Location: Reproduction Research
Title: Myelination is Decreased in the Brain Stem of Small Piglets Compared to Larger Littermates During Late Gestation Authors
Submitted to: Midwestern Section of the American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: December 8, 2009
Publication Date: July 1, 2010
Citation: Vallet, J.L., Miles, J.R. 2010. Myelination is Decreased in the Brain Stem of Small Piglets Compared to Larger Littermates During Late Gestation [abstract]. Journal of Animal Science. 88 (E-Supplement 3):119-120. (Abstract #249). Technical Abstract: Preweaning mortality is associated with low birth weights. Reduced myelination in the brain of low birth weight piglets has been reported, however, these studies measured brain cholesterol, which is not myelin. Thus, we compared myelination in brain regions associated with coordinated movement and reflexes during late gestation. Gilts were mated at estrus, and four gilts each were killed on days 92, 100, and 110 of gestation. Cerebellar, brain stem and spinal cord tissues were obtained from the largest and smallest fetus in each litter. Myelin basic protein (MBP) mRNA was quantified in each tissue using real time rtPCR. Myelin was recovered from each tissue by differential centrifugation, and was then subjected to SDS-PAGE and TLC to examine MBP and lipids, respectively. MBP mRNA increased with advancing gestation in all three tissues examined (P </= 0.05), and was decreased in brain stem of small piglets compared to large piglets (P < 0.01). Two major coomassie stained protein bands corresponding to myelin basic proteins (HMWMBP and LMWMBP, respectively, confirmed by immunoblotting) were observed by SDS-PAGE. Six prominent lipid bands were obtained by TLC. Protein and lipid bands were quantified using densitometry. The MBP and lipid bands obtained from brain stem increased with advancing day of gestation (P ranging from < 0.1 to < 0.0001) and were decreased in brain stems of small piglets compared to the large piglets (P ranging from < 0.1 to < 0.01). Significant day by fetal size interactions (P < 0.1 to P < 0.01) for MBP and lipid bands from cerebellum indicated that cerebellar myelination in the smallest fetuses was decreased compared to the largest fetuses on day 100 of gestation but recovered by day 110. Myelination in spinal cord increased with day of gestation (P < 0.05 to P < 0.0001 for MBP and lipids) and was not different between smallest and largest fetuses. These results confirm that myelination of brain regions, but not spinal cord, of small piglets is decreased compared to large littermates during late gestation with brain stem being most affected.