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Ethanol regulation of serum glucocorticoid kinase 1 expression in DBA2/J mouse prefrontal cortex.

Costin BN, Dever SM, Miles MF - PLoS ONE (2013)

Bottom Line: Three separate results suggested that ethanol regulated Sgk1 via circulating glucocorticoids: acute ethanol increased glucocorticoid receptor binding to the Sgk1 promoter; adrenalectomy blocked ethanol induction of Sgk1 mRNA; and chronic ethanol exposure during locomotor sensitization down-regulated HPA axis activation and Sgk1 induction by acute ethanol.Chronic ethanol modifies both SGK1 protein and HPA-mediated induction of Sgk1 mRNA.These adaptive molecular responses of glucocorticoid-responsive gene expression and SGK1 in prefrontal cortex may contribute to mechanisms underlying behavioral responses to chronic ethanol exposure.

View Article: PubMed Central - PubMed

Affiliation: Virginia Commonwealth University Alcohol Research Center, Virginia Commonwealth University, Richmond, Virginia, USA.

ABSTRACT

Background: We previously identified a group of glucocorticoid-responsive genes, including Serum Glucocorticoid kinase 1 (Sgk1), regulated by acute ethanol in prefrontal cortex of DBA2/J mice. Acute ethanol activates the hypothalamic pituitary adrenal axis (HPA) causing release of glucocorticoids. Chronic ethanol dysregulates the HPA response in both humans and rodents, possibly contributing to important interactions between stress and alcoholism. Because Sgk1 regulates ion channels and learning and memory, we hypothesized that Sgk1 contributes to HPA-dependent acute and adaptive neuronal responses to ethanol. These studies characterized acute and chronic ethanol regulation of Sgk1 mRNA and protein and their relationship with ethanol actions on the HPA axis.

Results: Acute ethanol increased Sgk1 mRNA expression in a dose and time dependent manner. Three separate results suggested that ethanol regulated Sgk1 via circulating glucocorticoids: acute ethanol increased glucocorticoid receptor binding to the Sgk1 promoter; adrenalectomy blocked ethanol induction of Sgk1 mRNA; and chronic ethanol exposure during locomotor sensitization down-regulated HPA axis activation and Sgk1 induction by acute ethanol. SGK1 protein had complex temporal responses to acute ethanol with rapid and transient increases in Ser422 phosphorylation at 15 min. following ethanol administration. This activating phosphorylation had functional consequences, as suggested by increased phosphorylation of the known SGK1 target, N-myc downstream-regulated gene 1 (NDRG1). After repeated ethanol administration during locomotor sensitization, basal SGK1 protein phosphorylation increased despite blunting of Sgk1 mRNA induction by ethanol.

Conclusions: These results suggest that HPA axis and glucocorticoid receptor signaling mediate acute ethanol induction of Sgk1 transcription in mouse prefrontal cortex. However, acute ethanol also causes complex changes in SGK1 protein expression and activity. Chronic ethanol modifies both SGK1 protein and HPA-mediated induction of Sgk1 mRNA. These adaptive molecular responses of glucocorticoid-responsive gene expression and SGK1 in prefrontal cortex may contribute to mechanisms underlying behavioral responses to chronic ethanol exposure.

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Sgk1 mRNA expression following ethanol sensitization.Behavioral sensitization followed by Q-rtPCR analysis of Sgk1 and Nr3c1. Panels show: (a) Total locomotor activity (cm/10min.) for saline only (SS), acute ethanol (SE) and ethanol sensitized (EE) groups. * p < 0.05 versus chronic saline (SS), # p < 0.05 versus acute ethanol (SE) (b) Sgk1 levels in SS, SE and EE treated mice 4 hours following following saline (SS) or ethanol (SE, EE) treatment on day 14. * p < 0.05 versus SS and EE treated animals (c) Nr3c1 levels in SS, SE and EE treated mice as in panel b.
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pone-0072979-g003: Sgk1 mRNA expression following ethanol sensitization.Behavioral sensitization followed by Q-rtPCR analysis of Sgk1 and Nr3c1. Panels show: (a) Total locomotor activity (cm/10min.) for saline only (SS), acute ethanol (SE) and ethanol sensitized (EE) groups. * p < 0.05 versus chronic saline (SS), # p < 0.05 versus acute ethanol (SE) (b) Sgk1 levels in SS, SE and EE treated mice 4 hours following following saline (SS) or ethanol (SE, EE) treatment on day 14. * p < 0.05 versus SS and EE treated animals (c) Nr3c1 levels in SS, SE and EE treated mice as in panel b.

Mentions: Prior microarray studies in our lab and others had identified Sgk1 to be an acute ethanol responsive gene and we confirmed this finding via Q-rtPCR (Figure 2a–d). However, since we predicted that the HPA axis is involved in ethanol regulation of Sgk1 and chronic ethanol exposure is known to dysregulate the HPA axis, we performed studies to determine if Sgk1 was regulated following chronic ethanol administration as in locomotor sensitization. To answer this question, we evaluated Sgk1 and Fkbp5 (another acute ethanol and glucocorticoid-responsive gene) levels acutely and chronically following ethanol sensitization studies. One-way ANOVA showed an overall effect of treatment on locomotor activity (F2,21= 41.96, p < 0.01) (Figure 3a). Post-hoc analysis revealed that ethanol-ethanol (EE) treated animals had significantly greater locomotor activity compared to saline-ethanol (SE) and saline-saline (SS) treated animals. In addition, SE treated animals showed greater locomotor activity than SS treated animals.


