Studies on the Effects of Betamethasone, L-Carnitine, and Betamethasone-L-Carnitine Combinations on the Dipalmitoyl Phosphatidylcholine Content and Phosphatidylcholine Species Composition in Foetal Rat Lungs

Abstract

Summary: Administration of L-caniitine or betamethasone to pregnant rats failed to increase either the total phospholipid or dipalmitoylphosphatidylcholine (DPPC) contents in foetal rat lungs on the 20th day of j gestation, eompared to cpntrols. The combined administration of betamethasone (0.3 mg/kg) and L-carnitine ; (80 mg/kg) resulted in a pronounced increase of dipalmitoylphosphatidylcholine (7.8 ±2.5 mg/g dry weight) j coinpared with the control group (5.4 ± 1.8 mg/g dry weight), and compared with the groups receiving betamethasone (5.9 ±1.9 mg/g dry weight) or L-carnitine (5.6 + 1.5 mg/g dry weight) alone. The proportion of dipalmitoylphosphatidylcholine in the phosphatidylcholine species increased from 20.9 ±2.1% in the foetal lungs of the control group to 22.6 ± 5.0% in the L-carnitine group, to 24.3 + 3.3% (p < 0.01) in the betämethasone-i-carnitine (20 mg/kg) group, to 25.2 ± 3.5% (p < 0.01) in the betamethasone group, to 27.1 + 2.6% (p < 0.01) in the betamethasone-L-carnitine (40 mg/kg) group, and to 28.4 ± 3.7% (p < 0.01) in the betamethasone-L^carnitine (80 mg/kg) group, while the palmitic acid portion in the phosphatidylcholine fatty acids was nearly unchanged. A pronounced increase of palmitoyl-myristoyl phosphatidylcholine (PC-30), the second disaturated phosphatidylcholine species present in lungs in significant amounts beside dipalmitoylphosphatidylcholine, was noted only in betamethasone treated animals. Furthermore, after betamethasone and betamethasone^carnitine treatment, a significant diminution (p < 0.01) of the proportion of palmitoyl-palmitoleyl phosphatidylcholine (16 : 0/16 : l-PC) in the phosphatidylcholine species was demonstrated. After L-carnitine and betamethasone-L-carnitine treatment a significant increase (p < 0.01) of the Proportion of palmitoleyl-palmitoyl phosphatidylcholine (16 :1/16 : 0-PC) in the phosphatidylcholine species was found. Administration of L-carnitine to pregnant rats (either alone or in combination with betamethasone) resulted in a significant elevation (p < 0.01) of the carnitine levels in the foetal lungs to approximately twice those of the controls. The results suggest that a betamethasone-L-carnitine combination has both additive effects and effects specific for the combination, neither of which are found when carnitine or betamethasone is administered alone.

Studies on the Effects of L-Thyroxine, L-Carnitine and an L-Thyroxine-L-Carnitine Combination on Dipalmitoyl Phosphatidylcholine Content and on Phosphatidylcholine Species Composition in Fetal Rat Lungs

“…Obviously there are specific effects of a carnitine-thyroxine combination compared with the effects of carnitine or thyroxine treatment. In a former study we showed that carnitine potentiated the effects of betamethasone on DPPC content of fetal rat lungs (7). Therefore, treatment with a carnitine combination may be of more benefit decreasing the incidence of respiratory distress syndrome than the administration of thyroxine (or betamethasone) alone.…”

“…P C 32 monoenic species. The PC 32 monoenic species can be characterized as palmitoyl-palmitoley1 PC ( 16:0/ 16: 1 PC) and palmitoleyl-palmitoy1 PC (16: 1/16:0 PC) (6). The portion of palmitoyl-palmitoleyl PC in total PC decreased significantly (p < 0.01) after the combined administration of thyroxine and carnitine in comparison with the control value.…”

“…In addition, we found that maternal administration of a carnitine-betamethasone combination resulted in a significant increase in DPPC content of fetal rat lungs in comparison with untreated controls and with animals treated with carnitine or betamethasone alone (7).…”

“…We have shown that carnitine, like betamethasone, influenced the DPPC content in fetal rat lungs (6), likely via two dissimilar mechanisms. In addition, we found that maternal administration of a carnitine-betamethasone combination resulted in a significant increase in DPPC content of fetal rat lungs in comparison with untreated controls and with animals treated with carnitine or betamethasone alone (7).…”

Alternatives to the antenatal glucocorticoid treatment for the prevention of respiratory distress syndrome

“…phospholipids and also the formation of lecithin via methylation could be stimulated by carnitine. In animal experiments, LOHNIN-GER and coworkers were able to show that the combination of carnitine and betamethasone due to their different mechanisms, leads to a larger increase of phosphatidylcholin in the lung of the fetal rat than single dosages of the two substances [8]. Comparable results were found in the carnitine/thyroxin group.…”