Freeze-fracture studies of cytoplasmic inclusions occurring in experimental lipidosis as induced by amphiphilic cationic drugs.

The ultrastructure of cytoplasmic inclusions, which characterize experimental lipidosis as induced by several amphiphilic cationic drugs, was studied by means of freeze-fracturing and thin-sectioning. Retinal and adrenal tissues of rats chronically treated with high oral doses of chlorphentermine were used. In thin sections the cytoplasmic inclusions, which were previously shown to represent lysosomes overloaded with polar lipids, exhibit lamellated or lattice-like internal patterns. The present freeze-fracture observations are interpreted as to indicate that the lamellated inclusions contain polar lipids in the lamellar phase, whereas those with lattice-like patterns contain polar lipids in a hexagonal phase.     

Increase in tissue concentration of acetylcholine in guinea pigs in vivo induced by administration of choline

Administration of choline chloride (200 μmoles/kg) intravenously to guinea pigs caused an increase in the concentrations of choline and acetylcholine in adrenals, heart, kidneys, lungs, and liver within 2 min. These results suggest that raising the concentration of choline in plasma will accelerate the formation of acetylcholine in the organs cited. No significant increase in concentration of choline or acetylcholine occurred in brain.     

Systemic availability and abortion-inducing effects of nocloprost after intravenous, subcutaneous and intragastric administration to pregnant guinea pigs

Nocloprost was administered to 3 groups of 4 pregnant guinea pigs intravenously and subcutaneously in a dose of 30 micrograms/kg and intragastrically in a dose of 100 micrograms/kg. Plasma nocloprost levels were measured at defined times up to 24 h p. adm. with a specific radioimmunoassay and induction of abortion monitored simultaneously. In one animal per group uterus pressure was recorded continuously up to 8 hours p.adm. Animals were sacrificed 7 days p.adm. and the number and state of fetuses in utero evaluated. Systemic availability of unchanged drug was 100% after intravenous (AUCi.v. = 8.6 +/- 2.0 ng h/ml) and subcutaneous (AUCs.c. = 11.5 +/- 1.2 ng h/ml) administration and approximately 30% after intragastric administration (AUCi.g. = 8.9 +/- 2.0 ng h/ml). The incidence of abortion after intragastric administration corresponded to that after subcutaneous administration. After intravenous injection the abortion rate was somewhat less, indicating that equal AUC-values do not necessarily indicate identical pharmacological effects.     

The effects of induced lathyrism on Sr85 uptake in rats during late prenatal development

During the last one-third of their gestational period, lathyritic rats incorporate significantly lower amounts of Sr85 as revealed by whole body counting techniques. This difference was maximum at term. The study provides evidence for lathyritic disturbance in the initial phases of mineralization of hard tissue matrices.     

Inhibition of adrenal steroid metabolism by administration of 1-aminobenzotriazole to guinea pigs

Prior in vitro investigations demonstrated that the P450 suicide substrate, 1-aminobenzotriazole (ABT), was a potent inhibitor of xenobiotic metabolism but had no effect on steroidogenic enzymes in the guinea pig adrenal cortex. Studies were done to determine if ABT administration to guinea pigs in vivo also selectively inhibited adrenal xenobiotic metabolism. At single doses of 25 or 50 mg/kg, ABT effected rapid decreases in spectrally detectable adrenal P450 concentrations. The higher dose caused approx. 75% decreases in microsomal and mitochondrial P450 levels within 2 h. The decreases in P450 were sustained for 24 h but concentrations returned to control levels within 72 h. Accompanying the ABT-induced decreases in adrenal P450 content were proportionately similar decreases in P450-mediated xenobiotic and steroid metabolism. Microsomal benzo(a)pyrene hydroxylase, benzphetamine N-demethylase, 17-hydroxylase and 21-hydroxylase activities were decreased to 20–25% of control values by the higher dose of ABT. Mitochondrial 11β-hydroxylase and cholesterol sidechain cleavage activities were similarly diminished by ABT treatment. Adrenal 3β-hydroxysteroid dehydrogenase activity, by contrast, was not affected by ABT, indicating specificity for P450-catalyzed reactions. The results demonstrate that ABT in vivo is a non-selective inhibitor of adrenal steroid- and xenobiotic-metabolizing P450 isozymes. The absence of ABT effects on steroid metabolism in vitro suggests that an extra-adrenal metabolite may mediate the in vivo inhibition of steroidogenesis.     

