L-tryptophan binding to hepatic nuclei: Age and species differences

Summary The present experiments report differences in in vitro nuclear binding affinity for L-tryptophan 1) between livers of young (6 1/2 weeks old) and older (30 weeks old) NZBWF₁ mice, but not so in similar aged Swiss mice, and also, 2) in livers of hamsters compared to livers of guinea pigs. In vitro hepatic nuclear specific binding affinity after tube-feeding L-tryptophan (520mg/100g body weight) to mice 1 h before killing revealed less in young than in older NZWBF₁ mice, comparable to the above in vitro assay studies. In vitro nuclear binding affinity for L-tryptophan of livers of hamsters was significantly less than that of livers of guinea pigs or Swiss mice. In general, the degree of stimulatory effect on hepatic protein synthesis, as measured by in vitro [¹⁴C]leucine incorporation into protein using microsomes of animals tube-fed L-tryptophan 1 h before killing compared to that of animals tubefed water, correlated with the basal nuclear specific binding affinity to L-tryptophan of the animals (ages and species) used.This study was supported by U.S. Public Health Service Research Grant DK-45353 from the National Institute of Diabetes and Digestive and Kidney Diseases.     

The Annual Activity Pattern of Djungarian Hamsters (Phodopus sungorus) Is Affected by Wheel‐Running Activity

Djungarian hamsters (Phodopus sungorus) exhibit pronounced winter acclimatization with changes in body mass, gonads, fur, and thermogenic capacity induced by decreasing daylength. To determine whether the annual activity pattern reflects the crucial role of the photoperiod for the hamsters' seasonality, animals with and without access to a running wheel (RW) were exposed to natural lighting conditions (～52°N) and ambient temperatures. Registration of locomotion in hamsters with a RW revealed a clear activity pattern closely related to dusk and dawn throughout the year. In contrast, animals without RW access showed a less stable phase relationship between the activity and the day‐night cycle in autumn and winter. During these seasons, the activity phase either exceeded the dark phase or even became indistinguishable from the rest phase. This correlated not only with increased locomotion during the light phase but also over the whole 24 h period, especially in autumn. In RW hamsters, a similar but attenuated trend was found that possibly reflects foraging due to increased food hoarding before winter. The more stable correlation between activity time and night length in RW hamsters might be explained by a suppressing effect of light on wheel‐running behavior (negative masking) and/or a stabilizing effect of running exercise on rhythmicity. In a further experiment, the phase‐reference points lights‐off and lights‐on within artificial light‐dark (LD) cycles were compared to sunset and sunrise in an intermediate ratio of light and dark and in long days. With respect to the defined phase‐reference points of the zeitgeber, the phase relation between activity and the LD cycle was similar in natural and corresponding artificial lighting conditions, and dependent on the LD ratio.     

Dipetalonema viteae: isoelectric focusing and immunochemical studies on somatic extracts of adult worms and microfilariae.

Isoelectric focusing (IEF) of a somatic extract of adult worms (SEAW) yielded nine fractions. Most of the applied protein antigen was recovered in five fractions with pI values of 5.2, 4.4, 4.3, 4.0, and 3.3, respectively. The nine IEF fractions of SEAW gave a total of 37 bands following electrophoresis on polyacrylamide gel (PAGE). IEF fractionation of a somatic extract of microfilariae (SEM) yielded nine fractions. Two fractions with pI values of 4.4 and 3.2, respectively, contained most of the applied protein. The nine IEF fractions of SEM gave a total of 32 bands following PAGE. Crossed immunoelectrophoresis (CI) of SEM and SEAW against serum from hyperinfected hamsters yielded five and eight precipitation peaks, respectively. CI of SEM and SEAW against their homologous rabbit antisera gave 7 and 10 major precipitation peaks, respectively. Immunodiffusion of the nine IEF fractions from both SEM and SEAW against both their homologous and heterologous rabbit antisera indicated three and four precipitin bands peculiar only to SEM and SEAW, respectively. The remaining 23 bands from both preparations showed lines of identity.     

Abnormalities in Amino Acid Neurotransmitters in Discrete Brain Regions of Genetically Dystonic Hamsters

The concentrations of 11 amino acids, including the neurotransmitters gamma-aminobutyric acid, glutamate, aspartate, glycine, and taurine, were determined by HPLC in 12 brain regions of genetically dystonic (dtSZ) hamsters and age-matched nondystonic controls. Since dystonia in mutant dtSZ hamsters is transient and disappears after about 70 days of age, amino acids were determined at the age of maximum severity of dystonia (30-40 days) and after disappearance of the disease, to examine which neurochemical changes were related to dystonia. In dtSZ hamsters with the maximum severity of dystonia, significant changes in concentrations of the neurotransmitters gamma-aminobutyric acid, glutamate, aspartate, and taurine were found in several regions involved in motor functions, e.g., cerebellum, thalamus, and corpus striatum. Most of these changes were not permanent but disappeared in parallel with dystonia, implicating a causal relationship between altered aminoacidergic neurotransmission and dystonia in mutant dtSZ hamsters.     

