Cleft Palate In Rats Research Articles

An Evaluation of Wound Healing Efficacy of a Film Dressing Made from Polymer-integrated Amnion Membrane

ABSTRACT A film dressing is an easy and common wound management, which is flexible to cover many types of superficial injuries. In a recent study, we developed a scaffold from poly (1,8-octanediolco-citrate) incorporated decellularized amnion membrane (DAM-POC). The DAM-POC scaffold was biocompatible and could enhance soft and hard tissue regeneration when applied to repair the cleft palate in rat. The efficacy of the DAM-POC scaffold in oral repair had led us to hypothesize that it could be employed extensively in the medical field as a wound dressing. This study aimed to investigate the feasibility and efficacy of the DAM-POC scaffold as a film dressing in accelerating wound healing when applied in multiple tissue injuries. Our results demonstrated that both the DAM and DAM-POC scaffolds were biocompatible and anti-adhesive without causing severe foreign body reactions when covering wounds in abdominal wall, back muscle, tibia bone, and liver. In addition, the DAM-POC scaffold was superior to the DAM scaffold in reducing inflammation, preventing fibrosis, and regenerating tissues. In conclusion, the DAM-POC scaffold might potentially be adopted as a film dressing in a wide range of therapeutic applications and healing situations to protect the damaged tissues from the external environment and prevent infections.

Reconstruction of Drug-induced Cleft Palate Using Bone Marrow Mesenchymal Stem Cell in Rodents.

Background:Triamcinolone acetonide (TAC) (Kenacort*) is a commonly used synthetic glucocorticoid in today's medical practice. The drug is also a potential agent in inducing cleft palates in rats. This drug has been used to induce cleft palate in the fetus of the pregnant rats to bring out a suitable animal model for human cleft lip and palate. The drug was given intraperitoneally to induce congenital cleft palate in pregnant mother rats.Aim:The aim of this study is to induce congenital cleft palate in pregnant Wister albino rats and reconstruct the defect with bone marrow mesenchymal stem cells (BMSCs) isolated from the same species along with PLGA (poly lactic co glycolic acid) scaffold.Methods:Twenty female animals were divided into two groups. Each group contains 10 animals. The animals were allowed to mate with male rat during the esterase period and the day, in hich vaginal plug was noticed was taken to be day 0. The pregnant rats were given triamcinolone acetonide (Kenacort* 10 mg/1 ml intramuscularly/intravenous [IM/IV] injections) injection intraperitoneally at two different dosages as the existing literature. The injection was given on the 10, 12, and 14th day of gestation. The clinical changes observed were recorded, and the change in the body weight was noted carefully. Group 1 which received 0.5 mg/kg body weight of TAC had many drug toxic effects. Group 2 which received 0.05 mg/kg body weight produced cleft palate in rat pups. The pups were divided into three groups. Group A control group without cell transplant, the cleft was allowed to close by itself. Group B containing palate reconstructed with plain PLGA scaffold (Bioscaffold, Singapore) without BMSC, Group C containing BMSC and PLGA scaffold (Bioscaffold, Singapore), Group C operated for the cleft palate reconstruction using BMSCs and PLGA scaffold. There was faster and efficient reconstruction of bone in the cleft defect in Group C while there was no defect closure in Group A and B.Results:There was complete reconstruction of the cleft palate in the group of rat pups which received BMSCs along with PLGA scaffold. Bone growth in the cleft defect was faster; complete fusion of the defect was achieved.Conclusion:The dosage of drug used for inducing cleft palate was standardized in rodents for a definitive congenital cleft palate model. The cleft palate induced was reconstructed using BMSCs and PLGA scaffold. This was compared with a control group and the other group with plain PLGA used for reconstruction of the palate. This study will invite future research in the effect of the drug on human beings, especially on pregnant mothers.

