Studies on the pharmacological bases of fetal toxicity of drugs (IV). Effect of endotoxin and starvation on serum protein binding of salicylic acid in pregnant rats

Our previous paper reported that the fetotoxic effects of aspirin (ASA) were enhanced by bacterial endotoxin (LPS), and the effects of ASA were attributed to its major metabolite, salicylic acid (SA), as indicated by high SA concentrations in fetus and placenta. In order to clarify the mechanisms of the enhancement by LPS, serum total protein, albumin and free fatty acid (FFA) levels and SA-binding capacity of serum protein were investigated in pregnant rats. The following results were obtained: 1) FFA levels increased steadily after day 16 of pregnancy, and SA-binding capacity of serum protein decreased gradually after day 18, as the pregnancy proceeded to full term. 2) LPS injection decreased total protein and albumin levels in normal and starved rats on day 15 of pregnancy. 3) Starvation and/or LPS injection potentiated the increase of FFA level and reduced significantly SA-binding capacity of serum protein in the rats on day 15 of pregnancy. 4) Serum protein showing low SA-binding capacity from LPS-treated rats recovered normal SA-binding capacity when FFA was removed from serum protein by charcoal treatment. These data suggested the decrease of the SA-protein binding in serum by the increased level of FFA, an inhibitor of the binding, and the decreased level of albumin as a possible mechanism for the potentiation of the fetotoxicities of ASA by LPS.     

Dissociation between maternal and fetal toxicity of methyl isocyanate in mice and rats

The contribution of maternal hormonal changes and pulmonary damage on the fetal toxicity of methyl isocyanate (MIC) was studied in mice and rats. Exposure to MIC decreased maternal plasma progesterone levels in mice that lost but not in mice that retained pregnancy. Fetal toxicity of MIC was not related to changes in maternal plasma corticosterone levels. Neither chronic administration of progesterone nor the suppression of pulmonary edema with dexamethasone decreased fetal toxicity of MIC. Embryos exposed in utero or in vitro to MIC vapor exhibited a concentration-dependent decrease in growth in culture. An acute dose (3 mmol/kg) of the MIC metabolites (methylamine, dimethylamine, trimethylamine, dimethyl urea) did not exert fetal toxicity. These data suggest that the fetal toxicity of MIC is partly independent of maternal toxicity and may result from its transfer across the placenta and interaction with fetal tissues.     

Anti-inflammatory action of interleukin 1 through the pituitary-adrenal axis in rats

The influence of lipopolysaccharide (LPS) and the endogenous pyrogens, recombinant human interleukin 1 (rHu-IL 1) and tumor necrosis factor (rHu-TNF), on acute inflammation was investigated in rats. LPS (0.3-3 micrograms/kg i.v.), rHu-IL 1 alpha (3-30 micrograms/kg), rHu-IL 1 beta (0.3-3 micrograms/kg) and rHu-TNF (3-30 micrograms/kg) inhibited the hind paw edema induced by carrageenan in a dose-related manner. The potency of rHu-IL 1 beta was 10 times or more than of rHu-IL 1 alpha. rHu-IL 1 alpha and rHu-TNF also inhibited the dextran-induced hind paw edema. Both types of rHu-IL 1 (0.001-10 ng/paw) neither inhibited nor enhanced the edema when given directly into the inflamed paw. rHu-IL 1 alpha did not show any significant anti-edema activity in adrenalectomized rats. The 3 cytokines tested caused a significant increase in the plasma levels of ACTH and corticosterone after i.v. administration; the potency of rHu-IL 1 beta was about 10 times that of rHu-IL 1 alpha. These results suggest that both rHu-IL 1 and rHu-TNF inhibit paw edema at least in part through pituitary-adrenal axis stimulation, and that rHu-IL 1 has no pro-inflammatory action in the paw edema induced by carrageenan in rats.     

