Text

theses

Nursing supports neonatal porcine reproductive tract development by delivering milk-borne bioactive factors (MbFs) from mother to offspring as proposed in the lactocrine hypothesis. In pigs, studies showed that age and nursing support postnatal uterine and testicular development between birth [postnatal day (PND) 0] and PND 2 via a lactocrine mechanism and define the developmental program. However, age-sensitive events associated with development of the neonatal porcine uterine transcriptome have not been defined during this period. Additionally, the extent to which nursing affects the development of the porcine cervix is unknown. Furthermore, the extent to which MbFs, particularly insulin-like growth factor-1 (IGF1), affect development of the porcine cervix remains to be determined. Research aims were to (1) define the age-sensitive uterine transcriptome in gilts at birth compared to animals at PND 2; (2) determine the effects of age and nursing on porcine cervical histoarchitecture and cell proliferation; and (3) determine whether a single feeding of colostrum or milk replacer at birth, with or without oral IGF1 supplementation, supports cervical cell proliferation and development using a new 12 h neonatal pig bioassay. Results showed that in uteri of PND 2 as compared to PND 0 gilts, 3283 genes were differentially expressed and multiple age-sensitive biological processes and pathways, including ‘immune response’ and ‘Wnt-β-catenin signaling’, were affected. Additionally, results indicated that both age and nursing supported cervical development histologically by PND 14 and cell proliferation by PND 2 and 14. Furthermore, oral IGF1 increased cervical cell proliferation when administered in milk replacer, but not with colostrum. However, IGF1 supplementation in either colostrum or milk replacer increased cervical IGF1 signaling cascade markers B-cell lymphoma 2 and phospho-AKT compared to gilts fed colostrum or milk replacer alone. In conclusion, the global changes in uterine gene expression identified here within the first 48 h after birth provide a foundation for future studies to better understand the mechanisms and pathways governing FRT development. Collectively, results presented here reinforce and extend previous findings that both age and lactocrine signaling are effectors of organizationally critical structural changes in developing female reproductive tissues with potential to determine reproductive capacity in adulthood.

ETD_6012

Ph.D.

Includes bibliographical references

by Meredith E. Camp

doi:10.7282/T35B046F

ETD doctoral

The author owns the copyright to this work.