Blood alcohol concentration and microencephaly: a dose-response study in the neonatal rat

The relationships among microencephaly, peak blood alcohol concentration (BAC), and dose of alcohol were examined in a rat model of third-trimester fetal alcohol effects. Ethyl alcohol was administered to neonatal rats from postnatal day 4 to day 10 during the brain growth spurt via an artificial rearing technique. Groups of rats received one of nine doses of alcohol (0.0, 2.5, 3.3, 4.0, 4.5, 5.3, 6.6, 7.5, or 8.5 g/kg body weight) administered in 8 hours each day. BACs were determined on postnatal days 6 and 7 at times corresponding to peak and trough BACs, respectively. On postnatal day 10, brains were removed, and total brain weights, cerebellar weights and brainstem weights were measured. Pups receiving 4.0 g/kg/day or less had mean peak BACs below 150 mg/dl and did not exhibit significant microencephaly when compared with controls. Higher dosages further increased the peak BAC and produced significant microencephaly. While a dose of 4.5 g/kg/day was sufficient to decrease significantly both total brain weight and cerebellar weight, a minimum dose of 6.6 g/kg/day was required for significant restriction of brainstem weight. The dose of 7.5 g/kg/day yielded a mean peak BAC of 420 mg/dl and reduced total brain weight, cerebellar weight, and brainstem weight by 33%, 52%, and 22%, respectively, relative to controls. Exposure to 8.5 g/kg/day was uniformly lethal. Peak BAC and total brain weight were highly correlated (r = -.916). As peak BAC increased, total brain weight decreased linearly. Comparisons with previous studies indicate that condensing the daily dose of alcohol effectively reduced the threshold doses for microencephaly and lethality.     

The influence of the water with decreased content of heavy stable hydrogen and oxygen (18O) isotope on development of radiation injuries at gamma-radiation in low dose

The investigations of the water with decreased content of heavy stable hydrogen and of oxygen (18O) isotope received by the method of rectification were conducted on development of radiation injuries in organisms of the experimental animals. The objects of the investigation were male mice of Balb/c line. The animals were irradiated at the unit PX-gamma-30 with the gamma-radiation source 60Co in the dose of 25 sGy. It was observed that the water with decreased content of heavy stable hydrogen and of oxygen (18O) isotope influences positively the processes of restoration. It was manifested in decrease of the degree of gravity of radiation injuries in immune system organs (thymus and spleen), peripheral blood and marrow cells.     

The influence of inoculum size and time post-infection on the number and position of Toxocara canis larvae recovered from the brains of outbred CD1 mice

Outbred CD1 mice were administered doses of 1000 and 3000 Toxocara canis eggs and postmortem took place on days 7, 42 and 120 post-infection. Mice were killed by cervical dislocation and brains were sagitally bisected and fixed in 10% neutral buffered formalin prior to histological preparation and examination. The number of T. canis larvae were counted per brain and per section and the number of larvae cited for the first time per section were also recorded. These observations were compared by dose administered and by day of postmortem. The total number of larvae per brain and per section was higher for the 3000 dose compared to the 1000 dose. A different pattern emerged for the number of larvae observed in the brain over the three postmortem days depending upon the dose received. For the 1000 dose larval numbers increase from day 7 to day 120 whereas for the 3000 dose the opposite trend occurs. Larvae were assigned to one of five regions in the brain - the telencephalon, diencephalon, cerebellum, medulla, pons and brain stem and the olfactory bulb. Larvae did not show a random distribution in the brain. The majority of larvae were recorded from the telencephalon and the cerebellum. The percentage of sections with larvae in them is higher for the 3000 dose compared to the 1000 dose for all regions of the brain. For the majority of regions, the percentage of sections with larvae in them increases between day 7 and 42 and then decreases by day 120 and this is most pronounced for the cerebellum. For the telencephalon and diencephalon only, more larvae were detected on the right hand side of the brain compared to the left hand side. Statistical analysis revealed that dose and brain region are significant factors which influence the number of larvae observed in histological sections of the brain but day post-infection is not.     

Cytosol reception of estradiol and nuclear acception of estrogen-receptor complexes in target organs of female rats after gamma-irradiation

Condition of cytosol reception of estradiol and nuclear acception of estrogen-receptor complexes in target organs of female rats subjected to gamma-radiation was studied. It was established that the action of ionizing radiation of 0.5 and 1.0 Gy dose (dose rate 6.2 sGy per minute) was combined with a decrease (liver, uterus) of cytosol estrogen-receptor complexes and their modification and that those effects were realized through the lessening of the nuclear acception capability in liver cells of radiation-exposed animals.     

