title: Wild-type offspring of heterozygous prolactin receptor-null female mice have maladaptive β-cell responses during pregnancy.
abstract: Abstract  β-Cell mass increases during pregnancy in adaptation to the insulin resistance of pregnancy. This increase is accompanied by an increase in β-cell proliferation, a process that requires intact prolactin receptor (Prlr) signalling. Previously, it was found that during pregnancy, heterozygous prolactin receptor-null (Prlr(+/-)) mice had lower number of β-cells, lower serum insulin and higher blood glucose levels than wild-type (Prlr(+/+)) mice. An unexpected observation was that the glucose homeostasis of the experimental mouse depends on the genotype of her mother, such that within the Prlr(+/+) group, the Prlr(+/+) offspring derived from Prlr(+/+) mothers (Prlr(+/+(+/+))) had higher β-cell mass and lower blood glucose than those derived from Prlr(+/-) mothers (Prlr(+/+(+/-))). Pathways that are known to regulate β-cell proliferation during pregnancy include insulin receptor substrate-2, Akt, menin, the serotonin synthetic enzyme tryptophan hydroxylase-1, Forkhead box M1 and Forkhead box D3. The aim of the present study was to determine whether dysregulation in these signalling molecules in the islets could explain the maternal effect on the phenotype of the offspring. It was found that the pregnancy-induced increases in insulin receptor substrate-2 and Akt expression in the islets were attenuated in the Prlr(+/+(+/-)) mice in comparison to the Prlr(+/+(+/+)) mice. The expression of Forkhead box D3, which plays a permissive role for β-cell proliferation during pregnancy, was also lower in the Prlr(+/+(+/-)) mice. In contrast, the pregnancy-induced increases in phospho-Jak2, tryptophan hydroxylase-1 and FoxM1, as well as the pregnancy-associated reduction in menin expression, were comparable between the two groups. There was also no difference in expression levels of genes that regulate insulin synthesis and secretion (i.e. glucose transporter 2, glucokinase and pancreatic and duodenal homeobox-1) between these two groups. Taken together, these results suggest that the in utero environment of the Prlr(+/-) mother confers long-term changes in the pancreatic islets of her offspring such that when the offspring themselves became pregnant, they cannot adapt to the increased insulin demands of their own pregnancy.
authors.affiliation: University of Calgary, Health Sciences Centre, 3330 Hospital Drive NW, Room 2281, Calgary, Alberta, Canada T2N 4N1. carol.huang@albertahealthservices.ca
authors.forename: Carol
authors.initials: C
authors.lastname: Huang
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D016640:Diabetes, Gestational / Q000097:blood / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors / Q000378:metabolism; D005786:Gene Expression Regulation; D006579:Heterozygote; D007328:Insulin / Q000097:blood*; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism; D007333:Insulin Resistance; D050417:Insulin-Secreting Cells / Q000378:metabolism* / Q000473:pathology; D053614:Janus Kinase 2 / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010766:Phosphorylation; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011981:Receptors, Prolactin / Q000172:deficiency* / Q000235:genetics; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction; D014365:Tryptophan Hydroxylase / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors; C101757:Foxd3 protein, mouse; C491524:Foxm1 protein, mouse; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526298:Irs2 protein, mouse; C484898:Men1 protein, mouse; D011518:Proto-Oncogene Proteins; D011981:Receptors, Prolactin; D012097:Repressor Proteins; C487801:Tph1 protein, mouse; D014365:Tryptophan Hydroxylase; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D051057:Proto-Oncogene Proteins c-akt