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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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Fluorescent immunostaining of GLUT-1 and GLUT-8 in the mammary gland of dams fed CON, 5-HTP or L-TRP diets on day 9 of lactation.(A) GLUT-1 (red) and the luminal epithelial cell marker, keratin 8 (K8) (green, A1–A3), and the vascular endothelial cell marker, griffonia simplicifolia lectin 1 (GS1; green, A4–A6). (B) GLUT-8 (red) and K8 (green, B1–B3), GS1 (green, B4–B6), and the myoepithelial cell marker, smooth muscle actin (SMA, green, B7–B9). Cell nuclei for all sections were visualized with DAPI (blue). Inset contains a negative control (no primary antibodies).
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pone-0057847-g005: Fluorescent immunostaining of GLUT-1 and GLUT-8 in the mammary gland of dams fed CON, 5-HTP or L-TRP diets on day 9 of lactation.(A) GLUT-1 (red) and the luminal epithelial cell marker, keratin 8 (K8) (green, A1–A3), and the vascular endothelial cell marker, griffonia simplicifolia lectin 1 (GS1; green, A4–A6). (B) GLUT-8 (red) and K8 (green, B1–B3), GS1 (green, B4–B6), and the myoepithelial cell marker, smooth muscle actin (SMA, green, B7–B9). Cell nuclei for all sections were visualized with DAPI (blue). Inset contains a negative control (no primary antibodies).

Mentions: Using immunofluorescence we demonstrated that GLUT-1 is present in K8+ mammary luminal epithelium (Figure 5 a1–a3) but not in GS1+ endothelium (Figure 5 a4–a6). Similarly, GLUT-8 was detected in K8+ mammary luminal epithelium (Figure 5 b1–b3) but was also detected in GS1+ endothelium (Figure 5 b4–b6) but not in SMA+ myoepithelium (Figure 5 b7–b9). Additionally, it appears that GLUT-1 and GLUT-8 in the 5-HTP group are not only present on the basolateral portion of the mammary epithelium, but also appear to be dispersed within the epithelia, possibly in specific organelles within the epithelial cells.


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)

Fluorescent immunostaining of GLUT-1 and GLUT-8 in the mammary gland of dams fed CON, 5-HTP or L-TRP diets on day 9 of lactation.(A) GLUT-1 (red) and the luminal epithelial cell marker, keratin 8 (K8) (green, A1–A3), and the vascular endothelial cell marker, griffonia simplicifolia lectin 1 (GS1; green, A4–A6). (B) GLUT-8 (red) and K8 (green, B1–B3), GS1 (green, B4–B6), and the myoepithelial cell marker, smooth muscle actin (SMA, green, B7–B9). Cell nuclei for all sections were visualized with DAPI (blue). Inset contains a negative control (no primary antibodies).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3585179&req=5

pone-0057847-g005: Fluorescent immunostaining of GLUT-1 and GLUT-8 in the mammary gland of dams fed CON, 5-HTP or L-TRP diets on day 9 of lactation.(A) GLUT-1 (red) and the luminal epithelial cell marker, keratin 8 (K8) (green, A1–A3), and the vascular endothelial cell marker, griffonia simplicifolia lectin 1 (GS1; green, A4–A6). (B) GLUT-8 (red) and K8 (green, B1–B3), GS1 (green, B4–B6), and the myoepithelial cell marker, smooth muscle actin (SMA, green, B7–B9). Cell nuclei for all sections were visualized with DAPI (blue). Inset contains a negative control (no primary antibodies).
Mentions: Using immunofluorescence we demonstrated that GLUT-1 is present in K8+ mammary luminal epithelium (Figure 5 a1–a3) but not in GS1+ endothelium (Figure 5 a4–a6). Similarly, GLUT-8 was detected in K8+ mammary luminal epithelium (Figure 5 b1–b3) but was also detected in GS1+ endothelium (Figure 5 b4–b6) but not in SMA+ myoepithelium (Figure 5 b7–b9). Additionally, it appears that GLUT-1 and GLUT-8 in the 5-HTP group are not only present on the basolateral portion of the mammary epithelium, but also appear to be dispersed within the epithelia, possibly in specific organelles within the epithelial cells.

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