The levels of Pdx1/insulin, Cacna1c and Cacna1d, and β-cell mass in a rat model of intrauterine undernutrition.
OBJECTIVE
To elucidate the underlying mechanisms responsible for β-cell mass and function in response to intrauterine growth restriction (IUGR).


METHODS
Offspring from undernourished mother rats with birth weight < -2 SD (IUGR group) and from standard-nourished rats with birth weight between mean +/- 1SD normal birth weight (NBW group) were examined. Levels of fasting glucose, serum insulin, and insulin-like growth factor-1 (IGF-1) were analyzed. Entire pancreas or islet-like cell clusters (ICCs) were collected to evaluate relative β-cell mass and determine the genetic and protein profiles of pancreatic and duodenal homeobox 1 (Pdx1), Cacna1c and Cacna1d using real-time PCR, immunohistochemical staining, and western blotting at day (d) of birth and at d21 of age.


RESULTS
Fasting serum insulin and IGF-1 concentrations were significantly lower in the IUGR group than in the NBW group at d0 and d21. The levels of Pdx1 and insulin mRNAs in IUGR pancreas were also decreased. At birth, the ratios of β-cell mass to body weight were not significantly different between the two groups. However, by d21 the relative β-cell mass in IUGR had not grown to compensate for the increase in body weight, as compared to the NBW group (p < 0.05). The Cacna1c and Cacna1d proteins were significantly higher in the NBW group than that in the IUGR group at birth, but there were no statistical differences at d21.


CONCLUSIONS
Decreased Pdx1 levels and IGF-1 concentration restrain β-cell mass and insulin expression in rat offspring from undernourished mothers. However, Cacna1c and Cacna1d expression were able to reach normal levels as the IUGR rats were aged, indicating that these factors were not responsible for the IUGR rat phenotype of insulin resistance and β-cell dysfunction in later life.
Xu
Yan-Ping
YP
Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine and Zhejiang Key Laboratory for Diagnosis and Therapy of Neonatal Diseases, Hangzhou, China.
Liang
Li
L
Wang
Xiu-Min
XM
D000818:Animals; D000831:Animals, Newborn; D001724:Birth Weight / Q000502:physiology; D015220:Calcium Channels / Q000032:analysis / Q000097:blood*; D020746:Calcium Channels, L-Type / Q000032:analysis / Q000097:blood*; D002452:Cell Count; D004195:Disease Models, Animal; D005260:Female; D005317:Fetal Growth Retardation / Q000097:blood / Q000209:etiology / Q000473:pathology*; D018398:Homeodomain Proteins / Q000032:analysis / Q000097:blood*; D007328:Insulin / Q000032:analysis / Q000097:blood*; D050417:Insulin-Secreting Cells / Q000378:metabolism / Q000473:pathology*; D044342:Malnutrition / Q000097:blood / Q000150:complications / Q000473:pathology*; D039382:Maternal Nutritional Physiological Phenomena; D009929:Organ Size; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D015534:Trans-Activators / Q000032:analysis / Q000097:blood*
C504728:Cacna1c protein, rat; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D018398:Homeodomain Proteins; D007328:Insulin; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; C093712:Cacna1d protein, rat