isotretinoin and Cleft-Palate

The impact of in-utero isotretinoin exposure has been widely reported, with many affected pregnancies failing to reach term.

Topics: Abnormalities, Drug-Induced; Cleft Lip; Cleft Palate; Diagnosis, Differential; Female; Fingers; Humans; Infant; Isotretinoin; Magnetic Resonance Imaging; Pregnancy; Prenatal Exposure Delayed Effects; Syndactyly; Teratogens; Toes

The teratogenicity of 13-cis-retinoic acid (RA) either administered alone or following pretreatment with phenobarbital sodium (PB), was assessed. Groups of gravid CF-1 mice were administered dosages of either 10, 100, 200, or 400 mg/kg of RA orally on either days 11, 12 or 13 of gestation, in order to determine structural alterations. In addition, separate groups of mice were orally pretreated with 80 mg/kg/day of PB on days 7 through 10 of gestation prior to the administration of RA. Skeletal alterations attributed to maternal administration of either 100, 200 or 400 mg/kg of RA on days 11-13 included delayed ossification of the limbs and supraoccipital bone, the presence of extra ribs, and various sternebral defects. Soft tissue alterations included cleft palate and dilation of the renal pelves which occurred following maternal exposure on days 11 and 12-13, respectively. Significant decreases in the incidence of cleft palate and delayed ossification of the limbs were observed in those dams administered RA on days 11 or 12, respectively, following prior treatment with PB. These data suggest that administration of PB, a prototypical hepatic microsomal enzyme inducer, may partially antagonize the teratogenicity of RA.

Topics: Abnormalities, Drug-Induced; Administration, Oral; Animals; Animals, Newborn; Body Weight; Bone and Bones; Cleft Palate; Female; Isotretinoin; Male; Mice; Organ Size; Osteogenesis; Phenobarbital

Isotretinoin (13-cis-RA) is known to be teratogenic in humans and laboratory animals. The relatively low potency of 13-cis-RA in NRMI mice in comparison to the all-trans isomer has been proposed to be due to minimal transfer across the placenta (Creech-Kraft et al., '87). To further delineate the teratogenic potential of 13-cis-RA, a dose-response, temporal study was conducted in vivo and in vitro using submerged limb culture and image analysis evaluation of development. Dose-dependent embryotoxicity was produced by treatment on GD 7, while later treatments produced inconsistent effects on resorption rate and fetal weight. Treatment on either GD 7 or GD 8 produced a number of malformations in dose-dependent manner. Most common were tail and cleft palate defects, which were produced by 13-cis-RA on each of the days tested (GD 7-GD 11), with peak malformations occurring on GD 9 and GD 10 for tail and cleft palate, respectively. Most limb defects were produced after GD 10 and GD 11 exposure. The observed frequency of defects confirmed that in ICR mice 13-cis-RA is about 10-fold less potent than all-trans-RA as a limb teratogen (Kwasigroch and Kochhar, '80; Kochhar and Penner, '87). Effects observed via image analysis following maintenance of limbs in serum-free culture medium were dose dependent. Low dose treatment produced occasional polydactyly. The intermediate dose caused somewhat variable region-dependent increases in cartilaginous bone anlagen area. The high dose of 13-cis-RA produced irregular limb outlines, a reduction in bone anlagen area, and an inhibition of alcian blue staining of cartilage without affecting morphogenesis of bone anlagen. These results confirm that, when the effects of the administered doses are evaluated, 13-cis-RA is a much less potent teratogen in comparison to the all-trans isomer. More importantly, the results show that retinoids can enhance (at low and intermediate doses), depress (at high doses), or eliminate (high dose) chondrogenenic expression during limb morphogenesis in vitro. This indicates that retinoids such as 13-cis-RA can manipulate events in development in a variety of ways (i.e., produce malformations, interfere with chondrogenic expression without affecting morphogenesis, and stimulate growth) in a dose- and time-dependent manner. Although the ability of RA to act as a true morphogen has recently been questioned (Wanek et al., '91; Noji et al., '91), the results presented here support the position that RA can

