The role of serotonin-modulated anticonsolidation protein in memory formation in rats in a shuttle box

Two series of experiments were carried out in Wistar male rats. In the first series, rats were trained to acquire conditioning in a shuttle box to 50% and 80% learning criteria. In the animals of the experimental group that achieved 50% learning criterion, a significant decrease in the levels of serotonin-modulated anticonsolidation protein (SMAP) (solid phase, indirect ELISA-test) was observed in the temporal cortex as compared to the animals of the active control group. In the animals of the experimental group that achieved 80% learning criterion, such a decrease was found in the occipital and temporal cortex. In the second series of the experiments, animals of the experimental group were injected with SMAP in saline at a concentration of 1.5 mg/ml in a volume of 10 microl through the cannula implanted into the left lateral ventricle of the brain. Control animals were administered with heating-inactivated SMAP in the same amount. The substances were injected to the animals under light ether anesthesia daily 40 min prior to learning sessions. Learning sessions were carried out in the shuttle box for several days to 50% learning criterion. The experimental rats achieved learning criterion within 7-8 days, whereas intact and control animals reached the same criterion within 4 days. Furthermore, the experimental group of animals differed in increased levels of fear, anxiety and aggression which did not decline throughout the whole learning period. The conclusion was made that SMAP participated in negative regulation of the memory trace formation.     

Study on potential effects of "902-MHz GSM-type Wireless Communication Signals" on DMBA-induced mammary tumours in Sprague-Dawley rats

The aim of the study was to detect whether long-term exposure to "902-MHz GSM-type Wireless Communication Signals" ("radio-frequency (RF)-exposure") would affect 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumours in female Sprague-Dawley rats. Five hundred female rats were each given a single oral dose of 17 mg DMBA per kg body weight (bw) at an age of 46-48 days. Three groups of 100 animals each were RF-exposed (902 MHz; crest factor 8; pulse width=0.57 ms) from the next day onwards to normal whole-body averaged doses (expressed as specific absorption rate, SAR) of 0.4, 1.3 or 4.0 W/kg bw (low/mid/high-dose group) for 4h/d, 5d/week, during 6 months. A sham-exposed and a cage-control group remained without RF-exposure (<0.01 mW/kg). Animals were weekly weighed and palpated for mammary tumours; all mammary glands were examined histopathologically. There were several statistically significant differences between RF-exposed groups and the sham-exposed group, as follows: All RF-exposed groups had, at different times, significantly more palpable tissue masses. There were fewer animals with benign neoplasms, but more with malignant tumours in the high-dose group. In addition, there were more adenocarcinomas in the low-dose group, more malignant neoplasms in the low- and high-dose groups, more animals with adenocarcinomas in the high-dose group, and fewer animals with fibroadenomas in the low- and mid-dose groups. The cage-control group had, when compared with the sham-exposed group, statistically significantly more palpable tissue masses, more benign and also more malignant neoplasms. The cage-control group had in most aspects the highest incidence and malignancy of neoplasms among all groups. None of the above findings in RF-exposed animals produced a clear dose-response relation and the responses of the cage-control group were either similar to or stronger than those of any of the RF-exposed group. The significant differences between the sham-exposed animals and one or more RF-exposed groups may be interpreted as evidence of an effect of RF-exposure. In the context of the results of the cage-control group, in the light of controversial results reported in the literature, and given the fact that the DMBA-mammary tumour model is known to be prone to high variations in the results, it is the authors' opinion that the differences between the groups are rather incidental ones.     

