Expression of insulin-like growth factor binding protein-2 during postnatal development of the rat neurointermediate pituitary.
The expression of insulin-like growth factor binding protein-2 (IGFBP-2) during postnatal development of the rat neurointermediate pituitary was characterized using immunocytochemistry and in situ hybridization. Glial cells in the neural lobe (NL) showed robust expression of IGFBP-2 throughout the postnatal period and continuing into adulthood. These were identified as pituicytes by the presence of S-100 protein; IGFBP-2 was not present in microglia in the NL. IGFBP-2 immunoreactivity was more punctate in mature pituicytes, suggesting a possible association with the cell membrane. No expression of IGFBP-2 by brain astrocytes was observed at any age examined, even in regions such as the median eminence and subfornical organ that lack a blood-brain barrier. IGFBP-2 was also localized immunocytochemically in melanotropes and glial-like cells of the intermediate lobe (IL). Positive cells were most numerous in neonates and declined thereafter, with immunoreactivity undetectable by 65 days of age. IGFBP-2 mRNA was detected in the IL only at 1 day of age. These findings are consistent with a potential role for IGFBP-2 in modulating effects of the insulin-like growth factors during development of the neurointermediate lobe. The constitutive expression of high levels of IGFBP-2 by mature pituicytes also suggests that this protein could be secreted and/or influence a variety of processes in the mature NL, such as glial proliferation, axonal growth, or morphological plasticity of pituicytes.
Zhou
X
X
Department of Biology, Montana State University, Bozeman 59771, USA.
Herman
J P
JP
Paden
C M
CM
D000818:Animals; D001253:Astrocytes / Q000737:chemistry; D001921:Brain / Q000166:cytology; D002467:Cell Nucleus / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry; D015870:Gene Expression; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000032:analysis* / Q000235:genetics; D010902:Pituitary Gland / Q000737:chemistry* / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D009418:S100 Proteins / Q000032:analysis
D018971:Insulin-Like Growth Factor Binding Protein 2; D012333:RNA, Messenger; D009418:S100 Proteins