ABSTRACT Transgenic mice technology in conjunction with other molecular biological and embryo manipulation techniques has made it possible to manipulate the mouse genome to elucidate the molecular mechanisms of normal and abnormal embryonic development. This genetic technology also permits the isolation of novel genes involved in developmental events. It has and certainly will greatly contribute to the better under- standing of the pathogenesis of congenital anomalies. However, the majority of con- genital anomalies in humans occur from multifactorial causes including not only genetic but also various environmental factors. Thus, transgenic mice can be utilized as an excellent genetic tool on which all the available conventional teratological techniques and informations are concentrated to elucidate molecular mechanisms and the holistic picture of congenital anomaly formation.
ABSTRACT It has been well known that there is a high incidence of congenital malformations in newborns from diabetic mothers when the mothers’ diabetes control before and during pregnancy is poor. We treated 438 pregnant diabetics who bore 443 children between February 1%4 and June 1992. Among these children, there were 51 cases (1 1.5%) with congenital malformations, 21 cases with major anomalies (4.7%) and 30 cases with minor anomalies (6.8%). The type of malformations are not related to special organs; heart malformations and cleft lips are relatively frequent compared to other types of malformations. The mechanism of the congenital malformations in newborns from diabetic mothers remains un- clear. However, clinically and experimentally it has been found to be due to fuel-mediated teratogenesis. Since October 1978, HbAi has been used as an index of diabetic control and the relationship between congenital malformations and the mother’s diabetes con- trol has been observed. 1) There is no difference in the incidence of malformations in children from IDDM and NIDDM mothers. However, there are more severe malformations in the children from IDDM mothers compared to those from NIDDM mothers. 2) Mothers who bore children with major malformations had all made their first visit to our hospital after pregnancy. HbAi in the IDDM mothers who had children with mal- formations at the first visit was 11%. 3) In the NIDDM mothers, even if HbAi levels are near normal, children with major malformations were born and there was little relationship between congenital malformations and the mothers’ diabetes control. These data suggest that there are two kinds of congenital malformations in children from diabetic mothers, fuel-mediated teratogenesis, and malformations as seen in children from non-diabetic mothers.
ABSTRACT SLE is a representative autoimmune disease which develops preferentially in women of childbearing age. Its frequent occurrence makes the coincidence of SLE and pregnancy an important clinical problem. SLE is thought to be multifactorial dis- ease. A familial prevalence was found to be 3% which was significantly higher when compared with Japanese prevalence of SLE. When women with SLE become pregnant, the fetus is at high risk and is adversely affected showing the high prevalence of fetal loss. Antiphospholipid antibodies were thought to be one of the causative factors. Ne- onetal lupus erythematosus (NLE) including lupus like skin lesions and congenital complete heart block (CCHB) is associated with maternal anti-SS-A and SS-B antibodies. The disease resolves with normalization of the maternal antibodies by the 8th month after delivery with the exception of the CCHB which is almost universally irriversible. When the sera from 4 maternal patients with NLE and 32 patients with normal delivery were analyzed by immunoblotting using recombinant 60 and 52 kD SS-A, and SS-B purified from calf thymus extract, the frequency of anti-52 kD SS-A and SS-B in patients with NLE was significantly higher than that of patients with normal delivery. Anti-SS- A/SS-B antibodies may react with the SS-A/SS-B antigens in fetal heart tissue as fetal levels of IgG increases which is almost simultaneously as when the SS-A/SS-B antigens appear in the fetal heart tissue. The pathogenesis of tissue damage mediated by autoimmune mechanisms specifically dependent on the biology of pregnancy is recognized to be due to passively acquired autoimmune injury.
