Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/16/1998
Publication Date: N/A
Technical Abstract: Leptin has been implicated in the regulation of energy metabolism and growth. In humans, treatment with growth hormone will decrease adipose leptin expression, and serum leptin levels are elevated in growth hormone deficient patients. Successful generation of a 349bp product from porcine placental RNA using RT-PCR confirmed the expression of leptin in this tissue. This is the first known report of placental leptin mRNA expression in a livestock species. A porcine leptin riboprobe was developed and used in hybridization assays to quantify placental leptin mRNA levels and evaluate effects of recombinant porcine somatotropin (rpST) on placental leptin expression. Twenty-five gilts were unilaterally hysterectomized, ovariectomized to reduce uterine capacity, which exacerbates the positive effects of rpST on fetal and placental development. These gilts were inseminated at first estrus and assigned to three treatment groups: control l(n=10, daily injections of 1ml saline d0-64 of gestation), early (n=5, daily injections of 5mg rpST d0-30), and late (n=10, daily injections of 5mg rpST d30-64). Placental samples were collected on d65. Leptin and IGF-1 mRNA expression in these samples were quantified by densitometry and normalized to 28S rRNA expression. Early treatment with rpST elevated IGF-1 mRNA expression relative to control and late placental samples. Although no differences in leptin mRNA levels were seen across treatment groups, a positive correlation between IGF-1 and leptin expression was observed across treatments. In summary, treatment with rpST does not appear to directly regulate placental leptin mRNA levels, but the association between IGF-1 and leptin expression may indicate an indirect means by which leptin transcription is regulated in the placenta.