Effects of Osmotic Stress on the mRNA Expression of , , , , and in the Pituitary and Osmoregulatory Organs of Black Porgy, .

In euryhaline teleost black porgy, , the glucocorticoid receptor (), growth hormone receptor (), prolactin ()-receptor (), and sodium-potassium ATPase alpha subunit () play essential physiological roles in the osmoregulatory organs, including the gill, kidney, and intestine, during osmotic stress. The present study aimed to investigate the impact of pituitary hormones and hormone receptors in the osmoregulatory organs during the transfer from freshwater (FW) to 4 ppt and seawater (SW) and vice versa in black porgy. Quantitative real-time PCR (Q-PCR) was carried out to analyze the transcript levels during salinity and osmoregulatory stress.

Localization of the Neuropeptide Arginine Vasotocin and Its Receptor in the Osmoregulatory Organs of Black Porgy, : Gills, Kidneys, and Intestines.

The neurohypophysial hormone arginine vasotocin () and its receptor () regulates ions in the osmoregulatory organs of euryhaline black porgy (). The localization of and transcripts in the osmoregulatory organs has yet to be demonstrated. Thus, in the present study, we performed an in situ hybridization analysis to determine the localization of and in the gills, kidneys, and intestines of the black porgy.

Expression and Transcript Localization of , and in the Early Brain of the Orange-Spotted Grouper .

We investigated the developmental expression and localization of and transcripts in the brain of the juvenile orange-spotted grouper in response to steroidogenic enzyme gene at various developmental ages in relation to gonadal sex differentiation. The transcripts were significantly higher from 110-dah (day after hatching) and gradually increased up to 150-dah. The mRNA, on the other hand, showed a decreased expression during this period, in contrast to expression.

Differential Expression of Hypothalamic and Gill- System With Osmotic Stress in the Euryhaline Black Porgy, .

The local gill production of corticotropin releasing hormone () and -receptor () is hypothesized to play important roles during seawater (SW) and freshwater (FW) acclimation in euryhaline black porgy (). The mRNA expression of , , and / () was examined in SW and FW diencephalon (Dien) and in the gills at different exposure time by Q-PCR analysis. The hybridization results indicate that mRNA hybridization signals were more abundant in FW fish in the gigantocellular (PMgc) and parvocellular (PMpc) part of the magnocellular preoptic nucleus versus SW fish.

Neurohypophysial Hormones Associated with Osmotic Challenges in the Brain and Pituitary of the Euryhaline Black Porgy, .

Our study showed differential expression of the ()/ () in the brain and pituitary gland of the euryhaline black porgy () during osmotic stress. A decrease in serum osmolality and increased cortisol levels were observed after acute transfer from seawater (SW) to freshwater (FW). The increased expressions of , (: ), and (: transcripts on day 1 and and transcripts on days 7 and 30 were found in the brains and pituitary glands of FW fish.

The acute salinity changes activate the dual pathways of endocrine responses in the brain and pituitary of tilapia.

To analyze and compare the stress and osmoregulatory hormones and receptors in pituitary during acute salinity changes, the expression patterns of corticotropin releasing hormone (crh) in hypothalamus, prolactin (prl) releasing peptide (pRrp) in telencephalon and diencephalon, glucocorticoid receptors 2 (gr2), and mineralocorticoid receptor (mr), crh-r, pro-opiomelanocorticotropin (pomc), pRrp, prl, dopamine 2 receptor (d2-r), growth hormone (gh), gh-receptor (gh-r) and insulin-like growth hormone (igf-1) transcripts in pituitary were characterized in euryhaline tilapia. The results indicate that the crh transcripts increased in the hypothalamus and rostral pars distalis of the pituitary after the transfer of fish to SW. Similarly, the pRrp transcripts were more abundant in SW acclimated tilapia forebrain and hypothalamus.

Neurosteroidogenic enzymes and their regulation in the early brain of the protogynous grouper Epinephelus coioides during gonadal sex differentiation.

The regulatory role of neurosteroids in the early brain during gonadal sex differentiation is unclear. The aim of this study was to investigate the expression and cellular localization of key steroidogenic enzymes in the early brain of the protogynous orange-spotted grouper Epinephelus coioides and the temporal expressions has been correlated with gonadal sex differentiation. In this study, we showed that peak neurosteroidogenesis occurs in the early brain during gonadal sex differentiation.

Differential expression patterns and localization of glucocorticoid and mineralocorticoid receptor transcripts in the osmoregulatory organs of tilapia during salinity stress.

The glucocorticoid receptor (GR) plays an essential role during seawater (SW) acclimation. However, the regulation of GR isoforms 1 and 2 (GR1 and GR2) and the mineralocorticoid receptor (MR) during SW acclimation is poorly understood. To address this, we localized and examined the GR1, GR2 and MR transcripts in the tilapia gill, kidney and intestine.

Increase in estrogen signaling in the early brain of orange-spotted grouper Epinephelus coioides: a mini-review.

Despite neurosteroidogenic enzymes are playing important roles in the regulation of brain development and function, the potential link between brain and gonad by the action of steroid hormones during gonadal sex differentiation is still not clear in teleosts. In this mini-review, we summarized our understanding on the early brain development related to the synthesis of neurosteroids and receptor signaling during gonadal sex differentiation in protogynous orange-spotted grouper, Epinephelus coioides (functional females for the first 6 years of life and start to sex change around the age of 7 years) and protandrous black porgy (functional males for the first 2 years of life but begin to change sex during the third year). We found a similar profile in the increased expression of brain aromatase gene (aromatatse B or cyp19a1b), aromatase activity, estradiol (E(2)), and estrogen signaling in the brain of both grouper and black porgy fish during gonadal sex differentiation.