A Comparison Study of Effects of Vitamin E and Silymarin on Phenytoin-Induced Cleft Palate in Rats

A Comparison Study of Effects of Vitamin E and Silymarin on Phenytoin-Induced Cleft Palate in Rats

Induction of cleft palate in aniline hydrochloride‐treated rats: Possible effect of maternal methemoglobinemic hypoxia

ABSTRACT Aniline hydrochloride (AH), a methemoglobin formation‐stimulating substance, at a dosage level of 520 mg/kg which does not induce apparent fetal death, was injected subcutaneously into pregnant rats once on day 14, 15 or 16 of gestation in order to assess the stage specificity of cleft palate induction. Also, doses of 260, 390, 520 and 650 mg/kg were administered to pregnant rats on day 15 of gestation, and the dose‐response relationships with respect to fetal cleft palate and maternal methemo‐globinemia induction were studied. In the stage‐specificity study, paleness, decreased body weight gain and elevated methemoglobin concentration were noted in the dams treated with AH. Upon fetal examinations, although reduced body weight was noted in all AH‐treated groups, cleft palate was observed only in fetuses from those dams treated on day 15 of gestation. In the dose‐dependency study, AH induced maternal methemoglobinemia, decreased fetal body weight and increased the incidence of cleft palate dose dependently when administered at dosage levels of 260, 390, 520 and 650 mg/kg on day 15 of gestation. Additionally, administration of methylene blue, a methemoglobinemia‐preventing substance, to the AH‐treated dams ameliorated maternal methemoglobinemia and reduced the incidence of fetal cleft palate. In summation, it is considered that AH stage‐specifically induces cleft palate in rats and that cleft palate is caused not by a direct teratogenic effect of AH but by maternal hypoxia due to methemoglobinemia.

Palatal Slit and Cleft Palate in Rats Treated with Glucocorticoids II. Comparative Teratogenicity of Prednisolone, Triamcinolone Acetonide and Hydrocortisone

AbstractThe induction of abnormal palatal development by three glucocorticoids; prednisolone, triamcinolone acetonide and hydrocortisone was evaluated in rat fetuses. Pregnant rats were injected subcutaneously with either prednisolone (12.5‐100 mg/kg/day), triamcinolone acetonide (0.25‐2 mg/kg/day) or hydrocortisone (100 mg/kg/day) on days 14 and 15 of gestation. These females were humanely killed on day 20 of gestation and viable fetuses were inspected for their palatal abnormalities. The frequencies of cleft palate were significantly higher in the group treated with 100 mg/kg/day prednisolone (10.6%), and in the groups treated with 0.5, 1 and 2 mg/kg/day triamcinolone acetonide (8.6%, 26.1% and 58.3%, respectively) than the control frequency of 0%. Triamcinolone acetonide was 70 times as potent as prednisolone in inducing palatal slit, with ED50 value of 1.0 mg/kg/day and 70 mg/kg/day, respectively. Hydrocortisone showed no potentiality for the induction of cleft palate and palatal slit. Other developmental abnormalities including omphalocele and general edema, late resorption, and growth retardation were induced by triamcinolone acetonide and prednisolone. These findings indicate that triamcinolone acetonide has a significantly higher potentiality for the induction of palatal slit in rats, as well as in mice, compared to prednisolone and hydrocortisone.

Palatal Slit and Cleft Palate in Rats Treated with a Glucocorticoid 1. Teratogenicity of Dexamethasone

ABSTRACTThe sensitive period and the dose‐response characteristics for dexametha‐sone‐induced cleft palate and palatal slit in rats were examined. Pregnant rats were injected subcutaneously with dexamethasone in a single dose of 2–6 mg/kg on one day between day 8 and 16 of the gestational period or once each day for two successive days (days 14 and 15 of gestation). All animals were euthanized on day 20 of gestation and the palatal condition of their fetuses was inspected after fixation under a dissecting microscope. The sensitive stage of palatal slit and cleft palate induction was determined and the dose‐response relationship was analyzed by the log‐probit transformation method.No maternal lethality was elicited in any of the treatment groups. High frequencies of palatal slit and cleft palate were induced when dexamethasone was administered as a single dose on any individual day from day 12 to day 14 of gestation. Omphalocele and general edema were also found to be significantly more frequent in the high‐dose group treated on days 12–14 of gestation. All groups treated showed a reduction in fetal body weight. The response data for palatal slit and cleft palate after administration of dexamethasone fitted to similar linear regression slopes, suggesting a similarity in the underlying mechanisms for palatal slit and cleft palate induction in rats. ED50 values were 3.48 mg/kg for palatal slit and 6.64 mg/kg for cleft palate. These findings indicate that dexamethasone treatment is effective in inducing palatal slit and cleft palate in rats, as well as in mice. Key words: glucocorticoid, dexamethasone, palatal slit, cleft palate, sensitive stage, doseresponse, rats

Diagnosis of induced cleft palate in rats from defective patterns of differentiation of isoenzymes.

