Transgenerational Effects of Synthetic Glucocorticoids on Offspring Behaviour and HPA Development in Guinea Pigs

Glucocorticoids are essential for fetal maturation. However, exposure to high levels of glucocorticoids (i.e. maternal stress/anxiety or synthetic glucocorticoid treatment [sGC]) alters the trajectory of development and increases the risk for chronic diseases later in life. Approximately 10% of pregnant women are at risk for delivering prematurely and receive treatment with sGC to reduce neonatal morbidity and mortality. Studies in children and animals demonstrated that single- and multiple-course sGC program alterations in hypothalamic-pituitary-adrenal (HPA) function and stress-associated behaviours in first generation (F1) offspring. Emerging studies in animals determined that sGC results in transmission of HPA and behavioural effects to the next generation (F2) of offspring, but no study has investigated transmission to the third generation (F3). We hypothesized that prenatal treatment with sGC results in maternal and paternal transmission of altered HPA activity and stress-related behaviours to three generations of guinea pig offspring. Prenatal treatment with either single- or multiple-course sGC resulted in transmission of effects to F2, but there were fewer effects with single-course treatment. Prenatal treatment with multiple-course sGC resulted in maternal transmission to F3. The strongest effects of sGC occurred in juvenile females from the paternal line; increased HPA response to stress, hyperactivity, impaired attention. Molecular analyses in the brains of these animals revealed that sGC programs large changes in gene expression that dissipate across generations. DAVID pathway analysis identified significant changes in the expression of genes associated with the HPA and behavioural phenotypes. This is the first study to demonstrate transgenerational programming to F3 of HPA activity and behaviours resulting from prenatal sGC transmitted. Paternal transmission to F3 strongly implicates epigenetic mechanisms. Transgenerational programming by sGC is a hallmark of in utero sGC exposure irrespective of current or past dosing regimens. These studies highlight the importance of developing new treatment approaches that maximize therapeutic efficacy while minimizing long-term adverse outcomes.Ph.D.2019-11-03 00:00:0

P-gp function in GD50 BECs is unresponsive to pro-inflammatory cytokines.

<p>P-glycoprotein (P-gp) activity in brain endothelial cell (BEC) cultures derived from gestational day (GD) 50 male guinea pigs following treatment with 10⁰–10⁴ pg/mL A–C) interleukin-1β (IL-1β), D–F) interleukin-6 (IL-6) or G–I) tumor necrosis factor-α (TNF-α) for 1, 4 or 24 hours (N = 4). P-gp activity is displayed as percent change from untreated control cells (zero line). Values displayed as mean ± S.E.M.</p

Baseline P-gp Activity in BECs increases with developmental age.

<p>P-glycoprotein (P-gp) activity in brain endothelial cell (BEC) cultures derived from gestational day (GD) 40, 50, 65 and postnatal day (PND) 14 male guinea pigs (N = 4). P-gp activity is displayed as percent change from GD40 BECs (zero line). P-gp function was calculated over relative cell count. Values displayed as mean ± S.E.M. A significant difference from GD40 indicated by (*) P<0.05; (***) P<0.001.</p

Pro-inflammatory cytokines inhibit <i>abcb1</i> mRNA expression.

<p><i>Abcb1</i> mRNA expression in brain endothelial cell (BEC) cultures derived from postnatal day (PND) 14 male guinea pigs following treatment with 10³ and 3.3×10³ pg/mL A–B) interleukin-1β (IL-1β), C–D) interleukin-6 (IL-6) or E–F) tumor necrosis factor-α (TNF-α) for 4 (A,C,E) or 24 hours (B,D,F) (N = 7–8). Expression is displayed as percent of untreated control cell expression (i.e. 100% line) and taken over the reference gene, <i>beta-actin</i>. Values displayed as mean ± S.E.M. A significant difference from control indicated by (**) P<0.01; (***) P<0.001.</p

Pro-inflammatory cytokines inhibit P-gp function in GD65 BECs in a dose-dependent manner.

<p>P-glycoprotein (P-gp) activity in brain endothelial cell (BEC) cultures derived from gestational day (GD) 65 male guinea pigs following treatment with 10⁰–10⁴ pg/mL A–C) interleukin-1β (IL-1β), D–F) interleukin-6 (IL-6) or G–I) tumor necrosis factor-α (TNF-α) for 1, 4 or 24 hours (N = 4). P-gp activity is displayed as percent change from untreated control cells (zero line). Values displayed as mean ± S.E.M. A significant difference from control indicated by (*) P<0.05; (**) P<0.01.</p

The inhibitory effects of pro-inflammatory cytokines on P-gp function are greatest in PND14 BECs.

<p>P-glycoprotein (P-gp) activity in brain endothelial cell (BEC) cultures derived from postnatal day (PND) 14 male guinea pigs following treatment with 10⁰–10⁴ pg/mL A–C) interleukin-1β (IL-1β), D–F) interleukin-6 (IL-6) or G–I) tumor necrosis factor-α (TNF-α) for 1, 4 or 24 hours (N = 8). P-gp activity is displayed as percent change from untreated control cells (zero line). Values displayed as mean ± S.E.M. A significant difference from control indicated by (*) P<0.05; (**) P<0.01.</p