Bile Acid Composition in Neonatal Life in Rats

Abstract

Bile acid (BA) metabolism was studied in the intestine, liver and plasma of rats at 0–1 day (neonates); 14 days (preweaning); 22 days (weaning) and 60 days (young adults) of age, as well as in the maternal tissues. In the intestine, total BA content (μmol/l00g body weight) decreased during neonatal life and reached maternal levels at 60 days. In the liver, BA increased up to 14 days and then decreased at 22 and 60 days of age, but these concentrations were higher than those found in the neonate and the mother. The serum concentrations in 14-and 22-day-old rats were more than 30 times higher than in the newborns. At 60 days, serum BA content was still twice that of the mother. BA composition in the intestine and the liver showed a reduction in 12α-hydroxylated BA associated with an increase in chenodeoxycholic acid and 6β-hydroxylated BA during neonatal life. These data indicate an increased synthesis of chenodeoxycholic and 6β-hydroxylated BA after birth. It further suggests a possible defect in excretory mechanisms in neonatal life.

Asynchronous expression and colocalization of Bsep and Mrp2 during development of rat liver

“…Then, the size of the pool of bile salts continues to increase, although the rate of increase slows and concentration of bile salts at birth is yet to reach the levels of adulthood (27). After birth, secretion and reabsorption of bile salts in suckling rats continue to be reduced compared with adult animals (43,52). The clear correlation between the Bsep gene expression and the time of birth when hepatocytes reveal all structural features of fully differentiated cells suggests that the molecular basis for Bsep function is already formed by this time.…”

“…The staining was strongest and most readily detectable in the liver of newborn rats and especially 1-wk-old pups. These observations are likely reflecting the different amount of proteins at their final, canalicular localization and/or the need for them to be supplied continuously and to ensure the functional maturation of the canaliculi, because it is known that processes of secretion and reabsorption of bile salts in suckling rats are still functionally incomplete (43,52). They also imply that subapical compartment, an important crossing of incoming and outgoing messages in the hepatocyte, may be involved in the process of delivery of canalicular transporters.…”

Distinct forms of cytochrome P-450 are responsible for 6β-hydroxylation of bile acids and of neutral steroids

“…In fact, a complex hormonal regulatory system present in the rat blocks the expression of androstenedione 6/J-hydroxylase in adult females [21,34,47,48]. In contrast, bile acid 6,?hydroxylation is probably functional in both sexes throughout life [49], and may be especially important in the perinatal period. During this period of development, the hydrophobic-hydrophilic balance of bile acids is shifted towards a relative deficiency of trihydroxylated bile acids [50].…”

Variations in Free Amino Acids in Tissues of Rats from Birth to Puberty

“…Alanine depletion occurs both in kidney and liver, at a time when alanine aminotransferase activity in these tissues reaches adult values [6]. On the other hand, the induction of biliary acid syn thesis at midlactation [26], although the bile salt synthesis and secretion is low in compar ison with adults [27], may explain the fall in concentration of taurine and glycine in the liver. Furthermore, since the solid diet did not contain taurine, the fall in concentration of this amino acid in kidney and skeletal muscle may have resulted from the high de mands of the liver, but without raising the low concentrations of taurine in the plasma [14].…”