ABSTRACT The incidences of various complications during pregnancy are not significantly different between epileptic and nonepileptic mothers in the majority of papers so far reported. More than 70 to 80% of women with epilepsy will have no change in seizure frequency, while 5% will have fewer seizures than before and the remaining patients will have more seizures during pregnancy provided that their drug compliance is good. Intrauterine growth, in particular, of head circumference of fetus is delayed. However, this retardation disappears within few years after birth. The risk of congenital malformations of the offspring born to treated epileptic mothers is greater than in the general population. Among risk factors for teratogenesis that had been considered to date, only antiepileptic drug (AED)-related factors had proved to be significantly related to the occurrence of malformations. Among AEDs, methylphenobarbital, valproate, primidone, carbamazepine and phenytoin are teratogenic, particularly when they are used in combination. Follow up EEG of children born to epileptic mothers revealed that the incidence of abnormal EEG was 44%, and 28 to 38% showed epileptiform patterns. Only 7% of offspring had epileptic seizures. In the offspring without clinical seizures revealed that most of the epileptiform patterns disappear after the age 10. Recommendations concerning AED therapy during pregnancy are also discussed.
ABSTRACT Recent advances in immunohistochemistry have revealed the precise distribution of various neurotransmitter systems, their projections and ultrastructure in the brain. Based on these data, the structure and function of specific neurons or a group of neurons in the brain can be understood in terms of the dynamics of the neurotransmitters they utilize. This strategy of neuroscience may be utilized to explore higher brain functions such as learning, memory, cognition and sleep. Prenatal exposure of pregnant rats to methylazoxymethanol acetate (MAM) on day 15 of gestation produces off- spring with severe microcephaly (MAM-rats). These MAM-rats show various behavioral abnormalities in learning, memory and cognition as well as hyperactivity and reduction of paradoxical sleep. Developmental abnormalities of serotonin (5HT) fibers in the cerebral cortex and 5HT neurons in raphe nuclei are examined. The cell deficits of cortical target neurons and irregularly arranged cortical layers were observed. Developmental abnormalities of 5HT neurons are discussed in terms of target dependent secondary de- generation. Vasoactive intestinal polypeptide (VIP) has an important role in behavioral modification. VIP is suggested to have a functional correlation with 5HT in the brain. The reduction of VIP neurons and hypo-aggregation of their axonal boutons were observed in the cerebral cortex and hippocampus of infant MAM-rats. However, in adult MAM-rats, VIP axonal boutons showed layer-dependent hyper- or hypo-aggregation compared with the age-matched control. The difference in the number of VIP neurons became small between the controls and MAM-rats. These immunohistochemical obser- vations of brain defects have an important implication for understanding the abnormal behavior of MAM-rats.
ABSTRACT Administration of N, W-bis (dichloroacetyl)-l,8-octamethylenediamine, bisdiamine, to pregnant Donryu rats on a single day of gestation induced unilateral and bilateral diaphragmatic hernias in fetuses with high incidence. The protruded liver was not covered with a serous membrane or a muscular layer. Incidence of unilateral diaphragmatic hernia on the left side was high when bisdiamine was administered on day 9 or 13 of gestation, and that on the right side was high when administered on day 12 of gestation. Incidence of bilateral diaphragmatic hernia was high when bisdiamine was administered on day 12 of gestation. Differences in sensitivity to hernia formation ac- cording to day of bisdiamine administration between right and left sides may reflect differences in developmental chronology between the two sides. Two distinct times for induction of left diaphragmatic hernia might be attributed to at least two different mechanisms. The present model is expected to help analyzing not only anatomical characteristics of congenital diaphragmatic hernia but also possible mechanisms responsible for their development.
ABSTRACT The effect on pyrimethamine (PYR) pharmacokinetics of folic acid (FA) which potentiated the PYR teratogenesis was studied in rats. Gavage administration of PYR 1.6 mg/kgBW/day from day 11 to day 15 of gestation did not cause any malformation, but with concomitant dosing of FA 50 mg/kg/day in feed caused malforma- tions in 75% of fetuses. Neither the plasma concentration-time profile nor the plasma protein binding of the gavaged PYR was affected by the Concomitant dosing of FA in the non-pregnant rats. The pregnant rats which received the gavaged PYR with or without FA in feed for 5 days (from day 11 to day 15 of gestation) were killed at 4 or 12 hrs after the last dosing of PYR, and their plasma and fetuses were subjected to determination of PYR. The PYR concentration in the maternal plasma was comparable in both groups. The PYR concentration in fetuses of the PYR alone group was significantly higher than that of the PYR with FA group 4 hr after but not 12 hr after the last dosing. These results indicated that the pharmacokinetics of PYR was not affected by the concomitant dosing of FA, suggesting that FA potentiated the PYR teratogenesis by other mechanisms than pharmacokinetic modifications.
