Effect of pepsin digestion on the antivenom activity of equine immunoglobulins

Enzyme digestion of animal-derived sera followed by antibody purification is a classical process used to prepare snake antivenoms worldwide. In this work, we have studied the effect of the harsh conditions prevailing during the digestion step on the activity of the final product, F(ab′)₂. To this purpose, the recovery of the activity of anti-Bothrops hyperimmune equine plasma was determined after pepsin digestion under different sets of processing conditions. The balance between pH level and reaction time was found to be critical, reflecting a compromise between complete cleavage of immunoglobulins and strong denaturation of the F(ab′)₂ fragments. For pH in the range 2.8–3.2, 30–65% of the initial activity was lost depending mainly on the processing time, as determined by a competition ELISA technique. Pepsin digestion was also carried out with purified immunoglobulins from the same plasma. SDS PAGE run on the digested immunoglobulins allowed us to verify that the lightest isotypes were more resistant to digestion than the heavier ones. In conclusion, for equine F(ab′)₂ antivenom production, it seems convenient to carry out digestion at pH values sufficiently low to ensure that total IgG breakdown is achieved in the shortest time compatible with precise operation in the production scale.     

Differential effects of methamphetamine and cocaine on behavior and extracellular levels of dopamine and 3,4-dihydroxyphenylalanine in the nucleus accumbens of conscious rats

The stress-induced hyperthermia procedure, in which effects of drugs on basal (T₁) and stress-induced body temperature (T₂) are measured, predicts anxiolytic drug effect. Serotonergic drugs alter these responses and here, we studied the role of 5-HT_1A receptors in stress-induced hyperthermia by using 5-HT_1A receptor knockout mice. Three strains (129/Sv, Swiss Webster and C57Bl6) were used because genetic background can significantly modulate the null phenotype. We found that GABA-ergic drugs with an anxiolytic profile and stimulate ₂ subunit containing GABA_A receptors, including diazepam and L838,417, result in reduced ΔT (ΔT = T₂ − T₁). The ₁ subunit containing GABA_A receptor was found to be primarily involved in regulation of basal body temperature T₁ and its stimulation can induce hypothermia. In addition, stimulation of 5-HT_1A receptors by buspirone results in a reduced ΔT, while stimulation of 5-HT₇ receptors primarily results in hypothermia. The null mutation of 5-HT_1A receptors resulted in differences in drug-sensitivity that was further modulated by the genetic background. In particular, the null mutation on the SW and C57Bl6 backgrounds resulted in differential diazepam/L838,417 and 5-CT responses respectively. This indicates an interaction between the 5-HT_1A receptor and genetic background and demonstrates the importance of selecting the background strain in a receptor knockout model.     

Neutralization of kinin-releasing enzymes from viperid venoms by antivenom IgG fragments

The activities of kinin-releasing enzymes in the venoms of Vipera xanthina xanthina, V. lebetina obtusa, V. aspis aspis, V. lebetina schweizeri, V. ammodytes ammodytes and V. berus berus were determined using a specific radioimmunoassay for kinin. The kinin-releasing activities of all the viperid venoms measured in vitro were neutralized, to varying extents, by two commercially available monospecific antivenoms in the form of F(ab′)₂ (Zagreb) and Fab (TAb) immunoglobin fragments, indicating a high degree of cross-neutralization of those enzymes.     

Increased susceptibility to mouse hepatitis virus 3 of peritoneal macrophages exposed to dieldrin

