Expression of the IGF system in human adrenal tissues from early infancy to late puberty: implications for the development of adrenarche.
IGF-1, IGF-2, and type 1 IGF receptor (IGF-R1) mRNA expression and immunolocalization and cell proliferation index were studied in human adrenals from early infancy to late puberty. Adrenals were obtained from transplantation donors or from necropsies of endocrinologically normal subjects. Subjects were divided into three age groups: group 1, <3 mo of age, involution of fetal adrenals; group 2, 3 mo to 6 y of age, preadrenarche; and group 3, older than 6 y up to 20 y of age, postadrenarche. Cell proliferation index (Ki-67) in the outer, subcapsular, zona glomerulosa was significantly higher than in zona fasciculata of all groups and in zona reticularis or fetal zone. IGF-1 mRNA (semiquantitative reverse transcriptase-PCR and Northern blot) in group 2 was significantly higher than in group 1 and group 3 (p < 0.05). IGF2 mRNA in group 1 was significantly higher than in the other groups. IGF-R1 mRNA in group 3 was significantly higher than in group 2 but not different from group 1. Strong IGF-1, IGF-2, and IGF-R1 immunostaining signal was observed in the outer, subcapsular, zona glomerulosa and in zona fasciculata in the three groups, whereas a very weak IGF-1 and IGF-R1 immunostaining signal was found in fetal zone cells of group 1 and in zona reticularis of group 3. We propose that IGF-1 could be a factor involved in the postnatal mechanism of progenitor adrenal cell proliferation and migration. Our data also suggest that IGF-1 is not a direct regulatory factor of adrenal androgen production by zona reticularis cells.
Baquedano
María Sonia
MS
Laboratorio de Investigacion, Hospital de Pediatria Garrahan, Buenos Aires Argentina.
Berensztein
Esperanza
E
Saraco
Nora
N
Dorn
Gabriela Vanesa
GV
de Davila
Maria T
MT
Rivarola
Marco A
MA
Belgorosky
Alicia
A
D000293:Adolescent; D000311:Adrenal Glands / Q000254:growth & development / Q000378:metabolism*; D050499:Adrenarche; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D017526:Receptor, IGF Type 1 / Q000235:genetics
D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D017526:Receptor, IGF Type 1