Role of the maternal acute phase response and tumor necrosis factor alpha in the developmental toxicity of lipopolysaccharide in the CD-1 mouse

The acute phase response (APR) functions to reset metabolic homeostasis following infectious, toxic, or traumatic insult. TNF-alpha, a putative mediator of the APR, has been associated with fetal death in rodents and preterm labor and delivery in humans. We hypothesized that physiologic changes associated with the maternal APR may play a role in adverse embryo/fetal outcome. Pregnant CD-1 mice injected i.p. with lipopolysaccharide (LPS), a model inducer of the APR, on gestation day (gd) 9 showed a dose-related increase in embryo death on gd 10. Histology indicated placental infarct and necrosis. Maternal serum TNF-alpha levels, measured by ELISA following administration of 0.05 mg/kg LPS on gd 9, were found to increase significantly and peak within 1 to 1.5 h. Pretreatment with 0.01 mg/kg LPS on gd 8 ameliorated embryotoxicity of the 0.05 mg/kg LPS treatment on gd 9 and also eliminated the increase in serum TNF-alpha. Direct LPS exposure in whole embryo culture was nontoxic. These data support a maternally mediated mechanism of LPS embryolethality, and suggest that TNF-alpha may be an important mediator of this developmental toxicity.     

Teratogenic and fetal toxicity following intravenous theophylline administration in pregnant rabbits is related to maternal drug plasma levels

This study investigated the teratogenic and fetal toxicity of i.v. theophylline and its relationship to maternal plasma levels in pregnant rabbits. From days 6-18 of gestation, each dose of theophylline (15, 30 and 60 mg/kg/day at a rate of 0.5 ml/kg/min) was administered i.v. to pregnant rabbits using an automatic infusion pump. Theophylline showed reversible toxicity: accelerated respiration, sluggish startle reactions, dilation of the auricular vessels and polyuria were observed in dams treated with 60 mg/kg/day but not in animals given 15 or 30 mg/kg/day. Fetuses from the dam group treated with 60 mg/kg/day exhibited teratogenic toxicity such as cleft palate and skeletal variation of the 13th rib. Fetal toxicity was also observed including abortion, increased number of late deaths and decreased body weight appearing on day 29 of gestation. No toxicity was observed in fetuses from the dam group treated with 15 or 30 mg/kg/day. However, in the 30 and 60 mg/kg/day theophylline-treated groups, maternal plasma concentrations (Cmax) during the treatment period were approximately 56 and 106 micrograms/ml, respectively. It is therefore suggested that the risk of teratogenic and fetal toxicity caused by theophylline is dependent on its dosage. In conclusion, caution should be taken when administering theophylline or aminophylline to pregnant individuals at doses that could result in high neonate peak blood levels.     

Placental and fetal toxicity of albendazole sulphoxide in Wistar rats

This work characterized the effects of albendazole sulphoxide (ABZSO) on placental and fetal parameters in Wistar rats on day 20 of gestation. ABZSO was fed in laboratory chow at 0, 2.5, 5, 10, 20 or 30 mg/kg/d from day 6 to 15 of gestation to pregnant rats. Data of resorptions, placental and fetal characteristics and fetal skeletal malformations were recorded. Resorption percentages in the 20 and 30 mg/kg/d groups were significantly higher compared to the control group. Placentas of ABZSO-treated rats had lower weight and smaller size than untreated rats. The fetal weight and size were lower in the 5 mg/kg/d dose compared to no treatment. In the 5, 10 and 20 mg/kg/d groups, reductions in ossification process were observed. ABZSO induced malformations and/or fetal death when orally administered to pregnant rats. This data contributes to characterization of the reproductive toxicity of ABZSO, the main active metabolite of albendazole.     

Endotoxin inhibition of drinking behaviour in the rat

Intravenous (i.v. 320 and 640 micrograms/kg) and intracerebroventricular (i.c.v.; 1 microgram/rat) injection of Escherichia coli lipopolysaccharide (LPS) powerfully inhibited drinking induced by 24 h water deprivation. Pretreatment with acetylsalicylic acid (ASA) into the preoptic area (POA) completely abolished the effect induced by i.v. LPS, but did not modify that elicited by i.c.v. LPS. Intraperitoneal ASA injections significantly reduced the antidipsogenic effect of i.c.v. LPS. Electrolytic ablation of the subfornical organ (SFO) did not modify the effect induced by either i.v. or i.c.v. LPS. Present findings indicate that: (1) the antidipsogenic effect of i.v. LPS is mediated by prostaglandin synthesis into the POA, (2) the SFO is not involved in this effect, and (3) prostaglandins in other brain areas, besides POA, modulate the effect of i.c.v. LPS. It is suggested that at least two different brain sites, inside the blood-brain barrier, might be involved in the antidipsogenic effect of LPS.     

