Endocrine-dependent accumulation of IGF-I by hypothalamic glia.
Tanycytes are specialized glial cells of the hypothalamus and median eminence. Immunoreactive insulin-like growth factor I (IGF-I) levels fluctuate in tanycytes with the natural variations in sex steroids associated with the ovarian cycle. To determine whether these changes are as a result of differences in IGF-I accumulation, the peptide was labelled with digoxigenin and injected into the lateral cerebral ventricle. Tanycyte-like cells specifically accumulated digoxigenin-labelled IGF-I. This accumulation was mediated by IGF-I receptors and showed marked differences during the oestrous cycle, being low in the afternoon of pro-oestrus and high in the afternoon of oestrus. These results indicate that the accumulation by tanycytes of IGF-I or IGF-I fragments capable of receptor-mediated internalization is under endocrine control, suggesting that hypothalamic glia may be involved in neuroendocrine regulation.
Fernandez-Galaz
M C
MC
Instituto Cajal, CSIC, Madrid, Spain.
Torres-Aleman
I
I
Garcia-Segura
L M
LM
D000818:Animals; D004076:Digoxigenin / Q000008:administration & dosage; D004702:Endocrine Glands / Q000502:physiology*; D004971:Estrus / Q000502:physiology; D005260:Female; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism*; D007276:Injections, Intraventricular; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D009457:Neuroglia / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar
D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D004076:Digoxigenin