GSM and DCS wireless communication signals: combined chronic toxicity/carcinogenicity study in the Wistar rat

A total of 1170 rats comprised of 65 male and 65 female Han Wistar rats per group were exposed for 2 h/day, 5 days/ week for up to 104 weeks to GSM or DCS wireless communication signals at three nominal SARs of 0.44, 1.33 and 4.0 W/kg. A preliminary study confirmed that the highest exposure level was below that which was capable of causing a measurable increase in the core temperature of the rat. Additional groups for each modulation were sham exposed, and there was also an unrestrained, unexposed (cage) control group. Fifteen male and 15 female rats per group were killed after 52 weeks. From the remaining 50 male and 50 female rats per group, surviving animals were killed after 104 weeks. Evaluations during the study included mortality rate, clinical signs, recording of palpable masses, body weight, food consumption, ophthalmoscopic examination, and clinical pathological investigations. Terminal investigations included organ weight measurement and macroscopic and microscopic pathology examinations. There was no adverse response to the wireless communication signals. In particular, there were no significant differences in the incidence of primary neoplasms, the number of rats with more than one primary neoplasm, the multiplicity and latency of neoplasms, the number of rats with metastases, and the number of benign and malignant neoplasms between the rats exposed to wireless communication signals and rats that were sham exposed.     

Modification of the repair processes in chemical mutagenesis in Drosophila melanogaster]

The effect of 1,4-dihydroisonicotinic acid derivative (1,4-DHINA), glutapyrone, on the frequency of sex-linked recessive lethals (SLRL), which were induced by ethyl methanesulfonate (EMS) in spermatozoa, was studied in Drosophila males and females under different exposure conditions. This test was used to analyze repair processes in EMS mutagenesis. Glutapyrone manifested the protective effect after precultivation of males at the stage of larvae and females with glutapyrone. This preparation was shown to have no effect on the frequency of EMS-induced mutations under other conditions (precultivation and subsequent cultivation of mature males with glutapyrone). These data confirmed a key role of indirect mechanisms responsible for the effect of the examined antimutagen. Glutapyrone may be assumed to improve the synthesis or functioning of enzymes involved in the repair of O6-ethylguanine. After adaptive treatment of Drosophila with low doses of the mutagen, glutapyrone increased the fertility of parents but did not suppress chemical mutagenesis.     

Cytogenetic evaluation of arsenic trioxide toxicity in Sprague-Dawley rats

Acute exposure to arsenic trioxide has been reported to induce death and/or multiple organ damage with symptoms including nausea, vomiting, diarrhea, gastrointestinal hemorrhage, cerebral edema, tachycardia, dysrhythmias and hypovolemic shock. Its toxic effects are due to its ability to bind to sulfhydryl groups of proteins and to inhibit energy production. Although the chronic exposure to arsenic trioxide has been linked to various types of cancer, such as skin, liver, lung, bladder and kidney neoplasms, studies of its carcinogenic potential in animals have not been conclusive. In this study, we investigated the genotoxic potential of arsenic trioxide in bone-marrow cells obtained from Sprague-Dawley rats; using chromosomal aberrations (CA), mitotic index (MI) and micronuclei (MN) formation as the toxicological endpoints. Four groups of six male rats each, weighing approximately 60+/-2 g per rat, were injected intraperitoneally, once a day for 5 days with doses of 5, 10, 15 and 20 mg/kg body weight (BW) of arsenic trioxide dissolved in distilled water. A control group was also made of six animals injected with distilled water without chemical. All the animals were sacrificed at the end of the treatment period. Chromosome and micronuclei preparation was obtained from bone-marrow cells following standard protocols. Arsenic trioxide exposure significantly increased the number of structural chromosomal aberrations, the frequency of micronucleated cells and decreased the mitotic index in treated groups when compared with the control group. Our results demonstrate that arsenic trioxide has a clastogenic/genotoxic potential as measured by the bone-marrow CA and MN tests in Sprague-Dawley rats.     

Effect of allicin from garlic powder on serum lipids and blood pressure in rats fed with a high cholesterol diet

