Analysis of lung surfactant in the metamorphosing bullfrog (Rana catesbeiana)

Abstract

In bullfrog (Rana catesbeiana) tadpoles, the lung begins to function at an advanced stage of metamorphosis. As a preliminary step for investigation of the mechanisms involved in lung maturation, pulmonary surfactant was prepared from tadpoles at advanced stages of metamorphosis and its biochemical properties were analyzed. Surfactant phospholipid analysis revealed that the major constituent was phosphatidylcholine (PC), as examined in the animals at late climax (stage 24). Other detectable phospholipids were phosphatidylethanolamine, phosphatidylserine, sphingomyelin, and phosphatidylglycerol, a marker lipid in mammalian surfactant. As in mammals, PC in the surfactant was rich in saturated fatty acids, about 50% of fatty acid moieties being palmitic acid. The content of surfactant PC in the lung increased moderately around mid-climax and markedly at the end of climax. The effect of antiserum against bullfrog prolactin (PRL) on the pulmonary surfactant was studied in climactic tadpoles. The content of surfactant PC in the lung of the antiserum-treated larvae was lower than that in the lung of the normal rabbit serum-injected larvae, whereas the content of PC in the whole lung did not differ between the antiserum-treated and control groups. The results suggest that synthesis of surfactant in the amphibian lung is enhanced as metamorphosis progresses and that PRL is involved in lung maturation.

Administration of unmodified prolactin (U-PRL) and a molecular mimic of phosphorylated prolactin (PP-PRL) during rat pregnancy provides evidence that the U-PRL:PP-PRL ratio is crucial to the normal development of pup tissues

“…Thus, in human premature infants, cord blood PRL concentrations (Haugh et al 1978) and amniotic fluid PRL (Gluckman et al 1978) can be correlated with fetal lung maturation and augmented surfactant formation. In fetal rabbits, fetal intramuscular injection of PRL increased surfactant production in utero (Hamosh & Hamosh 1977), and in bullfrogs anti-PRL antisera decreased surfactant production during metamorphosis (Oguchi et al 1994). The loss of epithelial integrity seen in the lungs of PP-PRL-exposed pups would certainly be consistent with decreased or absent surfactant production.…”

“…Effects of PP-PRL on maternal behavior are currently under investigation through appropriate collaboration. A role for PRL in lung development has been discussed for some time (Hamosh & Hamosh 1977, Gluckman et al 1978, Hauth et al 1978, Oguchi et al 1994. Most of the work has considered the possibility that PRL promotes the production of surfactant.…”

Characteristic analysis of prolactin and its receptor genes fromRana chensinensis and expression pattern during metamorphosis

“…There have been few attempts to research the roles of PRL and PRLR in various organs during the metamorphosis of amphibians. Studies have shown that PRL plays roles in the regulation of hydromineral balance and maintenance of lung function (Takada, 1989;Oguchi et al, 1994). Epithelial sodium channel activity is regulated by PRL in A6 cells, and PRL has the ability to both stimulate and inhibit vascular function in vertebrates, including amphibians (Greenlee et al, 2014).…”

Cloning of a cDNA for Xenopus prolactin receptor and its metamorphic expression profile

“…In addition, a high level of mRNA expression was observed in the skin and lung. In Rana catesbeiana , PRL is involved in development of the Na transport system in the skin ( Takada 1989) and lung maturation ( Oguchi et al 1994 ). These results support the idea that PRL plays roles in the regulation of hydromineral balance and maintenance of lung function in Xenopus .…”