The effects of choline on soman-induced analgesia and toxicity

The effects of acute choline (Ch) administration on the hot plate (HP) analgesia produced by soman and by morphine and on the toxicity produced by soman were examined in male rats. Morphine (9.0 mg/kg, IP) and soman (80 micrograms/kg, SC), but not Ch (60 mg/kg, IP), produced HP analgesia. Pretreatment with Ch (100 mg/kg, IP; given 20 min earlier) reduced morphine and soman analgesia by 68% and 38% respectively. Ch (LD50 = 405.8 mg/kg, IP) at doses above 200 mg/kg rapidly produced signs of cholinergic stimulation which disappeared by one hr. A fixed dose of Ch (100 mg/kg) altered neither the expression of toxic cholinergic signs produced by varying doses (from 75.9 to 151.4 micrograms/kg) of soman, nor the 24-hr LD50 (124.0 micrograms/kg, SC) of soman. Doses of Ch ranging from 213.8 to 269.2 mg/kg when given 40 min prior to a fixed dose (93.3 micrograms/kg) of soman resulted in persistent signs of cholinergic hyperstimulation, but again, did not affect the mortality produced by soman. The results demonstrate that acute Ch pretreatment increased the severity of cholinergic stimulation and reduced the HP analgesia, but were not accompanied by potentiation or antagonism of the lethal action of soman.     

Corticosterone decreases toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in hypophysectomized rats

Male Sprague-Dawley rats were hypophysectomized by an established surgical technique. Hypophysectomy aggravated the toxicity (mortality and mean time to death) of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 125 micrograms/kg ip) when compared to sham-operated rats (100% mortality with 9 +/- 1 d mean time to death vs. 90% mortality with 32 +/- 6 d mean time to death, respectively). However, administration of corticosterone (25 micrograms/ml in drinking water) to hypophysectomized rats resulted in an attenuation of the toxicity (40-60% mortality with 40-90 d mean time to death) to a range of TCDD doses (125, 250, 500 micrograms/kg) much higher than the LD50 (about 60 micrograms/kg TCDD) in nonhypophysectomized rats (about 30 d mean time to death). Furthermore, thyroid hormone supplementation in hypophysectomized rats dosed with 125 micrograms/kg TCDD restored the toxicity of TCDD to approximately "normal." Based on these data it is concluded that one or more as yet unknown key factors that are important in the modulation of the toxicity of TCDD reside in the pituitary.     

吡非尼酮的动物急性毒性

目的:研究一种新的抗纤维化药物吡非尼酮(PFD)的急性毒性。方法:观察一次性ip、igPFD对小鼠的急性毒性反应和死亡情况,一次性igPFD对大鼠和犬的急性毒性反应及死亡情况。结果:PFD的LD50分别为:1112mg/kg(小鼠ig);561mg/kg(小鼠ip);1221mg/kg(大鼠ig);Beagle犬igPFD的最大耐受剂量>1520mg/kg。结论:PFD对动物有一定的急性毒性作用,但属于低毒。     

Acute oral toxicity of colchicine in rats: effects of gender, vehicle matrix and pre-exposure to lipopolysaccharide

The oral toxicity of a single administration by gavage (10, 20 or 30 mg kg(-1) body weight) of colchicine (COL) was determined in young, mature male and female Sprague-Dawley rats. The effect of COL was evaluated in the presence or absence of additional treatment variables that included vehicle and lipopolysaccharide (LPS) pre-exposure. The vehicle for COL was either Half and Half cream (H & H) or saline, and each group included pretreatment with either saline or a low, minimally toxic dose (83 microg kg(-1) body weight) of LPS. Colchicine toxicity in both male and female age-matched rats was characterized by progressively more severe dose-related clinical signs of toxicity. These included mortality, decreased body weight and feed intake during the first several days after dosing, with recovery thereafter in surviving animals. There were differences in the severity of the toxic response to COL between male and female rats. The most notable sex-related difference was in COL lethality. Female rats were two times more susceptible to the lethal effects of COL than male rats. Saline or H & H delivery vehicles did not result in any apparent qualitative or quantitative differences in COL toxicity. LPS pretreatment significantly potentiated COL lethality in both males and females, although the potentiation in males was greater than in females. LPS pretreatment modestly increased the COL induced anorexic effect in surviving males, but not in surviving female animals. LPS did not appear to modulate either the body weights or clinical signs of COL induced toxicity in surviving males or females.     