Interaction of a single dose (36 mg/kg body wt) of the organochlorine pesticide dieldrin with mouse peritoneal macrophages was examined in C57Bl/6, (C57Bl/6 X A/J)F1, and A/J strains of different genetic resistance to mouse hepatitis virus 3 (MHV3) infection. In vivo studies showed increased susceptibility to MHV3 acute disease of C57Bl/6 and (C57Bl/6 X A/J)F1 animals challenged with the pesticide. Significant decrease of mean time of death in dieldrin-exposed, MHV3-infected susceptible C57Bl/6 mice was observed similarly upon po or ip administration of a single, sublethal dose of dieldrin. In addition, decrease of humoral response to the virus was quantified by determination of anti-MHV3 IgG antibodies in spleen cell supernatant fractions and in blood sera of dieldrin-exposed C57Bl/6 mice. A single dose of dieldrin did not alter the in vivo resistance of A/J animals to acute MHV3 disease. The resistant A/J mice, however, showed increased mortality upon two subsequent exposures to dieldrin followed by infection with high lethal doses of MHV3. Phagocytic activity, cell adherence capacity, and attachment and uptake of 3H-radiolabeled MHV3 by C57Bl/6 peritoneal macrophages were determined by in vitro studies. These affector activities of peritoneal macrophages were slightly decreased or unchanged in cells originating from animals exposed to the pesticide. However, the intrinsic activity of MHV3 restriction appeared to be affected in macrophages derived from dieldrin-treated animals: (i) peritoneal C57Bl/6 macrophages collected from the early phase of acute MHV3 disease contained increased MHV3 antigen and (ii) increased cytolysis was observed after in vitro MHV3 infection of macrophages originating from dieldrin-exposed C57Bl/6 mice.     

The role of endothelin pathway in modulation of airway reactivity to methacholine in C57Bl/6 and BALB/c mice

Endothelin peptides have been shown to increase cholinergic neurotransmission in the airway. Genetic differences in airway responsiveness to methacholine where reported in mice. The present study compared the airway reactivity to methacholine in C57Bl/6 and BALB/c mice, the involvement of endothelin on this reactivity and endothelin levels in lung homogenates. Whole airway reactivity was analyzed by means of an isolated lung preparation where lungs were perfused through the trachea with warm gassed Krebs solution at 5 ml/min, and changes in perfusion pressure triggered by methacholine at increasing bolus doses (0.1-100 microg) were recorded. We found that the maximal airway response to methacholine was much greater in C57Bl/6 than in BALB/c (Emax 34+/-2 vs 12+/-1 cmH(2)O, respectively). Bosentan (mixed endothelin A/B receptor antagonist; 10 mg/kg, i.p., 30 min before sacrifice) reduced lung responsiveness to methacholine in C57Bl/6 (58% at EC50 level) but had no effect in BALB/c mouse strain. This effect seems to be mediated by the endothelin ET(A) receptor since it was significantly reduced by the selective endothelin ET(A) receptor antagonist, BQ 123. Immunoreactive endothelin levels were higher in C57Bl/6 than in BALB/c lungs (43+/-5 vs 19+/-5 pg/g of tissue). In conclusion, airway reactivity to methacholine and lung endothelins content varies markedly between C57Bl/6 and BALB/c strains. Endothelins upregulate lung responsiveness to methacholine only in C57Bl/6, an effect achieved through the endothelin ET(A) receptor.     

Possible role of serotonin 5-HT2 receptors in mechanism of afobazole anxiolytic action: neurochemical study of inter-line differences in mice

Effects of separate and combined introduction of afobazole and SB-200646A (highly selective 5-HT2B/2C receptor antagonist) on the content of monoamines and their metabolites in brain structures of mice of C57/Bl/6 and BALB/C lines have been studied using neurochemical methods and high-performance liquid chromatography (HPLC). Afobazole (5 mg/kg, i.p.) significantly increased dopamine (DA) level in hypothalamus and amygdala of C57/Bl/6 mice, while no changes of DA content were observed in BALB/C mice. At the same time, the concentrations of DA metabolites dioxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the same structures as well as in striatum were decreased compared to control. Afobazole also led to a decrease in the content of 5-hydroxyindoleacetic acid (5-HIAA) and 5-HIAA/5-HT index in frontal cortex and amygdala of C57/Bl/6 mice; analogous decrease in the latter parameter was observed in striatum of BALB/C mice. The introduction of SB-200646A (10 mg/kg, i.p.) almost did not influence the neurochemical indices of the content and metabolism of monoamines, except for an increase in the HVA content in amygdala and the DOPAC and 5-HIAA concentrations in striatum of C57/Bl/6 mice. The joint introduction of afobazole and SB-200646A led to an increase in the content of norepinephrine (NE) in striatum of BALB/C mice and in hippocamp of mice of both lines. The data obtained may be indicative of the involvement of NE- and DA-ergic neurotransmitter systems in the mechanisms of afobazole action. Enhanced anxiolytic effect of the joint introduction of afobazole and SB-200646A can be interpreted as a positive modulation of the anxiolytic drug action related to the blocking of 5-HT2-type serortonin receptors. The results also reveal inter-line differences of neurochemical responses induced by combination of afobazole and selective antagonist of serotonin.     