Reaction and response of newborn guinea pigs to experimental Salmonella typhi infection

Newborn guinea pigs, orally infected with Salmonella typhi were examined at various intervals of time in order to determine bacterial distribution in tissues and to establish possible correlation with the clinical aspects manifested. Histopathological examination evidenced typical lesions in jejunum, ileum, caecum and especially in regional lymphatic tissues. Spleen, liver and mesenteric lymph nodes presented granulomatous lesions similar to those observed in in human typhoid fever. After oral administration, the animals reacted with anorexia, febrile reactions, bacteremia, diarrhoea, positive stool cultures, dehydration, lethargy and antibodies too were produced. Our results indicate that typhoid infection may be induced in newborn guinea pigs; the model may be used for an assessment of attenuated live typhoid vaccine control.     

Effect of exposure of pregnant rats to cadmium on prenatal and postnatal development of the young

Cadmium chloride in doses of 2, 12 and 40 mg Cd/kg was administered per os to pregnant rats from the 7th to 16th day of pregnancy. In another experiment female rats were exposed to cadmium oxide at a concentration of 0.02 mg Cd/m3 or 0.16 mg Cd/m3 for 5 hours a day and 5 days weekly for a period of 5 months or 1 mg Cd/m3 for 4 months. The exposure was then continued during mating and from the 1st to 20th day of pregnancy. A decrease in fertility was only observed in females exposed by inhalation to cadmium oxide at a concentration of 1 mg Cd/m3, at which concentration cadmium exhibits a considerable toxic effect on the whole organism. The young of females orally treated with CdCl2 in a dose of 40 mg Cd/kg displayed congenital defects in the form of sirenomelia or amelia, as well as raised cadmium levels in tissues. A retardation of intrauterine development manifested by lower body weight and slowed down osteogenesis was observed in the other groups. A cadmium concentration increase was not found in the tissues of the young in these groups. Inhalation exposure to 0.16 mg Cd/m3 of females prior to and during pregnancy induced in their young a decrease in viability, lower body weight gain, prolongation of latency in the negative-geotaxis test, lower locomotor activity and deteriorated development of the conditioned-reflex response. The offspring of females exposed to 0.02 mg Cd/m3 displayed lowered locomotor activity and worsened consolidation of the conditioned-reflex response.     

Acetaminophen metabolism in vivo by pregnant, fetal, and neonatal guinea pigs

Acetaminophen (50 mg/kg body weight) was administered by iv injection to pregnant guinea pigs (60-65 days of gestation) and by ip injection to cesarean-derived term (67 days of gestation) pups. At suitable time intervals after treatment, the concentrations of drug, glucuronide (GLU), and sulfate (SO4) in blood plasma, urine, and bile were measured by high-performance liquid chromatography (HPLC). At 60-65 days of gestation, guinea pig fetuses formed both GLU and SO4, an approximate ratio of 2:1 being observed with mean concentrations of the order of 43 and 27 micrograms/mL being measured for GLU and SO4, respectively at 180 min post-treatment. At the same time interval, the major detoxification product found in the blood plasma of the pregnant dams was GLU (104 micrograms/mL) with only minute amounts (4.2 micrograms/mL) of SO4 being detected. In cesarean-derived and acetaminophen-treated pups, euthanized at 2 or 4 hr post-treatment, plasma levels of GLU were approximately twofold higher relative to the concentration of SO4 at both time intervals. Significant differences were not observed in either bile or urine at 2 hr post-treatment but by 4 hr after treatment the levels of GLU found in the bile and urine were two- or threefold higher than those of SO4. In contrast to the adult guinea pig where GLU forms some 90% of the urinary excretory product and SO4 accounts for only 7%, the SO4 pathway of detoxification appears to be of significant importance to the fetal and neonatal animal.     