ATP-MgCl2 increases cisplatin toxicity in the dog and rat.

The purpose of this study was to examine if ATP-MgCl2, an agent that protects against acute cisplatin toxicity in vitro, protected against cisplatin toxicity in vivo. Baseline renal function measurements were obtained on dogs (n = 12) and rats (n = 20) on day -1. Dogs were given 90 mg m-2 cisplatin (n = 5), 90 mg m-2 cisplatin and 50 mumol kg-1 ATP-MgCl2 (n = 5), or 90 mg m-2 cisplatin and 150 mumol kg-1 ATP-MgCl2 (n = 2), in a slow bolus i.v. injection on day 0. Rats were given 4 mg kg-1 cisplatin i.p. (n = 6) and 25 mumol kg ATP-MgCl2 (n = 8) i.v. or 4 mg kg-1 cisplatin i.p. and 25 mumol kg-1 ATP-MgCl2 (n = 6) i.v. on day 0. Renal function was assessed on a routine basis for 14 days. All dogs had significantly decreased creatinine clearance following cisplatin administration. There were no significant differences in renal function tests between groups of dogs. One dog given 50 mumol kg-1 ATP-MgCl2 and both dogs given 150 mumol kg-1 ATP-MgCl2 in addition to cisplatin developed acute anuric renal failure and were euthanatized prior to completion of the study. Rats given 4 mg kg-1 cisplatin and 25 mumol kg-1 ATP-MgCl2 had significantly increased blood urea nitrogen and serum creatinine after drug administration, compared to rats given cisplatin alone. The results indicated that ATP-MgCl2 worsened in vivo cisplatin renal toxicity in the dog and rat.     

The effect of carboxylesterase inhibition on interspecies differences in soman toxicity

Subcutaneous administration of 2 mg/kg cresylbenzodioxaphosphorin oxide (CBDP) produced complete inhibition of carboxylesterase activity in plasma and lung of mice, rats, guinea pigs and rabbits, without inhibition of acetylcholinesterase activity in either brain or diaphragm. This CBDP treatment also reduced the subcutaneous soman LD50 in these species by 48-90% in comparison to the soman LD50 in control animals. The interspecies differences in the soman LD50 values that were seen in control animals were absent in CBDP-treated animals. The soman LD50 values in control animals were 125 micrograms/kg (mouse), 116 micrograms/kg (rat), 32.3 micrograms/kg (guinea pig) and 22.8 micrograms/kg (rabbit), whereas the soman LD50 values in CBDP-treated animals from these species were clustered in a narrow dose range (11.8-15.6 micrograms/kg) and were not significantly different. This suggests that the amount of CBDP-sensitive carboxylesterase available for detoxification of soman in each species may be an important determinant of interspecies differences in soman toxicity.     

Studies on absorption and metabolism of drugs in febrile animals. (III). Antipyretic effect of acetylsalicyclic acid and aminopyrine and their plasma concentrations in febrile rabbits induced with lipopolysaccharide (author's transl)]

The present investigation was an attempt to clarify the mechanism of combined effect of acetylsalicylic acid (ASA) and aminopyrine (AMI) in febrile rabbits as induced by lipopolysaccharide (LPS). In addition, the possible synergic effect of both agents was studied in relation to the plasma concentration. In febrile rabbits, the plasma concentration of ASA (500 mg/kg, p.o.) was a higher level than in the control, but the concentration of salicylic acid (SA), the metabolite of ASA, was similar to that in the control. The plasma concentration of AMI (100 mg/kg, p.o.) in febrile rabbits was lower than in the control. A dose-dependent antipyretic effect was seen in the successive doses from 125 to 500 mg/kg of ASA, and a similar tendency was also observed in AMI from 25 to 100 mg/kg. To observe the synergic effect of ASA and AMI, we prepared the following three combinations: I (ASA/AMI; 125 plus 75 mg/kg), II (ASA/AMI; 250 plus 50 mg/kg) and III (ASA/AMI; 375 plus 25 mg/kg). Plasma concentrations of ASA, SA and AMI were measured after oral administration of the preparations and these concentrations were lower than in the separate administration of ASA ans AMI. The antipyretic effect of the three preparations was weaker than the expected value, respectively.     