Apoptosis in stages of mouse hepatocarcinogenesis: failure to counterbalance cell proliferation and to account for strain differences in tumor susceptibility.

C3H/He and B6C3F1 show much higher liver cancer susceptibility than C57BL/6J mice. We studied the hypothesis that this difference might result from failure of apoptosis. Hepatocarcinogenesis was induced by a single dose of N-nitrosodiethylamine (NDEA), followed by phenobarbital (PB) for up to 90 weeks. We observed (1) earlier appearance of putative preneoplastic foci (PPF), hepatocellular adenoma (HCA), and carcinoma (HCC) in C3H/He than in C57Bl/6J mice and (2) an increase of hepatocellular DNA synthesis in C3H/He and C57Bl/6J mice, compared to normal liver, via PPF and HCA to HCC. PB enhanced DNA synthesis and growth of PPF, in the C3H/He strain only, and of HCA and HCC of both strains. Apoptoses were rare in unaltered livers as well as in preneoplastic lesions, but tended to increase in HCA and HCC of both strains. PB lowered apoptotic activity in PPF of C3H/He mice, but enhanced it in HCA and HCC of C57Bl/6J mice at late stages. In conclusion, the strain difference in growth rates of PPF and tumors is largely determined by higher rates of cell proliferation in C3H/He mice, with and without promotion by PB. Moreover, in C57Bl/6J mice the promoting effect of PB was restricted to HCA and HCC and was not seen in PPF. Apoptosis was generally low and was not a major cause of the strain difference in tumor susceptibility. In contrast with rat liver, inhibition of apoptosis appears to be a minor determinant of tumor promotion in mice.     

Capsaicin potentiates 1,25-dihydoxyvitamin D3- and all-trans retinoic acid-induced differentiation of human promyelocytic leukemia HL-60 cells.

Human promyelocytic leukemia HL-60 cells are differentiated into monocytic or granulocytic lineage when treated with 1,25-dihydroxyvitamin D₃ [1,25-(OH)₂D₃] or all-trans retinoic acid, respectively. In this study, the effect of capsaicin, an active component of the red pepper of the genus Capsocum, on cell differentiation was investigated in a HL-60 cell culture system. Treatment of HL-60 cells with 5–30 μg/ml capsaicin for 72 h inhibited cell proliferation and induced a small increase in cell differentiation. Interestingly, synergistic induction of HL-60 cell differentiation was observed when capsaicin was combined with either 5 nM 1,25-(OH)₂D₃ or 50 nM all-trans retinoic acid. Flow cytometric analysis indicated that combinations of 1,25-(OH)₂D₃ and capsaicin stimulated differentiation predominantly to monocytes whereas combinations of all-trans retinoic acid and capsaicin stimulated differentiation predominantly to granulocytes. Capsaicin enhanced protein kinase C activity in 1,25-(OH)₂D₃- and all-trans retinoic acid-treated HL-60 cells. In addition, inhibitors for protein kinase C [bisindolylmaleimide (GF-109203X), chelerythrine, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7)] and an inhibitor for extracellular signal-regulated kinase [2-(2′-amino-3′-methoxyphenyl)-oxanaphthalen-4-one (PD-098059)] significantly inhibited HL-60 cell differentiation induced by capsaicin in combination with either 1,25-(OH)₂D₃ or all-trans retinoic acid. These results indicate that capsaicin potentiates 1,25-(OH)₂D₃- or all-trans retinoic acid-induced HL-60 cell differentiation and that both protein kinase C and extracellular signal-regulated kinase are involved in the cell differentiation synergistically enhanced by capsaicin.     

Intra- and interstrain differences in models of "behavioral despair".

