-infected hamsters.

Carnosine is a naturally occurring dipeptide (beta-alanyl-L-histidine) found in muscles, brain and other tissues. This study was designed to test the ability of carnosine to offset metabolic disturbances induced by Schistosoma mansoni parasitism. Results indicate that parasitic infection caused elevation of liver weight/body weight in S. mansoni-infected hamsters, induced lipid peroxidation and reduced glycogen levels. Moreover, adenylate energy charge (AEC) and ATP/ADP and ATP/AMP concentration ratios were markedly lower in infected hamsters. Administration of carnosine (10 mg/day) for 15 days concurrent with infection effectively reduced worm burden and egg count. Administration of carnosine 2 and 4 weeks post-exposure only partially ameliorated the S. mansoni effects on metabolism. Carnosine treatment also normalized most of the parameters measured, including glycogen repletion, the antioxidant status and AEC. These finding support the use of carnosine for possible intervention in schistosomiasis.