Effects of prolonged oral administration of fumonisin B(1) and aflatoxin B(1) in rats

The effects of prolonged oral administration (21 days) of fumonisin B(1) (FB(1)) and aflatoxin B(1) (AFB(1)) were evaluated on male Wistar rats. The animals were housed in individual metabolic cages and submitted to the following treatments: 1-0 mug AFB(1) + 0 mg FB(1)/100g bw.; 2-72 mug AFB(1)+ 0 mg FB(1)/100 g bw; 3-0 mug AFB(1) + 0.5 mg FB(1) g bw; 4-0 mug AFB(1) + 1.5 mg FB(1)/100 g bw; 5-72 mug AFB(1) + 0.5 mg FB(1)/100g bw; 6-72 mu gAFB(1) + 1.5 mg FB(1)/100g bw. on day 21, the rats were sacrificed for evaluation. The results showed that treated animals presented differences in body weight and absolute/relative weights of liver and kidney as well as altered hepatic function and cholesterol blood levels. Rats fed with the greatest doses of AFB(1) and FB(1) gained less weight (2.79 g/day) at the end of the experimental period; their blood concentrations of liver enzymes aspartate aminotransferase (AST) and alkaline phosphatase (AP) were above control levels (130.35 mu /l and 471.00 mu /l, respectively). Blood cholesterol increased in the groups treated with the highest dose of FB(1) or FB(1) associated with AFB(1). Histopathology revealed the occurrence of apoptosis in the liver of rats exposed to FB(1). The association of aflatoxin B(1) with fumonisin B(1) at higher dose probably potentiated the effects of the higher dose of fumonisin B(1)acting singly.

Developmental lead exposure induces depressive-like behavior in female rats

The involvement of neurotoxicants in the etiology of emotional pathologies is becoming an issue in neurotoxicology. Lead (Pb) exposure during childhood has been associated with increased impulsivity, aggressivity, and delinquency. Considering the paucity of experimental studies investigating the involvement of developmental Pb exposure in emotional disorders, our objective was to investigate whether Pb exposure during pregnancy and/or lactation could be related to depressive symptoms in adult male and female rats. Wistar dams received 10 mg of Pb, as Pb acetate, or 13.4 mg of Na acetate, by gavage, daily, during pregnancy and lactation. By cross-fostering at the time of birth, pups were either exposed to Ph or Na acetate during pregnancy only, lactation only, or during both pregnancy and lactation. At 70 days of age, animals were submitted to the open-field test followed by the forced swimming test. Ph levels were measured in the blood of dams (weaning) and pups (after behavioral evaluation). The results demonstrated that exposure to Ph during both pregnancy and lactation induced, in males, an increased emotionality state detected in the open-field test, and in females, depressive-like behavior detected in the forced swimming test. These alterations were observed at residual blood Pb levels (i.e., around 5 mug/dL).

Latero-terminal neurorrhaphy without removal of the epineural sheath. Experimental study in rats.

Termino-lateral neurorrhaphies have been used up to the beginning of this century. After this period, they have no longer been reported. We tested the efficacy of a new type of latero-terminal neurorrhaphy and evaluated the role of the epineural sheath. A group of 10 rats had the fibular nerve sectioned and the distal ending was sutured to the lateral face of the tibial nerve without removing the epineurium. All experiments were made on the right side, the left one remaining untouched in half of the animals of each group. The other half were denervated by sectioning and inverting the endings of the fibular nerves. In this way, tibial cranial muscles were either normal or denervated in the left side and reinnervated through latero-terminal neurorrhaphy in the right side. After 7.7 months, the animals were subjected to electrophysiological tests, sacrificed, and the nerves and muscles were taken for histological exams. A response of the tibial cranial muscle was obtained in 75% of the animals. The distal ending of the fibular nerve showed an average of 498 nerve fibers. The average areas of the reinnervated tibial cranial muscles were (mu 2):841.30 for M2n and 1798.33 for M2d. We concluded that the termino-lateral neurorrhaphy was functional, conducting electrical stimuli and allowing the passage of axons from the lateral surface of a healthy nerve, to reconstitute the distal segment of a sectioned nerve. The presence of the epineurium was no impediment to axonal regeneration or to the passage of electrical stimuli.(ABSTRACT TRUNCATED AT 250 WORDS)

Free autogenous cartilage grafts to the mandible of rats-histological study.

The present study was designed to histologically evaluate the behavior of free autogenous cartilage grafts to the mandible of rats. A 3-mm segment was removed from the last rib of male adult rats and transplanted fresh to a receptor bed prepared on the mandibular ramus. The results showed that the grafts maintained their vitality up to 120 days and the perichondrium was biologically integrated to the osseous bed. Appositional growth of the grafts was found. New bone formation was observed in close proximity to the grafts, but newly formed trabeculae did not arise from perichondrium.

Efeito do envelhecimento sobre o comportamento mecânico dos músculos papilares de ratos Wistar.

