Limits...
Cortisol-induced masculinization: does thermal stress affect gonadal fate in pejerrey, a teleost fish with temperature-dependent sex determination?

Hattori RS, Fernandino JI, Kishii A, Kimura H, Kinno T, Oura M, Somoza GM, Yokota M, Strüssmann CA, Watanabe S - PLoS ONE (2009)

Bottom Line: Larvae maintained during the period of gonadal sex differentiation at a masculinizing temperature (29 degrees C; 100% males) consistently had higher cortisol, 11-ketotestoterone (11-KT), and testosterone (T) titres than those at a feminizing temperature (17 degrees C; 100% females).Administration of cortisol and a non-metabolizable glucocorticoid receptor (GR) agonist (Dexamethasone) to larvae at a "sexually neutral" temperature (24 degrees C) caused significant increases in the proportion of males.Cortisol role or roles during TSD of pejerrey seem(s) to involve both androgen biosynthesis- and GR-mediated processes.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan.

ABSTRACT

Background: Gonadal fate in many reptiles, fish, and amphibians is modulated by the temperature experienced during a critical period early in life (temperature-dependent sex determination; TSD). Several molecular processes involved in TSD have been described but how the animals "sense" environmental temperature remains unknown. We examined whether the stress-related hormone cortisol mediates between temperature and sex differentiation of pejerrey, a gonochoristic teleost fish with marked TSD, and the possibility that it involves glucocorticoid receptor- and/or steroid biosynthesis-modulation.

Methodology/principal findings: Larvae maintained during the period of gonadal sex differentiation at a masculinizing temperature (29 degrees C; 100% males) consistently had higher cortisol, 11-ketotestoterone (11-KT), and testosterone (T) titres than those at a feminizing temperature (17 degrees C; 100% females). Cortisol-treated animals had elevated 11-KT and T, and showed a typical molecular signature of masculinization including amh upregulation, cyp19a1a downregulation, and higher incidence of gonadal apoptosis during sex differentiation. Administration of cortisol and a non-metabolizable glucocorticoid receptor (GR) agonist (Dexamethasone) to larvae at a "sexually neutral" temperature (24 degrees C) caused significant increases in the proportion of males.

Conclusions/significance: Our results suggest a role of cortisol in the masculinization of pejerrey and provide a possible link between stress and testicular differentiation in this gonochoristic TSD species. Cortisol role or roles during TSD of pejerrey seem(s) to involve both androgen biosynthesis- and GR-mediated processes. These findings and recent reports of cortisol effects on sex determination of sequential hermaphroditic fishes, TSD reptiles, and birds provide support to the notion that stress responses might be involved in various forms of environmental sex determination.

Show MeSH

Related in: MedlinePlus

Percentage of males in groups treated with cortisol and the synthetic glucocorticoid receptor (GR) agonist Dexamethasone.All groups were reared at an intermediate temperature (24°C) during the trials. Groups treated with cortisol and Dexamethasone had increased proportions of males compared to the respective controls. Numbers within parenthesis indicate the sample number; asterisks indicate statistically significant differences between groups in the same trial (χ2; P≤0.05; GraphPad Prism v.4.00).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2717333&req=5

pone-0006548-g004: Percentage of males in groups treated with cortisol and the synthetic glucocorticoid receptor (GR) agonist Dexamethasone.All groups were reared at an intermediate temperature (24°C) during the trials. Groups treated with cortisol and Dexamethasone had increased proportions of males compared to the respective controls. Numbers within parenthesis indicate the sample number; asterisks indicate statistically significant differences between groups in the same trial (χ2; P≤0.05; GraphPad Prism v.4.00).

Mentions: We then administered exogenous cortisol to larvae reared at the MixPT (24°C) between 1 and 10 wah to analyze its effects on key molecular events involved in the sex differentiation process of this species, e.g. the expression of amh and cyp19a1a mRNA [22]–[24] and gonadal apoptosis [25], and on the sex ratios. We also measured the whole-body concentrations of cortisol in treated larvae but this analysis failed to demonstrate a significant difference in comparison to the control group (data not shown), probably as a result of the relatively long time elapsed between the last feeding (evening) and sampling (morning) and the rapid cortisol clearance (see [10], [21], [26]). Nevertheless, the analysis of mRNA transcript abundance showed that all individuals from the group administered cortisol (0.8 mg/g; n = 10) presented a male-like pattern of amh upregulation and cyp19a1a downregulation at 6 wah (Fig. 2; see [22]–[24]). Likewise, the TUNEL assay revealed a higher incidence of apoptosis in the gonads of cortisol-treated fish compared to the controls on week 6 (Fig. 3). Almost all of the cells in the anterior sections of the right lobe of the gonad of these larvae were TUNEL-positive, a pattern typically associated with masculinization in this species [25]. These early molecular signs of masculinization were corroborated by the histological analysis conducted 2–3 months after cortisol withdrawal. Thus, in three independent trials, groups administered cortisol consistently had higher percentages of males compared to the respective controls and those with the highest dosage (0.8 mg/g) were all male (Fig. 4). Mortalities were negligible after the first week, when the fish started to ingest the cortisol-treated diets, and hence could not have caused the observed sex ratio deviations.