Cleft palate was induced in 420 embryos of Sprague-Dawley rats with a single oral dose of 600 mg/kg beta-aminoproprionitrile (BAPN) on embryonal day 15, 7 hours. The cleft palate was accompanied by a pathological differentiation pattern of various isoenzymes in palatal shelves. These isoenzymes could be detected in amniotic fluid from the 16th to the 20th days of pregnancy when they also had a pathological differentiation pattern. We conclude that teratogenically induced cleft palate in rats is accompanied by a pathological differentiation pattern that can be traced by determination of isoenzymes in the palatal shelves as well as in amniotic fluid.

Maternal toxicity: a possible etiological factor in embryo-fetal deaths and fetal malformations of rodent-rabbit species.

Data from animal teratology studies were surveyed to determine whether embryo-fetal mortality and fetal malformations result from a primary action of the agent on the conceptus or if they are secondary to maternal toxicity--a consequence of administration with high dose levels of test chemicals. A fairly strong association between embryo-fetal mortality and maternal toxicity was revealed by analysis of data from hamsters, mice, rats, and rabbits in 234 studies of chemical and physical agents, of which 83 were conducted at both maternotoxic and nonmaternotoxic doses, 94 only at maternotoxic doses, and 49 at nonmaternotoxic doses. In the above studies, only nine chemicals (four each in hamsters and rabbits and one in rats) were reported to induce embryo-fetal deaths at apparently nonmaternotoxic doses. These findings tend to suggest a contributory role for maternal toxicity in the induction of embryo-fetal deaths. The previously reported hypothesis that certain fetal defects in mice may perhaps be caused by maternal toxicity was also found to be true in a review of data on hamsters, rats, and rabbits. Salient maternal toxicity-associated fetal malformations were exencephaly, encephalocele, micro- or anophalmia, and fused ribs in hamsters and defective (fused, missing, or extra) ribs, vertebrae, and sternebrae, ex-, an-, or microphthalmia, and cleft palate in rats and rabbits. These malformations occurred at low frequencies, generally with no readily apparent dose-response relationship. Presumptive evidence indicates that embryo-fetal deaths, and the above-mentioned fetal malformations in experimental animals, which in published literature are presently attributed to chemical induction for a large number of chemicals, may be a consequence of maternal toxicity per se.

Correlation between alterations in Meckel's cartilage and induction of cleft palate with beta-aminoproprionitrile in the rat.

The lathyrogen beta-aminoproprionitrile (BAPN) induces cleft palate in rats when administered at a critical time in secondary palate formation. BAPN is known to inhibit the crosslinking of newly synthesized collagen, but its primary site of action in producing cleft palate is unknown. In this study time-mated Sprague-Dawley rats were given a single oral dose of 600 mg/kg BAPN at five known gestational ages in the 48 hours before palatal shelf elevation, and the fetuses were studied on days 16, 17 and 18. Evaluation of craniofacial relations and palate development in BAPN-treated heads revealed that delayed palatal shelf elevation and resulting cleft palate were related to retrognathia of the mandible. However, shortening of the mandible was due primarily to vertical and lateral bending of Meckel's cartilage. High and retruded tongue positions that were present with the deformities in Meckel's cartilage interfered with palatal shelf movement to the horizontal plane. The group treated with BAPN at 15 days 7 hours, approximately 24 hours before normal palatal shelf elevation, had the most severe defects in Meckel's cartilage, the longest delay in palatal shelf elevation and the highest incidence of cleft palate. Inhibition of crosslinking of collagen in Meckel's cartilage appeared to weaken the cartilage during the critical period in facial development when extention of the tongue and mandible beneath the primary palate is required to facilitate palatal shelf elevation.

