Differential expression of insulin-like growth factor genes in rat central nervous system.
A sensitive solution-hybridization assay was used to investigate the expression of genes encoding insulin-like growth factors I and II (IGF-I and -II) in the rat central nervous system (CNS). mRNAs for both IGFs are synthesized throughout the CNS of adult rats but exhibit distinct regional differences for each growth factor. IGF-I mRNA is 8-10 times more abundant in the cervical-thoracic spinal cord and in the olfactory bulb than in whole brain and is enriched 3-fold in the midbrain and cerebellum. IGF-II mRNA is minimally enriched in the medulla-pons and cerebellum but is 3-5 times less abundant in the midbrain and corpus striatum than in total brain. During CNS development the content of IGF-I and IGF-II mRNAs is highest at embryonic day 14 and declines by a factor of 3-4 at birth, to values found in adult brain. Embryonic neurons and glia synthesize IGF-I mRNA during short-term cell culture; only glia produce IGF-II mRNA. These observations show that IGF-I and IGF-II are differentially expressed in the developing and adult CNS and suggest that each growth factor may play a unique role in the mammalian nervous system.
Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110.
P
P
Rotwein
S K
SK
Burgess
J D
JD
Milbrandt
J E
JE
Krause
D000375:Aging; D000818:Animals; D001921:Brain / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D004622:Embryo, Mammalian; D005314:Embryonic and Fetal Development; D005091:Exons; D005796:Genes; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000235:genetics*; D014158:Transcription, Genetic
D012333:RNA, Messenger; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II