Glucocorticoid-activation system mediated glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis programming alteration of adrenal dysfunction induced by prenatal caffeine exposure

Abstract

Glucocorticoids play a major factor in fetal maturation and fate decision after birth. We have previously demonstrated that prenatal caffeine exposure (PCE) resulted in adrenal dysplasia. However, its molecular mechanism has not been clarified. In the present study, a rat model of intrauterine growth retardation (IUGR) was established by PCE, and offspring were sacrificed. Moreover, NCI-H295 A cells were used to confirm glucocorticoid-related molecular mechanism. Results showed that PCE fetal weight decreased, and the IUGR rate increased, while serum corticosterone levels increased but insulin-like growth factor 1 (IGF1) levels decreased. Fetal adrenals exhibited an activated glucocorticoid-activation system, and the downregulated expression of IGF1 signal pathway and steroidal synthetases. For adult rats, there was no significant change in the glucocorticoid-activation system in the PCE group, the IGF1 signal pathway showed increased trend, and the expression levels of adrenal steroidal synthetases were close to normal. The data in vitro showed that the cortisol of 1200 nM can inhibit the expression of adrenocortical cell steroidal synthetases and IGF1 signal pathway when compared with the control. Meanwhile, the glucocorticoid-activation system was activated while GR inhibitor mifepristone can reverse the effect of cortisol. Furthermore, cortisol can also promote GR into the nucleus after its activation. Based on these findings, we speculated that high concentrations of glucocorticoid in utero led to GR in the nucleus through its activation and then inhibited the IGF1 signaling pathway by activating the glucocorticoid-activation system, which could further downregulate steroid synthesis.