Limits...
Limited impact on glucose homeostasis of leptin receptor deletion from insulin- or proglucagon-expressing cells.

Soedling H, Hodson DJ, Adrianssens AE, Gribble FM, Reimann F, Trapp S, Rutter GA - Mol Metab (2015)

Bottom Line: Whereas male mice further deleted for leptin receptors in β cells exhibited no abnormalities in glucose tolerance up to 16 weeks of age, females transiently displayed improved glucose tolerance at 8 weeks (11.2  ±  3.2% decrease in area under curve; p < 0.05), and improved (39.0  ±  13.0%, P < 0.05) glucose-stimulated insulin secretion in vitro.No differences were seen between genotypes in body weight, fasting glucose or β/α cell ratio.Deletion of LepR from α-cells, a minority of β cells, and a subset of proglucagon-expressing cells in the brain, exerted no effects on body weight, glucose or insulin tolerance, nor on pancreatic hormone secretion assessed in vivo and in vitro.

View Article: PubMed Central - PubMed

Affiliation: Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, du Cane Road, London W12 0NN, UK.

ABSTRACT

Aims/hypothesis: The adipose tissue-derived hormone leptin plays an important role in the maintenance of body weight and glucose homeostasis. Leptin mediates its effects by interaction with leptin receptors (LepRb), which are highly expressed in the hypothalamus and other brain centres, and at lower levels in the periphery. Previous studies have used relatively promiscuous or inefficient Cre deleter strains, respectively, to explore the roles of LepR in pancreatic β and α cells. Here, we use two newly-developed Cre lines to explore the role of leptin signalling in insulin and proglucagon-expressing cells.

Methods: Leptin receptor expression was measured in isolated mouse islets and highly-purified islet cells by RNASeq and quantitative RT-PCR. Mice lacking leptin signalling in pancreatic β, or in α and other proglucagon-expressing cells, were generated using Ins1Cre- or iGluCre-mediated recombination respectively of flox'd leptin receptor alleles. In vivo glucose homeostasis, changes in body weight, pancreatic histology and hormone secretion from isolated islets were assessed using standard techniques.

Results: Leptin receptor mRNA levels were at or below the level of detection in wild-type adult mouse isolated islets and purified cells, and leptin signalling to Stat3 phosphorylation was undetectable. Whereas male mice further deleted for leptin receptors in β cells exhibited no abnormalities in glucose tolerance up to 16 weeks of age, females transiently displayed improved glucose tolerance at 8 weeks (11.2  ±  3.2% decrease in area under curve; p < 0.05), and improved (39.0  ±  13.0%, P < 0.05) glucose-stimulated insulin secretion in vitro. No differences were seen between genotypes in body weight, fasting glucose or β/α cell ratio. Deletion of LepR from α-cells, a minority of β cells, and a subset of proglucagon-expressing cells in the brain, exerted no effects on body weight, glucose or insulin tolerance, nor on pancreatic hormone secretion assessed in vivo and in vitro.

Conclusions/interpretation: The use here of a highly selective Cre recombinase indicates that leptin signalling plays a relatively minor, age- and sex-dependent role in the control of β cell function in the mouse. No in vivo role for leptin receptors on α cells, nor in other proglucagon-expressing cells, was detected in this study.

No MeSH data available.


Related in: MedlinePlus

iGluCreLepRKOmice display normal glucose tolerance and fasting blood glucose levels. (A) Body weight followed for 30 weeks in male (green) and female (red) iGluCreLepRKO and LepRF/F mice (n = 12–19 mice per genotype). (B) Fasting blood glucose levels in 8 week old males and females (n = 6–11 mice per genotype). (C,D) Blood glucose concentration after IPGTT in male and female iGluCreLepRKO (square symbol) and LepRF/F (green triangle) mice. Blood glucose concentration after ITT in males: (E) iGluCreLepRKO, n = 8, LepRF/F, n = 7; and females: (F) iGluCreLepRKO, n = 8, LepRF/F, n = 10. Plasma glucagon levels during ITT, iGluCreLepRKO, n = 6, LepRF/F, n = 4, (G), and glucagon release from isolated islets in the presence of the indicated glucose concentrations: LG = 0.5 mM, HG = 10 mM glucose; n = 6 animals per genotype (H). When present, leptin was added to 10 nM. Data are expressed as the mean ± SEM and statistical comparison was through two-way ANOVA, *p < 0.05. Other details are provided in the Materials and Methods section.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4563029&req=5