The use of fresh aqueous garlic extract is known to be effective in reducing thromboxane formation by platelets in both in vivo and in vitro animal models of thrombosis. In the present study, we studied the effect of Lichtwer garlic powder (containing 1.3% alliin equivalent to 0.6% allicin) on the serum cholesterol, triglyceride, glucose, protein, and systolic blood pressure in rats fed with a high cholesterol diet. Experimental rats were fed a 2% high cholesterol diet with and without garlic powder for 6 weeks. Control rats were fed a normal diet. The aqueous garlic powder extract was given orally to rats on a daily basis. It was observed that cholesterol-fed animals had a significant increase in serum cholesterol compared to the control group of rats fed on a normal diet. However, when the rats were fed with a high cholesterol diet mixed with garlic powder, there was a significant reduction in their serum cholesterol levels compared with the group which were on a diet containing high cholesterol without garlic powder. Serum triglyceride levels were also significantly lowered by garlic powder when compared to control and high cholesterol diet group rats. The blood pressure of the high cholesterol diet animals was significantly higher compared to the animals receiving the control diet. The blood pressure of the animals receiving garlic powder and high cholesterol diet was significantly lower as compared to the high cholesterol and control diet group. No significant changes were observed in the serum glucose and protein in all of the rats. These results show that garlic is beneficial in reducing blood cholesterol, triglycerides levels and systolic blood pressure in hypercholesterolemic rats. Our experimental results show that garlic may beneficially affect two risk factors for atherosclerosis--hyperlipidemia and hypertension.     

Changes in the regulation of calcium metabolism and bone calcium content during growth in the absence of endogenous prolactin and during hyperprolactinemia: a longitudinal study in male and female Wistar rats

Since endogenous prolactin has been shown to enhance food consumption, calcium absorption, and bone calcium turnover in the pregnant rat, the role of endogenous prolactin in the regulation of calcium metabolism was investigated in 3-day balance studies of female Wistar rats from the age of 3 to 11 weeks. The study was divided into two parts. In part I, calcium metabolism in males and females was compared. In part II, 3-week old female rats were divided into 5 groups: (i) control animals receiving 0.9% NaCl; (ii) animals receiving 6 mg bromocriptine/kg/day (- PRLendo group); (iii) animals receiving 2.5 mg ovine prolactin/kg/day (+PRLexo); (iv) sham-operated animals receiving 0.9% NaCl, and (v) animals with two extra pituitaries implanted under the renal capsule, receiving 0.9% NaCl (AP group). Results showed that rapid growth occurred between 3 and 6 weeks with maximum fractional calcium absorption and calcium retention at 5 weeks of age in both sexes. The data also showed a physiological significance of endogenous prolactin in enhancing calcium absorption and retention in 5 week old rats. In an absence of prolactin, peak calcium absorption was delayed in 7-week old animals, and vertebral calcium content of 11-week old animals was reduced by 18%. Hyperprolactinemia in the AP group was found to enhance fractional calcium absorption and calcium retention at 7, 9, and 11 weeks and increased the femoral calcium content by 16%. It could be concluded that a physiological role of prolactin is the stimulation of calcium absorption and maintainance of bone calcium content during growth and development.     

The effect of chronic calcium treatment on thyroid C cells in ovariectomized rats

The purpose of this study was to investigate the influence of chronic calcium treatment on the structure and function of thyroid C cells in ovariectomzed adult female rats. Eighteen 3-month-old, female Wistar rats were divided into three groups. The first group was used as the sham-operated control, and the other two were surgically ovariectomized (Ovx). One month after gonadectomy, one group of Ovx rats was injected with 28.55 mg Ca-glucoheptonate (Ca)/kg b.w., while the other two groups were chronically treated with vehicle alone (Ovx and sham control). Two months after surgery, the animals were killed. In the thyroid C cells, calcitonin (CT) was localized with the peroxidase-antiperoxidase method. Stereology was used to evaluate morphometric changes in the volume of C cells, their nuclei and relative volume density. The number of C cells per unit area was calculated. Serum CT content was determined by radioimmunoassay. After chronic Ca treatment C cells were numerous with darker cytoplasm than in C cells of sham-operated control animals, but more degranulated than the corresponding cells of Ovx rats. Their volume was significantly decreased by 14% (p < 0.05), while the number was increased by 47% (p < 0.05) in comparison with corresponding controls. Serum CT concentration was decreased by 27% (n.s.) in comparison to sham-operated control. Calcium treatment of Ovx rats led to a 32% increase of serum CT concentration in relation to untreated Ovx animals. These results suggest that chronic Ca treatment of Ovx female rats positively affected CT release from thyroid C cells, without any significant changes in morphometric parameters.     