Effect of l-triiodothyronine on the mitochondrial α-glycerophosphate dehydrogenase activity,mitochondrial and total protein contents of brain of Singi fish (Heteropneustes fossilis bloch)

A single injection of various doses (0.25, 0.5, 5, 20 and 50 μg/g) of l-triiodothyronine increased the mitochondrial cytochrome-linked α-glycerophosphate dehydrogenase (EC 1.1.99.5) activity and mitochondrial protein content of brain of Singi fish on the 3rd day. l-Triiodothyronine at the dose of 0.1 μg/g did not alter the α-glycerophosphate dehydrogenase activity and mitochondrial protein content of brain. The total protein content of the brain also increased on the 3rd day with 0.5 μg of l-triiodothyronine per g. Increased enzyme activity followed a dose-response relationship of a non-linear fashion. The enhancement of the α-glycerophosphate dehydrogenase activity of fish brain with a dose of 0.5 μg/g was found from the 1st day and it reached to a maximum level from the 3rd to the 5th day. The enzyme activity then sharply declined on the 6th or 7th day. Cycloheximide inhibited the l-triiodothyronine-induced increase in the α-glycerophosphate dehydrogenase activity, mitochondrial and total protein content of fish brain.The present study thus reveals the responsiveness of fish brain to thyroid hormone, and α-glycerophosphate dehydrogenase activity can be taken as a biochemical indices for the expression of thyroid hormone action in fish brain.     

LABELLING OF ACETYLCHOLINE IN THE BRAIN OF MICE FED ON A DIET CONTAINING DEUTERIUM LABELLED CHOLINE: STUDIES UTILIZING GAS CHROMATOGRAPHY—MASS SPECTROMETRY

—A method to achieve labelling of the acetylcholine stores of the brain under ideal physiological conditions is described. To this end, mice fed on a choline free diet were supplied with deuterium labelled choline in the drinking water. Labelled and unlabelled choline in plasma and in the brain as well as labelled and unlabelled acetyicholine in the brain were measured by a gas chromatographic-mass spectrometric method. It was found that after 1–25 days on the deuterium choline diet, substantial amounts of the plasma choline and brain acetylcholine were displaced by deuterium choline and deuterium acetylcholine, respectively. Already on the first day, the mole ratio of deuterium choline/total choline in plasma was 0·22, and it approached a maximum of 0·57 on the 14th day. The mole ratios of deuterium acetylcholine/total acetylcholine in the brain were slightly but significantly lower than those of deuterium choline/total choline in plasma 1–14 days, but asymptotically approached the mole ratios of deuterium Ch/total Ch in plasma by 25 days. Intact brains submitted to incubation at room temperature for 10 min increased their total choline content by about 500 per cent. Concurrently, in brains from animals kept on a deuterium choline diet for 1–2 days, the level of deuterium choline rose only by 50 per cent after incubation. Deuterium choline levels increased, however, by 200–300 per cent in the brains from animals kept on the deuterium diet for longer time periods. On the basis of these data it is suggested that: (a) choline in plasma is partly supplied from the food and partly from endogenous sources; (b) plasma choline rapidly equilibrates (less than one day) with a pool of Ch in the brain which is responsible for biosynthesis of acetylcholine; (c) the size of this choline pool is in the order of 34–40 nmol/g.     

Consequences for posterity of two generations of an irradiation pregnant from females rats Wistar in small doses during a bookmark of reproduction system of fetuses development of posterity of the second generation and it reproduction function

With the purpose of study of consequences for development and reproduction functions of posterity of the second generation from females rats Wistar of a total unitary gamma-irradiation in dozes 0.25; 0.5 and 1 Gy (capacity of a doze 0.03 sGy/s) on 10th day of pregnancy (the period of the onset of fetuses reproduction system development) is investigated more than 630 females, 1400 with the age of 19th days, and about 3200 young rats. The revealed deviations(rejections) in development of posterity of two generations parents, antenatal irradiated in not sterilizing dozes, in he period of a beginning of formation of reproduction system, them a variety at different dozes of radiating influence, shown as at posterity of the irradiated mothers, and fathers, testify about instability genoms in a line of generations requiring the account and acceptance of necessary measures for preservation normal genofund.     

