Poster Session 2 - R10
1Margaret E. Eng, 1Alice Kostaki, 1,2Stephen G. Matthews
1 Dept. of Physiology, University of Toronto; 2 Obstetrics & Gynecology
OBJECTIVE: Glucocorticoids are key in the transition from fetal to neonatal life and may play a role in the maturation of blood-tissue barriers. Antenatal synthetic glucocorticoids (sGC) are administered in the management of preterm birth; however, a proportion of women deliver at term, potentially exposing the fetus to excess glucocorticoids. Recent work in our lab has shown that antenatal sGC exposure programs neural gene expression in juvenile offspring, and that these effects are transmitted over multiple generations. Tight junctions between sertoli cells make up the blood-testis barrier (BTB), providing immunological protection and are part of the spermatogenic process. Uptake of hormones, drugs, and toxins is also limited by the BTB, through the actions of drug transporters such as P-glycoprotein (P-gp; Abcb1) and breast cancer resistance protein (BCRP; Abcg2). Altered BTB function after sGC exposure that persists into post-natal life could have consequences for drug exposure and spermatogenesis. We hypothesize that antenatal sGC treatment will alter the expression of genes related to tight junction function, xenobiotic response, and drug transport at the fetal BTB, and this effect will persist to the juvenile BTB.
METHODS: Guinea pigs were chosen for this study as they have a longer gestation, and a similar pattern of neurodevelopment. Starting at GD40, pregnant dams were exposed to 3 courses of betamethasone (N=9) or vehicle (N=5), 10 days apart. Offspring were euthanized at PND14, and testes were removed, snap frozen on dry ice, and stored at -80˚C until RNA extraction. Levels of drug transporter and tight junction mRNA and protein were measured by qRT-PCR, and Western Blot respectively.
RESULTS: At PND14, sGC treatment significantly decreased Cldn5 and Jam-A expression (p<0.05). sGCs did not affect gene expression of drug transporters Abcb1, Abcg2, or Abcc4 at PND14, or protein expression of P-gp and BCRP.
CONCLUSION: This is the first study to demonstrate that antenatal sGC programs gene expression in the testes of juvenile offspring. Genes that were significantly decreased at PND14, 25 days after last exposure to sGCs, are related to maintaining tight junction function (Cldn5, Jam-A). There were no changes in expression of drug transporter genes or xenobiotic response. As the BTB plays an essential role in spermatogenesis, these findings may provide insight into the mechanisms underlying transmission of the effects of antenatal sGC. Long-term alterations in baseline barrier function in the testes may also have implications for drug protection and efficacy.