Thyroxine-induced cardiomegaly in rats of different age

In the present study the effect of thyroxine treatment on the development of cardiomegaly was compared in young (10-day-old) and adult (12-week-old) rats. L-thyroxine was administered subcutaneously in a dose of 1 mg per kg b.w. for 5 days. In young thyroxine-treated rats the heart weight increased by 79% in comparison with the control rats. The number of blood capillaries and muscle fibres per mm2 remained unchanged. The concentration of hydroxyproline was even lower than in control animals. The number of 3H-thymidine-labelled muscle cell nuclei was significantly higher both in the left and right ventricles of thyroxine treated rats. The density of capillaries and muscle fibres was significantly lower in adult rats than in the group of young animals. In adult thyroxine-treated animals the heart weight was higher by 36%, the number of capillaries and muscle fibres as well as the concentration of hydroxyproline was unchanged. Thyroxine induced significant increase in the number of DNA synthesizing nuclei of muscle cells in the left ventricle while the change in the right ventricular myocardium was not statistically significant. The present data indicate that a hyperplastic response of cardiac muscle cells to thyroxine occurs in both ventricles of young rats and also in the left ventricle of adult animals.     

Effect of prenatal hypobaric hypoxia on activity of the rat brain phosphoinositide system

Activity of the phosphoinositide system of intracellular signalization was studied in offspring of rats exposed to severe hypobaric hypoxia at the 14–16th (group 1) or the 18–20th day (group 2) of prenatal hypoxia. At the age of 15 days, in animals of both experimental groups the basal level of triphosphoinositides in the brain cortex was shown to be elevated as compared with control. In the group 1, this parameter also remains elevated in adult animals. Application of glutamate produces a more pronounced increase of the inositephosphates in brain slices of the 15-day old rats of the group 1 than in slices of animals of the control group. In the 15-day old rats of the group 2, as compared with control, the phosphoinositide response to glutamate application was reduced. No changes in the inositephosphate levels were revealed after application of glutamate upon slices of adult (the 90-day old) control animals and of adult rats of the group 2. In slices of adult rats of the group 1, on the contrary, the glutamate application produced an increase of the inositephosphate content. The obtained data indicate essential changes of the phosphoinositide metabolism in the brain of rats exposed to action of hypoxia at the period of prenatal development. The character and the severity of these changes depend on the period of development when action of hypoxia occurs.     

白地霉长期饲喂大鼠对食管和前胃影响的组织形态观察

在肿瘤病因研究中,霉菌与肿瘤发生的关系,近十多年来愈来愈受到人们的重视,目前已知约有10种真菌的毒素有致癌作用,能诱发出大、小鼠不同器官的肿瘤,如黄曲霉毒素与肝癌的关系为人们所共知(徐达道1973;孟昭赫,1973;严瑞琪,1978;Lancaster,1961;Schoental,1961)。自国内有关白地霉(Geotrichum candidum Link)致瘤与促癌作用实验研究等文章发表以来(杨简、高进,1980),引起了工、农、医有关部门极大的关注。早在1958年上海即利用废泔脚水做原料,发酵培养白地霉制咸蛋白质的补充食料“人造肉精”,初步试用饲养猪、鸡作为蛋白质饲料,更进而利用白地霉菌体提取核酸及     