fig7: iGluCreLepRKOmice display normal glucose tolerance and fasting blood glucose levels. (A) Body weight followed for 30 weeks in male (green) and female (red) iGluCreLepRKO and LepRF/F mice (n = 12–19 mice per genotype). (B) Fasting blood glucose levels in 8 week old males and females (n = 6–11 mice per genotype). (C,D) Blood glucose concentration after IPGTT in male and female iGluCreLepRKO (square symbol) and LepRF/F (green triangle) mice. Blood glucose concentration after ITT in males: (E) iGluCreLepRKO, n = 8, LepRF/F, n = 7; and females: (F) iGluCreLepRKO, n = 8, LepRF/F, n = 10. Plasma glucagon levels during ITT, iGluCreLepRKO, n = 6, LepRF/F, n = 4, (G), and glucagon release from isolated islets in the presence of the indicated glucose concentrations: LG = 0.5 mM, HG = 10 mM glucose; n = 6 animals per genotype (H). When present, leptin was added to 10 nM. Data are expressed as the mean ± SEM and statistical comparison was through two-way ANOVA, *p < 0.05. Other details are provided in the Materials and Methods section.

Mentions: No differences in growth curves were apparent between iGluCreLepRbKO and LepRbF/F mice (Figure 7A), nor were differences in fasting blood glucose detected (Figure 7B). Intraperitoneal glucose (Figure 7C,D) and insulin (Figure 7E,F) tolerance were also identical between genotypes. Likewise, there were no apparent differences in glucagon release in response to hypoglycaemia in vivo (Figure 7G), nor in vitro in response to low or high glucose (Figure 7H). A tendency for leptin (10 nM) to impair glucagon release at low glucose was apparent in wild-type, but not iGluCreLepRbKO mice (Figure 7H).


Limited impact on glucose homeostasis of leptin receptor deletion from insulin- or proglucagon-expressing cells.

Soedling H, Hodson DJ, Adrianssens AE, Gribble FM, Reimann F, Trapp S, Rutter GA - Mol Metab (2015)

iGluCreLepRKOmice display normal glucose tolerance and fasting blood glucose levels. (A) Body weight followed for 30 weeks in male (green) and female (red) iGluCreLepRKO and LepRF/F mice (n = 12–19 mice per genotype). (B) Fasting blood glucose levels in 8 week old males and females (n = 6–11 mice per genotype). (C,D) Blood glucose concentration after IPGTT in male and female iGluCreLepRKO (square symbol) and LepRF/F (green triangle) mice. Blood glucose concentration after ITT in males: (E) iGluCreLepRKO, n = 8, LepRF/F, n = 7; and females: (F) iGluCreLepRKO, n = 8, LepRF/F, n = 10. Plasma glucagon levels during ITT, iGluCreLepRKO, n = 6, LepRF/F, n = 4, (G), and glucagon release from isolated islets in the presence of the indicated glucose concentrations: LG = 0.5 mM, HG = 10 mM glucose; n = 6 animals per genotype (H). When present, leptin was added to 10 nM. Data are expressed as the mean ± SEM and statistical comparison was through two-way ANOVA, *p < 0.05. Other details are provided in the Materials and Methods section.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4563029&req=5