Genetic effects in Drosophila melanogaster induced by chronic low-dose irradiation

It was investigated the influence of the chronic gamma-irradiation in the dose rate of 0.17 sGy/h on the rate of genetic variability in the laboratory strains of Drosophila melanogaster with genotypic distinguishes in mobile genetic elements and defects in the DNA repair processes. It was shown that the rates of induction of recessive lethal mutations depended on genotype of investigated strains. In the different strains we have observed an increase as well as a decrease of the mutation rate. Also in was established that irradiation leads to the frequencies of the GD-sterility and mutability of the snw and h(w+) in the P-M and H-E dysgenic crosses. The obtained results suggest that mobile genetic elements play an important role in the forming of genetic effects in response to low dose irradiation.     

Circulating glucose, insulin and ketone bodies and enzymes of ketone body utilization in brain mitochondria from suckling rats treated with high L-thyroxine doses

The neo-T4 syndrome was induced by subcutaneous administration of a total dose of (150 micrograms) L-thyroxine (T4) to rats from their first day of live. Neo-T4 animals and their controls were sacrificed at 2, 4, 8, 11, 14, 22 and 25 days of age. A decrease in body weight was observed from the second day of life, and a decrease in brain weight from the eighth day of life in the neo-T4 animals. Blood glucose and plasma insulin levels were decreased from 2nd day through 22nd day of life. Total plasma ketone bodies and beta-OH butyrate levels increased in the neo-T4 animals with respect to controls. until 8th day, although acetoacetate increased only until 4th day. The activity of key enzymes in the ketone bodies utilization pathway (3-hydroxybutyrate dehydrogenase, 3-oxoacid CoA-transferase and acetoacetyl-CoA thiolase) were also measured in the animals brain. We found an activation of 3-hydroxybutyrate dehydrogenase until 11th day and 3-oxoacid CoA-transferase until 14th day, but no change in acetoacetyl CoA-thiolase was observed. Ketone bodies play a key role as energy substrates and precursors of brain lipids during the period of intense growth and myelination of the CNS. Considering the alterations described in this paper it seems that neo-T4 syndrome could be an interesting model for studying metabolism of those substances in brain.     

P25alpha/Tubulin polymerization promoting protein expression by myelinating oligodendrocytes of the developing rat brain

P25alpha/tubulin polymerization promoting protein (TPPP) is a brain specific phosphoprotein that displays microtubule bundling activity. In the mature brain, p25alpha/TPPP distributes to oligodendrocytes and choroid plexus epithelium. We mapped the spatial and temporal distribution of p25alpha/TPPP in the developing rat brain. Having localized its expression to neuronal tissue by Western blot analyses, the distribution of p25alpha/TPPP to developing oligodendrocytes was confirmed using a specific antibody. In the pre-natal and post-natal brain, p25alpha/TPPP was localized to the perinuclear cytoplasm of myelinating oligodendrocytes from embryonic (E) day E20 as verified from cellular co-localization with 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP). Oligodendrocyte progenitor cells and pre-myelinating oligodendrocytes identified by the expression of NG2 proteoglycan and CD9, respectively, both failed to contain p25alpha/TPPP. In contrast, P25alpha/TPPP co-localized with beta(IV)-tubulin from post-natal (p) day P10 suggesting that p25alpha/TPPP plays an important role for tubulin-related transport in developing, myelinating oligodendrocytes.     

Brief fasting decreases protein synthesis in the brain of adult rats

The influence of starvation on protein synthesis in the adult rat brain was studied in vivo by an intravenous injection of a flooding dose of unlabeled valine including a tracer dose ofL-[3,4(n)-³H]valine. Brief starvation (24 hours) induced a 20% decline in fractional and absolute rates of brain protein synthesis. This decline resulted from a 20% decrease in the efficiency of protein synthesis (g protein synthesized per day per g RNA) whereas the capacity for protein synthesis (g RNA per mg protein) was maintained. Prolonged starvation (5 days) was marked by no further significant changes in the fractional rate, absolute rate and efficiency of protein synthesis, whereas the capacity for protein synthesis cecreased slightly. The relative contribution of brain to wholebody body protein synthesis increased during fasting, and neither the protein nor the RNA brain content did change during the experiment. These results clearly indicate that brain proteins are spared in response to brief and prolonged food deprivation, and that brain protein synthesis is very sensitive to short-term fasting.     

