Circadian rhythms of somatostatin-immunoreactivity in the suprachiasmatic nucleus of the rat.
Twenty-four hour patterns in somatostatin (SS)-like immunoreactivity (LI) within the suprachiasmatic nucleus (SCN) were determined by enzyme immunoassay in rats blinded by bilateral orbital enucleation or kept sighted under light-dark conditions. A remarkable circadian rhythm was found in the concentration of SS-LI in the SCN under blinded conditions. The peak time appeared at about circadian time (CT) 4 in the early subjective day and the trough at around CT 16 or 20 in the subjective night. Light-dark cycles did not alter the circadian patterns of SS-LI observed in the blinded rat SCN. These results indicate the presence of an endogenous circadian rhythm in SS-LI in the rat SCN, independent of environmental lightning cycles.
Laboratory of Neurophysiology, Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan.
K
K
Shinohara
Y
Y
Isobe
J
J
Takeuchi
S T
ST
Inouye
D000818:Animals; D001127:Arginine Vasopressin / Q000032:analysis; D002940:Circadian Rhythm; D007124:Immunoenzyme Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000032:analysis* / Q000276:immunology; D013493:Suprachiasmatic Nucleus / Q000737:chemistry*
D001127:Arginine Vasopressin; D013004:Somatostatin