To determine if Aza may have delayed puberty by affecting hormonal systems other than that controlling the hypothalamic-pituitary-ovarian axis, we measured serum prolactin (PRL), because PRL is produced independently from LH, delays puberty when secreted at subnormal levels, and disrupt estrus cyclicity when produced in excess 2. We found that serum PRL levels were identical in diluent and Aza-treated rats(C=1.9 ± 0.4 ng ml−1, n=8 vs Aza=1.8 ± 0.3 ng ml−1, n=7; t=0.433, p=0.67, Student t Test). To examine still another endocrine system, we measured serum corticosterone, an adrenal steroid known to delay the onset of puberty in rats when secreted in excess in response to stress 2. Instead of being elevated, corticosterone levels were reduced in 5-Aza treated rats (C=232.8 ± 49.5 ng ml−1, n=7 vs Aza=47.1 ± 11.8 ng ml−1, n=7; t=9.66, p<0.001, Student t Test), possibly due to a diminished ovarian estradiol output 27. Thus, the delay of puberty caused by Aza treatment is not due to either deregulation of PRL secretion or corticosterone hypersecretion. Altogether, these results suggest that inhibition of DNA methylation delays puberty by
