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Serotonin (5-HT) affects expression of liver metabolic enzymes and mammary gland glucose transporters during the transition from pregnancy to lactation.

Laporta J, Peters TL, Merriman KE, Vezina CM, Hernandez LL - PLoS ONE (2013)

Bottom Line: The aim of this experiment was to demonstrate the ability of feeding serotonin (5-HT; 5-hydroxytryptamine) precursors to increase 5-HT production during the transition from pregnancy to lactation and the effects this has on maternal energy metabolism in the liver and mammary gland.Feeding 5-HTP resulted in increased mRNA expression of key gluconeogenic and glycolytic enzymes in liver and glucose transporters 1 and 8 (GLUT-1, -8) in the mammary gland.Our results suggest that increasing 5-HT production during the transition from pregnancy to lactation increases mRNA expression of enzymes involved in energy metabolism in the liver, and mRNA abundance and distribution of glucose transporters within the mammary gland.

View Article: PubMed Central - PubMed

Affiliation: Department of Dairy Science, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.

ABSTRACT
The aim of this experiment was to demonstrate the ability of feeding serotonin (5-HT; 5-hydroxytryptamine) precursors to increase 5-HT production during the transition from pregnancy to lactation and the effects this has on maternal energy metabolism in the liver and mammary gland. Pregnant rats (n = 45) were fed one of three diets: I) control (CON), II) CON supplemented with 0.2% 5-hydroxytryptophan (5-HTP) or III) CON supplemented with 1.35% L-tryptophan (L-TRP), beginning on d13 of pregnancy through d9 of lactation (d9). Serum (pre and post-partum), milk (daily), liver and mammary gland tissue (d9) were collected. Serum 5-HT was increased in the 5-HTP fed dams beginning on d20 of gestation and remained elevated through d9, while it was only increased on d9 in the L-TRP fed dams. 5-HT levels were increased in mammary gland and liver of both groups. Additionally, 5-HTP fed dams had serum and milk glucose levels similar to the CON, while L-TRP had decreased serum (d9) and milk glucose (all dates evaluated). Feeding 5-HTP resulted in increased mRNA expression of key gluconeogenic and glycolytic enzymes in liver and glucose transporters 1 and 8 (GLUT-1, -8) in the mammary gland. We demonstrated the location of GLUT-8 in the mammary gland both in the epithelial and vascular endothelial cells. Finally, phosphorylated 5' AMP-activated protein kinase (pAMPK), a known regulator of intracellular energy status, was elevated in mammary glands of 5-HTP fed dams. Our results suggest that increasing 5-HT production during the transition from pregnancy to lactation increases mRNA expression of enzymes involved in energy metabolism in the liver, and mRNA abundance and distribution of glucose transporters within the mammary gland. This suggests the possibility that 5-HT may be involved in regulating energy metabolism during the transition from pregnancy to lactation.

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Effects of 5-HTP or L-TRP feeding on GLUT-1 and -8 expression in mammary gland of rats on day 9 of lactation.(A) GLUT-1 mRNA expression in the mammary gland of dams fed CON, 5-HTP, and L-TRP diets. GLUT-1 immunostaining in mammary glands collected on d9 of lactation from rats fed CON (B), 5-HTP (C), and L-TRP (D) diets. (E) GLUT-8 mRNA expressions in the mammary gland of dams fed CON, 5-HTP, and L-TRP diets. GLUT-8 immunostaining in mammary glands collected on d9 of lactation from dams fed CON (F), 5-HTP (G), and L-TRP (H) diets. Two asterisks (**) indicates statistical significance at P<0.01.
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pone-0057847-g004: Effects of 5-HTP or L-TRP feeding on GLUT-1 and -8 expression in mammary gland of rats on day 9 of lactation.(A) GLUT-1 mRNA expression in the mammary gland of dams fed CON, 5-HTP, and L-TRP diets. GLUT-1 immunostaining in mammary glands collected on d9 of lactation from rats fed CON (B), 5-HTP (C), and L-TRP (D) diets. (E) GLUT-8 mRNA expressions in the mammary gland of dams fed CON, 5-HTP, and L-TRP diets. GLUT-8 immunostaining in mammary glands collected on d9 of lactation from dams fed CON (F), 5-HTP (G), and L-TRP (H) diets. Two asterisks (**) indicates statistical significance at P<0.01.

Mentions: Entry of glucose into the mammary gland is an initial crucial step for the synthesis of milk lactose [28]. To date, GLUT-1 is thought to be the primary glucose transporter responsible for glucose uptake in the mammary gland, however several others have been detected in the mammary gland and little is known about their functions [28]. Mammary gland GLUT-1 mRNA expression was increased in dams consuming the L-TRP and 5-HTP diets (P<0.0082, Figure 4a). mRNA expression of GLUT-8 was increased in the mammary gland of dams consuming the 5-HTP exclusively (P = 0.023, Figure 4b). Antibody stains for GLUT-1 and -8 were positive in mammary tissue in animals consuming all three diets. While GLUT-1 was clearly located in epithelial cells (Figure 4b–4d), GLUT-8 appeared to be located in epithelial and stromal cells (Figures 4f–4h).