Protective effect of molybdenum on the acute toxicity of mercuric chloride

The effect of molybdenum on the acute toxicity of mercuric chloride was examined. Rats that were given mercuric chloride alone (0.03 mmol/kg, once, sc) all died within 2 days after treatment. However, rats pretreated with sodium molybdate (1.24 mmol/kg, once a day for 3 days, ip) all survived for 6 days after administration of the same dose of mercuric chloride. The pretreatment with molybdenum decreased the mercury content in the liver, kidney, and spleen, but the molybdenum content in the liver, kidney, and large intestine were increased in comparison with those of the rats given molybdenum alone. Moreover, pretreatment with molybdenum caused polyuria in contrast with anuria in rats given mercuric chloride alone. These data suggest that a protective mechanism of molybdenum is the ability of this metal to decrease the mercury content in the liver, kidney, and spleen by enhancement of urinary excretion of mercury.     

Toxicity of disodium sebacate

Investigations of the acute toxicity of disodium sebacate after oral, i.p. and i.v. administration were carried out on 220 Wistar rats (110 males and 110 females) and 204 New Zealand rabbits (102 males and 102 females). No oral acute toxicity was found. On the contrary LD50 +/- s.e. of 5500 +/- 830 mg/kg b.w. and 6000 +/- 850 mg/kg b.w. were found respectively for rats and rabbits after i.p. sebacate administration. When sebacate was given i.v., the median lethal dose +/- s.e. was 560 +/- 86.5 mg/kg b.w. for rats and 1400 +/- 267.2 mg/kg b.w. for rabbits. Similar results were obtained in corresponding groups of animals (in total 220 rats and 204 rabbits) given oral, i.p. and i.v. saline solutions with added glucose in order to obtain the same value of osmolarity and sodium ion concentration. The above results appear indicative of low toxicity of disodium sebacate, and suggest that the toxic effects found could be due to the sodium content of the compound administered. Similarly, subacute and chronic toxicity was investigated in forty rats and forty rabbits (twenty males and twenty females) fed disodium sebacate incorporated into pellets. When compared to the control animals, no significant differences in biological parameters (clinical, chemical and haematological values, growth curves and histological findings for the different organs) were observed in the test groups during the treatment period. In addition, fetal toxicity, teratogenicity and neonatal toxicity were investigated in twenty female rats and twenty female rabbits. Sebacic acid did not show any teratogenic effect and the development of the fetuses was regular.     

Influence of acute and chronic ethanol administration on the vasopressor effect of serotonin in pithed rats

In pithed rats, the intravenous administration of serotonin (3, 10, 30, 100, 300 and 1,000 micrograms/kg) produced a dose-dependent increase in blood pressure. This action of 5-HT was not changed by chronic ethanol intoxication (6.0 g/kg/day for 2 weeks). The pressor responses to serotonin were, in a dose-dependent manner, significantly reduced by acute ethanol administration (0.5, 1.0, 2.0 and 4.0 g/kg p.o.) and by ketanserin injection (0.03 mg/kg i.v.). However, ethanol (2.0 g/kg) did not amplify the dilator effect of serotonin in pithed rats pretreated with ketanserin (3.0 mg/kg i.v.). We also demonstrated that, in contrast to ketanserin (10(-7) mol/l), ethanol (0.05 mol/l) potentiated the serotonin-induced vasoconstriction of isolated rat tail arteries. These data suggest that the action of ethanol on the vasopressor effect of serotonin in pithed rats does not depend on its influence on serotonergic receptors in blood vessels.     

