Age‐dependent differential expression of genes involved in steroid signalling pathway in the brain of protandrous black porgy, Acanthopagrus schlegeli

Abstract

ABSTRACT:The mechanisms underlying brain sex differentiation in animals are poorly understood. In the present study, using black porgy, Acanthopagrus schlegeli, as primary experimental model, we investigated the temporal expression patterns of receptors for androgen (ar) and estrogen (esr1 and esr2a) in the brain during posthatching ages and analyzed them against the timing of gonadal germ cell development. We hypothesized that endogenous estrogens naturally masculinize the brain of black porgy. The expression of sex steroid receptors was studied in relation to a wider suite of other related genes (nr5a2, nr0b1, star, and cyp19a1b) to provide some insight into the monomale sex differentiation pattern observed in this species. Our results revealed a highly significant increase in esr1 together with the increase in esr2a at 120 dph (days posthatching), suggesting a significant role for esr in sex differentiation in this species. Temporal expression patterns of nr5a2, nr0b1, star, sex steroid receptors, and cyp19a1b in the brain provided evidence for their physiological roles in the monomale sex differentiation in this species. The expression of nr5a2, star, ar, esr1, esr2a, and cyp19a1b increased at 120 dph, a period when brain sex differentiation probably occurs in this species. The study also suggests that neurosteroidogenesis in black porgy may be regulated by both nr5a2-dependent and nr5a2-independent mechanisms. The results demonstrated striking differences in the abundance of the gene transcripts in discrete brain region throughout ontogeny. In addition, the sex steroid hormone levels and aromatase activity in brain at different developmental states and the changes in the gene expression patterns in response to aromatase inhibitor treatment are also discussed. ' 2009 Wiley Periodicals, Inc. Develop Neurobiol

Developmental expression of genes involved in neural estrogen biosynthesis and signaling in the brain of the orange-spotted grouper Epinephelus coioides during gonadal sex differentiation

“…This significant increase in the mRNA of StAR, considering its rate-limiting function and its role in the regulation of neurosteroidogenesis, also suggested a functional significance in the brain. Developmental expression changes of StAR have been reported in the protandrous black porgy brain, which showed high expression from 75 dah with significant increases at 120 dah in the forebrain and hypothalamus [6]. Moreover, Kim et al [55] reported that StAR mRNA was expressed at very low levels in various brain regions of the rat after adrenalectomy and gonadectomy.…”

“…Differential expression of ER˛, ERˇ1 and ERˇ2 was identified in different tissues of the fathead minnow (Pimephales promelas) during early development and in adults, indicating different mechanisms of regulation for the different ERs [41]. Tomy et al [6] reported that these two ER subtypes were expressed in the brain of male black porgy from 75 dah with a later peak during gonadal sex differentiation. The above observations suggest functional roles of each ER in adult and during early developmental ages, although the exact physiological roles of each ER subtype in neurosteroidogenesis with respect to brain development require further research.…”

“…In a previous study, we reported that the developmental expression of the mRNAs encoding four key neurosteroidogenic enzymes (cyp11a1, hsd3b1, cyp17a1 and cyp19a1b) in the brain of protandrous black porgy (Acanthopagrus schlegeli) had significant peaks during gonadal sex differentiation. Hence, we suggested that early brain sex steroids enhance male brain development (neurosteroidogenesis) during the period of gonadal sex differentiation [5,6]. Cytochrome P450 aromatase is the key enzyme that catalyzes the conversion of C19 androgens (androstenedione and testosterone, T) into C18 estrogens (estrone and estradiol-17␤, E2) in the brain, which regulates many physiological processes such as brain sexual differentiation and activation of female sexual behavior during development [7].…”

The Brain of Teleost Fish, a Source, and a Target of Sexual Steroids

“…The expression was about 30 times lower in the gonads than in the brain (Halm et al, 2003). Later, P450c17 expression was detected in the brain of different fish species, including the rice field eel (Yu et al, 2003), black porgy (Tomy et al, 2007, 2009), zebrafish (Wang and Ge, 2004; Diotel et al, 2011a), and rainbow trout (Vizziano-Cantonnet et al, 2011). In the tongue sole ( Cynoglossus semilaevis ), semiquantitative RT-PCR showed that cytochrome P450c17 was predominantly expressed in the ovaries and the brain (Chen et al, 2010a).…”

Sexually dimorphic transcriptomic responses in the teleostean hypothalamus: A case study with the organochlorine pesticide dieldrin

“…Other roles for SF-1 include regulation of feeding and sexual differentiation. In the protandrous black porgy, Acanthopagrus schlegeli , NR5A2 has been shown to be positively correlated in expression, along with androgen and estrogen receptors, during sexual differentiation of the brain (Tomy et al, 2009). Of interest in the current study is that when small molecules were overlaid onto the gene pathway, the NR5A1 and NR5A2 expression network in dieldrin + E 2 fed males also included testosterone and progesterone.…”