1221 MECHANISM OF DEXAMETHASONE-INDUCED CLEFT PALATE IN RATS: INHIBITION OF PROSTAGLANDIN AND THROMBOXANE SYNTHESIS IN FETAL PALATES IN VIVO

We have hypothesized that the teratogenic mechanism of glucocorticoids involves the same biochemical pathway as the mechanism of their anti-inflammatory hormonal action, i.e., inhibition of arachidonic acid release and of prostaglandin (PG) and thromboxane (TX) production. Arachidonic acid reversed the production of cleft palate in rats by dexamethasone and this reversal was blocked by indomethacin, an inhibitor of PG and TX synthesis (cyclo-oxygenase) (Fed. Proc. 3616:955, 1980). Pregnant rats were treated with dexamethasone 3.75mg/kg or vehicle on days 12 to 15 of pregnancy, a regimen giving about 80% cleft palate. Three hours after the last dose of steroid on day 15 fetuses were removed by c-section and palates from each litter were dissected, pooled, sonicated, and incubated at 37°C for 3 hours. 100μl aliquots were removed at 1 hr. and 3 hrs. and the reaction stopped with lml ethanol. Aliquots of the ethanol extracts were measured for PG and TX by radioimmunoassay. PG and TX synthesis was proportional to time of incubation. Dexamethasone inhibited significantly the production of F2α, E2, 6-keto F1α, and TX B2 by fetal palates to about 50% of control values. Thus, evidence has been presented for the precise biochemical mechanism of glucocorticoid-induced cleft palate.

Evidence for a role of arachidonic acid in glucocorticoid-induced cleft palate in rats.

AbstractWe have shown that arachidonic acid significantly reduces the production of cleft palate in rats by dexamethasone and that this corrective effect of arachidonic acid is blocked by indomethacin, an inhibitor of cyclooxygenase. Moreover, by using [3H]-arachidonic acid as a tracer we have shown that dexamethasone treatment depresses significantly the free [3H]arachidonic acid available to the microsomal cyclooxygenase in the fetal upper and lower jaws including the palate at the critical period of development. These observations suggest that glucocorticoids produce their palatal teratogenicity by limiting the release and consequently the availability of arachidonic acid at the critical period of development.

Biochemical mechanism of corticoid-induced cleft palate in rats linked to anti-inflammatory action

Glucocorticoids produce cleft palate in offspring of rodents in direct relation to their anti-inflammatory potency. Recently,the anti-inflammatory action of glucocorticoids has been shown to be inhibition of arachidonic acid release from membrane phospholipids in several different models of inflammation in direct relation to anti-inflammatory potency. Thus,we have determined whether the production of cleft palate in rat fetuses by dexamethasone 3.5 mg/kg on days 12 to 15 of gestation is affected by concurrent injections of arachidonic acid 300 mg/kg. This produced a marked correction of the degree of cleft palate produced by dexamethasone (59/146, 40.4% vs. 129/180, 71.7%; P=0. 034 Mann-Whitney test). Pregnant rats were also treated with either dexamethasone or saline on days 12 to 14 and 3H-arachidonic acid on day 15. After four hours fetuses of dexamethasone-treated animals had significantly increased uptake of 3H vs. controls. Moreover, the increased 3H was incorporated chiefly into phospholipid demonstrating a reverse of release of fetal palatal arachidonic acid.Thus, the teratogenic action of corticoids appears to be due to their anti-inflammatory action.

Tissue phosphatase changes following triamcinolone associated with cleft palate in rats

One theory of the development of cleft palate in rats involves the action of lysosomal enzymes secreted by epithelial cells at the time of fusion of the palatal shelves. To test this theory we studied the biochemistry of the palates of fetal rats daily between days 14 and 19 (from 3 days before to 3 days after palate closure). Triamcinolone was administered once im on gestation day 14 to Wistar rats; 0.5 mg/kg body weight produced approximately 50% cleft palates. Pooled control palatal tissue was compared with pooled experimental tissue; that from fetuses with clefts being pooled separately from those not affected. Acid phosphatase and beta-glucuronidase were assayed. Concentration vs. time curves for both enzymes were very similar. Prior to the time of palate closure both enzymes were present in low concentration. Between days 16 and 17, the normal time of closure, there was an abrupt increased in enzyme concentration, with experimental tissue showing a significant elevation over control tissue on days 17 and 18. Alkaline phosphatase was also present in small amounts before closure and significantly higher in control tissue on day 17. Protein was depressed in palates having clefts on day 17; thus the ratio of enzyme activities to protein synthesis was significantly elevated at a critical time. Unaffected experimental palates had a normal ratio. These results suggest imbalanced acid phosphatase, beta-glucuronidase, and alkaline phosphatase activity compared with protein synthesis at the time of palate closure following triamcinolone in rats.