In the present studies, base line and drug-induced performance of two mouse strains (C57Bl/6 and NIH-Swiss) was evaluated in the forced swim test (FST) and tail suspension test (TST). Intra- and interstrain comparisons indicate that the biological substrates mediating performance in these behavioral procedures are not identical. For example, in NIH-Swiss mice, a sevenfold difference in base line immobility was observed between the FST and TST. By contrast, the base line immobility in C57Bl/6 mice was similar in both procedures. Further, in C57Bl/6 mice, imipramine produced a "U-shaped" dose-response curve in the FST, whilst no evidence of a biphasic response was present in the TST at doses up to 45 mg/kg. In the FST, the AMPA receptor potentiator LY451646 produced a similar dose-response relationship in C57Bl/6 and NIH-Swiss mice, but the minimum effect dose (MED) was fivefold higher in NIH-Swiss mice. This potency difference appears due to both pharmacokinetic and pharmacodynamic factors. These intra- and interstrain differences in performance indicate that despite a face value similarity, the neurochemical pathways involved in mediating performance in these two widely used tests are not identical.     

Inbred strain differences in prepulse inhibition of the mouse startle response

 Prepulse inhibition is the phenomenon in which a weak prepulse stimulus suppresses the response to a startling stimulus. Patients with schizophrenia have impaired prepulse inhibition which is thought to reflect dysfunctional sensorimotor gating mechanisms. To investigate the potential genetic basis for differences in sensorimotor gating, the responses of 13 inbred strains of mice were evaluated using the prepulse inhibition paradigm. Ten male mice from A/J, AKR/J, BALB/cByJ, BUB/BnJ, C3H/HeJ, C57BL/6J, C57BL/10J, DBA/2J, FVB/NJ, ST/bJ, 129/J, 129/SvJ, 129/SvEvTac inbred strains were tested for acoustic prepulse inhibition of acoustic and tactile startle responses. There was a wide range of responses among the inbred strains of mice. Exact strain distributions were determined for each combination of prepulse sound level and startle stimulus. In general, mice from the 129/SvEvTac, AKR/J, 129/J, and 129/SvJ strains displayed high levels of prepulse inhibition of both the acoustic and tactile startle responses. C57BL/6J, C57BL/10J and BUB/BnJ mice showed low levels of prepulse inhibition. There was also a wide range in the amplitude of the acoustic and tactile startle responses. C57BL/10J and FVB/NJ mice displayed the greatest startle responses and DBA/2J, 129/J and 129/SvJ had the poorest startle responses. There was no correlation between the level of prepulse inhibition and the amplitude of the startle response. These findings indicate that inbred strains of mice may be a useful tool to study the genetic basis of sensorimotor gating. Received:8 October 1996 / Final version: 10 December 1996     

破伤风疫苗在BALB/c与NIH小鼠中的免疫效果比较

目的 对比破伤风疫苗在BALB/c与NIH小鼠中的免疫效果,探讨将BALB/c小鼠用于破伤风疫苗效力实验的可能。方法 将破伤风毒素系列稀释至适当的浓度范围,根据小鼠存活情况摸索合适的毒素浓度,重复实验,测定BALB/c和NIH小鼠的破伤风毒素半数致死量（median lethal dose,LD₅₀）。分别用BALB/c和NIH小鼠的破伤风毒素2 LD₅₀同时攻击BALB/c与NIH小鼠,考察BALB/c和NIH小鼠对破伤风毒素的敏感性。将破伤风疫苗稀释50、100、200倍,分别作为高剂量组、中剂量组、低剂量组免疫BALB/c和NIH小鼠,免疫4周后用50 LD₅₀破伤风毒素攻毒,观察小鼠死亡情况。结果   BALB/c小鼠的破伤风毒素2 LD₅₀为0.16 μg/ml;NIH小鼠的破伤风毒素2 LD₅₀为0.23 μg/ml。用0.16 μg/ml的破伤风毒素分别注射BALB/c和NIH小鼠各3组,每组6只,BALB/c小鼠死亡动物数为3、3、2,NIH小鼠死亡动物数为0、0、0。用0.23 μg/ml的破伤风毒素分别注射BALB/c和NIH小鼠各3组,每组6只,BALB/c小鼠死亡动物数为6、6、6,NIH小鼠死亡动物数为3、2、3。3批破伤风疫苗免疫后的BALB/c与NIH小鼠采用相同攻毒剂量,每组14只,BALB/c小鼠攻毒后,高剂量组存活数为13、14、14,中剂量组存活数为10、10、9,低剂量组存活数为4、3、4;NIH小鼠攻毒后,高剂量组存活数为10、10、10,中剂量组存活数为6、7、6,低剂量组存活数为0、0、1。结论   BALB/c小鼠比NIH小鼠对破伤风毒素具有更高的敏感性,能更好地对破伤风疫苗产生免疫应答,在破伤风疫苗效价测定实验中是一种较为理想的小鼠品系。     