OLFML3 expression is decreased during prenatal muscle development and regulated by microRNA-155 in pigs

The Olfactomedin-like 3 (OLFML3) gene has matrix-related function involved in embryonic development. MicroRNA-155 (miR-155), 21- to 23-nucleotides (nt) noncoding RNA, regulated myogenesis by target mRNA. Our LongSAGE analysis suggested that OLFML3 gene was differently expressed during muscle development in pig. In this study, we cloned the porcine OLFML3 gene and detected its tissues distribution in adult Tongcheng pigs and dynamical expression in developmental skeletal muscle (12 prenatal and 10 postnatal stages) from Landrace (lean-type) and Tongcheng (obese-type) pigs. Subsequently, we analyzed the interaction between OLFML3 and miR-155. The OLFML3 was abundantly expressed in liver and pancreas, moderately in lung, small intestine and placenta, and weakly in other tissues and postnatal muscle. There were different dynamical expression patterns between Landrace and Tongcheng pigs during prenatal skeletal muscle development. The OLFML3 was down-regulated (33-50 days post coitus, dpc), subsequently up-regulated (50-70 dpc), and then down-regulated (70-100 dpc) in Landrace pigs, while in Tongcheng pigs, it was down-regulated (33-50 dpc), subsequently up-regulated (50-55 dpc) and then down-regulated (55-100 dpc). There was higher expression in Tongcheng than Landrace in prenatal muscle from 33 to 60 dpc, and opposite situation from 65 to 100 dpc. Dual luciferase assay and real time PCR documented that OLFML3 expression was regulated by miR-155 at mRNA level. Our research indicated that OLFML3 gene may affect prenatal skeletal muscle development and was regulated by miR-155. These finding will help understanding biological function and expression regulation of OLFML3 gene in mammal animals.     

Influence of prenatal d-amphetamine administration on development and behavior of rats.

Beginning on the fifth day of gestation, rats were administered 1 or 3 mg/kg of $\text{d}$-amphetamine sulfate s.c. twice daily until term. The administration of $\text{d}$-amphetamine caused a dose-related increase in pup mortality. However, the increase in pup death could not be correlated with any gross pathological signs. The surviving 3 mg/kg amphetamine pups were analyzed for changes in motor behavior and brain biogenic amine levels. It was found that the amphetamine offspring showed a marked reduction in the ability to habituate to new surroundings, and this effect persisted for at least three months after birth. On day 35, brain levels of norepinephrine in the “amphetamine” offspring were decreased 21 percent. On day 84, in the “amphetamine offspring,” norepinephrine levels were reduced 18 percent in both the diencephalon and brainstem; dopamine levels were reduced 21 percent in the brainstem compared to control offspring.     

Changes in gamma-aminobutyric acid release induced by topical administration of drugs affecting its metabolism and receptors: studies in freely moving guinea pigs with epidural cups.

The effect of local application of drugs affecting gamma-aminobutyric acid metabolism and receptors on cortical aminoacid release has been investigated in freely-moving guinea pigs equipped with epidural cups. Topical treatment with gamma-aminobutyric acid reuptake and/or metabolism inhibitors (alone and in combination) produced a slow and progressive increase in cortical aminoacid release. The inhibition of gamma-aminobutyric acid-transaminase with ethanolamino-O-sulphate seemed to be a suitable procedure for enhancing the gamma-aminobutyric acid efflux without interfering with its autoreceptor-mediated negative feedback, tested with the gamma-aminobutyric acid agonist (+/-)baclofen and antagonist phaclofen. A substantial part of the gamma-aminobutyric acid outflowing from the cortex was of neuronal origin since tetrodotoxin halved the basal efflux in the presence of gamma-aminobutyric acid reuptake and/or metabolism inhibitors. These results, considered together, indicate that the epidural cup technique may be a useful approach to study changes in cortical gamma-aminobutyric acid release induced by drugs acting on gabaergic transmission and directly applied on the surface of the cortex.     

Pre- and postnatal toxicity induced in guinea pigs by N-nitrosomethylurea.

Oral administration of N-nitrosomethylurea at maximally tolerated doses to guinea pigs on alternate days from days 34-58 of pregnancy induced prenatal toxicity, as evidenced by a high frequency of stillbirths and intrauterine growth retardation, and postnatal toxicity, as evidenced by stunting and progressive mortality. Similar administration of N-nitrosomethylurethane at maximally tolerated doses did not induce such toxic effects.