fig7: iGluCreLepRKOmice display normal glucose tolerance and fasting blood glucose levels. (A) Body weight followed for 30 weeks in male (green) and female (red) iGluCreLepRKO and LepRF/F mice (n = 12–19 mice per genotype). (B) Fasting blood glucose levels in 8 week old males and females (n = 6–11 mice per genotype). (C,D) Blood glucose concentration after IPGTT in male and female iGluCreLepRKO (square symbol) and LepRF/F (green triangle) mice. Blood glucose concentration after ITT in males: (E) iGluCreLepRKO, n = 8, LepRF/F, n = 7; and females: (F) iGluCreLepRKO, n = 8, LepRF/F, n = 10. Plasma glucagon levels during ITT, iGluCreLepRKO, n = 6, LepRF/F, n = 4, (G), and glucagon release from isolated islets in the presence of the indicated glucose concentrations: LG = 0.5 mM, HG = 10 mM glucose; n = 6 animals per genotype (H). When present, leptin was added to 10 nM. Data are expressed as the mean ± SEM and statistical comparison was through two-way ANOVA, *p < 0.05. Other details are provided in the Materials and Methods section.
Mentions: No differences in growth curves were apparent between iGluCreLepRbKO and LepRbF/F mice (Figure 7A), nor were differences in fasting blood glucose detected (Figure 7B). Intraperitoneal glucose (Figure 7C,D) and insulin (Figure 7E,F) tolerance were also identical between genotypes. Likewise, there were no apparent differences in glucagon release in response to hypoglycaemia in vivo (Figure 7G), nor in vitro in response to low or high glucose (Figure 7H). A tendency for leptin (10 nM) to impair glucagon release at low glucose was apparent in wild-type, but not iGluCreLepRbKO mice (Figure 7H).

Bottom Line: Whereas male mice further deleted for leptin receptors in β cells exhibited no abnormalities in glucose tolerance up to 16 weeks of age, females transiently displayed improved glucose tolerance at 8 weeks (11.2  ±  3.2% decrease in area under curve; p < 0.05), and improved (39.0  ±  13.0%, P < 0.05) glucose-stimulated insulin secretion in vitro.No differences were seen between genotypes in body weight, fasting glucose or β/α cell ratio.Deletion of LepR from α-cells, a minority of β cells, and a subset of proglucagon-expressing cells in the brain, exerted no effects on body weight, glucose or insulin tolerance, nor on pancreatic hormone secretion assessed in vivo and in vitro.

View Article: PubMed Central - PubMed

Affiliation: Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, du Cane Road, London W12 0NN, UK.

ABSTRACT

Aims/hypothesis: The adipose tissue-derived hormone leptin plays an important role in the maintenance of body weight and glucose homeostasis. Leptin mediates its effects by interaction with leptin receptors (LepRb), which are highly expressed in the hypothalamus and other brain centres, and at lower levels in the periphery. Previous studies have used relatively promiscuous or inefficient Cre deleter strains, respectively, to explore the roles of LepR in pancreatic β and α cells. Here, we use two newly-developed Cre lines to explore the role of leptin signalling in insulin and proglucagon-expressing cells.

Methods: Leptin receptor expression was measured in isolated mouse islets and highly-purified islet cells by RNASeq and quantitative RT-PCR. Mice lacking leptin signalling in pancreatic β, or in α and other proglucagon-expressing cells, were generated using Ins1Cre- or iGluCre-mediated recombination respectively of flox'd leptin receptor alleles. In vivo glucose homeostasis, changes in body weight, pancreatic histology and hormone secretion from isolated islets were assessed using standard techniques.

Results: Leptin receptor mRNA levels were at or below the level of detection in wild-type adult mouse isolated islets and purified cells, and leptin signalling to Stat3 phosphorylation was undetectable. Whereas male mice further deleted for leptin receptors in β cells exhibited no abnormalities in glucose tolerance up to 16 weeks of age, females transiently displayed improved glucose tolerance at 8 weeks (11.2  ±  3.2% decrease in area under curve; p < 0.05), and improved (39.0  ±  13.0%, P < 0.05) glucose-stimulated insulin secretion in vitro. No differences were seen between genotypes in body weight, fasting glucose or β/α cell ratio. Deletion of LepR from α-cells, a minority of β cells, and a subset of proglucagon-expressing cells in the brain, exerted no effects on body weight, glucose or insulin tolerance, nor on pancreatic hormone secretion assessed in vivo and in vitro.

Conclusions/interpretation: The use here of a highly selective Cre recombinase indicates that leptin signalling plays a relatively minor, age- and sex-dependent role in the control of β cell function in the mouse. No in vivo role for leptin receptors on α cells, nor in other proglucagon-expressing cells, was detected in this study.

No MeSH data available.


Related in: MedlinePlus