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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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Feeding diets enriched in 5-HTP and L-TRP does not affect milk yield, pup growth or mammary gland structure.(A) Milk yield (MY) estimated by weigh-suckle-weigh method. (B) Daily litter weights (g, d1 to d9 of lactation). (C) Hematoxylin and eosin stained sections of mammary glands collected on d9 of lactation (20X magnification), in Sprague-Dawley rats fed CON, 5-HTP, and L-TRP.
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pone-0057847-g001: Feeding diets enriched in 5-HTP and L-TRP does not affect milk yield, pup growth or mammary gland structure.(A) Milk yield (MY) estimated by weigh-suckle-weigh method. (B) Daily litter weights (g, d1 to d9 of lactation). (C) Hematoxylin and eosin stained sections of mammary glands collected on d9 of lactation (20X magnification), in Sprague-Dawley rats fed CON, 5-HTP, and L-TRP.

Mentions: In high concentrations, 5-HT is known to induce mammary gland involution, therefore it was pertinent to determine the effects of increasing endogenous 5-HT production on milk synthesis as well as mammary gland structure [4], [25]. Milk yield was equal among all groups, until d8 and d9 of lactation, in which it increased in L-TRP animals (P<0.05, Figure 1a). Pup litter weights were not different between treatments throughout the experiment (Figure 1b). Additionally, maternal body weights were not different between cohorts (297.5±1.97, 278.8±3.44, and 276.3±4.16 means ± SEM, for CON, 5-HTP and L-TRP, respectively). Hematoxylin and eosin staining of mammary sections were used to confirm the integrity and structure of the mammary tissues (i.e., absence of vacuoles, decreased luminal space), which was similar among treatments at d9 of lactation per examination by a pathologist (Figure 1c). Alveolar lumen diameter was not significantly different between treatments (328.5±15.44, 367.5±27.13, and 329.1±17.45 means ± SEM, for CON, 5-HTP, and L-TRP, respectively).


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)

Feeding diets enriched in 5-HTP and L-TRP does not affect milk yield, pup growth or mammary gland structure.(A) Milk yield (MY) estimated by weigh-suckle-weigh method. (B) Daily litter weights (g, d1 to d9 of lactation). (C) Hematoxylin and eosin stained sections of mammary glands collected on d9 of lactation (20X magnification), in Sprague-Dawley rats fed CON, 5-HTP, and L-TRP.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585179&req=5

pone-0057847-g001: Feeding diets enriched in 5-HTP and L-TRP does not affect milk yield, pup growth or mammary gland structure.(A) Milk yield (MY) estimated by weigh-suckle-weigh method. (B) Daily litter weights (g, d1 to d9 of lactation). (C) Hematoxylin and eosin stained sections of mammary glands collected on d9 of lactation (20X magnification), in Sprague-Dawley rats fed CON, 5-HTP, and L-TRP.
Mentions: In high concentrations, 5-HT is known to induce mammary gland involution, therefore it was pertinent to determine the effects of increasing endogenous 5-HT production on milk synthesis as well as mammary gland structure [4], [25]. Milk yield was equal among all groups, until d8 and d9 of lactation, in which it increased in L-TRP animals (P<0.05, Figure 1a). Pup litter weights were not different between treatments throughout the experiment (Figure 1b). Additionally, maternal body weights were not different between cohorts (297.5±1.97, 278.8±3.44, and 276.3±4.16 means ± SEM, for CON, 5-HTP and L-TRP, respectively). Hematoxylin and eosin staining of mammary sections were used to confirm the integrity and structure of the mammary tissues (i.e., absence of vacuoles, decreased luminal space), which was similar among treatments at d9 of lactation per examination by a pathologist (Figure 1c). Alveolar lumen diameter was not significantly different between treatments (328.5±15.44, 367.5±27.13, and 329.1±17.45 means ± SEM, for CON, 5-HTP, and L-TRP, respectively).

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