Distinct pharmacological mechanisms leading to c-fos gene expression in the fetal suprachiasmatic nucleus.

Maternal treatment with cocaine or a D1-dopamine receptor agonist induces c-fos gene expression in the fetal suprachiasmatic nuclei (SCN). Other treatments that induce c-fos expression in the fetal SCN include caffeine and nicotine. In the current article, the authors assessed whether these different pharmacological treatments activate c-fos expression by a common neurochemical mechanism. The results indicate the presence of at least two distinct pharmacological pathways to c-fos expression in the fetal rat SCN. Previous studies demonstrate that prenatal activation of dopamine receptors affects the developing circadian system. The present work shows that stimulant drugs influence the fetal brain through multiple transmitter systems and further suggests that there may be multiple pathways leading to entrainment of the fetal biological clock.