Benzene hematotoxicity and leukemogenesis

Benzene is ubiquitous and accepted as a human carcinogen by regulatory agencies. Proposed regulations assume without proof that the carcinogenic response to benzene exposure is "one hit" implying a linear with no threshold. There is no solid experimental proof for this concept. This research involves exposure of CBA/Ca male mice to benzene vapor in varying concentrations. Exposure to 300 ppm 6 hrs/day, 5 days/week, for 16 weeks is highly leukemogenic. Exposure for the same time to 100 ppm is also leukemogenic. Concentrations from 25 ppm to 400 ppm 6 hrs/day, 5 days/week, for 10 exposures produce an increasing lymphopenia. Exposure to 100 ppm for the same exposure time produces anemia, decrease in stem cell content of marrow, and marrow cellularity. Further dose-effect studies are required to test the "one hit hypothesis" and to determine whether the same integral dose of benzene administered over variable exposure has the same or different biological responses. It is of concern that biologic effects are observed at 25 ppm only 2.5 times the present permissible time-weighted average exposure during a working day and research by others (see Discussion) has demonstrated an effect (noncarcinogenic) at 10 ppm.     

Appearance of a brain-specific antigen (S-100 protein) in the developing rat brain

Abstract— Thelevel of the S-100 protein, a brain-specific antigen, wasdetermined by quantitative complement fixation in the brain stem and cerebrum of the rat during postnatal maturation. The content was minimal at birth in the brain stem and rose to its adult value by day 25. Although S-100 protein could not be detected in the cerebrum of the 2-day-old rat, adult values were also present by the 25th day of age. Neither single dose X-irradiation with 750 rd to the head at 2 days of age or single dose X-irradiation at 11 days of age affected the adult level of S-100 protein in the brain stem or cerebrum. Similarly, hypophysectomy at 20 days of age had no effect on the subsequent levels of S-100 protein.     

Inhibition of monoamine synthesis by irreversible blockade of aromatic aminoacid decarboxylase with alpha-monofluoromethyldopa.

DL-α-monofluoromethyldopa is a potent enzyme-activated irreversible inhibitor of purified aromatic aminoacid decarboxylase. Single doses from 0.25 to 25 mg/kg cause partial to total inhibition of this enzyme in kidney and heart. Inhibition of brain enzyme becomes significant at doses above 2.5 mg/kg and is complete at 100 mg/kg. Enzyme activity begins to return after 24 hr, so that repetition of a dose at 12 hr intervals markedly increases the inhibition. Single doses of 100–250 mg/kg almost completely deplete kidney, heart and brain of endogenous catecholamines by blocking dopa decarboxylation. Serotonin is also decreased, presumbaly by the same mechanism.     

Immunocorrective action of tuftsin during exposure to ionizing radiation

The effect of the tetrapeptide tuftcin (Thr-Lys-Pro-Arg) on the humoral immune response in CBA mice exposed to sublethal irradiation in a dose of 450 sGy was studied. The drug was injected intraperitoneally for 5 days before (series I) or after (series II) radiation exposure. It has been shown that taftcin has no protective action but decreases considerably the immune response lowering due to radiation.     

The neuroteratogenicity of procarbazine in the rat: behavioral, morphological, and neurochemical aspects

Pregnant female Sprague-Dawley rats were treated from day 12 through day 15 of gestation with procarbazine, an antineoplastic drug, and their offspring were subjected to tests of locomotor development and behavior. Treatment levels ranged from 0.5 mg/kg/day, a dose that produced no abnormalities, to 10 mg/kg/day, a dose that caused a marked micrencephaly in the absence of other teratological changes. Despite marked morphological brain changes, preweaning locomotor development, as assessed by open-field swimming activity and vertical grid climbing, was normal in all offspring. Post-weaning passive avoidance learning and retention were also normal. Groups that had been treated prenatally with teratogenic doses (5.0 and 10.0 mg/kg/day) displayed less rearing behavior in the open field, while ambulation in the periphery of the open field arena was unaffected. Groups treated with subteratogenic doses (0.5 and 1.0 mg/kg/day) did not differ from control. In addition to the behavioral studies, sodium-dependent high-affinity choline uptake and choline acetyltransferase activity (CAT) were measured (per mg protein) in the cortex and hippocampus of animals that had been exposed prenatally to either teratogenic or subteratogenic doses of procarbazine. In spite of a substantial reduction in size of both brain structures in the group receiving a teratogenic dose, choline uptake and CAT did not differ from control.     