PURPOSE--To evaluate the effects of age on mechanical performance of rat myocardium. METHODS--Left ventricular papillary muscles were isolated from male Wistar rats at 1, 3, 6 and 12 months of age. Muscles were studied isometrically and isotonically, stimulated at 0.2 Hz, perfused with Krebs-Henseleit solution having an external calcium concentration of 2.52 mM, and maintained at 28 degrees C. RESULTS--Peak isometric developed tension was significantly higher in 1 month than 3, 6 and 12 months. Peak rate of isometric tension rise decreased substantially between 1, 3 and 12 months. Time to peak isometric developed tension showed a significant increase of both 3 and 12 months of age. Time to half relaxation increased significantly from 3 to 6 and from 3 to 12 months. Maximum rate of tension decline decreased from 3 to 6 and from 3 to 12 months. No difference in resting tension was noted among any group. Isotonically, peak shortening and time to peak shortening increased from 1 to 3 months of age. Time to half re-lengthening increased from 3 to 6 and from 3 to 12 months of age. No difference in peak shortening velocity, peak relaxation velocity and relative change in muscle length was noted among any groups. CONCLUSION--The maturation affects the mechanical performance of cardiac muscle.

Allogeneic transplants of rib cartilage preserved in 98% glycerol or 70% alcohol into the malar process of rats: a comparative histological study.

A comparative study was made of two methods of cartilage preservation, 98% glycerol and 70% alcohol. Rib cartilage was treated by either of these methods and transplanted into the malar process of rats. Cartilage grafts preserved by both methods were equally well tolerated. Resorption and bone substitution were similar in both groups after 120 days, although resorption was greater for the alcohol-preserved cartilage up until day 30. The possible reduction in antigenicity by the 98% glycerol did not produce any difference of behavior from the cartilage preserved in 70% alcohol.

Toxicologic evaluation of acute and subacute oral administration of Cucurbita maxima seed extracts to rats and swine

The extract prepared from dried seeds of Cucurbita maxima was administered to rats and pigs. Following a single dose or 4 weeks of daily oral administration, the extract produced no changes in serum glucose, urea, creatinine, total protein, uric acid, GOT, GPT, LDH or blood counts. Urine analysis (urea, uric acid, creatinine, total protein, Na and K), as well as histopathological investigation, showed no abnormalities. These results taken as a whole indicate that the seeds of C. maxima as used in Brazilian folk medicine are not toxic for rats and swine.

Interference of the blood clot on granulation tissue formation after tooth extraction. Histomorphological study in rats.

The interference of a blood clot in the first postoperative hours of dental extraction wounds was studied in rats. Sixty male albino rats were divided into two groups: Group I, immediately after extraction of right maxillary incisor the gingival mucosa was approximated and sutured; Group II, after 6 to 8 minutes postoperatively the blood clot was removed with saline irrigation and absorbent paper cones. The mucosa was then approximated and sutured. Six animals in each group were sacrificed after 12 hours, 1, 4, 7 and 10 days. There was a profound delay in healing in Group II since, although a new blood clot was later formed, it was not organized. The quality and the constitution, maintenance and retraction of the clot are the regulating factors in connective tissue formation during alveolar healing.

Tensile strength and histological changes of abdominal aorta of malnourished rats

The resistance of the abdominal aorta of rats after 6, 7 and 8 weeks of malnutrition, compared with control animals, was evaluated by longitudinal tensiometry. Weakness of this vessel in malnourished rats was demonstrated; microscopic examination of the aorta stained by Masson, Calleja and hematoxylin-eosin methods showed a decrease in amorphous ground substance and an increase in the width of elastic laminae. There was no visible alteration either in the endothelial lining layer or in the smooth muscle fibers. Such alterations of the aorta are, to the authors' knowledge, the first reported modifications in the peripheral vasculature after malnutrition.

Effects of protein malnutrition on glucose tolerance in rats with alloxan-induced diabetes

Protein-calorie malnutrition produces glucose intolerance and reduced insulin release in response to glucose. Rats adapted to low- or high-protein diets show an increased resistance to the diabetogenic action of a single dose of streptozotocin or alloxan. To determine the effects of dietary protein level on pancreatic function, we measured serum glucose levels under basal conditions and during the oral glucose tolerance test (GTT) performed before and after a single dose of alloxan administered to rats fed a 25% or a 6% protein diet for a period of 8 weeks. The incidence of mild hyperglycemia (serum glucose > 250 mg/dl) was greater among the rats fed the 25% protein diet (81%) than among those fed the 6% protein diet (42%). During the GTT performed before alloxan administration the serum glucose levels of the rats fed the 6% protein diet were not found to be significantly different from those of rats fed the 25% protein diet. During the GTT performed after alloxan injection all rats showed intolerance to the substrate (serum glucose > 160 mg/dl 120 min after glucose administration) regardless of whether basal serum glucose was normal or high. In summary, alloxan was less effective in producing basal hyperglycemia in the rats fed the 6% protein diet than in those fed the 25% protein diet but caused glucose intolerance during the oral GTT in both groups. Thus, it seems that feeding a 6% protein diet to rats offers only partial protection against the toxic effects of alloxan.

