Alteration of Reproductive Hormone Levels in Pregnant Sows Induced by Repeated ACTH Application and Its Possible Influence on Pre- and Post-natal Hormone Secretion of Piglets

Abstract

Abstract. Prenatal stress has been seen as a reason for reproductive failures in pig offspring mostly originated or mediated by changed maternal functions. Experiments were conducted in pregnant gilts (n=32) to characterize effects of elevated maternal glucocorticoids on the secretion of reproductive hormones (LH, progesterone) during the 1 st (EXP 1), 2 nd (EXP 2) and 3 rd (EXP 3) trimester of pregnancy (TP). Transiently elevated cortisol release was repeatedly achieved by application of 100 IU adenocorticotropic hormone (ACTH) (Synacthen Depot®) six times every second day beginning either on day 28 (EXP 1), day 49 (EXP 2) or day 75 of pregnancy (EXP 3). Glucocorticoid concentrations were examined in umbilical blood vessels of fetuses which mothers were subjected to ACTH at 2 nd and 3 rd TP (EXP 4). Furthermore, the pituitary function of newborn piglets of EXP 2 was checked by a LH-RH challenge test. In sows, LH concentrations were at low basal level (0.1-0.2 ng/ ml) but with pulsatory release pattern during each TP. The number of LH pulses/6 h (LSM ± SE) of saline treated Controls increased with ongoing pregnancy and decreased to the 3 rd TP (1.3 ± 0.2 in EXP 1 vs. 2.0 ± 0.1 in EXP 2 vs. 1.4 ± 0.1 in EXP 3, p<0.05). After ACTH treatment the number of LH pulses left unchanged in Experiments 1 and 2 (1.3 ± 0.2 and 1.5 ± 0.1) and decreased in EXP 3 (0.8 ± 0.2, p<0.05). Differences (p<0.05) were obtained comparing the LH pulse number of ACTH and saline treated sows at the 2 nd and 3 rd TP. Moreover, areas under the curve (AUC) of each LH pulse and of LH over baseline were significantly reduced by treatment. Levels of progesterone increased (p<0.05) for 150 to 170 min after each ACTH application both in EXP 1 and EXP 2, but not in EXP 3. The mean progesterone concentration was different between trimesters, and ACTH and Controls (1 st TP: 30.0 ± 0.9 and 24.4 ± 0.7 ng/ml; 2 nd TP: 35.5 ± 0.9 and 29.1 ± 1.0 ng/ml; 3 rd TP: 13.6 ± 0.2 and 13.1 ± 0.1 ng/ml; p<0.05). In fetuses (n=87) recovered 3 h after ACTH or saline (EXP 4), the plasma cortisol concentrations were significantly increased in umbilical vein (93.7 ± 5.5 vs. 47.0 ± 5.3 nmol/l) and artery (95.7 ± 5.4 vs. 66.4 ± 5.4 nmol/l), and in periphery (46.8 ± 5.3 vs. 27.1 ± 5.3 nmol/l) compared to controls. Plasma ACTH concentrations, however, did not differ in fetuses of both treatment groups. Postnatal LH-RH challenge tests (1 st and 28 th day post partum) induced LH surges in female piglets (n=67) both of ACTH and saline treated sows, but did not differ between groups (1 st day: 7.2 ± 0.8 vs. 8.1 ± 0.7 ng/ml; 28 th day: 10.5 ± 1.7 vs. 13.6 ± 2.2 ng/ml). However, basal LH of piglets whose mothers were submitted to ACTH during 2 nd TP was lower on 1 st day (1.7 ± 0.2 vs. 2.3 ± 0.2 ng/ml, p<0.05) but not on 28 th day (1.0 ± 0.2 vs. 1.1 ± 0.2 ng/ml). However in both groups, the basal LH was always higher on 1 st as on 28 th day (p<0.05). Thus, chronic intermittent ACTH administration is able to influence the release pattern of maternal reproductive hormones. However, ...

Growth and reproductive development of male piglets are more vulnerable to midgestation maternal stress than that of female piglets12

“…When the data from male and female piglets were combined for analysis, sow treatment had no effect on any litter or piglet characteristic. This is in accordance with previous research results showing that during midgestation neither the authentic stressors of rough handling (Lay et al, 2008) and mixing (Jarvis et al, 2006;Rutherford et al, 2009), nor the artificial stressors ACTH (Haussmann et al, 2000;Schneider et al, 2004;Brussow et al, 2005;Kanitz et al, 2006;Otten et al, 2007) and HCA (Kranendonk et al, 2006) affected gestation length (Haussmann et al, 2000;Jarvis et al, 2006;Kanitz et al, 2006;Kranendonk et al, 2006;Otten et al, 2007;Lay et al, 2008), litter size (Haussmann et al, 2000;Schneider et al, 2004;Brussow et al, 2005;Kanitz et al, 2006;Kranendonk et al, 2006;Otten et al, 2007;Lay et al, 2008;Rutherford et al, 2009), or number of stillborn pigs (Haussmann et al, 2000;Jarvis et al, 2006;Kranendonk et al, 2006;Otten et al, 2007;Lay et al, 2008).…”

“…At 0700 h on ED -1 (baseline), 1, 7, and 14 blood was collected from sows in the 3 treatment groups by jugular venipuncture into two 13 × 75 mm, 4.0 mL draw lithium heparin venous blood collection tubes (Becton Dickinson, Franklin Lake, NJ) for plasma cortisol and progesterone analyses. Increased progesterone concentrations have been observed in swine in response to exogenous GC (Schneider et al, 2004;Brussow et al, 2005) and feed restriction (Razdan et al, 2004) which may have androgenic, or conversely, anti-androgenic effects of developing offspring (CohenBendahan et al, 2005). On these days, HCA administration was delayed until after the collection.…”

Effect of Repeated Stress Treatments During the Follicular Phase and Early Pregnancy on Reproductive Performance of Gilts

“…2004a). At later stages of pregnancy, mimicked acute stress (ACTH‐injections at every 10 min during 6 h) did not interfered with pregnancy either; at day 28 of pregnancy the ACTH‐injections caused an increase in basal LH‐levels and a progesterone release and at later stages of pregnancy (day 49 or day 75), these ACTH‐injections furthermore decreased LH‐pulsatility (Brüssow et al. 2005), but these changes did not affect the progress of pregnancy.…”

Exogenous adrenocorticotropic hormone affects genome‐wide DNA methylation and transcriptome of corpus luteum in sows

“…These results indicate that the down-regulation of progesterone may be associated with the function of CL. It has been reported that ACTH or cortisol can inhibit the basal secretion of LH and the preovulatory LH surge by reducing GnRH release (38,39). The alteration of LH levels may influence progesterone secretion in CL.…”