Activity and gene expression profile of certain antioxidant enzymes to microcystin-LR induced oxidative stress in mice

Microcystins are cyclic heptapeptide toxins produced by certain strains of Microcystis aeruginosa and microcystin-LR (MC-LR) is the most toxic among the 70 variants isolated so far. These toxins have been implicated in both human and livestock mortality. In the present study we investigated the microcystin-LR induced oxidative stress in mice in terms of its effect on activity and gene expression profile of certain antioxidant enzymes and expression of heat shock protein-70 (HSP-70). Mice were treated with 0.5 LD₅₀ (38.31 μg/kg) and 1 LD₅₀ (76.62 μg/kg) and the biochemical variables were determined at 1, 3, 7 days and 15, 30, 60 and 120 min post-exposure for 0.5 and 1 LD₅₀ dose, respectively. A significant time-dependent increase in HSP-70 expression over control was observed at 1 LD₅₀ dose. The toxin induced significant increase in liver body weight index, hepatic lipid perxoidation and depletion of GSH levels at 1 LD₅₀ compared to control group. There was significant decrease in the activity of antioxidant enzymes glutathione peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione-S-transferase (GST) at 1 LD₅₀. Except catalase, there was no effect on other antioxidant enzymes at 0.5 LD₅₀ dose. In contrast to activity of antioxidant enzymes the gene expression profile did not show any significant difference compared to control at 1 LD₅₀. GR showed significant decrease in expression at 1, 3 and 7 days in animals dosed with 0.5 LD₅₀ MC-LR. The results of our in vivo study clearly show the oxidative stress induced by MC-LR, and a correlation with activity and regulation at gene expression level of antioxidant enzymes.     

Oral pseudomonas aeruginosa immunization enhances survival in mice subsequently burned and infected with P. aeruginosa

Mice fed 0 serotype-specific strains of P. aeruginosa for two weeks, had increased titers of IgM but not IgG antibodies to the strains fed. Immunized mice, burned and infected with P. aeruginosa, showed significant 0 serotype-specific enhanced survival. Survival of mice fed several 0 serotype-specific strains simultaneously increased when these mice were burned and infected with P. aeruginosa homologous to those fed except when a high exotoxin A producing strain was used. Mice fed purified exotoxin A showed an increased LD₅₀ when injected with graded toxin doses. Feeding both 0 serotype-specific P. aeruginosa plus exotocin A increased survival even with burn and infection using the high toxin producing strain. We conclude that feeding P. aeruginosa antigens provides successful immunization which avoids the effects of parental adminstration.     

Immunotoxic potencies of polychlorinated biphenyl (PCB), dibenzofuran (PCDF) and dibenzo-p-dioxin (PCDD) congeners in C57BL/6 and DBA/2 mice