Effects of lead and hyperthermia on prenatal brain growth of guinea pigs

The effects of lead at blood levels of 100 micrograms/100ml or less on the brains of young animals have not been clearly defined, and little is known of its effects and interactions with other agents on prenatal brain development. This study examined the effects of subclinical doses of lead acetate given to pregnant guinea pigs on the development of the embryo brain. At 9 A.M. on day 20 or 21 of pregnancy, guinea pigs were given 6, 12.5, or 25 mg/kg body weight of 0.5% lead acetate in distilled water by intraperitoneal injection. Some of the animals at each dose rate were also exposed to hyperthermia at 11 A.M. on the day of injection and the following day. Another group was exposed to hyperthermia without lead treatment. A saline-treated control group was used for comparison. Mean levels of lead in blood 1 hour after dosing ranged between 65 and 128 micrograms/100 ml and at 24 and 72 hours between 65 and 96 micrograms/100 ml. Brain weights of newborn guinea pigs in the 12.5- and 25-mg lead acetate group were significantly reduced compared with control values. Body weights of all groups receiving lead were not significantly different from those of controls. There was no indication of interaction between hyperthermia and lead acetate in doses of 6 or 12.5 mg/kg. At 25 mg/kg plus hyperthermia, there appeared to be a strong synergistic response, with an incidence of 88% micrencephaly compared with 5% in the group given 25 mg/kg without hyperthermia and 46% in the hyperthermia without lead group.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vivo distribution of lithium in plasma and brain

A single administration of LiCl (0.5, 2 and 4 mmol/kg) to adult male albino rats produced a dose dependent increase of Li level in plasma, whole brain and brain regions. The concentration of Li in whole brain and brain regions was much less than that in plasma. Further, it is also found that concentration of Li in plasma reached a peak at 8 hr while that of Li in whole brain and brain regions reached a peak at 12 hr after the administration. The distribution and retention of Li was found to be highest in hypothalamus followed by striatum, pons-medulla, cerebellum and cerebral cortex. Daily administration of LiCl at a dose of 0.5 and 2 mmol/kg/day showed a time and dose dependent increase in plasma Li level up to a period of 21 consecutive days. But at higher dose (4 mmol/kg/day), on the other hand, under similar condition showed a time dependent increase in plasma Li level up to a period of 14 consecutive days and then gradually decreased with prolongation of treatment to 21 consecutive days. In brain there was no such decrease, rather increase in Li level was observed with the prolongation of duration of treatment, highest concentration of Li was found in hypothalamus and striatum than the rest of the brain regions. These results suggest that under short term treatment with LiCl, the clearance rate of Li in brain cell is much slower than that in plasma. Both single and long-term exposure of LiCl produces a dose dependent increase of Li in plasma, whole brain and brain regions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of DNA in cytopenia induced by myelosan]

Wistar rats weighing 180-190 g received myleran per os in a single dose of 10 mg/kg, or fractionally (total dose of 25 mg/kg) for 18 days. After myleran administration the animals were injected 4-5 times (every other day) with a homologous DNA in a dose of 2 mg per rat or with a standard salt citrate. The DNA injection reduced the duration of leukopenia. With the least dose of myleran leukocyte count returned to the normal in 6 days in the treated animals and in 25 days in the untreated controls and with the highest dose -- in 15 and in 25 days, respectively, from the beginning of the treatment. The differences in the leukocyte count between the treated and control rats in both experiments were mainly due to the dynamics of neutrophils, the content of which in the treated animals exceeded that in the untreated animals by 54-110% in the course of 6-15 days in the first, and by 23-38% in the course of 10-23 days in the second experiment.     

The effect of nitroimidazoles on glucose utilization and lactate accumulation in mouse brain

The radiation sensitizers misonidazole (MISO) and desmethylmisonidazole (DMM) can produce central and peripheral neuropathy in patients and laboratory animals. Behavioral and pathological investigations have indicated that in the central nervous system this primarily involves the cochlear and vestibular systems. Nitroimidazoles can also interfere with glycolysis in vitro under aerobic and anaerobic conditions. In the present work we have studied the effect of MISO or DMM on lactate production and glucose utilization in mouse brain. It is observed that these compounds result in a 25% inhibition of lactate production in brain slices relative to the control at a 10 mM level. Additionally, MISO (1.0 mg/g/day) or DMM (1.4 mg/g/day) were administered daily (oral) for 1, 4, 7, or 14 days to examine the effect of these two drugs on the regional glucose utilization in C3Hf mouse brain. Five microcuries of 2-deoxy[14C]glucose was given following the last drug dose and autoradiographs of serial brain sections were made and analyzed by a densitometer. Following a single dose of either MISO or DMM, no significant differences in glucose uptake were observed when compared with controls. However, following 4, 7, and 14 doses the rate of glucose utilization was significantly reduced in the intoxicated animals. Larger reductions were measured in specific regions including the posterior colliculus, cochlear nuclei, vestibular nuclei, and pons with increasing effects observed at later stages. These results share a degree of correspondence with the regional brain pathology produced by these nitroimidazoles.