GLUT1 and lactose synthetase are critical genes for lactose synthesis in lactating sows

Abstract

BackgroundLactose synthesis rate is an important factor in milk production and quality in mammals. Understanding the lactose synthesis mechanism is crucial for the improvement of milk quantity and quality. However, research on the temporal gene changes regarding lactose synthesis during the whole lactation is still limited. The objective of this study was to determine gene expression profiles related to lactose synthesis in sows during lactation, and further identify the critical steps or key factors in the lactose synthesis pathway.MethodsTo determine the temporal change of factors related to lactose synthesis in sows, milk from eight multiparous Yorkshire sows (parity 3 to 6) was collected at 0 h, 2 h, 6 h, 12 h, 24 h, day 2, 3, 4, 7, 14, and 21 after birth of the first piglet. Lactose content, prolactin and progesterone concentration, and gene or protein expression related to lactose synthesis were measured.ResultsThe lactose yield increased gradually from D2 to D21 and reached a maximum at D14 (3-fold from D2) during lactation (P < 0.05). A similar trend was observed in IGF-1 and insulin concentrations in milk, both of which were greatest at D3 with a subsequent decrease during middle to late lactation. Conversely, milk prolactin and progesterone concentrations moderately decreased with the progression of lactation. The mRNA or protein expressions related to glucose transportation (GLUT1), glucose-galactose interconversion (HK1 and UGP2), UDP-galactose transportation (SLC35A2), and lactose synthetase (LALBA and B4GALT1) in the lactose synthesis pathway were significantly upregulated during early to middle lactation and plateaued by late lactation (P < 0.05).ConclusionsThese novel findings suggest that the increased lactose synthesis in lactation was related to the coordinated upregulation of genes or enzymes in the lactose synthesis pathway, and glucose transportation (GLUT1) and lactose synthetase (LALBA and B4GALT1) might be the critical steps in the lactose synthesis pathway of sows during lactation.

Polyherbal formula (ASILACT®) induces Milk production in lactating rats through Upregulation of α-Lactalbumin and aquaporin expression

“…Pup weight in the PHF groups increased in a dosedependent manner; however, no significant difference from the control was observed. This finding was consistent with a previous study, which suggested that pup weight gain was not consistent with increased milk production [17].…”

“…Combined with b-1,4-galactosyltransferase (B4GALTI), LALBA forms lactose synthase to convert glucose and galactose into lactose [7]. Lactose synthetase (LALBA and B4GALT1) and glucose transport (GLUT1) contribute to increased lactose synthesis in sows [17]. α-Lactalbumin and the activity of lactose synthase are enhanced by prolactin mediated by STAT5a [18,19].…”

Recent progress of porcine milk components and mammary gland function

“…B4GALT1 encodes type II membrane-bound glycoprotein, specifically β-1, 4-galactosyltransferase 1, lactose synthetase, which can transfer galactose to acceptor sugars [ 68 ]. Coincidently, Zhang et al [ 69 ] also found the mRNA and protein expression profiles of B4GALT1 increased significantly during the entirety of lactation in sows Furthermore, the increased mRNA and protein expression of LALBA was also observed in their research. α-lactalbumin, one of milk whey proteins, can facilitate the glucose identification and banding of B4GALT1, and improve the B4GALT1 activity by at least 30-fold [ 70 – 73 ].…”

Milk production and quality of Etawa crossbreed dairy goat that given Tithonia diversifolia, corn waste and concentrate based palm kernel cake

“…According to Sunehag et al (2002) and Rigout et al (2002), in the study of Y. Zhang et al (2018) stated that as the main substrate for lactose synthesis, glucose contributes around 80% of carbon in lactose in humans and 85% in cattle.…”