Ethanol regulation of serum glucocorticoid kinase 1 expression in DBA2/J mouse prefrontal cortex.

Costin BN, Dever SM, Miles MF - PLoS ONE (2013)

Sgk1 mRNA expression following ethanol sensitization.Behavioral sensitization followed by Q-rtPCR analysis of Sgk1 and Nr3c1. Panels show: (a) Total locomotor activity (cm/10min.) for saline only (SS), acute ethanol (SE) and ethanol sensitized (EE) groups. * p < 0.05 versus chronic saline (SS), # p < 0.05 versus acute ethanol (SE) (b) Sgk1 levels in SS, SE and EE treated mice 4 hours following following saline (SS) or ethanol (SE, EE) treatment on day 14. * p < 0.05 versus SS and EE treated animals (c) Nr3c1 levels in SS, SE and EE treated mice as in panel b.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3750005&req=5

pone-0072979-g003: Sgk1 mRNA expression following ethanol sensitization.Behavioral sensitization followed by Q-rtPCR analysis of Sgk1 and Nr3c1. Panels show: (a) Total locomotor activity (cm/10min.) for saline only (SS), acute ethanol (SE) and ethanol sensitized (EE) groups. * p < 0.05 versus chronic saline (SS), # p < 0.05 versus acute ethanol (SE) (b) Sgk1 levels in SS, SE and EE treated mice 4 hours following following saline (SS) or ethanol (SE, EE) treatment on day 14. * p < 0.05 versus SS and EE treated animals (c) Nr3c1 levels in SS, SE and EE treated mice as in panel b.
Mentions: Prior microarray studies in our lab and others had identified Sgk1 to be an acute ethanol responsive gene and we confirmed this finding via Q-rtPCR (Figure 2a–d). However, since we predicted that the HPA axis is involved in ethanol regulation of Sgk1 and chronic ethanol exposure is known to dysregulate the HPA axis, we performed studies to determine if Sgk1 was regulated following chronic ethanol administration as in locomotor sensitization. To answer this question, we evaluated Sgk1 and Fkbp5 (another acute ethanol and glucocorticoid-responsive gene) levels acutely and chronically following ethanol sensitization studies. One-way ANOVA showed an overall effect of treatment on locomotor activity (F2,21= 41.96, p < 0.01) (Figure 3a). Post-hoc analysis revealed that ethanol-ethanol (EE) treated animals had significantly greater locomotor activity compared to saline-ethanol (SE) and saline-saline (SS) treated animals. In addition, SE treated animals showed greater locomotor activity than SS treated animals.

Bottom Line: Three separate results suggested that ethanol regulated Sgk1 via circulating glucocorticoids: acute ethanol increased glucocorticoid receptor binding to the Sgk1 promoter; adrenalectomy blocked ethanol induction of Sgk1 mRNA; and chronic ethanol exposure during locomotor sensitization down-regulated HPA axis activation and Sgk1 induction by acute ethanol.Chronic ethanol modifies both SGK1 protein and HPA-mediated induction of Sgk1 mRNA.These adaptive molecular responses of glucocorticoid-responsive gene expression and SGK1 in prefrontal cortex may contribute to mechanisms underlying behavioral responses to chronic ethanol exposure.

View Article: PubMed Central - PubMed

Affiliation: Virginia Commonwealth University Alcohol Research Center, Virginia Commonwealth University, Richmond, Virginia, USA.

ABSTRACT

Background: We previously identified a group of glucocorticoid-responsive genes, including Serum Glucocorticoid kinase 1 (Sgk1), regulated by acute ethanol in prefrontal cortex of DBA2/J mice. Acute ethanol activates the hypothalamic pituitary adrenal axis (HPA) causing release of glucocorticoids. Chronic ethanol dysregulates the HPA response in both humans and rodents, possibly contributing to important interactions between stress and alcoholism. Because Sgk1 regulates ion channels and learning and memory, we hypothesized that Sgk1 contributes to HPA-dependent acute and adaptive neuronal responses to ethanol. These studies characterized acute and chronic ethanol regulation of Sgk1 mRNA and protein and their relationship with ethanol actions on the HPA axis.

Results: Acute ethanol increased Sgk1 mRNA expression in a dose and time dependent manner. Three separate results suggested that ethanol regulated Sgk1 via circulating glucocorticoids: acute ethanol increased glucocorticoid receptor binding to the Sgk1 promoter; adrenalectomy blocked ethanol induction of Sgk1 mRNA; and chronic ethanol exposure during locomotor sensitization down-regulated HPA axis activation and Sgk1 induction by acute ethanol. SGK1 protein had complex temporal responses to acute ethanol with rapid and transient increases in Ser422 phosphorylation at 15 min. following ethanol administration. This activating phosphorylation had functional consequences, as suggested by increased phosphorylation of the known SGK1 target, N-myc downstream-regulated gene 1 (NDRG1). After repeated ethanol administration during locomotor sensitization, basal SGK1 protein phosphorylation increased despite blunting of Sgk1 mRNA induction by ethanol.

Conclusions: These results suggest that HPA axis and glucocorticoid receptor signaling mediate acute ethanol induction of Sgk1 transcription in mouse prefrontal cortex. However, acute ethanol also causes complex changes in SGK1 protein expression and activity. Chronic ethanol modifies both SGK1 protein and HPA-mediated induction of Sgk1 mRNA. These adaptive molecular responses of glucocorticoid-responsive gene expression and SGK1 in prefrontal cortex may contribute to mechanisms underlying behavioral responses to chronic ethanol exposure.

Show MeSH
Related in: MedlinePlus