The dose-dependent effects of a single acute exposure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), 1,2,3,7,9-PeCDF, 1,3,6,8-tetrachlorodibenzofuran (TCDF), 3,3′,4,4′,5-pentachlorobiphenyl (pentaCB), and 3,3′,4,4′,5,5′-hexaCB on the suppression of the splenic plaque-forming cell (PFC) response to the T-cell-independent antigen trinitrophenyl-lipopolysaccharide were determined in C57BL/6 and DBA/2 mice. In addition, the induction of hepatic microsomal ethoxyresorufin O-deethylase (EROD) activity was also measured in these animals. 2,3,7,8-TCDD and 2,3,4,7,8-PeCDF were the most immunotoxic congeners in both strains of mice and with the exception of the latter congener, the ED₅₀ values for each compound were lower in the C57BL/6 than the DBA/2 mice. 2,3,7,8-TCDD induced hepatic microsomal EROD activity in both strains of mice whereas the other congeners were considerably less active or inactive as inducers. The results of this study demonstrated that for the halogenated aromatic hydrocarbons the immunotoxic response was a more sensitive indicator of exposure than the induction of CYP1A1 activity. The rank order for the immunotoxic potencies of the chlorinated aromatic compounds used in this study was 2,3,7,8-TCDD ≈ 2,3,4,7,8-PeCDF > 3,3′,4,4′,5-pentaCB ≈ 3,3′,4,4′,5,5′-hexaCB > 1,2,3,7,9-PeCDF > 1,3,6,8-TCDF. The order of activity for these congeners was similar for other Ah receptor-mediated responses and these results coupled with the differential responsiveness of the C57BL/6 and DBA/2 mice confirms the role of aryl hydrocarbon (Ah) receptor in mediating the suppression of this T-cell-independent response.     

An assay of the toxicity of the Atlantic puffer fish, Spheroides maculatus

Skin, muscle, liver, and gonadal extracts of the Atlantic puffer, Spheroides maculatus were assayed for toxicity in white mice. Extracts were injected intraperitoneally and were administered in the amounts of 1 ml per 20 g of body weight. The LD₅₀ of a composite skin extract, administered intraperitoneally in progressive doses per 20 g of body weight, was determined for white rats, white mice, chicks and frogs (Rana pipiens), while a LD₅₀ of a composite muscle extract was determined for the pinfish, Lagodon rhomboides.     

Ethanol-induced mouse strain differences in locomotor activity.

C57BL/6J mice showed dose dependent devreases in locomotor activity with increasing IP doses of ethanol (0.0, 0.75, 1.50 and 2.25 g/kg), while BALB/cJ mice showed dose dependent increases in activity; both strains were equally active with saline. Whether this finding represents decreased CNS responsivity in C57BL mice to ethanol's excitatory effect or increased response to its depressant action at sub-hypnotic doses is unclear, since anesthetic doses produce anesthesia of far shorter duration in the C57BL strain than in the BALB strain. It is possible that the biphasic action of alcohol is under the control of separate and distinct mechanisms, rather than a common one, and that these two mechanisms are differentially affected by alcohol. Endogenous as well as ethanol-induced neurochemical differences in biogenic amines may also be correlated with the gentic variation in CNS responsivity towards alcohol.     

Inherent differences in sensitivity to methylxanthines among inbred mice

The behavioral effects of caffeine, theophylline, paraxanthine, and theobromine on locomotor activity were analyzed in four strains of inbred mice that were previously shown to differ in their acute toxic responses to caffeine administered at high dosages. Dose response curves for the effects of caffeine, theophylline, paraxanthine and theobromine on locomotor activity were established in CBA/J, C57BL/6J, DBA/2J and SWR/J strains of inbred mice. Paraxanthine was the maximally effective methylxanthine in the CBA/J, DBA/2J and SWR/J strains, while in the C57BL/6J strain, caffeine was the maximally effective methylxanthine. Theophylline failed to stimulate locomotor activity in the C57BL/6J strain and theobromine failed to stimulate activity in all of the strains tested. Decreases in locomotor activity were seen at the 100 mg/kg dose of caffeine in the C57BL/6J mice and at the 100 mg/kg dose of theophylline in the C57BL/6J, DBA/2J and SWR/J strains. Theobromine produced decreases in locomotor activity in the C57BL/6J, DBA/2J and SWR/J strains of mice. In contrast to the other methylxanthines, paraxanthine failed to decrease activity across the range of doses tested (1.0-150 mg/kg). These data suggest that the methylxanthines have genetically specified multiple modes of action upon locomotor activity and that the use of genetically distinct strains of mice may have important value in the neurochemical and pharmacological dissection of methylxanthine-induced behavioral effects.     