Patterns of neural activation associated with exposure to odors from a familiar winner in male golden hamsters

The neural mechanisms underlying recognition of familiar individuals and responses appropriate to them are not well known. Previous studies with male golden hamsters have shown that, after a series of brief aggressive encounters, a loser selectively avoids his own, familiar winner but does not avoid other males. Using this paradigm, we investigated activity in 20 areas of the brain using immunohistochemistry for c-Fos and Egr-1 during exposure to a familiar winner compared to control groups not exposed to another male. Behavioral data showed that 1 day after fights males that lost avoided the familiar winner, suggesting that they recognized this individual. The c-Fos and Egr-1 immunohistochemistry showed that the losers exposed to familiar winners had a greater density of stained cells in the basolateral amygdala, the CA1 region of anterior dorsal hippocampus and the dorsal subiculum than control groups had in these areas. These results suggest that these brain areas may be involved in the memory for other males, the learned fear of familiar winners, or related processes.     

Comparative histopathology of Opisthorchis felineus and Opisthorchis viverrini in a hamster model: an implication of high pathogenicity of the European liver fluke

European liver fluke (Opisthorchis felineus) and Asian liver fluke (Opisthorchis viverrini) are similar in morphology but comparative pathology of the infections has not been described. We therefore did comparative histopathology of both parasites in an experimental animal model. The study was conducted in 3 groups of 105 Syrian golden hamsters; the first and second groups fed with 50 metacercariae of O. felineus (OF) or O. viverrini (OV) and the last group was uninfected controls. Five hamsters in each group were euthanized on weeks 1, 2, 4, 8, 12 and 24 post-infection. The liver tissue was fixed and processed for routine histopathology and immunohistochemistry for proliferation markers (BrdU or PCNA). Overall, the liver histopathology of O. felineus and O. viverrini infection was generally similar. However, various histopathogical features including intense inflammation, fibrosis, biliary and goblet cell hyperplasia and dysplasia occurred earlier in the OF group. In addition, the existence of precancerous lesions such as cholangiofibrosis in a long-term infection was observed only in this group. O. felineus is larger in size than O. viverrini which, together with its excreted and secreted antigens, likely is crucial in the induction of liver fluke induced disease. The differences in nature and timing of the histopathological profile indicate that opisthorchiasis caused by the European liver fluke O. felineus is more pathogenic than its Asian relative O. viverrini.     

山医群体近交系中国地鼠的G-显带核型和自发畸变率的研究

目的　阐明山医群体近交系中国地鼠G 显带核型和自发畸变率 ,完善中国地鼠的背景资料。方法　采用地鼠骨髓制备和G 显带法。结果　从 14只地鼠的 30个G 显带细胞中 ,7个G 显带细胞被选作模型分析。根据特有带型来识别各号染色体 ,绘制了模式图。此外 ,用常规Giemsa染色分析了 80 0个中期细胞 ,发现染色体断裂为 0 2 5 % ,无着丝粒畸变和不平衡易位均为 0 0 5 % ,自发畸变率很低。结论　山医群体近交系中国地鼠G 显带的识别为结构异常和基因作图提供了科学依据。     

Photoperiod-peptide interactions in the energy intake of Siberian hamsters

Siberian hamsters (Phodopus sungorous sungorous) decrease their food intake when exposed to short (“winter-like”) photoperiods. The cause of this naturally-occurring hypophagia is unknown, but it may be due to a heightened sensitivity to the factors that normally terminate food intake in long photoperiods, such as the putative satiety peptides. The purpose of the present investigation was to test whether there would be an enhanced sensitivity to the inhibitory effects of some of these peptides on food intake in short relative to long days. Ad lib-fed, adult female Siberian hamsters were housed in a long photoperiod (LD 14:10) and injected with bombesin, glucagon, cholecystokinin octapeptide (CCK-8) and calcitonin (CT). Food intake was monitored 1, 2, 4, 6, and 24 hr post-injection. Bombesin and glucagon had no effect on food intake in long day-housed hamsters. CCK-8 and CT inhibited food intake; however, CCK-8 did so without any apparent behavioral disruption, while CT produced a marked and prolonged depression of behavior. After 10 weeks of exposure to a short photoperiod (LD 8:16) the hamsters were tested again. The previously ineffective dose of bombesin greatly inhibited food intake following short photoperiod exposure. In addition, an increased inhibition of food intake by CCK-8 was also found. In contrast, glucagon did not decrease food intake and CT still produced its non-specific, behaviorally disruptive effects. To our knowledge, this is the first demonstration that the effectiveness of a putative satiety peptide can be dependent upon a change in the photoperiod. This heightened responsiveness of short photoperiod-exposed Siberian hamsters to the inhibitory effects of bombesin and cholecystokinin may account for the reduction in food intake that accompanies short day exposure in this species.     

Schistosoma mansoni: microfluorometric determination of circulating anodic antigen and antigen-antibody complexes in infected hamster serum

In this study the applicability of the defined antigen substrate spheres (DASS) system for the detection of circulating anodic antigen (CAA) in experimental Schistosoma mansoni infections in hamsters and mice is described. Using the DASS system as an antibody-antigen-labeled antibody technique, CAA could be detected both as a free circulating antigen and as the antigen-component of circulating antigen-antibody complexes.