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Light selectively alters vasoactive intestinal peptide and peptide histidine isoleucine immunoreactivity within the
H E Albers1, N Minamitani, E Stopa
1Department of Biology, Georgia State University, Atlanta 30303.
Abstract:
The concentration of vasoactive intestinal peptide (VIP)-, peptide histidine isoleucine (PHI)-, neurotensin (NT)- and substance P (SP)-like immunoreactivity (LI) within the suprachiasmatic nucleus (SCN) were determined by radioimmunoassay in rats housed in LD 14:10 h, constant light or constant dark. No day-night differences were observed in the concentration of VIP-, PHI-, NT- or SP-LI within the SCN. Exposure to constant light significantly depressed the SCN concentrations of VIP- and PHI-LI, but had no significant effects on SCN concentrations of NT- or SP-LI, or VIP- or PHI-LI concentrations within the cortex. These data represent the first evidence that VIP/PHI-containing neurons may be involved in mediating photic information within the SCN.