Does the male reproductive performance depend on the early lactation milk in rats?

This study investigated the role of the early lactation milk (ELM) on the male reproductive performance and the participation of GnRH on this effect in Wistar rats. Newborn males were divided into three experimental groups: 1) ELM-deprived pups, 2) ELM-deprived pups treated with exogenous GnRH 1, 7, 25, and 31 h after birth, and 3) non-ELM-deprived and without exogenous GnRH. In relation to the other two groups, the ELM-deprived male rats exhibited as adults: reduced fertility, decreased weight of both vas deferens and seminal vesicle, and reduced levels of fructose in the seminal vesicle and prostate gland. We suggest that the intake of ELM during the neonatal period is important to the later sexual development of rats, and that GnRH is somehow involved in such an effect.

Role of different proteolytic pathways in degradation of muscle protein from streptozotocin-diabetic rats

In vitro rates of overall proteolysis and the activities of four different proteolytic pathways (lysosomal, Ca2+ dependent, ATP dependent, and ATP independent), as well as rates of protein synthesis, were measured in soleus and extensor digitorum longus (EDL) muscles from streptozotocin- diabetic rats. In the acute phase (1-3 days) of diabetes, there was an increase in overall proteolysis that coincided with an increased activity of the Ca2+-dependent pathway in both soleus and EDL and of the ATP-dependent pathway in EDL. After longer periods (5-10 days) of diabetes, the overall rate of protein degradation decreased and reached values similar to or even lower than those of controls as a result of a reduction in the activities of Ca2+-dependent and ATP-dependent pathways. No change was detected at any time interval in the activity of the intralysosomal proteolytic system in muscles from diabetic animals. Rates of protein synthesis were already reduced 24 h after diabetes induction and decreased further thereafter. Insulin treatment restored to normal the activities of the proteolytic pathways and rates of protein synthesis.

Acute, subchronic and chronic 2,4-dichlorophenoxyacetic acid (2,4-D) intoxication in rats

The acute, subchronic and chronic toxicities of 2,4- dichlorophenoxyacetic acid (2,4-D) were studied in rats. Animals were exposed acutely (600 mg/kg), subchronically (200 ppm for 30 d) and chronically (200 ppm for 180 d) to 2,4-D by the oral route. Clinical, laboratory and histopathological methods were used as indicators of toxicity. After acute exposure, the herbicide decreased locomotor activity and induced ataxia, sedation, muscular weakness (mainly of the hind quarters) and gasping for breath; increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), alkaline phosphatase (AP), amylase activities and creatinine levels; decreased total protein (TP) and glucose levels; and increased hematocrit values. Subchronic and chronic 2,4-D exposures did not induce overt clinical signs or symptoms of intoxication. However, subchronic herbicide exposure increased AST activity and albumin and hematocrit values, and chronic exposure increased AST, AP and LDH activities, decreased amylase and glucose levels, but did not change hematocrit values. Chromatographic analysis of the serum of chronically exposed rats showed the presence of the herbicide; the amount found (3.76 ± 1.16 mg/ml) suggested the absence of 2,4-D accumulation within the body. Although macroscopic or histopathological lesions were not observed in acutely, subchronically or chronically 2,4-D exposed rats, the laboratory data obtained suggest tissue injuries after dosing, since the results are considered early indicators of primarily hepatic and muscle tissue damage.

Influence of the estrous cycle on the sensitivity to catecholamines in right atria from rats submitted to foot-shock stress

We investigated the mechanisms of the alterations in sensitivity to catecholamines in right atria from female rats exhibiting regular 4-day estrous cycles after three foot-shock sessions at estrus, metestrus, and diestrus or at diestrus, proestrus, and estrus. Right atria from stressed rats sacrificed at diestrus showed subsensitivity to noradrenaline and adrenaline. After in vitro sympathetic denervation (38 μM 6-hydroxydopamine) plus inhibition of neuronal reuptake (0.1 μM desipramine) subsensitivity to noradrenaline was abolished, but it was again evident when extraneuronal uptake was also inhibited (10 μM phenoxybenzamine and 30 μM corticosterone). The same pretreatment abolished the subsensitivity to adrenaline. After addition of 1 μM butoxamine, a β2-adrenoceptor antagonist, the tissues from stressed rats were subsensitive to adrenaline. Right atria from stressed rats sacrificed at estrus did not show any alteration in sensitivity to catecholamines. We conclude that after foot-shock stress, right atria from female rats sacrificed at diestrus showed subsensitivity of the chronotropic response to catecholamines as a result of a conformational alteration of β1-adrenoceptors, simultaneously with an increase in β2-adrenoceptor-mediated response. The mechanisms seem to be similar to those which underlie stress-induced alterations in catecholamine sensitivity in right atria from male rats. However, during estrus there are some protective factors that prevent the effects of stress on right atria.