Alterations of glucose-dependent insulinotropic polypeptide and expression of genes involved in mammary gland and adipose tissue lipid metabolism during pregnancy and lactation.
Gastric inhibitory polypeptide (GIP) is a gut derived peptide with multiple emerging physiological actions. Effects of pregnancy and lactation on GIP secretion and related gene expression were studied in Wistar rats. Pregnancy moderately increased feeding (p<0.05), whilst lactation substantially increased food intake (p<0.01 to p<0.001). Circulating GIP was unchanged during pregnancy, but non-fasting plasma glucose was significantly (p<0.01) decreased and insulin increased (p<0.05). Lactation was associated with elevated circulating GIP concentrations (p<0.001) without change of glucose or insulin. Oral glucose resulted in a significantly (p<0.001) decreased glycaemic excursion despite similar glucose-induced GIP and insulin concentrations in lactating rats. Pregnant rats had a similar glycaemic excursion but exhibited significantly lowered (p<0.05) GIP accompanied by elevated (p<0.001) insulin levels. Pregnant rats exhibited increased (p<0.001) islet numbers and individual islet areas were enlarged (p<0.05). There were no significant differences in islet alpha-cell areas, but all groups of rats displayed co-expression of glucagon and GIP in alpha-cells. Lactating rats exhibited significantly (p<0.01) increased intestinal weight, whereas intestinal GIP stores were significantly (p<0.01) elevated only in pregnant rats. Gene expression studies in lactating rats revealed prominent (p<0.01 to p<0.001) increases in mammary gland expression of genes involved in energy turnover, including GIP-R. GIP was present in intestines and plasma of 17 day old foetal rats, with substantially raised circulating concentrations in neonates throughout the period of lactation/suckling. These data indicate that changes in the secretion and action of GIP play an important role in metabolic adaptations during pregnancy and especially lactation.
School of Biomedical Sciences, University of Ulster, Coleraine, County Londonderry, United Kingdom.
R Charlotte
RC
Moffett
Nigel
N
Irwin
Jacqueline M E
JM
Francis
Peter R
PR
Flatt
D050153:Abdominal Fat / Q000378:metabolism*; D000284:Administration, Oral; D000818:Animals; D001786:Blood Glucose; D004041:Dietary Fats / Q000008:administration & dosage; D002149:Energy Intake; D005260:Female; D005749:Gastric Inhibitory Polypeptide / Q000097:blood*; D005786:Gene Expression Regulation; D007328:Insulin / Q000097:blood; D007422:Intestines / Q000033:anatomy & histology; D007774:Lactation / Q000378:metabolism; D050356:Lipid Metabolism; D008321:Mammary Glands, Animal / Q000378:metabolism*; D009929:Organ Size; D010179:Pancreas / Q000166:cytology / Q000378:metabolism; D011247:Pregnancy / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D059467:Transcriptome; D015430:Weight Gain
D001786:Blood Glucose; D004041:Dietary Fats; D007328:Insulin; D005749:Gastric Inhibitory Polypeptide