Download Protein Expression of L-Type Amino Acid Transporter-2 (LAT

136
Proc. 9th CU. Vet. Sci. Ann. Con., 2010.
Protein Expression of L-Type Amino Acid Transporter-2 (LAT-2) in Porcine
Mammary Tissue; Physiological Regulation at Early and Peak Lactation
B. Thongsong1*, S. Kalandakanond-Thongsong2, A. Rungsipipat3
1Department of Animal Husbandry, 2Department of Veterinary Physiology, 3Department of
Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330.
*Corresponding author: [email protected]
Keywords: LAT-2, lactation, protein expression, sow mammary
Introduction
The
physiological
regulation
during
lactation provides evidence that the mass of
mammary parenchymal tissues continue to
increase and grow by elongation and branching
of ducts into the mammary fat pad. Neilsen et al.
(2002) studied the effect of day of lactation on
amino acid uptake by porcine mammary glands
and found that milk production increased
quadratically as day of lactation increased and
reached maximum between day 15 and 21 of
lactation. Amino acid transporter is now
recognized as an important mechanism of amino
acid appearance in sow’s milk to support growth
performance of piglets. The L-type amino acid
transporter
(LAT)
principally
transports
branched-chain amino acids taken up in excess of
their appearance in milk. Thus, the L-type amino
acid transporter-2 (LAT-2) in mammary tissues
may be regulated by lactating period. However,
the regulatory mechanism of this protein
expression has not been yet studied in porcine
mammary tissues.
The objective of this study was to determine
the physiological regulation in the early (day 9th)
and the peak (day 19th) stage of lactation on the
localization and the protein expression of LAT-2
in lactating porcine mammary cells.
Material and Methods
Six mammary tissues were obtained from
multiparous crossbred sows allocated into 2
groups; in the early (day 9th) and the peak (day
19th) lactation. Some parameters were shown:
-protein expression and localization of LAT-2
protein in the sow mammary cells with LAT-2
antibody by immunohistochemistry.
-relative protein abundance of LAT-2 in sow
mammary cells by the western blot technique.
Statistical analysis; Differences between
groups were analyzed by Unpair t-test and
results were considered statistically significant at
p<0.05.
Results and Discussion:
Day 9th of
Day 19th of
lactating sow mammary cells
Figure 1. Protein expression and localization
of LAT-2 in sow mammary cells at early lactation
compared to those at peak lactation by Avidinbiotin peroxidase complex (ABC).
The positive immunohistochemical staining
with LAT-2 antibody showed mild to moderate
brown cytoplasmic staining especially in apical
surface of the membrane of mammary cells.
Day 9th of lactation
Day 19th of lactation
Marker
LAT-2
48 kD
β-actin
37 kD
Figure 2. Relative protein abundance of LAT-2 in
sow mammary cells at early lactation
compared to those at peak lactation by the
western blot technique.
The result shows that the lactating sows
showed protein expression of LAT-2 during
lactation. However, there was no significant
difference (p>0.05) when compared between at
the early (day 9th) and at the peak (day 19th)
lactation.
We are the first report found that the
lactating sow mammary tissues expressed LAT-2
protein at the apical part. The lack of knowledge
regarding porcine amino acid transport
physiology may be limiting the ability to
formulate the diets and to design feeding
strategies
that
optimize
amino/protein
requirement.
Acknowledgement:
This work was supported by research grants from the
Faculty of Veterinary Science (RG 7/2552), Chulalongkorn
University.
Reference
Nielsen et al. 2002. J. Anim. Sci. 80: 2401-2411