Insulin receptor substrate-1 (IRS-1) expression in rat brain.
IRS-1 is phosphorylated on tyrosine residues after insulin stimulation and participates in the early events of signal transduction in peripheral insulin-sensitive tissues. This study determined whether neuronal populations in the rat olfactory bulb and hippocampus (brain regions which have very high concentrations of insulin receptors) also express IRS-1 and contain phosphotyrosine, using in situ hybridization, receptor binding, and immunocytochemistry. IRS-1 mRNA was colocalized with insulin receptor mRNA in neuron cell bodies of hippocampus and olfactory bulb. Similarly, IRS-1 immunoreactivity in hippocampus and olfactory bulb was concentrated in layers that contain synapses of these neurons and have both high insulin binding and phosphotyrosine levels. Thus, IRS-1 and insulin receptors are coexpressed in discrete populations of neurons, suggesting a signal transduction mechanism by which insulin may influence metabolism and gene expression in the brain.
Baskin
D G
DG
Veterans Affairs Medical Center, Seattle, WA 98108.
Schwartz
M W
MW
Sipols
A J
AJ
D'Alessio
D A
DA
Goldstein
B J
BJ
White
M F
MF
D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D055504:Insulin Receptor Substrate Proteins; D008297:Male; D009474:Neurons / Q000378:metabolism; D009830:Olfactory Bulb / Q000166:cytology / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D019000:Phosphotyrosine; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D010750:Phosphoproteins; D012333:RNA, Messenger; D019000:Phosphotyrosine; D014443:Tyrosine