Source of ethane in expirate of rats ventilated with 100% oxygen

Ethane in alveolar expirate may have its source in organs other than the lung and be transported to the lung for elimination. We determined ethane production rates in rats (group I) ventilated with hydrocarbon-free air (HFA) before and after exsanguination. To determine whether the lung is the source of increased ethane production during exposure to 100% O2, we measured ethane in the expirate of nine exsanguinated, Sprague-Dawley rats (group II) mechanically ventilated with HFA and then with 100% O2. In all nine animals, ethane elimination rates on 100% O2 increased compared with HFA values. In five of the nine rats, HFA ventilation was reinstated after O2 (group III). In all five, ethane elimination fell with HFA ventilation compared with the value on 100%. Six rats with circulation intact were ventilated with HFA and then 100% O2 (group IV). Ethane production rate for group IV animals breathing HFA was not significantly different from the exsanguinated animals in group II while ventilated with HFA. The mean increase in ethane production for the group II animals was not significantly different from the group IV animals. Lung slices from four other rats (group V) were incubated in saline at 37 degrees C with FeCl2 (10 mg) added to enhance free radical formation. Paired lung samples from the same rat were incubated with either HFA or 100% O2. Headspace gas was analyzed chromatographically for ethane at 120 min. Mean ethane in the O2 samples was higher than for HFA. Rat lung tissue is the main source of increased ethane production during 100% O2 exposure.     

Effect of cyclophosphamide on rats experimentally infected with Cryptococcus neoformans

This study was undertaken to establish the function of T-lymphocytes in protective immunity against a cryptococcal infection in animals treated with Cyclophosphamide (Cy) pre or post infection and to determine how they relate to the progression of the disease.Inbred Suquía rats were infected either intranasally (i.n.) or intraperitoneally (i.p.) with 10⁵ viable Cryptococcus neoformans cells. The infected rats were divided in three groups. One of the groups (group I) was utilized as a control. The second group (group II) was treated with Cy 3 days before the infection. The third group (group III) was treated with Cy 3 days after the infection.At approximately 22 days post infection, C. neoformans growth in selected organs of all animals were determined. In addition, humoral and delayed-type hypersensitivity (DTH) response were assayed in the rats.When the Cy was applied after the infection the DTH was significantly diminished and inverse to the colony forming unit (CFU) which increased leading to the animals death. On the other hand, injection of the drug 3 days before infection did not modify the response, that was comparable in both treated and the control animals.In this study it were found haemagglutinating antibodies in sera from i.n. and i.p. infected rats although at minimal levels and were not present in all animals.The results show that with a low T-cell function induced as a consequence of injecting Cy after the infection, rats did not develop a normal DTH response to cryptococcal infections and were not able to control a cryptococcal infection as well as animals with normal T-cell function.     

Effect of intraperitoneal administration of Streptococcus group A and its cell fractions on the development of adjuvant arthritis in rats

The effect produced by the intraperitoneal injection of live and heat-killed group A streptococci, the fractions of their cell walls (both intact and sonicated) and cytoplasm was studied on 450 white rats with experimental adjuvant arthritis (AA). The injection of live streptococci into rats with AA decreased the swelling of joints (by 70-80% in the second half of the experiment), reduced the titers of rheumatoid-like factor (RLF), and inhibited the development of polyarthritis. The use of heat-killed streptococci gave a less pronounced antiarthritic effect, while the fraction of streptococcal cell walls, similarly to live streptococci, decreased the swelling of joints (by 27-64%); at the same time a considerable drop in the titers of RLF was observed in 3 experiments, and the development of polyarthritis was registered in 38% of the test animals and in 62% of the control animals. In rats with AA the cytoplasm not subjected to ultracentrifugal purification decreased the swelling of joints (by 21-50%) and the titers of RLF. In this case the development of polyarthritis was observed in 48% of the test animals and in 70% of the control animals.     

Acid-base balance and lactatemia in acute hypoxia in normoxic or hypoxic albino rats

Albino rats Wistar family were raised since birth in normobaric hypoxic environment (10% O2 in N2). This hypoxic animal group and a normoxic control group were subjected to acute hypoxia in two spaced tests. The rats were exposed for 15 minutes to 7% O2 and later to 5% O2 gas mixture. At the end of the test with 7% O2 the hypoxic animals since birth showed a smaller quantity of blood lactate and their acid-base balance was more acid when compared to control animals. These differences were significant. In the considered metabolic parameters the differences between the 2 groups became not significant at the end of the test with 5% O2. We believe that the found differences in mentioned parameters between hypoxic and normoxic animals, also according to cellular adaptative processes, occurred during the rearing in hypoxic environment. In the test with 5% O2 the seriousness of the hypoxia overcomes the effects of adaptative mechanisms in hypoxic animals since birth. We believe that hypoxic rats since birth represent, limitedly to some aspects, different metabolic models compared to normoxic animals.     