Comparison of neurobehavioral changes in three inbred strains of mice prenatally exposed to methylmercury

Pregnant mice of three inbred strains (BALB/c, C57BL/6J, C57BL/6Cr) were orally given methylmercury (MMC; 3 x 3 mg/kg body weight) or the equivalent volume of phosphate-buffered saline during days 12-14 of gestation and allowed to deliver. The behaviors of their male offspring were evaluated in an open field and their home cage and in a Morris water maze. In the open field test, the BALB/c and C57BL/6Cr MMC groups exhibited less total locomotor activity than did their respective control groups. However, there was no significant difference observed between the MMC and control C57BL/6J strain. In the BALB/c strain, the MMC group exhibited significantly more central locomotion and significantly less peripheral locomotion than did the control group. These results indicated that the prenatal exposure to MMC caused decreases in open-field activity in the C57BL/6Cr and BALB/c strains, concomitantly with a change in emotional status in BALB/c strain. For spontaneous activity in their home cage, all groups moved more actively in the dark phase than in the light phase except BALB/c MMC group. The BALB/c MMC group moved in the light phase as much as in the dark phase, indicating a disturbance of nocturnal rhythm of spontaneous activity. In the Morris water maze, the C57BL/6Cr and C57BL/6J control groups perform very well over the 5 consecutive days. The prenatal exposure to MMC caused significantly prolonged latency in the C57BL/6Cr and C57BL/6J, but not in BALB/c strain. This result indicated that the prenatal exposure to MMC impaired the performance in the Morris water maze differently among the strains. This study provides a basis for evaluating strain-specific neurobehavioral changes when the widely used three inbred strains of mice are chronically exposed to MMC.     

Effects of ethanol and pentobarbital on neuronal hexose uptake in inbred mice

The effect of ethanol and pentobarbital narcosis on 2-deoxyglucose uptake into brain synaptosomes prepared from inbred C57BL/6J and DBA/2J mice which exhibit differential central sensitivity to ethanol and heterogeneous ICR mice was examined. A reversible depression of synaptosomal uptake was exhibited in all strains administered ethanol acutely, occurring at 2 min in ICR and C57BL/6J mice and 15 min in DBA/2J. Uptake returned to control values in all strains at 30 min although the mice remained intoxicated. Brain glucose concentration was significantly elevated at this time. Pentobarbital administration was without effect on synaptosomal hexose transport in DBA/2J and C57BL/6J mice but increased it significantly in ICR mice at 30 min. Pentobarbital anesthesia did not alter brain glucose concentration. No correlation was apparent between synaptosomal 2-deoxyglucose uptake and differential CNS sensitivity to ethanol and pentobarbital. The effects of ethanol and pentobarbital on neuronal hexose transport is discussed with respect to reported changes in glycolytic metabolism produced by these agents.     

Effect of polysaccharides from Ganoderma lucidum on streptozotocin-induced diabetic nephropathy in mice

The effects of Ganoderma lucidum polysaccharides (GL-PS) on renal complication in streptozotocin-induced diabetic mice have been investigated in the present study. C57BL/6J mice were made diabetic by injection of streptozotocin and GL-PS (125 and 250 mg kg^- 1) was administered for 8 weeks. Body weight was monitored every week. Serum glucose, creatinine (Cr), blood urea nitrogen (BUN), triglyceride (TG) and urinary albumin excretion (UAE) were measured after 8 weeks of treatment. Glomerular size and mesangial matrix index were assayed by morphometric analysis. Renal expression of transforming growth factor-β₁ (TGF-β₁) were determined by immunochemistry. Renal malondialdehyde (MDA) level and superoxide dismutase (SOD) activities were also evaluated. GL-PS was able to reduce the serum Cr and BUN levels and UAE compared with diabetic model mice in a dose-dependent manner. Increasing serum glucose and triglyceride levels in diabetic mice could also be lowered by GL-PS. Moreover, GL-PS had the capacity to improve the renal morphometric changes and oxidative stress state of diabetic mice. In summary, GL-PS can improve the metabolic abnormalities of diabetic mice and prevent or delay the progression of diabetic renal complications.