This step is subject to both acute, and chronic,, stimulation, and trophic hormones regulate this step mainly at the level of gene transcription. Although limited information is also available to suggest that posttranscriptional and posttranslational events may be involved in the regulation of steroidogenesis, relatively little information is available on the biological factors that possibly mediate these events. Emerging evidence showing hormonal regulation of miRNAs in steroidogenic cells,, coupled with the identification of a diverse and large number of miRNAs, strongly suggest that miRNAs may be involved in the posttranscriptional/ posttranslational regulation of steroidogenesis. In this study, we first carried out a comprehensive analysis of miRNA profiling using control and in vivo hormone treated rat adrenals to identify miRNAs whose expression is altered in response to ACTH, 17aethinyl estradiol or dexamethosone treatment. Taking cues from the adrenal data, we also examined the effects of Bt2cAMP stimulation of rat ovarian granulosa cells 
and mouse testicular Leydig tumor cells, MLTC-1, on the expression of some of the relevant miRNAs. Chronic ACTH treatment in vivo significantly altered the Afatinib levels of many miRNAs in rat adrenal glands. In general, more miRNAs were Rapamycin upregulated than downregulated in response to ACTH treatment. Real-time PCR measurements demonstrated that ACTH treatment upregulated the expression of miRNA-212, miRNA-183, miRNA-182, miRNA-132 and miRNA-96, while down-regulating the expression of miRNA466b, miRNA-214, miRNA-503 and miRNA-27a. However, the levels of expression of these miRNAs differed considerably when measured by real-time-PCR as compared to their expression values detected by microarray analysis. This result is most likely due to the detection of both precursor and mature forms of miRNAs by microarray, and only the mature form by PCR. While our work was in progress, a microarray study reported the expression profile of mouse adrenal miRNAs under basal conditions and in response to acute treatment of mice with ACTH. In that study, 16 miRNAs were identified, whose levels of expression were maximally upregulated following 10 min treatment of mice with ACTH, whereas expression of one miRNA, mmumRNA-433, was down-regulated. Those miRNAs differentially expressed on the microarrays with greatest fold changes, miRNA-101a, miRNA-142-3p, miRNA-433 and miRNA-96, were further analyzed. Both microarray and qRTPCR data measurements indicated that the expression of these four miRNAs varied considerably with respect to ACTH treatment and time after treatment. Moreover, significant differences were also noted between microarray and qRT-PCR measurements. Interestingly, a comparison of our gene array list to the list presented in this publication indicates that none of the transcripts overlap. The reasons for this observed disparity are not clear, but may stem from many factors, including the use of two different types of rodent adrenals and two different ACTH treatment regimens. In addition to ACTH, we also performed a microarray analysis to screen the expression profiles of adrenal miRNAs from rats chronically treated with 17a-E2, a hypocholesterolemic and possible ACTH secretagogue. 17a-E2 treatment, like ACTH treatment, results in the induction of both adrenal LDL-R and SR-BI. To our knowledge, this is a first report describing the effects of 17a-E2 on the expression of adrenal miRNAs. Significant differences in expression of 163 miRNAs were observed between the adrenals from 17a-E2treated rats and control rats, with 63 miRNAs showing a change greater than 1.5-fold. The expression levels of miR-183, miR-96, and miR-182 were most highly up-regulated, whereas miR-122, miR-503, and miR-139-3p exhibited the greatest down-regulation as a result of 17a-E2 treatment.