Transcriptome Analysis Reveals the Endocrine Regulation on the Expression of IAG in Litopenaeus vannamei

The insulin-like androgenic gland hormone (IAG) plays a key role in male sexual differentiation and spermatogenesis in crustaceans. The expression of IAG is usually negatively regulated by neuropeptide hormones through the “eyestalk-AG” endocrine axis. However, the underlying mechanism is still largely unknown. In the present study, we performed a comparative transcriptome analysis on the androgenic gland (AG), the main secretory organ of IAG, of L. vannamei before and after unilateral eyestalk ablation. A total of 67 differentially expressed genes (DEGs) were identified, including some putative genes involved in sexual development. Interestingly, several genes related to molting and endocrine processes were found differentially expressed between the two treatments. Further investigation on the expression profiles of these genes and Lv-IAG showed that their expression patterns were closely correlated throughout the molting cycle. In addition, injection of 20-hydroxyecdysone (20E) could inhibit the expression of Lv-IAG at different molting stages in a dosage-dependent manner. The data indicated that ecdysteroids played important roles in regulating the Lv-IAG expression and might bridge the endocrine axis between eyestalk and AG. The present study provided new insights into understanding the regulation of sexual development in male crustacean.