Retinol binding protein 4 in dairy cows: its presence in colostrum and alteration in plasma during fasting, inflammation, and the peripartum period

Abstract

Retinol-binding protein 4 (RBP4) is a plasma protein involved in retinol transportation, and recent evidence in rodents suggests that RBP4 is also a metabolic regulator that modifies insulin sensitivity. To assess how RBP4 levels are regulated in ruminants, we determined the RBP4 concentrations in bovine plasma and milk using Western blot analysis. Plasma RBP4 levels in non-pregnant non-lactating (control) cows were around 45 mg/ml, which were sustained during 60-h fasting, but decreased significantly 4 h after lipopolysaccharide (LPS) administration. Basal plasma retinol concentration was around 30 mg/dl, but this decreased to approximately one-third and one-half of these values during fasting and 8 h after LPS challenge, respectively. Plasma RBP4 and retinol levels in cows 3-6 d before parturition were comparable to those of the controls. However, on the day of parturition both were significantly decreased and had returned to basal levels by two weeks after calving. Interestingly, RBP4 was clearly detected in colostrum (16 . 4±5 . 6 mg/ml) but was only faintly detected in milk from cows at 7 d and 15 d after calving. Retinol concentrations in colostrum were almost 10-fold higher than those in plasma, while those in milk were comparable to those in plasma. These results suggest that RBP4 and retinol levels are independently regulated under physiological and pathophysiological conditions and that RBP4, like retinol, is transferred from maternal stores to calves through colostrum.

Prepartal dietary energy alters transcriptional adaptations of the liver and subcutaneous adipose tissue of dairy cows during the transition period

“…We did not find any time-or treatment-related differences in the mRNA expression of RBP4 during the course of the study. Recent studies by Abd Eldaim et al (1) and Rezamand et al (39) report fluctuation in the plasma RBP4 concentration during the transition period, with a sharp decline immediately after parturition and rebound toward prepartum levels in early lactation. Our findings are in contrast to the findings of Rezamand et al (39), who observed that physiological state affected hepatic RBP4 expression during the periparturient period.…”

Immunometabolic Status during the Peripartum Period Is Enhanced with Supplemental Zn, Mn, and Cu from Amino Acid Complexes and Co from Co Glucoheptonate

“…Retinol concentration typically decreases around parturition due in part to the transfer of retinol and its derivatives into colostrum [ 37 ] and also because of the inflammation during this period [ 38 ]. Retinol is stored in the liver, and its transport to target tissues depends on retinol binding protein 4 ( RBP4 ) [ 39 ]. As RBP4 is Zn-dependent [ 40 ] the decrease in plasma retinol during the transition period may be partly associated with a direct (diet) or indirect (immune response) [ 41 ] Zn deficiency.…”

Effect of prepartal ad libitum feeding of grass silage on transcriptional adaptations of the liver and subcutaneous adipose tissue in dairy cows during the periparturient period

“…Abd Eldaim et al (2010) also reported that plasma RBP4 decreased immediately after parturition and returned to prepartum levels by 2 wk postpartum. The decline in plasma RBP4 can be attributed to its flux toward the mammary gland immediately after calving, although several factors, including inflammatory reactions and protein intake, may affect RBP4 synthesis.…”