Studies on the relationship between the endotoxin induced fever and the antipyretic effect of reserpine in rabbits (author's transl)]

It has been well documented that fever could be mediated with endogenous pyrogen released from reticuloendothelial system(RES) by administration of bacterial endotoxin(LPS) intravenously to rabbits. On the contrary, reserpine which has various pharmacological activities by depleting catecholamines decreases the normal body temperature as well as endotoxin induced fever. In this paper, we focussed our attention on the effect of reserpine on the production of endogenous pyrogen with relation to the antipyretic effect in endotoxin fever and obtained the following results: Endogenous pyrogen could be detected by intravenous administration of LPS(0.5 micrograms/kg) during the fever. However, endogenous pyrogen was undetectable with intracisternal administration of LPS(0.01 microgram/body) which provoked long-lasting fever. Reserpine (1 mg/kg, i.v.) decreased both body temperature induced by intracisternal administration of LPS(0.01 microgram/body) or intravenous administration of LPS(0.5 microgram/kg), however the degree was more extensive in cases of LPS-induced fever. Pretreatment of rabbits with reserpine (1 mg/kg, i.v.) suppressed the fever induced by an intravenous administration of LPS(0.5 microgram/kg), but did not suppress the release of endogenous pyrogen. These data suggest that endogenous pyrogen may not be an important factor in the pathogenesis of endotoxin fever.     

Colesevelam hydrochloride does not cause maternal or fetal toxicity in rats and rabbits

WelChol (colesevelam hydrochloride), a bile acid sequestrant for the treatment of hypercholesterolemia, was evaluated for adverse effects on reproduction and fetal development using standard preclinical tests. During gestation, Sprague-Dawley rats used in the developmental toxicity study received feed, feed/control article or feed plus 300, 1,000 or 3,000 mg/kg/day colesevelam whereas rats in the pre- and postnatal toxicity study received vehicle or 100, 300 or 1,000 mg/kg/day colesevelam via gavage. New Zealand white rabbits received control or 100, 500 or 1,000 mg/kg/day colesevelam via gavage. No deaths, premature deliveries or gross pathologic lesions were observed up to gestation day (GD) 20 for rats and GD 28 for rabbits. No significant differences in the number of pregnant animals, average litter size, percentage of viable fetuses, fetal body weights, number of corpora lutea, fetal viability, or gross malformations were observed versus controls. Pre- and postnatal effects were assessed in pregnant rats receiving 100, 300 or 1,000 mg/kg/day colesevelam from GD 6 to postpartum day 22. Gestation, parturition and lactation in F(0) generation dams were similar between treatment and control groups. Colesevelam did not affect physical or neurological development or induce gross pathological changes in F(1) generation rats. Colesevelam does not produce developmental toxicity in rats or rabbits, nor does it exhibit pre- or postnatal toxicity in rats at the tested doses.     

Induction of maternal toxicity in the rat by dermal application of retinoic acid and its effect of fetal outcome

Time-mated Sprague-Dawley rats were administered all-trans-retinoic acid (RA)_dermally on gestational days 11 through 14 at three dosage levels (25, 100, and 250 mg/kg body weight). Dams administered ethylenethiourea (ETU) dermally on gestational days 11 to 12 or RA orally on day 12 were used to indicate the strain's sensitivity to teratogenesis. The chemicals were dissolved in dimethylsulfoxide (DMSO) for dermal application or suspended in corn oil for treatment by gavage. The maternal weight gain, pup weight, number of resorptions and number of fetuses with gross malformations, and skeletal/organ-level anomalies were determined. Beginning with day 15, dams dermally treated with RA exhibited dermal lesions at the site of application, most dams showed vaginal bleeding by day 16, and approximately 20% did not survive to day 19. Relative to the DMSO control group, maternal weight gain in the dermal RA groups was decreased by approximately 50% at the lowest dose, with essentially no weight gain at the intermediate- and high-dose levels. The decrease in average fetal weight at the two higher doses was significant, whereas the resorption and malformation frequencies were not significantly increased by dermal treatment with RA. Without significantly affecting fetal weight or resorption frequency, dermal application of ETU significantly increased the frequency of skeletal anomalies, primarily tail defects. Oral administration of RA did not increase the malformation frequency nor produce significant maternal or fetotoxic effects. In summary, treatment of pregnant Sprague-Dawley rats by dermal application of RA dissolved in DMSO resulted in significant toxicity to the dam. The absence of a significant teratogenic effect following oral or dermal RA treatment may have been due to strain insensitivity or duration/timing of treatment. Whether the fetal weight reduction was a primary effect of treatment on the fetal/placental unit or simply secondary to maternal toxicity will require further investigation.