Diaphragmatic Hernia Induced in Rat Fetuses by Administration of Bisdiamine

Administration of N, N'-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 according 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.     

Congenital Diaphragmatic Hernia: Experimental Approach

Congenital diaphragmatic hernia is the only relatively common congenital malformation which requires operative treatment during the neonatal period, and the incidence is reported to be one in 2,000–5,000 births. Although a diaphragmatic defect can be easily corrected by pulling out the herniated viscera of the chest and closing the diaphragma, the mortality rate of infants with congenital diaphragmatic hernia is high despite improvements in neonatal intensive care, because the hypoplastic lungs on the affected side can not provide life support after birth. The severity of associated pulmonary hypoplasia is the most important factor determining survival in an infant with congenital diaphragmatic hernia. From experimental study, it should be emphasized that retardation in the lung growth, regardless of its potential for further growth, just at the time of pleuroperitoneal canal closure, may result in congenital diaphragmatic hernia; the hypoplastic lung on the side of herniation would not result from the compression of the lung by the herniated organs, but it may be induced by the limited space for further growth.     

Immunological Defects in a Bis(dichloroacetyl) diamine Induced Malformation Complex in Rats Closely Resembling the DiGeorge Syndrome

ABSTRACT: Spleen cells from newborn rats with bisdiamine-induced congenital malformation were examined for subpopulation of lymphocytes and responsiveness of the lymphocytes to phytohemagglutinin (PHA), concanavalin A (ConA) and lipopolysaccharide (LPS). T cells, but not B cells, were significantly diminished in the drug-treated newborn rats. Proliferative response of the lymphocytes to PHA and ConA, but not to LPS, was significantly depressed in the drug-treated newborns. Thus a defect in cell-mediated immunity was suggested to be associated with the congenital anomaly.
It is tempting to consider that this bisdiamine-induced malformation can be another animal model for the DiGeorge syndrome.     

Atrioventricular Septal Defect in Rat Fetuses Induced by Administration of Bisdiamine

ABSTRACT A high incidence of atrioventricular septal defect was induced in rat fetuses by administration of N, N -his (dichloroacetyl)-1, 8-octamethylenediamine, bisdiamine, to pregnant Donryu rats. Induction of atrioventricular septal defect was highly dependent on day of bisdiamine administration. When bisdiamine was administered singly on day 9.4 of gestation or consecutively on days 9 and 10 of gestation, the incidence of atrioventricular septal defect in fetuses increased. Survival rate decreased with increase in the amount of bisdiamine administered. Normalized incidence ⁵ for atrioventricular septal defect, which was calculated as a product of incidence and survival rate, was as high as 54.5% when 175 mg bisdiamine was administered on day 9.4 of gestation. Atrioventricular septal defect thus formed was of the complete type associated with either persistent truncus arteriosus or tetralogy of Fallot, indicating that the conotruncal portion was unexceptionally malformed. The present model is useful for analysis of development and pathogenesis of atrioventricular septal defect and also contributes to clarifying the normal development of atrioventricular valves and septa.     

Pathogenesis of Congenital Diaphragmatic Hernia Induced by Transplacental Infusion of Bisdiamine into Rats

Abstract: We studied the pathogenesis of congenital posterolateral diaphragmatic hernia induced by bisdiamine in rats. The frequency of live fetuses with left congenital diaphragmatic hemia (which resembles a hernia through the foramen of Bochdalek in man) was high (78.4%) when pregnant rats were administered bisdiamine by gavage once at a dose of 400 mg/kg on day 9 of pregnancy. Then the bisdiamine-treated rat fetuses were examined at successive developmental stages. Histopathological observation revealed that l) in the control fetus on day 14 of pregnancy, the mesothelial cells lining the pleural aspect of the pleuroperitoneal fold were eventually clustered close to the pleuroperitoneal opening, giving the appearance of a high wave lapping the shore; 2) in the affected fetus on day 14 of pregnancy, the mesothelial cells of the pleural aspect of the fold were scarce; 3) in the affected fetuses during days 14–16 of pregnancy, primary lung hypoplasia was seen. On day 19 of pregnancy, no remarkable differences in the gross appearance of the right lung were found between the affected and control fetuses. Each lung (right and left) of the affected embryos may be considered to have the potential for further growth and development. The development of the mesothelium of the pleura may be greatly influenced by the growth and enlargement of the thorax (mainly the lung), and a retardation of lung growth near the time of pleuroperitoneal canal closure may induce the hernia in diaphragm.