Substance P receptor regulates the photic induction of Fos-like protein in the suprachiasmatic nucleus of Syrian hamsters.
Substance P (SP) is a candidate neurotransmitter or neuromodulator for conveying light information from the retina to the hypothalamic suprachiasmatic nucleus (SCN) where a circadian oscillator(s) is located in mammals. Immediate early gene c-fos has been demonstrated to be induced in the SCN with a brief light exposure at the subjective night, and suggested to play an important role in the photic entrainment of the oscillator. To clarify the possibility of an involvement of the SP receptor in the photic-induction of c-fos in the SCN, we examined effects of a SP receptor antagonist, spantide, on the light-induced Fos-like protein immunoreactivity (Fos-lir) in the SCN of Syrian hamster. The light-induced Fos-lir was inhibited with the pretreatment of spantide in a dose-related manner and in an anatomically distinctive way. The higher dose of spantide (8 nmol) blocked light-induced Fos-lir substantially in the rostral and central areas of the SCN, and in the dorsal portion of the caudal SCN. However, it blocked Fos-lir only slightly in the ventral portion of the caudal SCN. These results suggest that the SP is involved in conveying light information to induce Fos protein in the hamster SCN, and that different neurotransmitter systems are involved in the light-induced Fos-lir in the different portions of hamster SCN.
Abe
H
H
Department of Physiology, Hokkaido University School of Medicine, Sapporo, Japan. habe@m1.hines.hokudai.ac.jp
Honma
S
S
Shinohara
K
K
Honma
K
K
D000818:Animals; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology; D002940:Circadian Rhythm; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D016762:Genes, fos / Q000187:drug effects / Q000528:radiation effects*; D007150:Immunohistochemistry; D007276:Injections, Intraventricular; D008027:Light; D008297:Male; D008647:Mesocricetus; D064729:Neurokinin-1 Receptor Antagonists; D009928:Organ Specificity; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D018040:Receptors, Neurokinin-1 / Q000502:physiology*; D013373:Substance P / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D013493:Suprachiasmatic Nucleus / Q000378:metabolism* / Q000528:radiation effects
D064729:Neurokinin-1 Receptor Antagonists; D016760:Proto-Oncogene Proteins c-fos; D018040:Receptors, Neurokinin-1; D013373:Substance P; C042867:spantide