Cleft palate in rodents after maternal treatment with various lathyrogenic agents.

AbstractIngestion of diets containing 50% ground sweet pea seeds (Lathyrus odoratus) by pregnant Sprague‐Dawley rats on days 10‐20 of gestation resulted in high frequencies of fetal resorption and surviving young with various degrees of edema, forelimb flexure, angulation of the vertebral column, micrognathia, cleft palate, and other defects. Pregnant A/J mice maintained on such a diet on days 9‐18 of gestation produced offspring with cleft palate and other malformations. The lathyrus factor, β‐aminopropionitrile (BAPN), given in multiple oral doses to pregnant rats at various times during pregnancy also produced high frequencies of resorption and of young with edema, cleft palate, and malformations of vertebrae and limbs. However, when single doses of 500 mg BAPN were administered on day 15 the resorption rate was markedly reduced whereas the frequency of cleft palate was greatly increased. Three other lathyrogenic agents produced high frequencies of cleft palate in rats: 50 mg aminoacetonitrile on day 15, 400 mg D‐penicillamine on days 10‐15, and 50 mg semicarbazide on days 10‐16. The period of greatest cleft palate susceptibility with all the agents tested was day 15.

Induction of Cleft Palate in Rats with Intra-amniotic Corticoids

TESTS of teratogenicity using tissue culture, laboratory rodents or primates may not yield results applicable to man1. Different species and even strains differ in their response to teratogens. In mice, the percentage induction of cleft palate after administration of corticoids varies from strain to strain2; in rats, the effect cannot be found at all3–5. The relative influences of maternal metabolism on the one hand, and of specificity of the morphogenetic processes in the embryo on the other, remain unknown. The development of a test for the teratogenic effect of drugs depends on the solution of this problem: strict species specificity of the embryonic morphogenetic mechanisms would absolutely preclude extrapolation from laboratory animals to humans.

Induction of cleft palate in rats with antiinflammatory drugs.

AbstractPregnant Holtzman rats were injected subcutaneously with anti‐inflammatory drugs from days 12–15 of gestation. Daily doses producing significant frequencies of cleft palate in the offspring ranged from 0.1–0.8 mg/day for triamcinolone, betamethasone, and dexamethasone. Cleft palate was not induced by methylprednisolone, prednisolone, and cortisone, even by daily doses ranging from 8–75 mg. Similar experiments were performed on A/J mice. The possible significance of these experiments in relation to testing potential teratogens and to the mechanism of palate closure is discussed.

A study of the form of experimental cleft palate in rats

It is generally accepted that cleft palate results from a complex interaction of genetic and environmental factors. In consequence, the findings of different experimental workers are difficult to compare. To simplify background influences, cleft palate was produced in a closed colony of Sprague-Dawley rats with vitamin A, 6-mercaptopurine, meclozine and amniocentesis. Each technique yielded lesions which, on study, showed a number of characteristic features. Hypervitaminosis A induced total and incomplete clefts, the latter involving hard and soft palate. Prognathia and micrognathia could occur, and there were often basocranial defects with deformity of the pharynx and Eustachian tubes. With 6-mercaptopurine, total and incomplete clefts were seen, but when only the soft palate was affected, the cleft was often asymmetrical. Very severe micrognathia but not prognathia could exist, and fusion of touching oral surfaces was minimal. Meclozine always produced total clefts with variable micrognathia, and fusion of touching oral surfaces was usual. Amniocentesis evoked total and incomplete clefts, the latter usually anteriorly placed. Among the conclusions which might be drawn, the following have general interest. 1. Delayed normal development does not adequately explain the variety of the clefts and their associated lesions, with the corollary that maldevelopment rather than retarded development underlies at least some of these anomalies. 2. As an extension of the above, cleft palate formation can result from multiple mechanisms. 3. Because clefts produced by amniocentesis were different from those following chemical teratogens, it is unlikely that disturbed amniotic fluid dynamics (especially oligohydramnios) played an important part in cleft production by the latter. 4. It is apparent, therefore, that similar end products of disturbed development in embryos can be reached by different pathways, a situation with its parallels in postnatal pathology.