Increase in duration of paradoxical sleep after carotid occlusion in rats

Nonlinear rats, which survived after occlusion of one or two common carotid arteries (N = 30, about 30% survived) were examined. Sham-operated animals formed a control group. In animals with ischemia, the total sleep duration in a three-hour period was substantially increased as compared to control group at the expense of a substantial growth (8-9 times) of paradoxical sleep (PS) phase. In the animals with ischemia, a sharp increase in PS was observed on the first postoperation day, and then PS gradually decreased from the first to the fortieth days. The results suggest the PS involvement in the brain intrinsic reparation functions.     

Skeletal and heart muscle protein turnover during long-term exposure to high environmental temperatures in young rats

A study was undertaken to determine the long-term effects of a hot environment on protein turnover in skeletal and cardiac muscles of young homeothermic animals. Three groups of 36 male 28 day old rats were housed at 35 degrees C (hot group), 25 degrees C (control group), or 25 degrees C but pair-fed to the intake of the hot group (pair-fed group). Rates of protein synthesis and degradation were measured in vivo on days 5, 10, 15, and 20. By day 20, soleus and gastrocnemius (skeletal muscle) protein masses were 7 and 14% lower in the hot group and 31 and 21% lower in the pair-fed group compared with the control group (P < 0.05). The fractional rate of protein synthesis (k(syn)) was on average 11% lower (P < 0.05) in the hot group compared with control rats and was not different from pair-fed rats. The fractional rate of skeletal muscle protein degradation (k(deg)) in hot rats was slightly lower than in control rats; k(deg) was on average 18% higher (P < 0.05) in the pair-fed group compared with the hot group and this difference appeared to be most prominent on day 5. In heart, by day 20, protein mass was 30% lower in the hot group and 40% lower in the pair-fed group compared with control rats (P < 0.05). k(syn) was on average 19% lower (P < 0.05) in the hot group compared with the control group, but not different from pair-fed rats. In the heart there were no differences in k(deg) among treatments. Plasma triiodothyronine (T3) concentration was lower in the hot group, but not in the pair-fed group, compared with controls. In conclusion, chronic exposure to hot environments was associated with lower skeletal and cardiac muscle mass and protein turnover; lower protein mass in this tissue was due to decreased k(syn); this is consistent with lower plasma T3 concentrations. In pair-fed rats, k(syn) was also reduced, but interestingly k(deg) was not, resulting in a greater loss of skeletal muscle mass. These results suggest that heat exposure invokes physiological adaptations to preserve skeletal muscle mass despite decreased food intake. In the heart, loss of protein was a result of decreased k(syn), which can be primarily ascribed to lower food intake.     

Effects of spreading depression on stress-induced changes in plasma prolactin and LH.

Female rats rendered "pseudopregnant" by treatment with PMS and hCG and ovariectomized rats injected with estradiol and progesterone (OVX-E2-P) were subjected to cortical spreading depression (SD). Within 7-10 min under ether anesthesia in a stereotaxic instrument a frontal craniotomy was performed and a cotton ball saturated with physiological saline (control) or 25% KCl was applied to the exposed dura, covered with dental cement and skin sutured. The animals were then placed in separate containers in an isolated room and decapitated for collection of trunk blood at 0, 15, 30, or 60 min after surgery. In PMS-hCH saline-treated control animals, prolactin levels had dropped by 15 and 30 min when compared with the zero-time values but by 60 min had increased significantly above the 30-min level. At that time (60 min), prolactin values in the KCl group were significantly lower than in the controls. Corticosterone levels were high at both 15 and 60 min in control and KCl groups. In OVX-E2-P control animals, plasma prolactin levels also rose at 60 min compared with 15- and 30-min samples and at 60 min were significantly higher than in the KCl group. In control animals, LH levels were lower at 15 and 60 min than at zero time, but they remained unchanged in the KCl group. The dato are interpreted as indicating that cortical SD suppresses the stress responses observed in saline-treated control animals.     