ABSTRACT Oral administration of pyrimethamine (PYR) 3.6 mg/kgBW/day to the pregnant rats from day 11 to day 15 of gestation caused malformations in all the fetuses, but concomitant intraperitoneal administration of folk acid (ip FA) 50 mg/kg/day inhibited the incidence of malformations by 25%. On the other hand, the same dose of oral FA (in feed) had an opposite effect on PYR teratogenesis; the incidences of mal- formed fetuses were 0% in the PYR 1.6 group, but 100% in the PYR with oral FA group. The plasma levels of 5-methyltetrahydrofolic acid (SMF), a principal transfer form of folate, were measured after single oral administration of PYR with or without FA (ip or oral) in non-pregnant female rats. The area under the plasma concentration-time curve (AUC) after the concomitant administration of PYR with ip FA was larger than that after PYR alone. This result indicated that the available 5MF for the peripheral tissues was increased by the concomitant administration of ip FA. The AUC after the concomitant administration of PYR with oral FA was smaller than that after PYR alone. These results suggested that ip FA increased the available 5MF to ameliorate, but oral FA decreased the availability to aggravate the PYR teratogenesis.
ABSTRACT The effects of the Ay gene on the sensitive periods of hydrocortisone-induced cleft palate and palatal slit were investigated in C57BL/6 (a/a) and its congenic strain of C57BL/6-AY (Ay/a) mice by using the single-dose administration method. Matings were conducted as follows (female x male): Group I, a/a x a/a; Group 11, a/a x AY/a; and Group III, Ay/a x a/a. Pregnant females were subcutaneously given a single dose of 200 or 400 mg/kg of hydrocortisone on day 11, 12, 13 or 14 of pregnancy and killed on day 18 for examination of palatal defects of live fetuses. Cleft palate was produced in all groups by treatment on days 11-13 of pregnancy at a dose of 200 mg/kg without any increase in fetal mortality. In Group I, the maximum incidence was observed on day 11 and followed by a rapid decrease thereafter. In Group 11, in which half of the fetuses were expected to carry the Ay gene, the incidence still remained high on day 12, although it was decreased to the level of Group I by day 13. In Group m, in which maternal mice as well as half of their fetuses carried the Ay gene, significantly higher incidences were observed on days 12 and 13 with the maximum value on day 12 when compared with those in Groups I and/or II. Palatal slit was also induced in all groups on each of treatment days at a dose of 200 mg/kg. Although the incidences in both Groups I and II were high on days 11 and 12 and gradually decreased thereafter, the value on day 13 was significantly higher in Group II than in Group I. In Group III, the maximum incidence was found on day 12 and the values on days 13 and 14 were still significantly higher than those in Groups I and/or II. These results indicate that the sensitive periods of hydrocortisone-induced cleft palate and palatal slit are prolonged into the later stage of embryonic development as a result of the AY-gene effects.
ABSTRACT The purpose of the present study was to determine the frequency of spontaneous axial skeletal variations detectable by the double staining technique in Crj: CD (SD) and Crj: Wistar rat fetuses. In addition, the frequencies of unossified skeletal variations were compared between SD and Wistar rats, and between same strain male and female rat fetuses. Fifteen types of the variations were detected. There were strain differences (4 types) and sex differences (3 types) in the frequencies of the variations. With the aid of double staining technique, skeletal variations such as supernumerary ribs or deformed ossification centers detected by the single staining technique could be classified in detail into many types. This study showed that the double staining technique improved detectability of skeletal variations and facilitated their evaluation in develop- mental toxicity studies.