Cortisol-induced masculinization: does thermal stress affect gonadal fate in pejerrey, a teleost fish with temperature-dependent sex determination?

Hattori RS, Fernandino JI, Kishii A, Kimura H, Kinno T, Oura M, Somoza GM, Yokota M, Strüssmann CA, Watanabe S - PLoS ONE (2009)

Percentage of males in groups treated with cortisol and the synthetic glucocorticoid receptor (GR) agonist Dexamethasone.All groups were reared at an intermediate temperature (24°C) during the trials. Groups treated with cortisol and Dexamethasone had increased proportions of males compared to the respective controls. Numbers within parenthesis indicate the sample number; asterisks indicate statistically significant differences between groups in the same trial (χ2; P≤0.05; GraphPad Prism v.4.00).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2717333&req=5

pone-0006548-g004: Percentage of males in groups treated with cortisol and the synthetic glucocorticoid receptor (GR) agonist Dexamethasone.All groups were reared at an intermediate temperature (24°C) during the trials. Groups treated with cortisol and Dexamethasone had increased proportions of males compared to the respective controls. Numbers within parenthesis indicate the sample number; asterisks indicate statistically significant differences between groups in the same trial (χ2; P≤0.05; GraphPad Prism v.4.00).
Mentions: We then administered exogenous cortisol to larvae reared at the MixPT (24°C) between 1 and 10 wah to analyze its effects on key molecular events involved in the sex differentiation process of this species, e.g. the expression of amh and cyp19a1a mRNA [22]–[24] and gonadal apoptosis [25], and on the sex ratios. We also measured the whole-body concentrations of cortisol in treated larvae but this analysis failed to demonstrate a significant difference in comparison to the control group (data not shown), probably as a result of the relatively long time elapsed between the last feeding (evening) and sampling (morning) and the rapid cortisol clearance (see [10], [21], [26]). Nevertheless, the analysis of mRNA transcript abundance showed that all individuals from the group administered cortisol (0.8 mg/g; n = 10) presented a male-like pattern of amh upregulation and cyp19a1a downregulation at 6 wah (Fig. 2; see [22]–[24]). Likewise, the TUNEL assay revealed a higher incidence of apoptosis in the gonads of cortisol-treated fish compared to the controls on week 6 (Fig. 3). Almost all of the cells in the anterior sections of the right lobe of the gonad of these larvae were TUNEL-positive, a pattern typically associated with masculinization in this species [25]. These early molecular signs of masculinization were corroborated by the histological analysis conducted 2–3 months after cortisol withdrawal. Thus, in three independent trials, groups administered cortisol consistently had higher percentages of males compared to the respective controls and those with the highest dosage (0.8 mg/g) were all male (Fig. 4). Mortalities were negligible after the first week, when the fish started to ingest the cortisol-treated diets, and hence could not have caused the observed sex ratio deviations.

Bottom Line: Larvae maintained during the period of gonadal sex differentiation at a masculinizing temperature (29 degrees C; 100% males) consistently had higher cortisol, 11-ketotestoterone (11-KT), and testosterone (T) titres than those at a feminizing temperature (17 degrees C; 100% females).Administration of cortisol and a non-metabolizable glucocorticoid receptor (GR) agonist (Dexamethasone) to larvae at a "sexually neutral" temperature (24 degrees C) caused significant increases in the proportion of males.Cortisol role or roles during TSD of pejerrey seem(s) to involve both androgen biosynthesis- and GR-mediated processes.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan.

ABSTRACT

Background: Gonadal fate in many reptiles, fish, and amphibians is modulated by the temperature experienced during a critical period early in life (temperature-dependent sex determination; TSD). Several molecular processes involved in TSD have been described but how the animals "sense" environmental temperature remains unknown. We examined whether the stress-related hormone cortisol mediates between temperature and sex differentiation of pejerrey, a gonochoristic teleost fish with marked TSD, and the possibility that it involves glucocorticoid receptor- and/or steroid biosynthesis-modulation.

Methodology/principal findings: Larvae maintained during the period of gonadal sex differentiation at a masculinizing temperature (29 degrees C; 100% males) consistently had higher cortisol, 11-ketotestoterone (11-KT), and testosterone (T) titres than those at a feminizing temperature (17 degrees C; 100% females). Cortisol-treated animals had elevated 11-KT and T, and showed a typical molecular signature of masculinization including amh upregulation, cyp19a1a downregulation, and higher incidence of gonadal apoptosis during sex differentiation. Administration of cortisol and a non-metabolizable glucocorticoid receptor (GR) agonist (Dexamethasone) to larvae at a "sexually neutral" temperature (24 degrees C) caused significant increases in the proportion of males.

Conclusions/significance: Our results suggest a role of cortisol in the masculinization of pejerrey and provide a possible link between stress and testicular differentiation in this gonochoristic TSD species. Cortisol role or roles during TSD of pejerrey seem(s) to involve both androgen biosynthesis- and GR-mediated processes. These findings and recent reports of cortisol effects on sex determination of sequential hermaphroditic fishes, TSD reptiles, and birds provide support to the notion that stress responses might be involved in various forms of environmental sex determination.

Show MeSH
Related in: MedlinePlus