Effects of 1,4-dihydropyridine derivatives (cerebrocrast, gammapyrone, glutapyrone, and diethone) on mitochondrial bioenergetics and oxidative stress: a comparative study

The potential protective action of 1,4-dihydropyridine derivatives (cerebrocrast, gammapyrone, glutapyrone, and diethone) against oxidative stress was assessed on mitochondrial bioenergetics, inner membrane anion channel (IMAC), Ca2+-induced opening of the permeability transition pore (PTP), and oxidative damage induced by the oxidant pair adenosine diphosphate (ADP)/Fe2+ (lipid peroxidation) of mitochondria isolated from rat liver. By using succinate as the respiratory substrate, respiratory control ratio (RCR), ADP to oxygen ratio (ADP/O), state 3, state 4, and uncoupled respiration rates were not significantly affected by gammapyrone, glutapyrone, and diethone concentrations up to 100 microM. Cerebrocrast at concentrations higher than 25 microM depressed RCR, ADP/O, state 3, and uncoupled respiration rates, but increased three times state 4 respiration rate. The transmembrane potential (deltapsi) and the phosphate carrier rate were also decreased. At concentrations lower than 25 microM, cerebrocrast inhibited the mitochondrial IMAC and partially prevented Ca2+-induced opening of the mitochondrial PTP, whereas gammapyrone, glutapyrone, and diethone were without effect. Cerebrocrast, gammapyrone, and glutapyrone concentrations up to 100 microM did not affect ADP/Fe2+-induced lipid peroxidation of rat liver mitochondria, while very low diethone concentrations (up to 5 microM) inhibited it in a dose-dependent manner, as measured by oxygen consumption and thiobarbituric acid reactive substances formation. Diethone also prevented deltapsi dissipation due to lipid peroxidation initiated by ADP/Fe2+. It can be concluded that: none of the compounds interfere with mitochondrial bioenergetics at concentrations lower than 25 microM; cerebrocrast was the only compound that affected mitochondrial bioenergetics, but only for concentrations higher than 25 microM; at concentrations that did not affect mitochondrial bioenergetics (< or = 25 microM), only cerebrocrast inhibited the IMAC and partially prevented Ca2+-induced opening of the PTP; diethone was the only compound that expressed antioxidant activity at very low concentrations (< or = 5 microM). Cerebrocrast acting as an inhibitor of the IMAC and diethone acting as an antioxidant could provide effective protective roles in preventing mitochondria from oxidative damage, favoring their therapeutic interest in the treatment of several pathological situations known to be associated with cellular oxidative stress.     

NTPDase activity in lymphocytes of rats infected by Trypanosoma evansi

Trypanosoma evansi is the aetiological agent of trypanosomosis in domestic animals. In this pathology, an inflammatory response can be observed and, as a consequence, the increase of extracellular adenine nucleotides such as ATP. These nucleotide concentrations are regulated by ectoenzymes such as NTPDase (EC 3.6.1.5, CD39), which catalyses the hydrolysis of ATP and ADP into AMP. In this study, the activity of NTPDase in lymphocytes of rats experimentally infected with T. evansi was evaluated. The animals were inoculated with the parasite and monitored by blood smear on a daily basis. The animals were then were divided into 4 groups according to the degree of parasitaemia and period of infection. The blood collections for enzyme analysis and lymphocyte count were performed on the 3rd (beginning of infection), 5th (acute infection) and 15th (chronic infection) days post-infection (p.i.). The control group was composed of non-infected animals. In the infected group a decrease in ATP hydrolysis (36%) was observed on the 3rd day p.i. and a decrease in ADP hydrolysis (62%) was observed on the 5th day p.i. when compared to the control. On the 15th day p.i., an increase in ATP (94%) and ADP (50%) hydrolysis was observed in the infected group. Considering these data it is suggested that NTPDase activity is altered on the surface of lymphocytes of rats infected with T. evansi at different time-points of infection.