title: Safety aspects of longitudinal administration of IGF-I/IGFBP-3 complex in neonatal mice.
abstract: OBJECTIVE
  Very preterm birth is associated with a high risk of morbidity. Infants born very preterm have low serum levels of insulin-like growth factor I (IGF-I), that further decrease after birth. IGF-I is essential for brain development and low serum levels have been associated with retinopathy of prematurity. The present study aimed to investigate the effects of prolonged administration of a low dose of rhIGF-I/rhIGFBP-3 on glucose levels and total body weight, as well as liver, spleen and brain weights, and gray and subcortical white matter in newborn mice.
  
  
  METHODS
  The study was performed as three different trials. In all experiments C57BL/6N mice were injected with a rhIGF-I/rhIGFBP-3 complex or saline. In the first experimental trial, blood glucose levels were assessed 30 min, 1 h, 1.5 h, 3 h, 6 h, 24 h and 48 h after the rhIGF-I/rhIGFBP-3 or saline injection on postnatal day (PND) 6. In the second trial, mice were injected daily from PND 3 to 11 and sacrificed on PND 12 for analysis of IGF-I serum levels. In the third trial, body and organ weights and effects on gray and white matter were assessed on PND 18 after PND 3-11 treatments as above. Effects on gray and white matter were measured using immunoreactivity for microtubule-associated protein-2 (MAP-2), myelin basic protein (MBP), 2',3'-cyclic nucleotide 3' phosphodiesterase (CNPase), neurofilament and oligodendrocyte lineage transcription factor 2 (Olig2).
  
  
  RESULTS
  Blood glucose levels were unchanged in the rhIGF-I/rhIGFBP-3-treated group compared to baseline. In the control group glucose levels increased 30 min after the second saline injection; levels were not elevated at the subsequent time point. Three hours after the rhIGF-I/rhIGFBP-3 or saline, glucose levels were lower in rhIGF-I/rhIGFBP-3-treated animals than in saline treated (p=0.026). At PND 18, total body weight was higher in rhIGF-I/rhIGFBP-3-treated mice compared with controls (p<0.05), but there were no differences between groups in brain, liver or spleen weights. No differences in gray matter area were found between groups. Analyses of white matter markers showed an increased number of Olig2-positive cells in rhIGF-I/rhIGFBP-3-treated mice compared with controls (p<0.001). There were no differences between groups in terms of MBP, CNPase or neurofilament immunoreactivity.
  
  
  CONCLUSIONS
  Prolonged administration of rhIGF-I/rhIGFBP-3 did not have a negative impact on blood glucose levels and was beneficial for total body growth.
authors.affiliation: Department of Pediatrics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden. gunnel.hellgren@vgregion.se
authors.forename: Gunnel
authors.initials: G
authors.lastname: Hellgren
authors.forename: Wei
authors.initials: W
authors.lastname: Han
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Wang
authors.forename: Chatarina
authors.initials: C
authors.lastname: Löfqvist
authors.forename: Henrik
authors.initials: H
authors.lastname: Hagberg
authors.forename: Carina
authors.initials: C
authors.lastname: Mallard
authors.forename: Ann
authors.initials: A
authors.lastname: Hellström
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001786:Blood Glucose / Q000187:drug effects*; D001823:Body Composition / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects*; D001921:Brain / Q000187:drug effects; D005260:Female; D007124:Immunoenzyme Techniques; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000008:administration & dosage* / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage* / Q000378:metabolism; D008099:Liver / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009929:Organ Size / Q000187:drug effects*; D011994:Recombinant Proteins / Q000008:administration & dosage*; D013154:Spleen / Q000187:drug effects
chemical_list: D001786:Blood Glucose; D018972:Insulin-Like Growth Factor Binding Protein 3; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I