Serotonin (5-HT) affects expression of liver metabolic enzymes and mammary gland glucose transporters during the transition from pregnancy to lactation.

Laporta J, Peters TL, Merriman KE, Vezina CM, Hernandez LL - PLoS ONE (2013)

Effects of 5-HTP or L-TRP feeding on GLUT-1 and -8 expression in mammary gland of rats on day 9 of lactation.(A) GLUT-1 mRNA expression in the mammary gland of dams fed CON, 5-HTP, and L-TRP diets. GLUT-1 immunostaining in mammary glands collected on d9 of lactation from rats fed CON (B), 5-HTP (C), and L-TRP (D) diets. (E) GLUT-8 mRNA expressions in the mammary gland of dams fed CON, 5-HTP, and L-TRP diets. GLUT-8 immunostaining in mammary glands collected on d9 of lactation from dams fed CON (F), 5-HTP (G), and L-TRP (H) diets. Two asterisks (**) indicates statistical significance at P<0.01.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3585179&req=5

pone-0057847-g004: Effects of 5-HTP or L-TRP feeding on GLUT-1 and -8 expression in mammary gland of rats on day 9 of lactation.(A) GLUT-1 mRNA expression in the mammary gland of dams fed CON, 5-HTP, and L-TRP diets. GLUT-1 immunostaining in mammary glands collected on d9 of lactation from rats fed CON (B), 5-HTP (C), and L-TRP (D) diets. (E) GLUT-8 mRNA expressions in the mammary gland of dams fed CON, 5-HTP, and L-TRP diets. GLUT-8 immunostaining in mammary glands collected on d9 of lactation from dams fed CON (F), 5-HTP (G), and L-TRP (H) diets. Two asterisks (**) indicates statistical significance at P<0.01.
Mentions: Entry of glucose into the mammary gland is an initial crucial step for the synthesis of milk lactose [28]. To date, GLUT-1 is thought to be the primary glucose transporter responsible for glucose uptake in the mammary gland, however several others have been detected in the mammary gland and little is known about their functions [28]. Mammary gland GLUT-1 mRNA expression was increased in dams consuming the L-TRP and 5-HTP diets (P<0.0082, Figure 4a). mRNA expression of GLUT-8 was increased in the mammary gland of dams consuming the 5-HTP exclusively (P = 0.023, Figure 4b). Antibody stains for GLUT-1 and -8 were positive in mammary tissue in animals consuming all three diets. While GLUT-1 was clearly located in epithelial cells (Figure 4b–4d), GLUT-8 appeared to be located in epithelial and stromal cells (Figures 4f–4h).

Bottom Line: The aim of this experiment was to demonstrate the ability of feeding serotonin (5-HT; 5-hydroxytryptamine) precursors to increase 5-HT production during the transition from pregnancy to lactation and the effects this has on maternal energy metabolism in the liver and mammary gland.Feeding 5-HTP resulted in increased mRNA expression of key gluconeogenic and glycolytic enzymes in liver and glucose transporters 1 and 8 (GLUT-1, -8) in the mammary gland.Our results suggest that increasing 5-HT production during the transition from pregnancy to lactation increases mRNA expression of enzymes involved in energy metabolism in the liver, and mRNA abundance and distribution of glucose transporters within the mammary gland.

View Article: PubMed Central - PubMed

Affiliation: Department of Dairy Science, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.

ABSTRACT
The aim of this experiment was to demonstrate the ability of feeding serotonin (5-HT; 5-hydroxytryptamine) precursors to increase 5-HT production during the transition from pregnancy to lactation and the effects this has on maternal energy metabolism in the liver and mammary gland. Pregnant rats (n = 45) were fed one of three diets: I) control (CON), II) CON supplemented with 0.2% 5-hydroxytryptophan (5-HTP) or III) CON supplemented with 1.35% L-tryptophan (L-TRP), beginning on d13 of pregnancy through d9 of lactation (d9). Serum (pre and post-partum), milk (daily), liver and mammary gland tissue (d9) were collected. Serum 5-HT was increased in the 5-HTP fed dams beginning on d20 of gestation and remained elevated through d9, while it was only increased on d9 in the L-TRP fed dams. 5-HT levels were increased in mammary gland and liver of both groups. Additionally, 5-HTP fed dams had serum and milk glucose levels similar to the CON, while L-TRP had decreased serum (d9) and milk glucose (all dates evaluated). Feeding 5-HTP resulted in increased mRNA expression of key gluconeogenic and glycolytic enzymes in liver and glucose transporters 1 and 8 (GLUT-1, -8) in the mammary gland. We demonstrated the location of GLUT-8 in the mammary gland both in the epithelial and vascular endothelial cells. Finally, phosphorylated 5' AMP-activated protein kinase (pAMPK), a known regulator of intracellular energy status, was elevated in mammary glands of 5-HTP fed dams. Our results suggest that increasing 5-HT production during the transition from pregnancy to lactation increases mRNA expression of enzymes involved in energy metabolism in the liver, and mRNA abundance and distribution of glucose transporters within the mammary gland. This suggests the possibility that 5-HT may be involved in regulating energy metabolism during the transition from pregnancy to lactation.

Show MeSH