Topics: Abnormalities, Drug-Induced; Animals; Body Weight; Cleft Palate; Culture Techniques; Dose-Response Relationship, Drug; Extremities; Female; Fetal Resorption; Fetal Viability; Gestational Age; Isotretinoin; Limb Deformities, Congenital; Maternal-Fetal Exchange; Mice; Mice, Inbred ICR; Pregnancy; Radiography; Tail

Abnormalities of the secondary palate were studied in an animal model in which features of Treacher Collins syndrome (TCS) and Nager or Miller syndromes (both of which are facially similar to Treacher Collins, but include limb malformations) were induced by acute maternal exposure to 13-cis-retinoic acid (13-cis-RA, isotretinoin, Accutane). Previous work in our laboratory has illustrated that excessive cell death in the proximal aspect of the maxillary and mandibular prominences of the first visceral arch and in the apical ectodermal ridge of the limb bud probably accounts for the characteristic craniofacial and limb abnormalities observed (Sulik et al, 1987; Sulik and Dehart, 1988). The current study shows that maternal treatment with 400 mg per kilogram 13-cis-RA at 8 days 14 hours (8d14hr) or 9d6hr post fertilization results in abnormalities of the secondary palate that vary in incidence and severity. Following the earlier treatment time, 82 percent (68 of 74) of the 18d fetuses were affected, with, severely hypoplastic, unfused palatal shelves present in 34 percent (25 of 74). The less severely affected fetuses had malformations that involved primarily the posterior aspect of the palatal shelves. This malformation (foreshortening of the posterior portion of the palate) constituted the major developmental alteration that resulted from treatment at the later time, at which time a 52 percent (26 of 50) malformation incidence was seen. The change in pattern of malformations with treatment time is consistent with the changing pattern of programmed cell death, which was observed to occur in the first visceral arch.

Topics: Animals; Branchial Region; Cell Survival; Cleft Palate; Female; Isotretinoin; Limb Deformities, Congenital; Mandibulofacial Dysostosis; Maxilla; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Morphogenesis; Palate; Pregnancy; Syndrome; Time Factors

Previous observations have indicated that isotretinoin (IT), a drug in common use for therapy of cystic acne, is teratogenic in humans but possesses low embryotoxicity in pregnant mice, probably because of its shorter half-life and limited placental transfer in rodents. In human volunteers and patients, one major blood metabolite of IT is 4-oxo-isotretinoin (4-oxo-IT) which undergoes slower elimination than IT and may itself be a participant in teratogenesis. To investigate the problem of species differences displayed by IT and the role of its metabolism, embryotoxic effects of 4-oxo-IT were examined after its single or repeated intubations into pregnant ICR mice and compared with the effects of a similar regimen of IT. The two compounds were also tested for their relative ability to suppress chrondrogenesis in the in vitro cell and organ culture assays. We found that a single dose of 4-oxo-IT, 100 mg/kg, given on day 11 of gestation (plug day = day 0 of gestation) produced a moderate incidence of limb reduction defects and cleft palate (39% and 27% of surviving fetuses, respectively), while a dose of 150 mg/kg affected virtually every fetus. IT, on the other hand, produced no defects in fetuses exposed to similar dose levels. Repeated intubations with IT, however, resulted in increasing the frequencies of limb reduction defects and cleft palate to levels obtained after 4-oxo-IT administration. We found that a 3-hour interval between IT intubations was more effective in this regard than an 8-hour interval. Repeated IT intubations also uncovered sharper stage-dependency of limb and palatal defects than obtained otherwise.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Abnormalities, Drug-Induced; Animals; Cartilage; Cleft Palate; Female; In Vitro Techniques; Isotretinoin; Limb Deformities, Congenital; Male; Mice; Mice, Inbred ICR; Pregnancy; Teratogens; Tretinoin